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Special Issue "Phenolics and Polyphenolics"

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products".

Deadline for manuscript submissions: closed (15 October 2010)

Special Issue Editors

Guest Editor
Prof. Dr. José Alberto Pereira

CIMO/Escola Superior Agrária, Instituto Politécnico de Bragança, Campus Sta Apolónia, Apartado 1 172, 5301-855 Bragança, Portugal
Website | E-Mail
Phone: +351273303277
Fax: +351 273325405
Interests: bioactive phytochemicals; phenolic compounds; antioxidant and antimicrobial activities; effect of agricultural practices on vegetable composition and quality; olives and olive oil chemistry
Guest Editor
Dr. Paula Andrade

REQUIMTE/LAQV, Laboratory of Pharmacognosy, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira 228, Porto 4050-313, Portugal
Website | E-Mail
Fax: +351-226093390
Interests: metabolite profiling of natural matrices; natural agents for inflammation; neurodegenerative disorders

Published Papers (105 papers)

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Editorial

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Open AccessEditorial Phenolics: From Chemistry to Biology
Molecules 2009, 14(6), 2202-2211; doi:10.3390/molecules14062202
Received: 5 June 2009 / Revised: 13 June 2009 / Accepted: 16 June 2009 / Published: 17 June 2009
Cited by 95 | PDF Full-text (288 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, few classes of natural products have received as much attention as phenolics and polyphenols. This special issue of Molecules, “Phenolics and Polyphenolics”, is a remarkable confirmation of this trend. Several aspects related to phenolics chemistry, comprising the several classes,
[...] Read more.
In recent years, few classes of natural products have received as much attention as phenolics and polyphenols. This special issue of Molecules, “Phenolics and Polyphenolics”, is a remarkable confirmation of this trend. Several aspects related to phenolics chemistry, comprising the several classes, will be discussed. In addition, the increasing interest in phenolics’ biological activities is covered, and several works addressing this matter are referred. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Research

Jump to: Editorial, Review

Open AccessArticle Chemical Constituents of Three Allium Species from Romania
Molecules 2013, 18(1), 114-127; doi:10.3390/molecules18010114
Received: 26 November 2012 / Revised: 16 December 2012 / Accepted: 19 December 2012 / Published: 21 December 2012
Cited by 23 | PDF Full-text (479 KB)
Abstract
The aim of this work was to study the chemical composition of Allium obliquum L., A. senescens L. subsp. montanum (Fries) Holub, and A. schoenoprasum L. subsp. schoenoprasum. Sulphur-containing compounds analysis was performed by an LC-MS method, the identification and quantification
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The aim of this work was to study the chemical composition of Allium obliquum L., A. senescens L. subsp. montanum (Fries) Holub, and A. schoenoprasum L. subsp. schoenoprasum. Sulphur-containing compounds analysis was performed by an LC-MS method, the identification and quantification of polyphenolic compounds through a HPLC-UV-MS method, and the presence of five sterols was simultaneously assessed by HPLC-MS-MS. Alliin was identified only in A. obliquum and A. senescens subsp. montanum extracts, whilst allicin was present in all extracts, with higher amounts in A. schoenoprasum and A. obliquum. The pattern of phenol carboxylic acids shows the presence of p-coumaric and ferulic acids in all species. Isoquercitrin was identified in A. obliquum and A. schoenoprasum, and rutin in A. senescens subsp. montanum and A. schoenoprasum. Luteolin and apigenin were identified only in A. obliquum. All three species contain glycosides of kaempferol and quercetol. β-Sitosterol and campesterol were identified in all species. The results obtained showed significant differences in the composition of the three Allium species. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC)
Molecules 2011, 16(2), 1418-1425; doi:10.3390/molecules16021418
Received: 16 November 2010 / Revised: 23 January 2011 / Accepted: 27 January 2011 / Published: 9 February 2011
Cited by 16 | PDF Full-text (165 KB)
Abstract
Dietary flavonoids exhibit beneficial health effects. Several epidemiological studies have focused on their biological activities, including antioxidant, antibacterial, antiviral, anti-inflammatory and cardiovascular properties. More recently, these compounds have shown to be promising cancer chemopreventive agents in cell culture studies. In particular, O-methylated
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Dietary flavonoids exhibit beneficial health effects. Several epidemiological studies have focused on their biological activities, including antioxidant, antibacterial, antiviral, anti-inflammatory and cardiovascular properties. More recently, these compounds have shown to be promising cancer chemopreventive agents in cell culture studies. In particular, O-methylated flavonoids exhibited a superior anticancer activity than the corresponding hydroxylated derivatives being more resistant to the hepatic metabolism and showing a higher intestinal absorption. In this communication we describe a convenient and efficient procedure in order to prepare a large panel of mono- and dimethylated flavonoids by using dimethyl carbonate (DMC), an ecofriendly and non toxic chemical, which plays the role of both solvent and reagent. In order to promote the methylation reaction under mild and practical conditions, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was added in the solution; methylated flavonoids were isolated in high yields and with a high degree of purity. This methylation protocol avoids the use of hazardous and high toxic reagents (diazomethane, dimethyl sulfate, methyl iodide). Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle The Relationship between Phenolics and Flavonoids Production with Total Non Structural Carbohydrate and Photosynthetic Rate in Labisia pumila Benth. under High CO2 and Nitrogen Fertilization
Molecules 2011, 16(1), 162-174; doi:10.3390/molecules16010162
Received: 24 November 2010 / Revised: 15 December 2010 / Accepted: 21 December 2010 / Published: 29 December 2010
Cited by 34 | PDF Full-text (130 KB)
Abstract
A factorial split plot 4 × 3 experiment was designed to examine and characterize the relationship among production of secondary metabolites (total phenolics, TP; total flavonoids, TF), carbohydrate content and photosynthesis of three varieties of the Malaysian medicinal herb Labisia pumila Benth. namely
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A factorial split plot 4 × 3 experiment was designed to examine and characterize the relationship among production of secondary metabolites (total phenolics, TP; total flavonoids, TF), carbohydrate content and photosynthesis of three varieties of the Malaysian medicinal herb Labisia pumila Benth. namely the varieties alata, pumila and lanceolata under CO2 enrichment (1,200 µmol mol-1) combined with four levels of nitrogen fertilization (0, 90, 180 and 270 kg N ha-1). No varietal differences were observed, however, as the levels of nitrogen increased from 0 to 270 kg N ha-1, the production of TP and TF decreased in the order leaves>roots>stems. The production of TP and TF was related to increased total non structural carbohydrate (TNC), where the increase in starch content was larger than that in sugar concentration. Nevertheless, the regression analysis exhibited a higher influence of soluble sugar concentration (r2 = 0.88) than starch on TP and TF biosynthesis. Photosynthesis, on the other hand, displayed a significant negative relationship with TP and TF production (r2 = -0.87). A decrease in photosynthetic rate with increasing secondary metabolites might be due to an increase in the shikimic acid pathway that results in enhanced production of TP and TF. Chlorophyll content exhibited very significant negative relationships with total soluble sugar, starch and total non structural carbohydrate. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Effect of Five Different Stages of Ripening on Chemical Compounds in Medlar (Mespilus germanica L.)
Molecules 2011, 16(1), 74-91; doi:10.3390/molecules16010074
Received: 11 November 2010 / Revised: 23 December 2010 / Accepted: 24 December 2010 / Published: 28 December 2010
Cited by 25 | PDF Full-text (604 KB)
Abstract
The study of changes of nutritional value of fruit during the ripening process can help estimate the optimal date for fruit harvesting to achieve the best quality for direct consumption and further utilization. The aim of this study was to monitor the changes
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The study of changes of nutritional value of fruit during the ripening process can help estimate the optimal date for fruit harvesting to achieve the best quality for direct consumption and further utilization. The aim of this study was to monitor the changes of chemical composition of medlar fruit (Mespilus germanica L.) measured at five various ripening stages including 134, 144, 154, 164 and 174 days after full bloom (DAFB). Fruits were analyzed and ascorbic acid (AA) and total phenolic compound content with respect to the total antioxidant activity were determined. In addition, selected micronutrients and macronutrients were monitored. The results of our experiments demonstrate that ascorbic acid, total phenolic compound content and total antioxidant activity decreased significantly with increasing time of ripeness. The decreasing tendency in potassium, calcium and magnesium contents during the ripening stages was also determined. During the ripening period, the content of all micronutrients as well as phosphorus and sodium was balanced, with no statistically significant differences between the monitored ripening stages, which can be considered as a positive fact with respect to ideal consumption quality of fruit. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Seasonal Variation in Total Phenolic and Flavonoid Contents and DPPH Scavenging Activity of Bellis perennis L. Flowers
Molecules 2010, 15(12), 9450-9461; doi:10.3390/molecules15129450
Received: 13 October 2010 / Revised: 14 December 2010 / Accepted: 20 December 2010 / Published: 21 December 2010
Cited by 27 | PDF Full-text (180 KB)
Abstract
Variations in total phenolic and flavonoid contents as well as antioxidant activity of Bellis perennis (common daisy) flowers were investigated. The flowers were collected monthly (from March to October, i.e., during the usual flowering season of the plant) at three localities in
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Variations in total phenolic and flavonoid contents as well as antioxidant activity of Bellis perennis (common daisy) flowers were investigated. The flowers were collected monthly (from March to October, i.e., during the usual flowering season of the plant) at three localities in three different years. Total flavonoids were determined spectrophotometrically by two methods: by formation of a complex with aluminium chloride after acidic hydrolysis of flower extracts (method 1) and by reaction with boric and oxalic acids in extracts without their modification (method 2). Total phenolics were determined spectrophotometrically using the Folin-Ciocalteu reagent. The antioxidant activity was determined spectrophotometrically by a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. The contents of flavonoids varied from 0.31 to 0.44 mg quercetin equivalent/100 mg dry weight (method 1) and from 1.37 to 2.20 mg pigenin-7-glucoside equivalent/100 mg dry weight (method 2). Total phenolics ranged from 2.81 to 3.57 mg gallic acid equivalent/100 mg dry weight. The antioxidant activity expressed as IC50 values varied from 66.03 to 89.27 µg/mL; it is about 50, 30, 20, and 10 times lower as compared with quercetin, ascorbic acid, Trolox®, and butylhydroxytoluene, respectively, and about five times higher in comparison with apigenin-7-glucoside. There is a significant correlation between antioxidant activity and total phenolics. No correlation between total flavonoid contents and antioxidant activity was observed. Contents of phenolics and flavonoids as well as antioxidant activity of daisy flowers vary to a relatively small extent during the year and are not dependant on the time of collection. Thus, the flowers possess comparable quality as to these characteristics over the whole flowering season of Bellis perennis. Effects of environmental factors on the amounts of secondary metabolites in plants are also discussed. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Antioxidant Activity of Lignin Phenolic Compounds Extracted from Kraft and Sulphite Black Liquors
Molecules 2010, 15(12), 9308-9322; doi:10.3390/molecules15129308
Received: 19 October 2010 / Revised: 13 December 2010 / Accepted: 14 December 2010 / Published: 16 December 2010
Cited by 38 | PDF Full-text (276 KB)
Abstract
The antioxidant activity of the phenolic compounds present in industrial black liquors obtained from the two cooking processes (kraft and sulphite) used in Portugal to produce Eucalyptus globulus pulp was evaluated. The black liquors treated at several pH values were extracted with ethyl
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The antioxidant activity of the phenolic compounds present in industrial black liquors obtained from the two cooking processes (kraft and sulphite) used in Portugal to produce Eucalyptus globulus pulp was evaluated. The black liquors treated at several pH values were extracted with ethyl acetate. Phenolic fractions were further separated by liquid chromatography of the crude extracts of kraft liquor at pH = 6 and sulphite liquor at the original pH. Total phenolic content was determined in terms of gallic acid equivalents (Folin-Ciocalteu colorimetric method), and the antioxidant activity in the crude extracts at several pH values and in the separated fractions was measured using the DPPH test for radical scavenging capacity. The total phenolic content of crude extracts and separated fractions ranged from 92.7 to 181.6 and from 91.6 to 1,099.6 mg GAE/g, respectively, while the antioxidant activity index (AAI) ranged from 2.20 to 3.41 and from 2.21 to 11.47 respectively, showing very strong antioxidant activity in all studied cases. The fractions separated by column chromatography were submitted to mass spectrometry analysis and the results were compared to others in the literature of natural products, mainly from Eucalyptus, and the characteristic bands of functional groups were identified by 1H-NMR and FTIR. These methods allowed the identification of 17 phenolic compounds. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Acanmontanoside, a New Phenylethanoid Diglycoside from Acanthus montanus
Molecules 2010, 15(12), 8967-8972; doi:10.3390/molecules15128967
Received: 18 October 2010 / Revised: 26 November 2010 / Accepted: 6 December 2010 / Published: 7 December 2010
Cited by 4 | PDF Full-text (117 KB)
Abstract
A new phenylethanoid glycoside acylated with syringic acid, namely acanmontanoside, was isolated from the aerial portions of Acanthus montanus (Nees). T. Anderson, along with decaffeoylverbascoside, verbascoside, isoverbascoside, leucosceptoside A, (2R)-2-O-b-D-glucopyranosyl-2H-1,4-benzoxazin-3(4H)-one (HBOA-Glc), (2R)-2-O
[...] Read more.
A new phenylethanoid glycoside acylated with syringic acid, namely acanmontanoside, was isolated from the aerial portions of Acanthus montanus (Nees). T. Anderson, along with decaffeoylverbascoside, verbascoside, isoverbascoside, leucosceptoside A, (2R)-2-O-b-D-glucopyranosyl-2H-1,4-benzoxazin-3(4H)-one (HBOA-Glc), (2R)-2-O-b-D-glucopyranosyl-4-hydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA-Glc), (3R)-1-octen-3-ol-3-O-b-D-xylopyranosyl-(1→6)-O-b-D-glucopyranoside and ebracteatoside B. The structure elucidations were based on physical data and spectroscopic analyses including 1D- and 2D-NMR. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Effects of Conventional Heating on the Stability of Major Olive Oil Phenolic Compounds by Tandem Mass Spectrometry and Isotope Dilution Assay
Molecules 2010, 15(12), 8734-8746; doi:10.3390/molecules15128734
Received: 18 October 2010 / Revised: 18 November 2010 / Accepted: 26 November 2010 / Published: 1 December 2010
Cited by 10 | PDF Full-text (248 KB)
Abstract
The quality of olive oils is sensorially tested by accurate and well established methods. It enables the classification of the pressed oils into the classes of extra virgin oil, virgin oil and lampant oil. Nonetheless, it would be convenient to have analytical methods
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The quality of olive oils is sensorially tested by accurate and well established methods. It enables the classification of the pressed oils into the classes of extra virgin oil, virgin oil and lampant oil. Nonetheless, it would be convenient to have analytical methods for screening oils or supporting sensorial analysis using a reliable independent approach based on exploitation of mass spectrometric methodologies. A number of methods have been proposed to evaluate deficiencies of extra virgin olive oils resulting from inappropriate technological treatments, such as high or low temperature deodoration, and home cooking processes. The quality and nutraceutical value of extra virgin olive oil (EVOO) can be related to the antioxidant property of its phenolic compounds. Olive oil is a source of at least 30 phenolic compounds, such as oleuropein, oleocanthal, hydroxytyrosol, and tyrosol, all acting as strong antioxidants, radical scavengers and NSAI-like drugs. We now report the efficacy of MRM tandem mass spectrometry, assisted by the isotope dilution assay, in the evaluation of the thermal stability of selected active principles of extra virgin olive oil. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Antioxidant Capacities and Total Phenolic Contents of 56 Wild Fruits from South China
Molecules 2010, 15(12), 8602-8617; doi:10.3390/molecules15128602
Received: 8 October 2010 / Revised: 17 November 2010 / Accepted: 24 November 2010 / Published: 29 November 2010
Cited by 40 | PDF Full-text (162 KB)
Abstract
In order to identify wild fruits possessing high nutraceutical potential, the antioxidant activities of 56 wild fruits from South China were systematically evaluated. The fat-soluble components were extracted with tetrahydrofuran, and the water-soluble ones were extracted with a 50:3.7:46.3 (v/v) methanol-acetic acid-water mixture.
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In order to identify wild fruits possessing high nutraceutical potential, the antioxidant activities of 56 wild fruits from South China were systematically evaluated. The fat-soluble components were extracted with tetrahydrofuran, and the water-soluble ones were extracted with a 50:3.7:46.3 (v/v) methanol-acetic acid-water mixture. The antioxidant capacities of the extracts were evaluated using the ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays, and their total phenolic contents were measured by the Folin-Ciocalteu method. Most of these wild fruits were analyzed for the first time for their antioxidant activities. Generally, these fruits had high antioxidant capacities and total phenolic contents. A significant correlation between the FRAP value and the TEAC value suggested that antioxidant components in these wild fruits were capable of reducing oxidants and scavenging free radicals. A high correlation between antioxidant capacity and total phenolic content indicated that phenolic compounds could be the main contributors to the measured antioxidant activity. The results showed that fruits of Eucalyptus robusta, Eurya nitida, Melastoma sanguineum, Melaleuca leucadendron, Lagerstroemia indica, Caryota mitis, Lagerstroemia speciosa and Gordonia axillaris possessed the highest antioxidant capacities and total phenolic contents among those tested, and could be potential rich sources of natural antioxidants and functional foods. The results obtained are very helpful for the full utilization of these wild fruits. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Antiseptic Activity and Phenolic Constituents of the Aerial Parts of Vitex negundo var. cannabifolia
Molecules 2010, 15(11), 8469-8477; doi:10.3390/molecules15118469
Received: 15 October 2010 / Revised: 11 November 2010 / Accepted: 15 November 2010 / Published: 18 November 2010
Cited by 22 | PDF Full-text (277 KB)
Abstract
Four phenolics, salviaplebeiaside (1), γ-tocopherol (2), chrysosplenol-D (4), and isovitexin (5), along with α-tocoquinone (3) and β-sitosterol (6) were isolated from the aerial parts of Vitex negundo var.
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Four phenolics, salviaplebeiaside (1), γ-tocopherol (2), chrysosplenol-D (4), and isovitexin (5), along with α-tocoquinone (3) and β-sitosterol (6) were isolated from the aerial parts of Vitex negundo var. cannabifolia. The isolation was performed using bio-assay tracking experiments. The structures of compounds 1-5 were established by spectroscopic means. The antibacterial activities of the compounds were assessed against Escherichia coli, Bacillus subtilis, Micrococcus tetragenus and Pseudomonas fluorescens. Chrysosplenol-D (4) exhibited activities against all the four spoilage microorganisms. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Flavonoids from Halostachys caspica and Their Antimicrobial and Antioxidant Activities
Molecules 2010, 15(11), 7933-7945; doi:10.3390/molecules15117933
Received: 11 October 2010 / Revised: 2 November 2010 / Accepted: 4 November 2010 / Published: 5 November 2010
Cited by 42 | PDF Full-text (223 KB)
Abstract
Seven flavonoids have been isolated from the aerial parts of Halostachys caspica C. A. Mey. (Chenopodiaceae) for the first time. By means of physicochemical and spectrometric analysis, they were identified as luteolin (1), chrysin (2), chrysin 7-O-β-D-glucopyranoside
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Seven flavonoids have been isolated from the aerial parts of Halostachys caspica C. A. Mey. (Chenopodiaceae) for the first time. By means of physicochemical and spectrometric analysis, they were identified as luteolin (1), chrysin (2), chrysin 7-O-β-D-glucopyranoside (3), quercetin (4), quercetin 3-O-β-D-glucopyranoside (5), isorhamentin-3-O-β-D-glucopyranoside (6), and isorhamentin-3-O-β-D-rutinoside (7). All flavonoids were evaluated to show a broad antimicrobial spectrum of activity on microorganisms including seven bacterial and one fungal species as well as pronounced antioxidant activity. Among them, the aglycones with relatively low polarity had stronger bioactivity than their glycosides. The results suggested that the isolated flavonoids could be used for future development of antimicrobial and antioxidant agents, and also provided additional data for supporting the use of H. caspica as forage. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Variability of Polyphenol Compounds in Myrtus Communis L. (Myrtaceae) Berries from Corsica
Molecules 2010, 15(11), 7849-7860; doi:10.3390/molecules15117849
Received: 6 September 2010 / Revised: 12 October 2010 / Accepted: 2 November 2010 / Published: 3 November 2010
Cited by 16 | PDF Full-text (150 KB)
Abstract
Polyphenol compounds were extracted from Myrtus communis L. berries (Myrtaceae) by maceration in 70% ethanol and analysed by HPLC-DAD and electrospray mass spectrometry. The Myrtus berries were collected at maturity from seven localities on the island of Corsica (France) and the sampling was
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Polyphenol compounds were extracted from Myrtus communis L. berries (Myrtaceae) by maceration in 70% ethanol and analysed by HPLC-DAD and electrospray mass spectrometry. The Myrtus berries were collected at maturity from seven localities on the island of Corsica (France) and the sampling was carried out during three years. The polyphenol composition of Corsican Myrtus berries was characterized by two phenolic acids, four flavanols, three flavonols and five flavonol glycosides. The major compounds were myricetin-3-O-arabinoside and myricetin-3-O-galactoside. Principal components analysis (PCA) is applied to study the chemical composition and variability of myrtle berries alcoholic extracts from the seven localities. Canonical analysis and PCA data distinguishes two groups of myrtle berries characterized by different concentrations of polyphenols according to soil and years of harvest. The variations in the polyphenol concentration were due to biotic and abiotic factors. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Synthesis and Tumor Cytotoxicity of Novel Amide Derivatives of β-Hederin
Molecules 2010, 15(11), 7871-7883; doi:10.3390/molecules15117871
Received: 9 October 2010 / Revised: 1 November 2010 / Accepted: 2 November 2010 / Published: 3 November 2010
Cited by 9 | PDF Full-text (319 KB)
Abstract
Thirteen novel triterpenoid saponins, designed as amide derivatives of the natural cytotoxic saponin β-hederin, were synthesized by a stepwise glycosylation strategy. The in vitro cytotoxic activity of these compounds was evaluated against five different tumor cell lines. Most of the evaluated compounds showed
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Thirteen novel triterpenoid saponins, designed as amide derivatives of the natural cytotoxic saponin β-hederin, were synthesized by a stepwise glycosylation strategy. The in vitro cytotoxic activity of these compounds was evaluated against five different tumor cell lines. Most of the evaluated compounds showed effective inhibitory activity against at least one tumor cell line at micromolar concentrations. The preliminary structure-activity relationships (SAR) indicate that mide derivatization at C-28 resulted in highly cytotoxic derivatives on specific tumor cell lines, and also resulted in an increase in the antitumor selectivity of β-hederin.  Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessCommunication Prooxidant/Antioxidant Ratio (ProAntidex) as a Better Index of Net Free Radical Scavenging Potential
Molecules 2010, 15(11), 7884-7892; doi:10.3390/molecules15117884
Received: 6 September 2010 / Revised: 1 October 2010 / Accepted: 19 October 2010 / Published: 3 November 2010
Cited by 10 | PDF Full-text (178 KB)
Abstract
The antioxidant activity of several Malaysian plant extracts was analyzed simultaneously with their pro-oxidant capacity. This ratio represents an index (ProAntidex) of the net free radical scavenging ability of whole plant extracts. We observed that ethanolic extracts of Nephelium lappaceum peel, Fragaria x
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The antioxidant activity of several Malaysian plant extracts was analyzed simultaneously with their pro-oxidant capacity. This ratio represents an index (ProAntidex) of the net free radical scavenging ability of whole plant extracts. We observed that ethanolic extracts of Nephelium lappaceum peel, Fragaria x ananassa leaf, Lawsonia inermis leaf, Syzygium aqueum leaf and grape seed had a lower Pro-Antidex than the commercially available Emblica™ extract which is an antioxidant agent with very low pro-oxidant activity. Among the aqueous extracts, Lawsonia inermis leaf, Nephelium mutobile leaf and grape seed had lower pro-oxidant activity compared to the Emblica™ extract. Among these extracts, aqueous extract of Nephelium mutobile leaf had a very low index of 0.05 compared to 0.69 for Emblica™. Most of the extracts had a far lower ProAntidex compared to the Vitamin C. The index enables us to identify extracts with high net free radical scavenging activity potential. The ProAntidex is beneficial as a screening parameter to the food industries and healthcare. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Chemometric Studies on Natural Products as Potential Inhibitors of the NADH Oxidase from Trypanosoma cruzi Using the VolSurf Approach
Molecules 2010, 15(10), 7363-7377; doi:10.3390/molecules15107363
Received: 16 September 2010 / Revised: 5 October 2010 / Accepted: 11 October 2010 / Published: 21 October 2010
Cited by 22 | PDF Full-text (667 KB)
Abstract
Natural products have widespread biological activities, including inhibition of mitochondrial enzyme systems. Some of these activities, for example cytotoxicity, may be the result of alteration of cellular bioenergetics. Based on previous computer-aided drug design (CADD) studies and considering reported data on structure-activity relationships
[...] Read more.
Natural products have widespread biological activities, including inhibition of mitochondrial enzyme systems. Some of these activities, for example cytotoxicity, may be the result of alteration of cellular bioenergetics. Based on previous computer-aided drug design (CADD) studies and considering reported data on structure-activity relationships (SAR), an assumption regarding the mechanism of action of natural products against parasitic infections involves the NADH-oxidase inhibition. In this study, chemometric tools, such as: Principal Component Analysis (PCA), Consensus PCA (CPCA), and partial least squares regression (PLS), were applied to a set of forty natural compounds, acting as NADH-oxidase inhibitors. The calculations were performed using the VolSurf+ program. The formalisms employed generated good exploratory and predictive results. The independent variables or descriptors having a hydrophobic profile were strongly correlated to the biological data. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Determination of Quercetin and Resveratrol in Whole Blood—Implications for Bioavailability Studies
Molecules 2010, 15(9), 6570-6579; doi:10.3390/molecules15096570
Received: 19 July 2010 / Revised: 27 August 2010 / Accepted: 14 September 2010 / Published: 20 September 2010
Cited by 33 | PDF Full-text (228 KB)
Abstract
Resveratrol (trans-3,4',5-trihydroxystilbene) and quercetin (3,3’,4’,5,7-pentahydroxyflavone) are two naturally occurring polyphenols with the potential to exert beneficial health effects. Since their low bioavailability is a major obstacle to biomedical applications, efforts are being made to improve their absorption and slow down phase
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Resveratrol (trans-3,4',5-trihydroxystilbene) and quercetin (3,3’,4’,5,7-pentahydroxyflavone) are two naturally occurring polyphenols with the potential to exert beneficial health effects. Since their low bioavailability is a major obstacle to biomedical applications, efforts are being made to improve their absorption and slow down phase II metabolism. An accurate evaluation of the corresponding levels in the bloodstream is important to assess delivery strategies, as well as to verify claims of efficacy based on in vitro results. In the present work we have optimized a simple method ensuring complete stabilization and extraction of resveratrol and quercetin from whole blood. The suitability of different protocols was evaluated by measuring the recovery of polyphenol and internal standard from spiked blood samples via HPLC/UV analysis. The optimized procedure ensured a satisfactory recovery of both internal standards and compounds. Comparing plasma and whole blood, up to 76% of the analyte, being associated with the cellular fraction, was unaccounted for when examining only plasma. This indicates the importance of analysing whole blood rather than plasma to avoid underestimating polyphenol absorption in bioavailability studies. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Preparative Separation of Phenolic Compounds from Halimodendron halodendron by High-Speed Counter-Current Chromatography
Molecules 2010, 15(9), 5998-6007; doi:10.3390/molecules15095998
Received: 30 July 2010 / Revised: 16 August 2010 / Accepted: 27 August 2010 / Published: 31 August 2010
Cited by 16 | PDF Full-text (276 KB)
Abstract
Three phenolic compounds, p-hydroxybenzoic acid (1), isorhamnetin-3-O-β-D-rutinoside (2), and 3,3'-di-O-methylquercetin (5), along with a phenolic mixture were successfully separated from the ethyl acetate crude extract of Halimodendron halodendron by high-speed counter-current chromatography
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Three phenolic compounds, p-hydroxybenzoic acid (1), isorhamnetin-3-O-β-D-rutinoside (2), and 3,3'-di-O-methylquercetin (5), along with a phenolic mixture were successfully separated from the ethyl acetate crude extract of Halimodendron halodendron by high-speed counter-current chromatography (HSCCC) with chloroform-methanol-water-acetic acid (4:3:2:0.05, v/v) as the two-phase solvent system. The phenolic mixture from HSCCC was further separated by preparative HPLC and purified by Sephadex LH-20 to afford quercetin (3) and 3-O-methylquercetin (4). Seven hundred mg of ethyl acetate crude extract was separated by HSCCC to obtain six fractions which were then analyzed by high performance liquid chromatography (HPLC). The HSCCC separation obtained total of 80 mg of the mixture of quercetin (3) and 3-O-methylquercetin (4) (26.43% and 71.89%, respectively) in fraction 2, 14 mg of 3,3'-di-O-methylquercetin (5) at 95.14% of purity in fraction 3, 15 mg of p-hydroxybenzoic acid (1) at 92.83% of purity in fraction 5, 12 mg of isorhamnetin-3-O-β-D-rutinoside (2) at 97.99% of purity in fraction 6. This is the first time these phenolic compounds have been obtained from H. halodendron, and their chemical structures identified by means of physicochemical and spectrometric analysis. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Antimicrobial and Antioxidant Activities of the Root Bark Essential Oil of Periploca sepium and Its Main Component 2-Hydroxy-4-methoxybenzaldehyde
Molecules 2010, 15(8), 5807-5817; doi:10.3390/molecules15085807
Received: 5 August 2010 / Revised: 16 August 2010 / Accepted: 23 August 2010 / Published: 24 August 2010
Cited by 34 | PDF Full-text (216 KB)
Abstract
The root bark essential oil of Periploca sepium Bunge (Asclepiadaceae/ Apocynaceae) obtained by hydrodistillation was investigated by GC and GC-MS. 2-Hydroxy-4-methoxybenzaldehyde was found to be the main component (78.8% of the total) among 17 identified compounds. 2-Hydroxy-4-methoxybenzaldehyde was separated and purified by preparative
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The root bark essential oil of Periploca sepium Bunge (Asclepiadaceae/ Apocynaceae) obtained by hydrodistillation was investigated by GC and GC-MS. 2-Hydroxy-4-methoxybenzaldehyde was found to be the main component (78.8% of the total) among 17 identified compounds. 2-Hydroxy-4-methoxybenzaldehyde was separated and purified by preparative thin layer chromatography, and was further identified by means of physicochemical and spectrometric analysis. Both the essential oil and 2-hydroxy-4-methoxybenzaldehyde exhibited antimicrobial activities on all test bacteria and fungi, with MBC/MFC values ranging from 125 μg/mL to 300 μg/mL, MIC values from 80 μg/mL to 300 μg/mL, and IC50 values from 63.29 μg/mL to 167.30 μg/mL. They also showed moderate antioxidant activity in the DPPH free radical scavenging, β-carotene bleaching and ferrozine-ferrous ions assays. The results indicated that the major portion of these antimicrobial and antioxidant activities was due to the presence of 2-hydroxy-4-methoxy-benzaldehyde in the oil, which could potentially be developed as an antimicrobial and antioxidant agent in the future. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Enantioselctive Syntheses of Sulfur Analogues of Flavan-3-Ols
Molecules 2010, 15(8), 5595-5619; doi:10.3390/molecules15085595
Received: 26 July 2010 / Revised: 12 August 2010 / Accepted: 12 August 2010 / Published: 13 August 2010
Cited by 8 | PDF Full-text (194 KB)
Abstract
The first enantioselective syntheses of sulfur flavan-3-ol analogues 18 have been accomplished, whereby the oxygen atom of the pyran ring has been replaced by a sulfur atom. The key steps were: (a) Pd(0) catalyzed introduction of –St-butyl group, (b)
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The first enantioselective syntheses of sulfur flavan-3-ol analogues 18 have been accomplished, whereby the oxygen atom of the pyran ring has been replaced by a sulfur atom. The key steps were: (a) Pd(0) catalyzed introduction of –S t-butyl group, (b) Sharpless enantioselective dihydroxylation of the alkene, (c) acid catalyzed ring closure to produce the thiopyran ring, and (d) removal of benzyl groups using N,N-dimethylaniline and AlCl3. The compounds were isolated in high chemical and optical purity. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Chalcones and Dihydrochalcones Augment TRAIL-Mediated Apoptosis in Prostate Cancer Cells
Molecules 2010, 15(8), 5336-5353; doi:10.3390/molecules15085336
Received: 19 May 2010 / Revised: 26 July 2010 / Accepted: 2 August 2010 / Published: 4 August 2010
Cited by 45 | PDF Full-text (1854 KB)
Abstract
Chalcones and dihydrochalcones exhibit chemopreventive and antitumor activity. TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) is a natural endogenous anticancer agent. We examined the cytotoxic and apoptotic effect of chalcones and dihydrochalcones on TRAIL-mediated apoptosis in LNCaP prostate cancer cells. The cytotoxicity was evaluated
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Chalcones and dihydrochalcones exhibit chemopreventive and antitumor activity. TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) is a natural endogenous anticancer agent. We examined the cytotoxic and apoptotic effect of chalcones and dihydrochalcones on TRAIL-mediated apoptosis in LNCaP prostate cancer cells. The cytotoxicity was evaluated by the MTT and LDH assays. The apoptosis was detected using annexin V-FITC by flow cytometry and fluorescence microscopy. The ΔΨm was evaluated using DePsipher staining by fluorescence microscopy. Our study showed that two tested chalcones (chalcone and 2’,6’dihydroxy-4’-methoxychalcone) and three dihydrochalcones (2’,6’-dihydroxy-4’4-dimethoxydihydrochalcone, 2’,6’-dihydroxy-4’-methoxydihydro- chalcone,  and 2’,4’,6’-trihydroxydihydrochalcone, called phloretin) markedly augmented TRAIL-induced apoptosis and cytotoxicity in LNCaP cells and confirmed the significant role of chalcones in chemoprevention of prostate cancer. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Regioselective O-Derivatization of Quercetin via Ester Intermediates. An Improved Synthesis of Rhamnetin and Development of a New Mitochondriotropic Derivative
Molecules 2010, 15(7), 4722-4736; doi:10.3390/molecules15074722
Received: 10 June 2010 / Revised: 22 June 2010 / Accepted: 2 July 2010 / Published: 6 July 2010
Cited by 19 | PDF Full-text (328 KB)
Abstract
The regioselective synthesis of several quercetin (3,3’,4’,5,7-pentahydroxy flavone) tetraesters bearing a single free OH on 5-C was achieved in good yield by proper choice of reaction conditions using common esterification procedures. Tetracetylated quercetin with the free OH on 7-C was selectively obtained instead
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The regioselective synthesis of several quercetin (3,3’,4’,5,7-pentahydroxy flavone) tetraesters bearing a single free OH on 5-C was achieved in good yield by proper choice of reaction conditions using common esterification procedures. Tetracetylated quercetin with the free OH on 7-C was selectively obtained instead via imidazole-promoted deacylation of the corresponding pentaester. Unambiguous structural characterization of the two isomeric tetraacetyl quercetin derivatives was obtained by combined HSQC and HMBC 2D-NMR analysis. These molecules can be used as starting materials for the regioselective synthesis of other derivatives. High yield syntheses of the natural polyphenol rhamnetin (7-O-methylquercetin) and of the new mitochondriotropic compound 7-(4-triphenylphosphoniumbutyl) quercetin iodide are reported as examples. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Phenolic Extracts from Acacia mangium Bark and Their Antioxidant Activities
Molecules 2010, 15(5), 3567-3577; doi:10.3390/molecules15053567
Received: 31 March 2010 / Revised: 8 May 2010 / Accepted: 12 May 2010 / Published: 14 May 2010
Cited by 14 | PDF Full-text (427 KB)
Abstract
Phenolic compounds are present at very high concentrations in the bark of Acacia mangium. These compounds are known to have strong antioxidant activity and thus different beneficial effects on human health. Phenolic compounds in bark of A. mangium were extracted and
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Phenolic compounds are present at very high concentrations in the bark of Acacia mangium. These compounds are known to have strong antioxidant activity and thus different beneficial effects on human health. Phenolic compounds in bark of A. mangium were extracted and their antioxidant activities were investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging and ferric-reducing antioxidant power (FRAP) assays. A central composite design has been employed to optimize the experimental conditions for a high total phenolic content and antioxidant activity. The desirability function approach has been employed to simultaneously optimize the three responses: total phenols, antiradical activity and FRAP. An extraction time of 90 min, liquid-solid ratio of 5, and temperature of 50 °C was predicted for the optimum experimental conditions using the desirability function. A significant linear relationship between antioxidant potency, antiradical activity and the content of phenolic compounds of bark extracts was observed. The structures of condensed tannins isolated from A. mangium were characterized by MALDI-TOF MS analyses. Condensed tannin oligomers from A. mangium were shown to be heterogeneous mixtures consisting of procyanidin and prodelphinidin structural units with polymerization degrees up to 9. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Characterization of Primary Standards for Use in the HPLC Analysis of the Procyanidin Content of Cocoa and Chocolate Containing Products
Molecules 2009, 14(10), 4136-4146; doi:10.3390/molecules14104136
Received: 5 August 2009 / Revised: 25 August 2009 / Accepted: 30 September 2009 / Published: 15 October 2009
Cited by 15 | PDF Full-text (200 KB)
Abstract
This report describes the characterization of a series of commercially available procyanidin standards ranging from dimers DP = 2 to decamers DP = 10 for the determination of procyanidins from cocoa and chocolate. Using a combination of HPLC with fluorescence detection and MALDI-TOF
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This report describes the characterization of a series of commercially available procyanidin standards ranging from dimers DP = 2 to decamers DP = 10 for the determination of procyanidins from cocoa and chocolate. Using a combination of HPLC with fluorescence detection and MALDI-TOF mass spectrometry, the purity of each standard was determined and these data were used to determine relative response factors. These response factors were compared with other response factors obtained from published methods. Data comparing the procyanidin analysis of a commercially available US dark chocolate calculated using each of the calibration methods indicates divergent results and demonstrate that previous methods may significantly underreport the procyanidins in cocoa-containing products. These results have far reaching implications because the previous calibration methods have been used to develop data for a variety of scientific reports, including food databases and clinical studies. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Molecular Docking Studies and Anti-enzymatic Activities of Thai Mango Seed Kernel Extract Against Snake Venoms
Molecules 2009, 14(4), 1404-1422; doi:10.3390/molecules14041404
Received: 16 January 2009 / Revised: 26 March 2009 / Accepted: 30 March 2009 / Published: 31 March 2009
Cited by 21 | PDF Full-text (957 KB) | HTML Full-text | XML Full-text
Abstract
The ethanolic extract from seed kernels of Thai mango (MSKE) (Mangifera indica L. cv. ‘Fahlun’) (Anacardiaceae) and its major phenolic principle (pentagalloyl glucopyranose) exhibited dose-dependent inhibitory effects on enzymatic activities of phospholipase A2 (PLA2), hyaluronidase and L-amino acid oxidase
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The ethanolic extract from seed kernels of Thai mango (MSKE) (Mangifera indica L. cv. ‘Fahlun’) (Anacardiaceae) and its major phenolic principle (pentagalloyl glucopyranose) exhibited dose-dependent inhibitory effects on enzymatic activities of phospholipase A2 (PLA2), hyaluronidase and L-amino acid oxidase (LAAO) of Calloselasma rhodostoma (CR) and Naja naja kaouthia (NK)venoms by in vitro tests. The anti-hemorrhagic and anti-dermonecrotic activities of MSKE against both venoms were clearly supported by in vivo tests. Molecular docking studies indicated that the phenolic molecules of the MSKE could selectively bind to the active sites or their proximity, or modify conserved residues that are critical for the catalysis of PLA2, and selectively bind to the LAAO binding pocket of both CR and NK venoms and thereby inhibit their enzymatic activities. The results imply a potential use of MSKE against snake venoms. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Polyphenols with Antiulcerogenic Action from Aqueous Decoction of Mango Leaves (Mangifera indica L.)
Molecules 2009, 14(3), 1098-1110; doi:10.3390/molecules14031098
Received: 1 January 2009 / Revised: 12 January 2009 / Accepted: 22 January 2009 / Published: 10 March 2009
Cited by 36 | PDF Full-text (197 KB) | HTML Full-text | XML Full-text
Abstract
This study was designed to determine the gastroprotective effect of a Mangifera indica leaf decoction (AD), on different experimental models in rodents. The administration of AD up to a dose of 5 g/kg (p.o.) did not produce any signs or symptoms of toxicity
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This study was designed to determine the gastroprotective effect of a Mangifera indica leaf decoction (AD), on different experimental models in rodents. The administration of AD up to a dose of 5 g/kg (p.o.) did not produce any signs or symptoms of toxicity in the treated animals, while significantly decreasing the severity of gastric damage induced by several gastroprotective models. Oral pre-treatment with AD (250, 500 or 1000 mg/kg) in mice and rats with gastric lesions induced by HCl/ethanol, absolute ethanol, non-steroidal anti-inflammatory drug (NSAID) or stress-induced gastric lesions resulted in a significant decrease of said lesions. Phytochemical analyses of AD composition demonstrated the presence of bioactive phenolic compounds that represent 57.3% of total phenolic content in this extract. Two main phenolic compounds were isolated, specifically mangiferin (C-glucopyranoside of 1,3,6,7-tetrahydroxyxanthone) and C-glucosyl-benzophenone (3-C-β-D-glucopyranosyl-4’,2,4,6-tetrahydroxybenzophenone). These findings indicate the potential gastroprotective properties of aqueous decoction from M. indica leaves. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Anti-hemorrhagic Activity of Four Brazilian Vegetable Species Against Bothrops jararaca Venom
Molecules 2009, 14(3), 1072-1080; doi:10.3390/molecules14031072
Received: 26 November 2008 / Revised: 30 December 2008 / Accepted: 21 January 2009 / Published: 9 March 2009
Cited by 19 | PDF Full-text (117 KB) | HTML Full-text | XML Full-text
Abstract
Around 20,000 snakebites are reported annually in Brazil and 90% of them are inflicted by species of the genus Bothrops. Intravenous administration of antibothropic antivenom neutralizes the systemic actions, but it is of little effect on the reversal of local symptoms and
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Around 20,000 snakebites are reported annually in Brazil and 90% of them are inflicted by species of the genus Bothrops. Intravenous administration of antibothropic antivenom neutralizes the systemic actions, but it is of little effect on the reversal of local symptoms and often induces adverse reactions, a context that drives the search for complementary treatments for snakebite accidents. Vegetable extracts with a range of antiophidian activities constitute an excellent alternative. In this study, we investigated the anti-hemorrhagic effects of Mouriri pusa Gardn. (Melastomataceae), Byrsonima crassa Niedenzu (Malpighiaceae), Davilla elliptica St. Hill. (Dilleniaceae) and Strychnos pseudoquina St. Hil. (Loganiaceae) against Bothrops jararaca venom. The methanolic extracts from M. pusa (leaves), B. crassa (leaves) and D. elliptica (leaves) showed total neutralization capacity against local hemorrhages. The amenthoflavone and quercetin fractions from B. crassa and the flavonoids fractions (quercetin and myricetin) from M. pusa and D. elliptica also showed total neutralization capacity. We conclude that flavonoids derived from myricetin, quercetin and amenthoflavone play an important role in the anti-hemorrhagic potential of these Brazilian vegetables species against B. jararaca venom. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Effect of [10]-Gingerol on [Ca2+]i and Cell Death in Human Colorectal Cancer Cells
Molecules 2009, 14(3), 959-969; doi:10.3390/molecules14030959
Received: 4 December 2008 / Revised: 7 February 2009 / Accepted: 17 February 2009 / Published: 2 March 2009
Cited by 19 | PDF Full-text (169 KB) | HTML Full-text | XML Full-text
Abstract
The effect of [10]-gingerol on cytosol free Ca2+ concentration ([Ca2+]i) and viability is large unknown. This study examines the early signaling effects of [10]-gingerol on human colorectal cancer cells. It was found that this compound caused a slow
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The effect of [10]-gingerol on cytosol free Ca2+ concentration ([Ca2+]i) and viability is large unknown. This study examines the early signaling effects of [10]-gingerol on human colorectal cancer cells. It was found that this compound caused a slow and sustained rise of [Ca2+]i in a concentration-dependent manner. [10]-Gingerol also induced a [Ca2+]i rise when extracellular Ca2+ was removed, but the magnitude was reduced by 38%. In a Ca2+-free medium, the [10]-gingerol-induced [Ca2+]i rise was partially abolished by depleting stored Ca2+ with thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor). The elevation of [10]-gingerol-caused [Ca2+]i in a Ca2+-containing medium was not affected by modulation of protein kinase C activity. The [10]-gingerol-induced Ca2+ influx was insensitive to L-type Ca2+ channel blockers. At concentrations of 10-100 mM, [10]-gingerol killed cells in a concentration-dependent manner. These findings suggest that [10]-gingerol induces [Ca2+]i rise by causing Ca2+ release from the endoplasmic reticulum and Ca2+ influx from non-L-type Ca2+ channels in SW480 cancer cells. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Comparison of Phenolic Acids and Flavan-3-ols During Wine Fermentation of Grapes with Different Harvest Times
Molecules 2009, 14(2), 827-838; doi:10.3390/molecules14020827
Received: 17 October 2008 / Revised: 20 January 2009 / Accepted: 6 February 2009 / Published: 18 February 2009
Cited by 23 | PDF Full-text (204 KB) | HTML Full-text | XML Full-text
Abstract
To explore the effects of harvest time on phenolic compounds during wine fermentation, grape berries (Vitis vinifera L. cv. Vidal) were harvested at 17.5, 22.8 and 37.2º Brix and were used to make dry wine, semi-sweet wine and icewine with low alcohol
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To explore the effects of harvest time on phenolic compounds during wine fermentation, grape berries (Vitis vinifera L. cv. Vidal) were harvested at 17.5, 22.8 and 37.2º Brix and were used to make dry wine, semi-sweet wine and icewine with low alcohol levels, respectively. Phenolic acids and flavan-3-ols were assayed during the fermentation of wines by means of reverse phase-high performance liquid chromatography (RP-HPLC). The results showed that concentrations of most of the phenolic acids and flavan-3-ol in musts increased with harvest time delay and higher total levels of these species were detected in all wines, compared with those measured before fermentation (the total phenolic acid content in wines was 1.5-2.0 fold that of in musts). Except for p-coumaric acid and (-)-epicatechin, other phenolic acids and flavan-3-ols had similar variation patterns (wave-like rise) during fermentation in dry wine and semi-sweet wine. However, some detected compounds, including gentisic acid, p-hydroxybenzoic acid, caffeic acid, p-coumaric acid and sinapic acid showed obviously different trends from the other two wines in the icewine making process. It is thus suggested that the harvest time has a decisive effect on phenols in final wines and influences the evolution of phenolic acids and flavan-3-ols during wine fermentation. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle A Convenient Synthesis of Type A Procyanidins
Molecules 2009, 14(2), 807-815; doi:10.3390/molecules14020807
Received: 11 December 2008 / Revised: 10 January 2009 / Accepted: 13 February 2009 / Published: 17 February 2009
Cited by 10 | PDF Full-text (151 KB) | HTML Full-text | XML Full-text
Abstract Type A procyanidins can be synthesized in good yields from the condensation of benzopyrilium salts 8 and either catechin or phloroglucinol. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Ethanolic Extract of Propolis (EEP) Enhances the Apoptosis- Inducing Potential of TRAIL in Cancer Cells
Molecules 2009, 14(2), 738-754; doi:10.3390/molecules14020738
Received: 28 November 2008 / Revised: 20 January 2009 / Accepted: 31 January 2009 / Published: 13 February 2009
Cited by 50 | PDF Full-text (337 KB) | HTML Full-text | XML Full-text
Abstract
Ethanolic extract of propolis (EEP) is one of the richest sources of phenolic acids and flavonoids. EEP and its phenolic compounds have been known for various biological activities including immunopotentiation, chemopreventive and antitumor effects. Tumor necrosis factor related apoptosis inducing ligand (TRAIL) is
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Ethanolic extract of propolis (EEP) is one of the richest sources of phenolic acids and flavonoids. EEP and its phenolic compounds have been known for various biological activities including immunopotentiation, chemopreventive and antitumor effects. Tumor necrosis factor related apoptosis inducing ligand (TRAIL) is a naturally occurring anticancer agent that preferentially induces apoptosis in cancer cells and is not toxic toward normal cells. We examined the cytotoxic and apoptotic effect of EEP and phenolic compounds identified in propolis in combination with TRAIL on HeLa cancer cells. HeLa cells were resistant to TRAIL-induced apoptosis. Our study demonstrated that EEP and its components significantly sensitize to TRAIL induced death in cancer cells. The percentage of the apoptotic cell after exposure to 50 μg/mL EEP and 100 ng/mL TRAIL increased to 71.10±1.16%. The strongest cytotoxic effect in combination with TRAIL on HeLa cells exhibited apigenin and CAPE at the concentration of 50 μM (58.87±0.75% and 49.59±0.39%, respectively). In this report, we show for the first time that EEP markedly augmented TRAIL mediated apoptosis in cancer cells and confirmed the importance of propolis in chemoprevention of malignant tumors. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Optimization and Comparison of Five Methods for Extraction of Coniferyl Ferulate from Angelica sinensis
Molecules 2009, 14(1), 555-565; doi:10.3390/molecules14010555
Received: 15 November 2008 / Revised: 15 January 2009 / Accepted: 19 January 2009 / Published: 23 January 2009
Cited by 16 | PDF Full-text (555 KB) | HTML Full-text | XML Full-text
Abstract
Coniferyl ferulate, which is noted for its multiple pharmacological activities and chemical instability, is abundant in Angelica sinensis. In this paper, five methods, namely sonication extraction (SE), pressurized liquid extraction (PLE), supercritical fluid extraction (SFE), hydrodistillation (HD) and decoction (DC) for extraction
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Coniferyl ferulate, which is noted for its multiple pharmacological activities and chemical instability, is abundant in Angelica sinensis. In this paper, five methods, namely sonication extraction (SE), pressurized liquid extraction (PLE), supercritical fluid extraction (SFE), hydrodistillation (HD) and decoction (DC) for extraction of coniferyl ferulate, as well as ferulic acid, Z/E-ligustilide and Z/E-butylidenephthalide, from A. sinensis were optimized and compared. The results showed that the order of extraction efficiency was: PLE»SE>SFE>>HD, DC. The compositions of the SE, PLE and SFE extracts, which had a high ratio of coniferyl ferulate, were very similar, while no coniferyl ferulate was obtained by HD and DC, though they had high selectivity for the extraction of ligustilide and ferulic acid, respectively. It was noteworthy that the content of ligustilide and coniferyl ferulate was not detectable in the decoction, the commonly used oral administration form of Traditional Chinese Medicines in clinical practice. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Antimutagenic Activity and Radical Scavenging Activity of Water Infusions and Phenolics from Ligustrum Plants Leaves
Molecules 2009, 14(1), 509-518; doi:10.3390/molecules14010509
Received: 24 November 2008 / Revised: 15 January 2009 / Accepted: 21 January 2009 / Published: 22 January 2009
Cited by 26 | PDF Full-text (230 KB) | HTML Full-text | XML Full-text
Abstract
Water infusions of Ligustrum delavayanum and Ligustrum vulgare leaves and eight phenolics isolated therefrom have been assayed in vitro on ofloxacin-induced genotoxicity in the unicellular flagellate Euglena gracilis. The tested compounds luteolin, quercetin, luteolin-7-glucoside, luteolin-7-rutinoside, quercetin-3-rutinoside, apigenin-7-rutinoside, tyrosol and esculetin inhibited the
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Water infusions of Ligustrum delavayanum and Ligustrum vulgare leaves and eight phenolics isolated therefrom have been assayed in vitro on ofloxacin-induced genotoxicity in the unicellular flagellate Euglena gracilis. The tested compounds luteolin, quercetin, luteolin-7-glucoside, luteolin-7-rutinoside, quercetin-3-rutinoside, apigenin-7-rutinoside, tyrosol and esculetin inhibited the mutagenic activity of ofloxacin (43 µM) in E. gracilis. Water infusions from leaves of L. delavayanum and L. vulgare showed higher antimutagenic effect (pt < 0.001). The activity of these samples against ofloxacin (86 µM)-induced genotoxicity was lower, but statistically significant (pt < 0.05), excluding the water infusion of L. delavayanum leaves (pt < 0.01). Efficacy of quercetin, luteolin-7-rutinoside, apigenin-7-rutinoside was insignificant. The antimutagenic effect of most phenolics we studied could be clearly ascribed to their DPPH scavenging activity, substitution patterns and lipophilicity. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Synthesis and Analysis of Resorcinol-Acetone Copolymer
Molecules 2009, 14(1), 364-377; doi:10.3390/molecules14010364
Received: 27 November 2008 / Revised: 6 January 2009 / Accepted: 12 January 2009 / Published: 13 January 2009
Cited by 7 | PDF Full-text (327 KB) | HTML Full-text | XML Full-text
Abstract
Synthesis and characterization of resorcinol-acetone copolymer is described. The polymer was prepared by trifluoroacetic acid-catalyzed polymerization of resorcinol with acetone. According to the 1H-NMR, 13C-NMR, and MALDI-TOF Mass spectra data, the obtained polymer had three types of repeating units: isopropylidene bridged-resorcinol,
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Synthesis and characterization of resorcinol-acetone copolymer is described. The polymer was prepared by trifluoroacetic acid-catalyzed polymerization of resorcinol with acetone. According to the 1H-NMR, 13C-NMR, and MALDI-TOF Mass spectra data, the obtained polymer had three types of repeating units: isopropylidene bridged-resorcinol, chromane ring, and spiro-shaped double chromane ring, indicating that polymerization proceeded via simultaneous addition-condensation and cyclization of resorcinol with acetone. The obtained polymer can be useful not only for the development of plastic materials such as thermosets, adhesives, and coatings but also for the synthesis of biomaterials such as antimicrobial agents, pesticides, and medicines. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Antioxidant Phenolic Substances of Turkish Red Wines from Different Wine Regions
Molecules 2009, 14(1), 289-297; doi:10.3390/molecules14010289
Received: 11 October 2008 / Revised: 9 December 2008 / Accepted: 4 January 2009 / Published: 9 January 2009
Cited by 18 | PDF Full-text (178 KB) | HTML Full-text | XML Full-text
Abstract
In this study, five biologically phenolic antioxidant Turkish red wines from different regions of Turkey were determined using HPLC with PDA detection. The antioxidant capacities (AC) of the investigated wines are also determined and the relationship between the phenol content and antioxidant capacity
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In this study, five biologically phenolic antioxidant Turkish red wines from different regions of Turkey were determined using HPLC with PDA detection. The antioxidant capacities (AC) of the investigated wines are also determined and the relationship between the phenol content and antioxidant capacity is discussed. The results show that Kalecik Karası, Merlot and Cabernet Sauvignon AC values ranged between 15.8-18.7 mmol/L, 15.8-17.6 mmol/L and 18.1-22.6 mmol/L, respectively. Generally, Cabernet Sauvignon wines not only had higher levels of phenolic antioxidants, such as catechin, epicatechin and gallic acid, but also higher antioxidant capacities compared to Kalecik Karası and Merlot wines. When the results were compared on the basis of geographical area, Aegean red wines were found to contain generally higher levels of biologically important phenolics and thus to have more antioxidant capacity compared to the wines of the other regions studied. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Molecular Docking Studies and Anti-Tyrosinase Activity of Thai Mango Seed Kernel Extract
Molecules 2009, 14(1), 257-265; doi:10.3390/molecules14010257
Received: 16 November 2008 / Revised: 18 December 2008 / Accepted: 4 January 2009 / Published: 7 January 2009
Cited by 29 | PDF Full-text (595 KB) | HTML Full-text | XML Full-text
Abstract
The alcoholic extract from seed kernels of Thai mango (Mangifera indica L. cv. ‘Fahlun’) (Anacardiaceae) and its major phenolic principle (pentagalloylglucopyranose) exhibited potent, dose-dependent inhibitory effects on tyrosinase with respect to L-DOPA. Molecular docking studies revealed that the binding orientations of the
[...] Read more.
The alcoholic extract from seed kernels of Thai mango (Mangifera indica L. cv. ‘Fahlun’) (Anacardiaceae) and its major phenolic principle (pentagalloylglucopyranose) exhibited potent, dose-dependent inhibitory effects on tyrosinase with respect to L-DOPA. Molecular docking studies revealed that the binding orientations of the phenolic principles were in the tyrosinase binding pocket and their orientations were located in the hydrophobic binding pocket surrounding the binuclear copper active site. The results indicated a possible mechanism for their anti-tyrosinase activity which may involve an ability to chelate the copper atoms which are required for the catalytic activity of tyrosinase. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Phenolic and Theobromine Contents of Commercial Dark, Milk and White Chocolates on the Malaysian Market
Molecules 2009, 14(1), 200-209; doi:10.3390/molecules14010200
Received: 14 October 2008 / Revised: 3 December 2008 / Accepted: 8 December 2008 / Published: 5 January 2009
Cited by 14 | PDF Full-text (110 KB) | HTML Full-text | XML Full-text
Abstract
Chocolate contains a wide range of antioxidants that includes soluble phenolic compounds (phenolic acids, catechin, epicatechin, and proanthocyanidins), insoluble polymeric phenolics and methylxanthines. The objective of this study was to determine phenolic and theobromine contents in dark (DC), milk (MC), and white (WC)
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Chocolate contains a wide range of antioxidants that includes soluble phenolic compounds (phenolic acids, catechin, epicatechin, and proanthocyanidins), insoluble polymeric phenolics and methylxanthines. The objective of this study was to determine phenolic and theobromine contents in dark (DC), milk (MC), and white (WC) chocolates commonly found in the Malaysian marketplace. Total phenolic and flavonoids were determined by means of a spectrometric assay, while catechin, epicatechin and theobromine were quantified using a reverse-phase HPLC method. Dark chocolates exhibited the highest phenolics and flavonoids contents, followed by milk and white chocolates. Catechin and epicatechin were major flavonoids detected in dark chocolates. Theobromine was detected in dark and milk chocolates, but not in white chocolates. A high correlation (r= 0.93) between total phenolic and flavonoid contents, indicating that the major phenolic compounds in dark chocolates belong to the flavonoid class. When nutrition and health promotion are of concern, dark chocolates would be recommended over milk and white chocolates owing to their higher contents of antioxidant phenolic compounds. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Photodegradation of Acidolysis Lignin from BCMP
Molecules 2008, 13(12), 3129-3139; doi:10.3390/molecules13123129
Received: 11 November 2008 / Revised: 19 November 2008 / Accepted: 3 December 2008 / Published: 15 December 2008
Cited by 2 | PDF Full-text (209 KB) | HTML Full-text | XML Full-text
Abstract
A mild acidic dioxane extraction method was employed to isolate lignin from hardwood bleached chemimechanical pulp (BCMP). The isolated lignin was then purified and undergone elemental analysis. To study the photodegradation behavior, the lignin samples were impregnated onto the Whatman filter papers and
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A mild acidic dioxane extraction method was employed to isolate lignin from hardwood bleached chemimechanical pulp (BCMP). The isolated lignin was then purified and undergone elemental analysis. To study the photodegradation behavior, the lignin samples were impregnated onto the Whatman filter papers and irradiated with UV light for various periods. The photolyzed lignin was then recovered and analyzed by 1H-NMR spectroscopy. Phenylpropane-based formula (C9) of CMP pulp lignin and the photolyzed samples were then established with elemental analysis and 1H-NMR spectroscopy data. The results indicated that the benzaldehyde and benzoic acid type compounds were the main photodegradation products of BCMP lignin. The lignin photodegradation probably involved the degradation of phenylcoumaran units. Irradiation also increased the phenolic hydroxyl group content and decreased that of methoxyl groups, due to demethoxylation. The degrees of aromatic ring condensation were increased upon continuing the irradiation time, which imples the formation of condensed structures in photolyzed lignin. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Pyrogallol Structure in Polyphenols is Involved in Apoptosis-induction on HEK293T and K562 Cells
Molecules 2008, 13(12), 2998-3006; doi:10.3390/molecules13122998
Received: 28 October 2008 / Revised: 27 November 2008 / Accepted: 3 December 2008 / Published: 4 December 2008
Cited by 17 | PDF Full-text (188 KB) | HTML Full-text | XML Full-text
Abstract
As multiple mechanisms account for polyphenol-induced cytotoxicity, the development of structure-activity relationships (SARs) may facilitate research on cancer therapy. We studied SARs of representatives of 10 polyphenol structural types: (+)-catechin (1), (-)-epicatechin (2), (-)-epigallocatechin (3), (-)-epigallocatechin gallate (4), gallic acid (5), procyanidin B2
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As multiple mechanisms account for polyphenol-induced cytotoxicity, the development of structure-activity relationships (SARs) may facilitate research on cancer therapy. We studied SARs of representatives of 10 polyphenol structural types: (+)-catechin (1), (-)-epicatechin (2), (-)-epigallocatechin (3), (-)-epigallocatechin gallate (4), gallic acid (5), procyanidin B2 (6), procyanidin B3 (7), procyanidin B4 (8), procyanidin C1 (9), and procyanidin C2 (10). Amongst them, the polyphenols containing a pyrogallol moiety (3-5) showed the most potent cytotoxicic activity. These compounds evoked a typical DNA-laddering phenomenon in HEK293T, which indicated that the induction of apoptosis at least partly mediates their cytotoxic activity. Anti-oxidative capacity of compounds 3-5 were comparable to those of the trimers 9 and 10, which were not cytotoxic. Therefore, we suggest that pyrogallol moiety is important for fitting of polyphenols to their putative target molecule(s) in non-oxidative mechanism. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Biocatalytically Oligomerized Epicatechin with Potent and Specific Anti-proliferative Activity for Human Breast Cancer Cells
Molecules 2008, 13(11), 2704-2716; doi:10.3390/molecules13112704
Received: 18 August 2008 / Revised: 26 September 2008 / Accepted: 7 October 2008 / Published: 1 November 2008
Cited by 16 | PDF Full-text (506 KB) | HTML Full-text | XML Full-text
Abstract
Catechins, naturally occurring flavonoids derived from wine and green tea, are known to exhibit multiple health benefits. Epigallocatechin gallate (EGCG) is one of the most widely investigated catechins, but its efficacy in cancer therapy is still inconsistent and limited. The poor stability of
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Catechins, naturally occurring flavonoids derived from wine and green tea, are known to exhibit multiple health benefits. Epigallocatechin gallate (EGCG) is one of the most widely investigated catechins, but its efficacy in cancer therapy is still inconsistent and limited. The poor stability of EGCG has contributed to the disparity in the reported anti-cancer activity and other beneficial properties. Here we report an innovative enzymatic strategy for the oligomerization of catechins (specifically epicatechin) that yields stable, water-soluble oligomerized epicatechins with enhanced and highly specific anti-proliferative activity for human breast cancer cells. This one-pot oxidative oligomerization is carried out in ambient conditions using Horseradish Peroxidase (HRP) as a catalyst yielding water-soluble oligo(epicatechins). The oligomerized epicatechins obtained exhibit excellent growth inhibitory effects against human breast cancer cells with greater specificity towards growth-inhibiting cancer cells as opposed to normal cells, achieving a high therapeutic differential. Our studies indicate that water-soluble oligomeric epicatechins surpass EGCG in stability, selectivity and efficacy at lower doses. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Evaluation of the Antioxidant Activity of Syzygium cumini Leaves
Molecules 2008, 13(10), 2545-2556; doi:10.3390/molecules13102545
Received: 21 August 2008 / Revised: 10 October 2008 / Accepted: 13 October 2008 / Published: 16 October 2008
Cited by 40 | PDF Full-text (515 KB) | HTML Full-text | XML Full-text
Abstract
The antioxidant activity of Syzygium cumini leaf extracts was investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging and ferric-reducing antioxidant power (FRAP) assays. The methanolic extract and its four water, ethyl acetate, chloroform, and n-hexane fractions were prepared and subjected to antioxidant evaluation.
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The antioxidant activity of Syzygium cumini leaf extracts was investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging and ferric-reducing antioxidant power (FRAP) assays. The methanolic extract and its four water, ethyl acetate, chloroform, and n-hexane fractions were prepared and subjected to antioxidant evaluation. The results showed that the ethyl acetate fraction had stronger antioxidant activity than the other ones. HPLC data indicated that S. cumini leaf extracts contained phenolic compounds, such as ferulic acid and catechin, responsible for their antioxidant activity. A significant linear relationship between antioxidant potency, free radical-scavenging ability and the content of phenolic compounds of leaf extracts supported this observation. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle A Comparative Study of the Radical-scavenging Activity of the Phenolcarboxylic Acids Caffeic Acid, p-Coumaric Acid, Chlorogenic Acid and Ferulic Acid, With or Without 2-Mercaptoethanol, a Thiol, Using the Induction Period Method
Molecules 2008, 13(10), 2488-2499; doi:10.3390/molecules13102488
Received: 1 September 2008 / Revised: 7 October 2008 / Accepted: 9 October 2008 / Published: 15 October 2008
Cited by 29 | PDF Full-text (200 KB) | HTML Full-text | XML Full-text
Abstract
Phenolcarboxylic acid antioxidants do not act in vivo as radical-scavengers in isolation, but rather together with GSH (glutathione), a coantioxidant, they constitute an intricate antioxidant network. Caffeic acid, p-coumaric acid, ferulic acid and chlorogenic acid with or without 2-mercaptoethanol (ME), as a
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Phenolcarboxylic acid antioxidants do not act in vivo as radical-scavengers in isolation, but rather together with GSH (glutathione), a coantioxidant, they constitute an intricate antioxidant network. Caffeic acid, p-coumaric acid, ferulic acid and chlorogenic acid with or without 2-mercaptoethanol (ME), as a substitute for GSH, was investigated by the induction period (IP) method for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN, a source of alkyl radicals, R.) and benzoyl peroxide (BPO, a source of peroxy radicals, PhCOO.) using differential scanning calorimetry (DSC). Upon PhCOO. radical scavenging, the stoichiometric factors (n, number of free radical trapped by one mole of antioxidant) for caffeic acid, ferulic acid, p-coumaric acid and chlorogenic acid were 2.4, 1.8, 1.7 and 0.9, whereas upon R. radical scavenging, the corresponding values were 1.3, 1.2, 1.0 and 0.8, respectively. Antioxidants with n values close to 2 suggest the stepwise formation of semiquinone radicals and quinones. By contrast, those with n values close to 1 suggest the formation of dimers after single-electron oxidation, possibly due to recombination of corresponding aryloxy radicals. The ratio of the rate constant of inhibition to that of propagation (kinh/kp) declined in the order chlorogenic acid > p-coumaric acid > ferulic acid > caffeic acid. The ratio of the observed IP for the phenolcarboxylic acid/2-mercapto-ethanol (ME) mixture (1:1 molar ratio) (A) to the calculated IP (the simple sum of phenol acid antioxidant and ME) (B) was investigated. Upon R. scavenging, the caffeic acid or p-coumaric acid/ME mixture was A/B > 1, particularly the former was 1.2, suggesting a synergic effect. By contrast, upon PhCOO. scavenging, the corresponding mixture was A/B < 1, particularly the latter was 0.7, suggesting an antagonistic effect. Upon both radicals scavenging, the A/B for the ferulic acid or chlorogenic acid/ME mixture was approximately 1. The reported beneficial antioxidant, anti-inflammatory and anticancer effects of caffeic acid and p-coumaric acid may be related to their prooxidant-antioxidant balance in the presence of GSH. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Evaluation of Flavonoids and Furanocoumarins from Citrus bergamia (Bergamot) Juice and Identification of New Compounds
Molecules 2008, 13(9), 2220-2228; doi:10.3390/molecules13092220
Received: 1 August 2008 / Revised: 1 September 2008 / Accepted: 9 September 2008 / Published: 18 September 2008
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Abstract
Bergamot juice (BJ) contains different classes of flavonoids (e.g. flavanones and flavones) that can exert beneficial effects on human health. The aim of this study was to evaluate the qualitative and quantitative composition of a BJ obtained from fruits harvested in Southern Italy
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Bergamot juice (BJ) contains different classes of flavonoids (e.g. flavanones and flavones) that can exert beneficial effects on human health. The aim of this study was to evaluate the qualitative and quantitative composition of a BJ obtained from fruits harvested in Southern Italy (Calabria) at the end of their maturation period. The identity of several flavonoids and furanocoumarins was assessed by co-chromatography, UV spectra and molecular weight comparison. The unknown compounds were dissociated by induced collision (CID-MS) and their identity established through the characteristic ions product. By this approach a complete profile of about twenty compounds (furano-coumarins, flavonoids C- and O-glycosides) present in BJ was obtained. Furthermore, three acylated flavanones, present in amounts of 20.1±1.1, 89.3±2.2 and 190.1±3.1 mg/L, respectively, and which seem to correspond to di-oxalate derivatives of neoeriocitrin, naringin and neohesperidin, were identified for the first time in BJ. The other main flavanones were naringin, neohesperidin and neoeriocitrin, and their content was 167.5±1.8, 123.9±1.7 and 73.3±1.6 mg/L, respectively. Concerning flavones, the total amount in BJ was about 160 mg/L and the main ones were vicenin-2, stellarin-2, rhoifolin and neodiosmin. Bergapten and bergamottin were the primary furanocoumarins in BJ and their amounts were 9.0±0.4 and 18.2±0.5 mg/L, respectively. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Phytochemical Contents and Antioxidant Capacities of Two Aloe greatheadii var. davyana Extracts
Molecules 2008, 13(9), 2169-2180; doi:10.3390/molecules13092169
Received: 10 June 2008 / Revised: 22 August 2008 / Accepted: 23 August 2008 / Published: 12 September 2008
Cited by 34 | PDF Full-text (190 KB) | HTML Full-text | XML Full-text
Abstract
Aloe greatheadii var. davyana (Asphodelaceae) is used among rural South African communities to treat arthritis, skin cancer, burns, eczema, psoriasis, digestive problems, high blood pressure and diabetes, despite very little supporting scientific evidence. Due to increased interest by both the scientific community and
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Aloe greatheadii var. davyana (Asphodelaceae) is used among rural South African communities to treat arthritis, skin cancer, burns, eczema, psoriasis, digestive problems, high blood pressure and diabetes, despite very little supporting scientific evidence. Due to increased interest by both the scientific community and industry regarding the medicinal uses of this plant species, we identified, quantified and compared the phytochemical contents and antioxidant capacities of two extracts of A. greatheadii; a leaf gel extract (LGE) and a 95 % aqueous ethanol leaf gel extract (ELGE), using various modified extraction procedures, GC-MS and spectrophotometry. Apart from extensively characterizing this medicinal plant with regards to its organic acid, polyphenols/phenolic acid, alcohol, aldehyde, ketone, alkane, pyrimidine, indole, alkaloid, phytosterol, fatty acid and dicarboxylic acid contents and antioxidant capacities, we describe a modified extraction procedure for the purpose of general phytochemical characterization, and compare this to a 95 % aqueous ethanol extraction technique. From the results it is clear that A. greatheadii contains a variety of compounds with confirmed antioxidant capacity and other putative health benefits (such as blood glucose, cholesterol and cortisol lowering properties) relating to the prevention or treatment of diabetes, cardiovascular disease, cancer and hypertension. The results also indicate that separate ethyl acetate/diethyl ether and hexane extractions of the LGE, better serve for general phytochemical characterization purposes, and 95 % aqueous ethanol extraction for concentrating selective groups of health related compounds, hence justifying its use for biological in vivo efficacy studies. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Flavonoids and a New Polyacetylene from Bidens parviflora Willd
Molecules 2008, 13(8), 1931-1941; doi:10.3390/molecules13081931
Received: 20 July 2008 / Revised: 19 August 2008 / Accepted: 26 August 2008 / Published: 28 August 2008
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Abstract
Fifteen flavonoids, 1-7 and 9-16, and a polyacetylene, 8, were isolated from the ethanol extract of the dried whole plant of Bidens parviflora Willd. by various chromatographic techniques. Their structures have been elucidated on the basis of spectroscopic analyses and chemical studies. Compound
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Fifteen flavonoids, 1-7 and 9-16, and a polyacetylene, 8, were isolated from the ethanol extract of the dried whole plant of Bidens parviflora Willd. by various chromatographic techniques. Their structures have been elucidated on the basis of spectroscopic analyses and chemical studies. Compound 8 is new and was identified as 3-(R),8(E)-decene-4,6-diyne-1,3,10-triol. All the flavonoid compounds were isolated for the first time from this plant species. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Phenolic Compounds in Field Horsetail (Equisetum arvense L.) as Natural Antioxidants
Molecules 2008, 13(7), 1455-1464; doi:10.3390/molecules13071455
Received: 12 June 2008 / Revised: 1 July 2008 / Accepted: 15 July 2008 / Published: 17 July 2008
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Abstract
In this paper, the study of antioxidant activity and phenolic composition of three different extracts (EtOAc, n-BuOH and H2O) of field horsetail (Equisetum arvense L.) is presented. The antioxidant activity has been evaluated measuring the total reducing power (expressed by Ascorbate
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In this paper, the study of antioxidant activity and phenolic composition of three different extracts (EtOAc, n-BuOH and H2O) of field horsetail (Equisetum arvense L.) is presented. The antioxidant activity has been evaluated measuring the total reducing power (expressed by Ascorbate Equivalent Antioxidant Capacity - AEAC), inhibition of lipid peroxidation, and free radical scavenging capacity (RSC) towards 2,2-diphenyl-1- picrylhydrazyl (DPPH radical) and nitric oxide (NO), respectively. In addition, the total flavonoid content (TFC) and phenolic constituents of each extract have been determined. The results obtained show that the highest RSC regarding both DPPH and NO radicals is expressed by EtOAc extract (EC50=2.37 μg/mL and EC50=90.07 μg/mL, respectively), and the lowest by H2O extract (EC50=37.2 μg/mL and EC50>333.33 μg/mL, respectively). n- BuOH extract showed the highest total reducing power (AEAC=13.40 μg/mL). Differences in the phenolic composition of examined extracts are found comparing the HPLC chemical profiles. Although, isoquercitrin is the main flavonoid in both EtOAc and n-BuOH extracts, a considerable amount of di-E-caffeoyl-meso-tartaric acid was presented in the n-BuOH extract. In H2O extract high content of phenolic acids and low percentage of flavonoids were detected. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Electrochemical Behavior and Antioxidant and Prooxidant Activity of Natural Phenolics
Molecules 2007, 12(10), 2327-2340; doi:10.3390/12102327
Received: 15 June 2007 / Revised: 4 October 2007 / Accepted: 4 October 2007 / Published: 24 October 2007
Cited by 139 | PDF Full-text (138 KB) | HTML Full-text | XML Full-text
Abstract
We have investigated the electrochemical oxidation of a number natural phenolics (salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, protocatechuic acid, o-coumaric acid, m-coumaric acid, p-coumaric acid, caffeic acid, quercetin and rutin) using cyclic voltammetry. The antioxidant properties of these
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We have investigated the electrochemical oxidation of a number natural phenolics (salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, protocatechuic acid, o-coumaric acid, m-coumaric acid, p-coumaric acid, caffeic acid, quercetin and rutin) using cyclic voltammetry. The antioxidant properties of these compounds were also studied. A structural analysis of the tested phenolics suggests that multiple OH substitution and conjugation are important determinants of the free radical scavenging activity and electrochemical behavior. Compounds with low oxidation potentials (Epa lower than 0.45) showed antioxidant activity, whereas compounds with high Epa values (>0.45) act as prooxidants. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Acetylcholinesterase Inhibition by Flavonoids from Agrimonia pilosa
Molecules 2007, 12(9), 2130-2139; doi:10.3390/12092130
Received: 28 November 2006 / Revised: 21 August 2007 / Accepted: 21 August 2007 / Published: 3 September 2007
Cited by 98 | PDF Full-text (301 KB) | HTML Full-text | XML Full-text
Abstract
In a bioassay-guided search for acetylcholinesterase (AChE) inhibitors from 180 medicinal plants, an ethyl acetate extract of whole plants of Agrimonia pilosa ledeb yielded tiliroside (1), 3-methoxy quercetin (2), quercitrin (3) and quercetin (4). We report herein for the first time that all
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In a bioassay-guided search for acetylcholinesterase (AChE) inhibitors from 180 medicinal plants, an ethyl acetate extract of whole plants of Agrimonia pilosa ledeb yielded tiliroside (1), 3-methoxy quercetin (2), quercitrin (3) and quercetin (4). We report herein for the first time that all four flavonol compounds showed significant inhibitory effects on AChE, particularly quercetin (4), which showed twice the activity of dehydroevodiamine (DHED). Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Antioxidant Capacity and In Vitro Prevention of Dental Plaque Formation by Extracts and Condensed Tannins of Paullinia cupana
Molecules 2007, 12(8), 1950-1963; doi:10.3390/12081950
Received: 28 May 2007 / Revised: 1 August 2007 / Accepted: 1 August 2007 / Published: 20 August 2007
Cited by 39 | PDF Full-text (116 KB) | HTML Full-text | XML Full-text
Abstract
Chemical evaluation of the semi-purified fraction from the seeds of guaraná, Paullinia cupana H.B.K. var. sorbilis (Mart.) Ducke, yielded the following compounds: caffeine, catechin, epicatechin, ent-epicatechin, and procyanidins B1, B2, B3, B4, A2,
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Chemical evaluation of the semi-purified fraction from the seeds of guaraná, Paullinia cupana H.B.K. var. sorbilis (Mart.) Ducke, yielded the following compounds: caffeine, catechin, epicatechin, ent-epicatechin, and procyanidins B1, B2, B3, B4, A2, and C1. Measurement of the antioxidant activity by reduction of the DPPH radical confirmed the anti-radical properties of the aqueous (AqE) and crude (EBPC) extracts and semi-purified (EPA and EPB) fractions. The EPA fraction showed radical-scavenging activity (RSA) and protected DPPH from discoloration at 5.23±0.08 (RSD%=1.49) μg/mL, and for the phosphomolybdenum complex showed a higher Relative Antioxidant Capacity (RAC) at 0.75±0.01 (1.75). The EPA fraction had a total polyphenolics content of 65.80%±0.62 (RSD%=0.93). The plant drug showed 5.47% ± 0.19 (RSD%=3.51) and 6.19% ± 0.08 (RSD%=1.29) for total polyphenolics and methylxanthines, respectively. In vitro assessment of the antibacterial potential of the Paullinia cupana extracts against Streptococcus mutans showed that these could be used in the prevention of bacterial dental plaque. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle (-)-Epicatechin-3-gallate, a Green Tea Polyphenol Is a Potent Agent Against UVB-induced Damage in HaCaT Keratinocytes
Molecules 2007, 12(8), 1845-1858; doi:10.3390/12081845
Received: 25 May 2007 / Revised: 10 August 2007 / Accepted: 10 August 2007 / Published: 14 August 2007
Cited by 35 | PDF Full-text (386 KB) | HTML Full-text | XML Full-text
Abstract
(-)-Epicatechin-3-gallate (ECG) is a polyphenolic compound similar to (-)-epigallocatechin-3-gallate (EGCG) which is abundant in green tea. Numerous workers have proposed that EGCG protects epidermal cells against UVB-induced damage. However, little has been known about whether ECG protects keratinocytes against UVB-induced damage. We decided
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(-)-Epicatechin-3-gallate (ECG) is a polyphenolic compound similar to (-)-epigallocatechin-3-gallate (EGCG) which is abundant in green tea. Numerous workers have proposed that EGCG protects epidermal cells against UVB-induced damage. However, little has been known about whether ECG protects keratinocytes against UVB-induced damage. We decided to investigate the protective effects and underlying mechanisms of ECG on UVB-induced damage. Cell viability was determined by the MTT assay. Activation of ERK1/2, p38 and JNK was analyzed by Western blotting. Intracellular H2O2 production and DNA content was analyzed by flow cytometry. Lipid peroxidation was assayed by colorimetry. In our study, we found that ECG dose-dependently attenuated UVB-induced keratinocyte death. Moreover, ECG markedly inhibited UVB-induced cell membrane lipid peroxidation and H2O2 generation in keratinocytes, suggesting that ECG can act as a free radical scavenger when keratinocytes were photodamaged. In parallel, H2O2-induced the activation of ERK1/2, p38 and JNK in keratinocytes could be inhibited by ECG. UVB-induced pre-G1 arrest leading to apoptotic changes of keratinocytes were blocked by ECG. Taken together, we provide here evidence that ECG protects keratinocytes from UVB-induced photodamage and H2O2-induced oxidative stress, possibly through inhibition of the activation of ERK1/2, p38 and JNK and/or scavenging of free radicals. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessCommunication Effect of Cooking Processes on the Contents of Two Bioactive Carotenoids in Solanum lycopersicum Tomatoes and Physalis ixocarpa and Physalis philadelphica Tomatillos
Molecules 2007, 12(8), 1829-1835; doi:10.3390/12081829
Received: 21 March 2007 / Revised: 31 July 2007 / Accepted: 31 July 2007 / Published: 13 August 2007
Cited by 9 | PDF Full-text (74 KB) | HTML Full-text | XML Full-text
Abstract
Calculation of the HPLC chromatographic retention times of different carotenoids supported our improved chromatographic separation of β-carotene and lutein in four tomatoes and two tomatillo varieties in fresh form and after three different cooking procedures: pot boiling, cooking in a pressure cooker and
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Calculation of the HPLC chromatographic retention times of different carotenoids supported our improved chromatographic separation of β-carotene and lutein in four tomatoes and two tomatillo varieties in fresh form and after three different cooking procedures: pot boiling, cooking in a pressure cooker and microwaving. A good separation was achieved experimentally using an Ultrasphere ODS column and gradient elution with an acetonitrile-tetrahydrofuran-water mobile phase. It was shown that diverse tomato species contained different amounts of β-carotene (6-400 μg/100 mg) and lutein (2-30 μg/100 mg). The concentration in fresh samples was higher than in cooked tomatoes. The β–carotene content in fresh tomatillo varied between 2 and 20 μg/100 mg. Microwaving caused partial destruction of the β-carotene and lutein in tomatillos. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle High-Yielding Synthesis of Methyl Orthoformate-Protected Hydroxytyrosol and Its Use in Preparation of Hydroxytyrosyl Acetate
Molecules 2007, 12(8), 1762-1770; doi:10.3390/12081762
Received: 30 May 2007 / Revised: 31 July 2006 / Accepted: 1 August 2007 / Published: 8 August 2007
Cited by 6 | PDF Full-text (96 KB) | HTML Full-text | XML Full-text
Abstract
The new methyl orthoformate of the powerful antioxidant hydroxytyrosol (or 2- (3,4-dihydroxyphenyl)ethanol) has been synthesized by a two-step high yielding procedure. The protection stabilizes hydroxytyrosol against fast oxidation and allows both easy chromatographic purification and long term storage. The protective group is hydrolyzed
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The new methyl orthoformate of the powerful antioxidant hydroxytyrosol (or 2- (3,4-dihydroxyphenyl)ethanol) has been synthesized by a two-step high yielding procedure. The protection stabilizes hydroxytyrosol against fast oxidation and allows both easy chromatographic purification and long term storage. The protective group is hydrolyzed over pH = 10 and below pH = 5, thus allowing the release of the active principle under physiological conditions. The use of the methyl orthoformate-protected hydroxytyrosol allows the preparation of protected hydroxytyrosyl esters, like the acetate herein reported, by selective esterification of the alcoholic function. The subsequent quantitative deprotection under non-aqueous and mild conditions affords the hydroxytyrosyl acetate in high yields. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Characterization of Phenolic Compounds in Pinus laricio Needles and Their Responses to Prescribed Burnings
Molecules 2007, 12(8), 1614-1622; doi:10.3390/12081614
Received: 30 May 2007 / Revised: 19 July 2007 / Accepted: 19 July 2007 / Published: 30 July 2007
Cited by 20 | PDF Full-text (54 KB) | HTML Full-text | XML Full-text
Abstract
Fire is a dominant ecological factor in Mediterranean-type ecosystems. Management strategies include prescribed (controlled) burning, which has been used in the management of several species, such as Pinus nigra ssp laricio var. Corsicana, a pine endemic to Corsica of great ecological and
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Fire is a dominant ecological factor in Mediterranean-type ecosystems. Management strategies include prescribed (controlled) burning, which has been used in the management of several species, such as Pinus nigra ssp laricio var. Corsicana, a pine endemic to Corsica of great ecological and economic importance. The effects of prescribed burning on Pinus laricio have been little studied. The first aim of this study was to characterize total and simple phenolic compounds in Pinus laricio. The second aim was to understand: i) the short term (one to three months) and medium term (three years) effects of prescribed burning, and ii) the effects of periodic prescribed burning on the production of phenolic compounds in Pinus laricio. The first result of this study is the presence of total and simple phenolic compounds in the needles of Pinus laricio. 3-Vanillyl propanol is the major compound. After a prescribed burning, the synthesis of total phenolic compounds increases in Pinus laricio for a period of three months. Total phenolic compounds could be used as bioindicators for the short-term response of Pinus laricio needles to prescribed burning. Simple phenolic compounds do not seem to be good indicators of the impact of prescribed burning because prescribed burnings are low in intensity. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Leishmanicidal and Cholinesterase Inhibiting Activities of Phenolic Compounds from Allanblackia monticola and Symphonia globulifera
Molecules 2007, 12(8), 1548-1557; doi:10.3390/12081548
Received: 15 May 2007 / Revised: 8 July 2007 / Accepted: 9 July 2007 / Published: 20 July 2007
Cited by 44 | PDF Full-text (68 KB) | HTML Full-text | XML Full-text
Abstract
In a preliminary antiprotozoal screening of several Clusiaceae species, the methanolic extracts of Allanblackia monticola and Symphonia globulifera showed high in vitro leishmanicidal activity. Further bioguided phytochemical investigation led to the isolation of four benzophenones: guttiferone A (1), garcinol (2), cambogin (3) and
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In a preliminary antiprotozoal screening of several Clusiaceae species, the methanolic extracts of Allanblackia monticola and Symphonia globulifera showed high in vitro leishmanicidal activity. Further bioguided phytochemical investigation led to the isolation of four benzophenones: guttiferone A (1), garcinol (2), cambogin (3) and guttiferone F (4), along with three xanthones: allanxanthone A (5), xanthone V1 (6) and globulixanthone C (7) as active constituents. Compounds 1 and 6 were isolated from S. globulifera leaves, while compounds 2-5 were obtained from A. monticola fruits. Guttiferone A (1) and F (4) showed particulary strong leishmanicidal activity in vitro, with IC50 values (0.2 μM and 0.16 μM, respectively) comparable to that of the reference compound, miltefosine (0.46 μM). Although the leishmanicidal activity is promising, the cytotoxicity profile of these compounds prevent at this state further in vivo biological evaluation. In addition, all the isolated compounds were tested in vitro for their anticholinesterase properties. The four benzophenones showed potent anticholinesterase properties towards acetylcholinesterase (AChE) and butylcholinesterase (AChE). For AChE, the IC50 value (0.66 μM) of garcinol (2) was almost equal to that of the reference compound galanthamine (0.50 μM). Furthermore, guttiferone A (1) and guttiferone F (4) (IC50 = 2.77 and 3.50 μM, respectively) were more active than galanthamine (IC50 = 8.5) against BChE. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle The Anti-apoptosis Effects of Daidzein in the Brain of D-Galactose Treated Mice
Molecules 2007, 12(7), 1455-1470; doi:10.3390/12071455
Received: 30 May 2007 / Revised: 3 July 2007 / Accepted: 13 July 2007 / Published: 19 July 2007
Cited by 12 | PDF Full-text (309 KB) | HTML Full-text | XML Full-text
Abstract
The purpose of this study was to explore the neuroprotective effects of daidzein on the apoptotic pathway in the hippocampus and cortex of D-galactose treated mice. For this purpose we have examined the expression of bcl-2 mRNA, bax mRNA and caspase-3 in the
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The purpose of this study was to explore the neuroprotective effects of daidzein on the apoptotic pathway in the hippocampus and cortex of D-galactose treated mice. For this purpose we have examined the expression of bcl-2 mRNA, bax mRNA and caspase-3 in the hippocampus and cortex of D-galactose-treated mice after fed with 10 or 5 mg/kg of daidzein. The results of in situ hybridization experiments indicate that daidzein could help increase the transcriptions of bcl-2 and decrease the transcriptions of bax in those brain regions of D-galactose-treated mice. Furthermore, immunohistochemical studies showed that daidzein could reduce the expression of caspase-3 in both brain regions. These results suggest that daidzein in soybean can inhibit the D-gal induced apoptosis via Bcl-2/Bax apoptotic pathway and be a potential medical candidate for neurodegeneration therapy. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Structural Characterisation by ESI-MS of Feruloylated Arabino-oligosaccharides Synthesised by Chemoenzymatic Esterification
Molecules 2007, 12(7), 1367-1375; doi:10.3390/12071367
Received: 12 June 2007 / Revised: 3 July 2007 / Accepted: 3 July 2007 / Published: 9 July 2007
Cited by 13 | PDF Full-text (229 KB) | HTML Full-text | XML Full-text
Abstract The chemoenzymatic synthesis of feruloylated arabino-oligosaccharides has been achieved, using a feruloyl esterase type C from Sporotrichum thermophile (StFaeC).The structure of the feruloylated products was confirmed by ESI-MSn. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle A Simplified Procedure for Indole Alkaloid Extraction from Catharanthus roseus Combined with a Semi-synthetic Production Process for Vinblastine
Molecules 2007, 12(7), 1307-1315; doi:10.3390/12071307
Received: 30 May 2007 / Revised: 1 July 2007 / Accepted: 4 July 2007 / Published: 5 July 2007
Cited by 15 | PDF Full-text (75 KB) | HTML Full-text | XML Full-text
Abstract
Dried leaves of Catharanthus roseus were extracted with aqueous acidic 0.1 M solution of HCl. Alkaloid-embonate complexes were obtained as precipitates by treating the extract with an alkaline (NaOH) solution of embonic acid (4,4-methylene-bis-3-hydroxynaphtalenecarboxylic acid). The precipitate mainly consisted of catharanthine and vindoline
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Dried leaves of Catharanthus roseus were extracted with aqueous acidic 0.1 M solution of HCl. Alkaloid-embonate complexes were obtained as precipitates by treating the extract with an alkaline (NaOH) solution of embonic acid (4,4-methylene-bis-3-hydroxynaphtalenecarboxylic acid). The precipitate mainly consisted of catharanthine and vindoline embonates and it was directly used as the starting material for a semi-synthesis of the anti-cancer bisindole alkaloid vinblastine. The coupling reaction involved oxidation of catharanthine in aqueous acidic medium by singlet oxygen (1O2), continuously produced in situ by the reaction between H2O2 with NaClO. An excess of NaBH4 was used for the reduction step. Analysis of the reaction mixture indicated a maximum yield of 20% for vinblastine at pH 8.3, based on the initial amount of catharanthine concentration. Direct-injection electrospray ionization mass spectrometry in positive ion mode was used for the identification of vinblastine. The mass spectra of vinblastine were dominated by the corresponding protonated molecular ion [M+H]+ at m/z 811 and the characteristic fragment ions matched with those of the standard compound. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle (-)-Catechin in Cocoa and Chocolate: Occurence and Analysis of an Atypical Flavan-3-ol Enantiomer
Molecules 2007, 12(7), 1274-1288; doi:10.3390/12071274
Received: 30 May 2007 / Revised: 2 July 2007 / Accepted: 2 July 2007 / Published: 4 July 2007
Cited by 53 | PDF Full-text (155 KB) | HTML Full-text | XML Full-text
Abstract
Cocoa contains high levels of different flavonoids. In the present study, the enantioseparation of catechin and epicatechin in cocoa and cocoa products by chiral capillary electrophoresis (CCE) was performed. A baseline separation of the catechin and epicatechin enantiomers was achieved by using 0.1
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Cocoa contains high levels of different flavonoids. In the present study, the enantioseparation of catechin and epicatechin in cocoa and cocoa products by chiral capillary electrophoresis (CCE) was performed. A baseline separation of the catechin and epicatechin enantiomers was achieved by using 0.1 mol·L−1 borate buffer (pH 8.5) with 12 mmol·L-1 (2-hydroxypropyl)-γ-cyclodextrin as chiral selector, a fused-silica capillary with 50 cm effective length (75 μm I.D.), +18 kV applied voltage, a temperature of 20°C and direct UV detection at 280 nm. To avoid comigration or coelution of other similar substances, the flavan-3-ols were isolated and purified using polyamide-solid-phase-extraction and LC-MS analysis. As expected, we found (-)-epicatechin and (+)-catechin inunfermented, dried, unroasted cocoa beans. In contrast, roasted cocoa beans and cocoa products additionally contained the atypical flavan-3-ol (-)-catechin. This is generally formed during the manufacturing process by an epimerization which converts (-)-epicatechin to its epimer (-)-catechin. High temperatures during the cocoa bean roasting process and particularly the alkalization of the cocoa powder are the main factors inducing the epimerization reaction. In addition to the analysis of cocoa and cocoa products, peak ratios were calculated for a better differentiation of the cocoa products. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Solar Ultraviolet-B Radiation Increases Phenolic Content and Ferric Reducing Antioxidant Power in Avena sativa
Molecules 2007, 12(6), 1220-1232; doi:10.3390/12061220
Received: 1 May 2007 / Revised: 26 June 2007 / Accepted: 26 June 2007 / Published: 29 June 2007
Cited by 22 | PDF Full-text (96 KB) | HTML Full-text | XML Full-text
Abstract
We examined the influence of solar ultraviolet-B radiation (UV-B; 280-320 nm) on the maximum photochemical efficiency of photosystem II (Fv/Fm), bulk-soluble phenolic concentrations, ferric-reducing antioxidant power (FRAP) and growth of Avena sativa. Treatments involved placing filters on frames
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We examined the influence of solar ultraviolet-B radiation (UV-B; 280-320 nm) on the maximum photochemical efficiency of photosystem II (Fv/Fm), bulk-soluble phenolic concentrations, ferric-reducing antioxidant power (FRAP) and growth of Avena sativa. Treatments involved placing filters on frames over potted plants that reduced levels of biologically effective UV-B by either 71% (reduced UV-B) or by 19% (near-ambient UV-B) over the 52 day experiment (04 July - 25 August 2002). Plants growing under near-ambient UV-B had 38% less total biomass than those under reduced UV-B. The reduction in biomass was mainly the result of a 24% lower leaf elongation rate, resulting in shorter leaves and less total leaf area than plants under reduced UV-B. In addition, plants growing under near-ambient UV-B had up to 17% lower Fv/Fm values early in the experiment, and this effect declined with plant age. Concentrations of bulk-soluble phenolics and FRAP values were 17 and 24% higher under near-ambient UV-B than under reduced UV-B, respectively. There was a positive relationship between bulk-soluble phenolic concentrations and FRAP values. There were no UV-B effects on concentrations of carotenoids (carotenes + xanthophylls). Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Antiradical Activity of Paulownia tomentosa (Scrophulariaceae) Extracts
Molecules 2007, 12(6), 1210-1219; doi:10.3390/12061210
Received: 27 May 2007 / Revised: 21 June 2007 / Accepted: 25 June 2007 / Published: 27 June 2007
Cited by 14 | PDF Full-text (278 KB) | HTML Full-text | XML Full-text
Abstract
Paulownia tomentosa is a large indecidous tree planted mostly for its fast growing wood and decoratative purposes. The tree is also used in traditional Chinese medicine. As a part of our study of natural polyphenols, the fruits of Paulownia tomentosa were extracted by
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Paulownia tomentosa is a large indecidous tree planted mostly for its fast growing wood and decoratative purposes. The tree is also used in traditional Chinese medicine. As a part of our study of natural polyphenols, the fruits of Paulownia tomentosa were extracted by EtOH and than subjected to liquid/liquid extraction. Fractions were analysed by TLC and HPLC to determine presence of phenolic substantaces. We identified and quantified acteoside (1) and isoacteoside (2) in the EtOAc and n-BuOH extracts; mimulone (3) and diplacone (4) in the MeOH extract. To determine the antiradical activity of extracts we used the anti DPPH and peroxynitrite assays. The activity was expressed as Trolox C equivalents, IC50 for DPPH scavenging and a time dependency course was established. The polyphenols content was determined; results were expressed as gallic acid equivalents. Using these methods we found the fractions of the n-BuOH, EtOAc and MeOH extracts that display antiradical activity, which could be exploited as potential pharmaceuticals. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Phenolic Compounds and Antimicrobial Activity of Olive (Olea europaea L. Cv. Cobrançosa) Leaves
Molecules 2007, 12(5), 1153-1162; doi:10.3390/12051153
Received: 23 February 2007 / Revised: 24 May 2007 / Accepted: 24 May 2007 / Published: 26 May 2007
Cited by 159 | PDF Full-text (73 KB) | HTML Full-text | XML Full-text
Abstract
We report the determination of phenolic compounds in olive leaves by reversed-phase HPLC/DAD, and the evaluation of their in vitro activity against several microorganisms that may be causal agents of human intestinal and respiratory tract infections, namely Gram positive (Bacillus cereus,
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We report the determination of phenolic compounds in olive leaves by reversed-phase HPLC/DAD, and the evaluation of their in vitro activity against several microorganisms that may be causal agents of human intestinal and respiratory tract infections, namely Gram positive (Bacillus cereus, B. subtilis and Staphylococcus aureus), Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) and fungi (Candida albicans and Cryptococcus neoformans). Seven phenolic compounds were identified and quantified: caffeic acid, verbascoside, oleuropein, luteolin 7-O-glucoside, rutin, apigenin 7-O-glucoside and luteolin 4’-O-glucoside. At low concentrations olive leafs extracts showed an unusual combined antibacterial and antifungal action, which suggest their great potential as nutraceuticals, particulalry as a source of phenolic compounds. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Flavanol Derivatives from Rhizophora stylosa and Their DPPH Radical Scavenging Activity
Molecules 2007, 12(5), 1163-1169; doi:10.3390/12051163
Received: 18 May 2007 / Revised: 15 May 2007 / Accepted: 16 May 2007 / Published: 26 May 2007
Cited by 18 | PDF Full-text (73 KB) | HTML Full-text | XML Full-text
Abstract
A new acetylated flavanol, 3,7-O-diacetyl (–)-epicatechin (3), and seven known flavanol derivatives, (–)-epicatechin (1), 3-O-acetyl (–)-epicatechin (2), 3,3′,4′,5,7-O-pentaacetyl (–)-epicatechin (4), (+)-afzelechin (5), (+)-catechin (6), cinchonain Ib (7), and proanthocyanidin B2 (8), were isolated from the stems and twigs of
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A new acetylated flavanol, 3,7-O-diacetyl (–)-epicatechin (3), and seven known flavanol derivatives, (–)-epicatechin (1), 3-O-acetyl (–)-epicatechin (2), 3,3′,4′,5,7-O-pentaacetyl (–)-epicatechin (4), (+)-afzelechin (5), (+)-catechin (6), cinchonain Ib (7), and proanthocyanidin B2 (8), were isolated from the stems and twigs of the mangrove plant Rhizophora stylosa and identified. The crude extract, the different fractions and all of the purified compounds were evaluated for DPPH radical scavenging activity. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Antioxidant Activity of a New Aromatic Geranyl Derivative of the Resinous Exudates from Heliotropium glutinosum Phil.
Molecules 2007, 12(5), 1057-1063; doi:10.3390/12051057
Received: 5 April 2007 / Revised: 15 May 2007 / Accepted: 15 May 2007 / Published: 21 May 2007
Cited by 19 | PDF Full-text (58 KB) | HTML Full-text | XML Full-text
Abstract
Heliotropium glutinosum Phil. (Heliotropiceae) is a resinous bush that grows at a height of 2000 m in Chañaral, Chile. From the resinous exudates of Heliotropium glutinosum Phil. a new aromatic geranyl derivative: 4-methoxy-3-[(2)-7’-methyl-3’-hydroxymethyl-2’,6’-octadienyl] phenol (1) and three flavonoids: 5,3'-dihydroxy-7,4'-dimethoxyflavanone (2), 5,4'-dihydroxy-7-methoxyflavanone
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Heliotropium glutinosum Phil. (Heliotropiceae) is a resinous bush that grows at a height of 2000 m in Chañaral, Chile. From the resinous exudates of Heliotropium glutinosum Phil. a new aromatic geranyl derivative: 4-methoxy-3-[(2)-7’-methyl-3’-hydroxymethyl-2’,6’-octadienyl] phenol (1) and three flavonoids: 5,3'-dihydroxy-7,4'-dimethoxyflavanone (2), 5,4'-dihydroxy-7-methoxyflavanone (3) and 4'-acetyl-5-hydroxy-7-methoxyflavanone (4) were isolated and their structures were determined. Their antioxidant activity were evaluated using the bleaching of ABTS and DPPH derived cation radical methods and expressed in terms of FRE (fast reacting equivalents) and TRE (total reacting equivalents), where FRE is a good measure of the quick protection of a given compound against oxidants and TRE measures the degree of long-term protection of the antioxidant, or how effective it is against a strong oxidative stress. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Evaluation of Antioxidative Activity of Croatian Propolis Samples Using DPPH· and ABTS·+ Stable Free Radical Assays
Molecules 2007, 12(5), 1006-1021; doi:10.3390/12051006
Received: 10 April 2007 / Revised: 26 April 2007 / Accepted: 2 May 2007 / Published: 15 May 2007
Cited by 25 | PDF Full-text (199 KB) | HTML Full-text | XML Full-text
Abstract
Propolis is one of the richest sources of plant phenolics (flavonoids and phenolic acids), which are widely recognized as rather strong antioxidants. The aim of our work was to use colored stable free radical (DPPH· and ABTS·+) spectrophotometric and thin-layer chromatographic
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Propolis is one of the richest sources of plant phenolics (flavonoids and phenolic acids), which are widely recognized as rather strong antioxidants. The aim of our work was to use colored stable free radical (DPPH· and ABTS·+) spectrophotometric and thin-layer chromatographic (TLC) assays to study the antioxidative behavior of the phenolics (caffeic acid, galangin and pinocembrin) most commonly present in Croatian propolis samples obtained from different Croatian regions. We propose a mathematical model providing a more sophisticated interpretation of the obtained results and a new parameter named antioxidative efficiency (AOE) is introduced. The kinetic behaviour of chosen standards determined by spectrophotometric assays follows the exponential decrease of the absorption curve. Explained numerically, AOE represents the absolute value of the first derivative of an absorbance curve in the point A0/e (where A0 is the absorbance measured at t = 0 and e is the natural logarithm base). The advantage of this newly introduced parameter is that it provides an easy and accurate mutual comparison between the rates of antioxidative efficiency of different propolis samples. A TLC assay was only applicable in the case of the DPPH· radical. Dose-response curves were described using a linear function with AOE expressed as a coefficient of the slope. The chromatographic method was shown to be very rapid, reliable and easy-to-perform. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Effects of Quercetin on Mushroom Tyrosinase and B16-F10 Melanoma Cells
Molecules 2007, 12(5), 1045-1056; doi:10.3390/12051045
Received: 12 April 2007 / Revised: 14 May 2007 / Accepted: 14 May 2007 / Published: 15 May 2007
Cited by 29 | PDF Full-text (208 KB) | HTML Full-text | XML Full-text
Abstract
In searching for tyrosinase inhibitors from plants using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, quercetin was found to be partially oxidized to the corresponding o-quinone under catalysis by mushroom tyrosinase (EC 1.14.18.1). Simultaneously, L-DOPA was also oxidized to dopaquinone and
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In searching for tyrosinase inhibitors from plants using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, quercetin was found to be partially oxidized to the corresponding o-quinone under catalysis by mushroom tyrosinase (EC 1.14.18.1). Simultaneously, L-DOPA was also oxidized to dopaquinone and both o-quinones were further oxidized, respectively. The remaining quercetin partially formed adducts with dopaquinone through a Michael type addition. In general, flavonols form adducts with dopaquinone as long as their 3-hydroxyl group is free. Quercetin enhanced melanin production per cell in cultured murine B16-F10 melanoma cells, but this effect may be due in part to melanocytotoxicity. The concentration leading to 50% viable cells lost was established as 20 μM and almost complete lethality was observed at 80 μM. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Cancer Preventive Mechanismsof the Green Tea Polyphenol (-)-Epigallocatechin-3-gallate
Molecules 2007, 12(5), 946-957; doi:10.3390/12050946
Received: 15 March 2007 / Revised: 30 April 2007 / Accepted: 1 May 2007 / Published: 3 May 2007
Cited by 72 | PDF Full-text (187 KB) | HTML Full-text | XML Full-text
Abstract
Accumulating evidence indicates that consumption of tea, especially green tea, is good for preventing cancer. To elucidate the cancer preventive mechanisms of green tea, much effort has been devoted to investigating the anticancer effects of (-)-epigallocatechin-3-gallate (EGCG), the major component of green tea.
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Accumulating evidence indicates that consumption of tea, especially green tea, is good for preventing cancer. To elucidate the cancer preventive mechanisms of green tea, much effort has been devoted to investigating the anticancer effects of (-)-epigallocatechin-3-gallate (EGCG), the major component of green tea. It has been revealed that EGCG restrained carcinogenesis in a variety of tissues through inhibition of mitogen-activated protein kinases (MAPK), growth factor-related cell signaling, activation of activator protein 1 (AP-1) and nuclear factor-B (NF-κB), topoisomerase I, matrix metalloproteinases and other potential targets. Therefore, EGCG is a multipotent anticancer agent, which not only provides solid evidence to support the anticancer potential of green tea, but also offers new clues for discovering multiple-targeted anticancer drugs. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessCommunication How Many Drugs Are Catecholics
Molecules 2007, 12(4), 878-884; doi:10.3390/12040878
Received: 27 March 2007 / Revised: 23 April 2007 / Accepted: 25 April 2007 / Published: 30 April 2007
Cited by 25 | PDF Full-text (58 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
By examination of the 8659 drugs recorded in the Comprehensive Medicinal Chemistry (CMC) database, 78 catecholics (including five pyrogallolics) were identified, of which 17 are currently prescribed by FDA. Through analyzing the substitutent patterns, ClogPs and O-H bond dissociation enthalpies(BDEs) of
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By examination of the 8659 drugs recorded in the Comprehensive Medicinal Chemistry (CMC) database, 78 catecholics (including five pyrogallolics) were identified, of which 17 are currently prescribed by FDA. Through analyzing the substitutent patterns, ClogPs and O-H bond dissociation enthalpies(BDEs) of the catecholic drugs, some molecular features that may benefit circumventing the toxicity of catecholics were revealed: i) strong electron-donating substituents are excluded; ii) ClogP 3; iii) an energy penalty exists for quinone formation. Besides, the present analyses also suggest that the clinical usage and dosage of currently prescribed catecholic drugs are of importance in designing or screening catecholic antioxidants. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Effects of Different Carriers on the Production of Isoflavone Powder from Soybean Cake
Molecules 2007, 12(4), 917-931; doi:10.3390/12040917
Received: 2 April 2007 / Revised: 24 April 2007 / Accepted: 25 April 2007 / Published: 30 April 2007
Cited by 7 | PDF Full-text (134 KB) | HTML Full-text | XML Full-text
Abstract
The objectives of this study were to use soybean cake as the raw material for the production of isoflavone powder and compare the effects of different carriers as well as drying methods on the powder quality. Results showed that with spray drying, a
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The objectives of this study were to use soybean cake as the raw material for the production of isoflavone powder and compare the effects of different carriers as well as drying methods on the powder quality. Results showed that with spray drying, a level of 40 % maltodextrin as carrier produced the highest yield (mass) of isoflavone powder, followed by 10 % gelatin and 1 % sodium alginate. However, a reversed trend was observed for the isoflavone content. With 1 % sodium alginate, freeze drying generated the greatest yield of isoflavone powder, followed by vacuum drying and spray drying. The isoflavone content also exhibited the same tendency. With poly-g-glutamicacid (g-PGA) as carrier, all six levels studied (0.57, 0.28, 0.14, 0.028, 0.014 and 0.003 %) were capable of forming powder containing high amounts of total isoflavone, which was comparable to that using 1% sodiumalginate by freeze drying. Both high- and low-molecular-weight g-PGA showed similar effects in terms of powder yield and isoflavone content. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Identificationof Major Phenolic Compounds of Chinese Water Chestnut and their Antioxidant Activity
Molecules 2007, 12(4), 842-852; doi:10.3390/12040842
Received: 7 April 2007 / Revised: 20 April 2007 / Accepted: 23 April 2007 / Published: 25 April 2007
Cited by 22 | PDF Full-text (137 KB) | HTML Full-text | XML Full-text
Abstract
Chinese water chestnut (CWC) is one of the most popular foods among Asian people due to its special taste and medical function. Experiments were conducted to test the antioxidant activity and then determine the major phenolic compound components present in CWC. CWC phenolic
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Chinese water chestnut (CWC) is one of the most popular foods among Asian people due to its special taste and medical function. Experiments were conducted to test the antioxidant activity and then determine the major phenolic compound components present in CWC. CWC phenolic extract strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against α,α-diphenyl-β-picrylhydrazyl (DPPH) radicals, superoxide anions and hydroxyl radicals, which was superior to ascorbic acid and butylated hydroxytoluene (BHT), two commercial used antioxidants. Furthermore, the CWC extract was found to have a relatively higher reducing power, compared with BHT. The major phenolic compounds present in CWC tissues were extracted, purified and identified by high-performance liquid chromatograph (HPLC) as (–)-gallocatechin gallate, (–)-epicatechin gallate and (+)-catechin gallate. This study suggests that CWC tissues exhibit great potential for antioxidant activity and may be useful for their nutritional and medicinal functions. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Evaluation of the Antioxidant Properties of Litchi Fruit Phenolics in Relation to Pericarp Browning Prevention
Molecules 2007, 12(4), 759-771; doi:10.3390/12040759
Received: 14 March 2007 / Revised: 25 March 2007 / Accepted: 30 March 2007 / Published: 11 April 2007
Cited by 97 | PDF Full-text (97 KB)
Abstract
Phenolics were extracted from litchi fruit pericarp (LFP) tissues, purified and their antioxidant properties analyzed. LFP phenolics strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against α,α-diphenyl-β-picrylhydrazyl (DPPH·) and hydroxyl radicals and superoxide anions. The degradation of deoxyribose by
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Phenolics were extracted from litchi fruit pericarp (LFP) tissues, purified and their antioxidant properties analyzed. LFP phenolics strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against α,α-diphenyl-β-picrylhydrazyl (DPPH·) and hydroxyl radicals and superoxide anions. The degradation of deoxyribose by hydroxyl radicals was inhibited by phenolics acting mainly as iron ion chelators, rather than by directly scavenging the radicals. Phenolics from litchi fruit pericarp were found to display similar reducing power activity as ascorbic acid. The effect of phenolic compound treatment on pericarp browning and electrolyte leakage of litchi fruit was also evaluated and it was observed that application of exogenous litchi phenolics to harvested litchi fruit significantly prevented pericarp browning and delayed increases in electrolyte leakage. These results suggest that litchi pericarp tissue phenolics could be beneficial in scavenging free radicals, maintaining membrane integrity and, thereby inhibiting pericarp browning of litchi fruit. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Screening Non-colored Phenolics in Red Wines using Liquid Chromatography/Ultraviolet and Mass Spectrometry/Mass Spectrometry Libraries
Molecules 2007, 12(3), 679-693; doi:10.3390/12030679
Received: 13 December 2006 / Revised: 24 March 2007 / Accepted: 29 March 2007 / Published: 30 March 2007
Cited by 107 | PDF Full-text (141 KB) | HTML Full-text | XML Full-text
Abstract
Liquid chromatography/ultraviolet (LC/UV) and mass spectrometry/mass spectrometry (MS/MS) libraries containing 39 phenolic compounds were established by coupling a LC and an ion trap MS with an electrospray ionization (ESI) source, operated in negative ion mode. As a result, the deprotonated [M-H]- molecule was
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Liquid chromatography/ultraviolet (LC/UV) and mass spectrometry/mass spectrometry (MS/MS) libraries containing 39 phenolic compounds were established by coupling a LC and an ion trap MS with an electrospray ionization (ESI) source, operated in negative ion mode. As a result, the deprotonated [M-H]- molecule was observed for all the analyzed compounds. Using MS/MS hydroxybenzoic acid and hydroxycinnamic acids showed a loss of CO2 and production of a [M-H-44] - fragment and as expected, the UV spectra of these two compounds were affected by their chemical structures. For flavonol and flavonol glycosides, the spectra of their glycosides and aglycones produced deprotonated [M-H]- and [A-H]- species, respectively, and their UV spectra each presented two major absorption peaks. The UV spectra and MS/MS data of flavan-3-ols and stilbenes were also investigated. Using the optimized LC/MS/MS analytical conditions, the phenolic extracts from six representative wine samples were analyzed and 31 phenolic compounds were detected, 26 of which were identified by searching the LC/UV and MS/MS libraries. Finally, the presence of phenolic compounds was confirmed in different wine samples using the LC/UV and LC/MS/MS libraries. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Identification of the Products of Oxidation of Quercetin by Air Oxygenat Ambient Temperature
Molecules 2007, 12(3), 654-672; doi:10.3390/12030654
Received: 13 January 2007 / Revised: 22 March 2007 / Accepted: 25 March 2007 / Published: 27 March 2007
Cited by 43 | PDF Full-text (223 KB) | HTML Full-text | XML Full-text
Abstract
Oxidation of quercetin by air oxygen takes place in water and aqueous ethanol solutions under mild conditions, namely in moderately-basic media (pH ∼ 8-10) at ambient temperature and in the absence of any radical initiators, without enzymatic catalysis or irradiation of the reaction
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Oxidation of quercetin by air oxygen takes place in water and aqueous ethanol solutions under mild conditions, namely in moderately-basic media (pH ∼ 8-10) at ambient temperature and in the absence of any radical initiators, without enzymatic catalysis or irradiation of the reaction media by light. The principal reaction products are typical of other oxidative degradation processes of quercetin, namely 3,4-dihydroxy-benzoic (proto-catechuic) and 2,4,6-trihydroxybenzoic (phloroglucinic) acids, as well as the decarboxylation product of the latter – 1,3,5-trihydroxybenzene (phloroglucinol). In accordance with the literature data, this process involves the cleavage of the γ-pyrone fragment (ring C) of the quercetin molecule by oxygen, with primary formation of 4,6-dihydroxy-2-(3,4-dihydroxybenzoyloxy)benzoic acid (depside). However under such mild conditions the accepted mechanism of this reaction (oxidative decarbonylation with formation of carbon monoxide, CO) should be reconsidered as preferably an oxidative decarboxylation with formation of carbon dioxide, CO2. Direct head-space analysis of the gaseous components formed during quercetin oxidation in aqueous solution at ambient temperature indicates that the ratio of carbon dioxide/carbon monoxide in the gas phase after acidification of the reaction media is ca. 96:4 %. Oxidation under these mild conditions is typical for other flavonols having OH groups at C3 (e.g., kaempferol), but it is completely suppressed if this hydroxyl group is substituted by a glycoside fragment (as in rutin), or a methyl substituent. An alternative oxidation mechanism involving the direct cleavage of the C2-C3 bond in the diketo-tautomer of quercetin is proposed. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Methyl Jasmonate and Salicylic Acid Induced Oxidative Stress and Accumulation of Phenolics in Panax ginseng Bioreactor Root Suspension Cultures
Molecules 2007, 12(3), 607-621; doi:10.3390/12030607
Received: 24 January 2007 / Revised: 13 March 2007 / Accepted: 18 March 2007 / Published: 23 March 2007
Cited by 60 | PDF Full-text (124 KB) | HTML Full-text | XML Full-text
Abstract
To investigate the enzyme variations responsible for the synthesis of phenolics, 40 day-old adventitious roots of Panax ginseng were treated with 200 μM methyl jasmonate (MJ) or salicylic acid (SA) in a 5 L bioreactor suspension culture (working volume 4 L). Both treatments
[...] Read more.
To investigate the enzyme variations responsible for the synthesis of phenolics, 40 day-old adventitious roots of Panax ginseng were treated with 200 μM methyl jasmonate (MJ) or salicylic acid (SA) in a 5 L bioreactor suspension culture (working volume 4 L). Both treatments caused an increase in the carbonyl and hydrogen peroxide (H2O2) contents, although the levels were lower in SA treated roots. Total phenolic, flavonoid, ascorbic acid, non-protein thiol (NPSH) and cysteine contents and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical reducing activity were increased by MJ and SA. Fresh weight (FW) and dry weight (DW) decreased significantly after 9 days of exposure to SA and MJ. The highest total phenolics (62%), DPPH activity (40%), flavonoids (88%), ascorbic acid (55%), NPSH (33%), and cysteine (62%) contents compared to control were obtained after 9 days in SA treated roots. The activities of glucose 6-phosphate dehydrogenase, phenylalanine ammonia lyase, substrate specific peroxidases (caffeic acid peroxidase, quercetin peroxidase and ferulic acid peroxidase) were higher in MJ treated roots than the SA treated ones. Increased shikimate dehydrogenase, chlorogenic acid peroxidase and β-glucosidase activities and proline content were observed in SA treated roots than in MJ ones. Cinnamyl alcohol dehydrogenase activity remained unaffected by both MJ and SA. These results strongly indicate that MJ and SA induce the accumulation of phenolic compounds in ginseng root by altering the phenolic synthesis enzymes. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Phenolic Content and Antioxidant Properties of Soybean (Glycine max (L.) Merr.) Seeds
Molecules 2007, 12(3), 576-581; doi:10.3390/12030576
Received: 13 February 2007 / Revised: 6 March 2007 / Accepted: 14 March 2007 / Published: 21 March 2007
Cited by 48 | PDF Full-text (59 KB) | HTML Full-text | XML Full-text
Abstract
The contents and antioxidant ability of various classes of phenolic compounds present in the seeds of twenty soybean hybrids were evaluated. Total phenolics, tannins and proanthocyanidins were determined spectrophotometrically, after extraction of seeds with 70% aqueous acetone. In addition, the flavonoid contents were
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The contents and antioxidant ability of various classes of phenolic compounds present in the seeds of twenty soybean hybrids were evaluated. Total phenolics, tannins and proanthocyanidins were determined spectrophotometrically, after extraction of seeds with 70% aqueous acetone. In addition, the flavonoid contents were determined. The antioxidant activity of aqueous acetone extracts was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity assay. The highest contents of total phenolics were found in Serbian cultivar 1511 and Chinese cultivar LN92-7369, which also displayed the highest total antioxidant activity. Conversely, genotypes poor in phenolics also showed low levels of DPPH-radical scavenging activity. The results suggested that besides protein and oil contents, the phenolic contents should be also considered as an important characteristic feature of soybean seeds, and as a potential selection criterion for antioxidant activity in soybean. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Characterization of Flavonoid Subgroups and Hydroxy Substitution by HPLC-MS/MS
Molecules 2007, 12(3), 593-606; doi:10.3390/12030593
Received: 15 January 2007 / Revised: 13 March 2007 / Accepted: 14 March 2007 / Published: 21 March 2007
Cited by 88 | PDF Full-text (96 KB) | HTML Full-text | XML Full-text
Abstract
HPLC-DAD coupled with mass spectrometry in the positive ionization mode was applied to study the fragmentation of twelve selected flavonoids. Compounds belonging to all the major subgroups found in common plants, i.e. flavonols, flavones, dihydroflavonols, flavanones and flavanols were studied. Compound standards were
[...] Read more.
HPLC-DAD coupled with mass spectrometry in the positive ionization mode was applied to study the fragmentation of twelve selected flavonoids. Compounds belonging to all the major subgroups found in common plants, i.e. flavonols, flavones, dihydroflavonols, flavanones and flavanols were studied. Compound standards were injected into the spectrometer and produced characteristic mass spectra. The fragmentation of each compound was studied and it was shown that the dehydration andcarbon monoxide losses from the [M+H]+ ion by the members of each subgroup produced specific fragments, thus allowing the characterization of the flavonoid subgroups. Moreover, fragments resulting from fission of the C-rings are specific of each subgroup and revealed the substitution pattern of A- and B-rings. In order to verify the identifying efficiency of the positive ionization mode through these characteristic fragmentations, the unknown flavonoids of an Origanum vulgare diethyl ether extract were separated withthe HPLC system and the major peaks were successfully identified with the mass spectrometer. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessCommunication Preparative Separation and Identification of the Flavonoid Phlorhizin from the Crude Extract of Lithocarpus Polystachyus Rehd
Molecules 2007, 12(3), 552-562; doi:10.3390/12030552
Received: 6 February 2007 / Revised: 13 March 2007 / Accepted: 13 March 2007 / Published: 20 March 2007
Cited by 21 | PDF Full-text (100 KB) | HTML Full-text | XML Full-text
Abstract
The flavonoid phlorhizin is abundant in the leaves of Sweet Tea(ST, Lithocarpus Polystachyus Rehd). Phlorhizinwas preparatively separated and purified from a crude ST extract containing 40% total flavonoids by static adsorption and dynamic desorption on ADS-7 macroporous resin and neutral alumina column chromatography.
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The flavonoid phlorhizin is abundant in the leaves of Sweet Tea(ST, Lithocarpus Polystachyus Rehd). Phlorhizinwas preparatively separated and purified from a crude ST extract containing 40% total flavonoids by static adsorption and dynamic desorption on ADS-7 macroporous resin and neutral alumina column chromatography. Only water and ethanol were used as solvents and eluants throughout the whole separation and purification process. Using a phlorhizin standard as the reference compound, the target compound separated from the crude ST extracts was analyzed by thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and electrosprayionization mass spectrometry (EIS-MS) and identified as 99.87% pure (by HPLC-UV) phlorhizin. The results showed that 10g of the targetcompound could be obtained from 40g of the crude extracts in a single operation, indicating a 40% recovery. Therefore, this represents an efficientand environmentally-friendly technology for separating and purifying phlorhizinfrom ST leaves. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Effect of Extraction Conditions on Measured Total Polyphenol Contents and Antioxidant and Antibacterial Activities of Black Tea
Molecules 2007, 12(3), 484-496; doi:10.3390/12030484
Received: 8 January 2007 / Revised: 6 March 2007 / Accepted: 12 March 2007 / Published: 13 March 2007
Cited by 57 | PDF Full-text (84 KB) | HTML Full-text | XML Full-text
Abstract
Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethyl-formamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was
[...] Read more.
Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethyl-formamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was found to be in the range of 0.44-114.01 mg gallic acid equivalents (GAE)/g dry weight tea, depending on the solvent used and the length of the extraction process. In general, aqueous acetone or DMF extracts displayed the highest polyphenol contents and antioxidant activity, while absolute acetone was the least efficient solvent. Antioxidant activities of tea extracts tested using the reducing power and 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods ranged from 0.09 to 1.18 and from 2.60 to 95.42 %, respectively, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations. Aqueous solvent black tea extracts also possessed antibacterial activity, depending on the solvent used and bacterial species tested. Staphylococcus aureus was found to be the most sensitive to all tea extracts, except for the methanol extract. Tea extracts were not effective against Y. enterocolitica, L. monocytogenes and E. coli O157:H7. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Phenolic Antioxidants Identified by ESI-MS from Yerba Maté (Ilex paraguariensis) and Green Tea (Camelia sinensis) Extracts
Molecules 2007, 12(3), 423-432; doi:10.3390/12030423
Received: 21 December 2006 / Revised: 3 March 2007 / Accepted: 4 March 2007 / Published: 12 March 2007
Cited by 141 | PDF Full-text (160 KB) | HTML Full-text | XML Full-text
Abstract
Aqueous extracts of green yerba maté (Ilex paraguariensis) and green tea (Camellia sinensis) are good sources of phenolic antioxidants, as already described in the literature. The subject of this study were organic extracts from yerba maté, both green and
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Aqueous extracts of green yerba maté (Ilex paraguariensis) and green tea (Camellia sinensis) are good sources of phenolic antioxidants, as already described in the literature. The subject of this study were organic extracts from yerba maté, both green and roasted, and from green tea. Their phenolic profiles were characterized by direct infusion electrospray insertion mass spectrometry (ESI-MS) and their free radical scavenging activity was determined by the DPPH assay. Organic extracts containing phenolic antioxidants might be used as natural antioxidants by the food industry, replacing the synthetic phenolic additives used nowadays. Ethanolic and aqueous extracts from green yerba maté, roasted yerba maté and green tea showed excellent DPPH scavenging activity (>89%). The ether extracts from green and roasted yerba maté displayed a weak scavenging activity, different from the behavior observed for the green tea ether extract. The main phenolic compounds identified in green yerba maté water and ethanolic extracts were: caffeic acid, quinic acid, caffeoyl glucose, caffeoylquinic acid, feruloylquinic acid, dicaffeoylquinic acid and rutin. After the roasting process two new compounds were formed: caffeoylshikimic acid and dicaffeoylshikimic acid. The ethanolic extracts from yerba maté, both roasted and green, with lower content of phenolic compounds (3.80 and 2.83 mg/mL) presented high antioxidant activity and even at very low phenolic concentrations, ether extract from GT (0.07 mg/mL) inhibited DPPH over 90%. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessCommunication Mistletonone, a Novel Antioxidative Diarylheptanoid from the Branches and Leaves of Viscum coloratum
Molecules 2007, 12(3), 312-317; doi:10.3390/12030312
Received: 5 February 2007 / Revised: 13 February 2007 / Accepted: 18 February 2007 / Published: 6 March 2007
Cited by 10 | PDF Full-text (68 KB) | HTML Full-text | XML Full-text
Abstract
Mistletonone, a novel diarylheptanoid, was isolated from the branches and leaves of Viscum coloratum (Kom.) Nakai (Loranthaceae). It was identified as 1,7-di-(p-hydroxyphenyl)-5-hydroxyl-cis-2,3-epoxy-1-one on the basis of spectral evidence. The compound showed significant scavenging effects on hydroxyl radicals and superoxide
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Mistletonone, a novel diarylheptanoid, was isolated from the branches and leaves of Viscum coloratum (Kom.) Nakai (Loranthaceae). It was identified as 1,7-di-(p-hydroxyphenyl)-5-hydroxyl-cis-2,3-epoxy-1-one on the basis of spectral evidence. The compound showed significant scavenging effects on hydroxyl radicals and superoxide anion radicals in the direct assay using the electron spin resonance (ESR) technique. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Comparison of ChemicalComposition and Free Radical Scavenging Ability of Glycosidically Bound andFree Volatiles from Bosnian Pine (Pinus heldreichii Christ. var. leucodermis)
Molecules 2007, 12(3), 283-289; doi:10.3390/12030283
Received: 8 February 2007 / Revised: 23 February 2007 / Accepted: 23 February 2007 / Published: 2 March 2007
Cited by 7 | PDF Full-text (56 KB) | HTML Full-text | XML Full-text
Abstract
The results obtained show that Bosnian pine is richin glycosidically bound volatile compounds with strong free radical scavengingproperties. Since volatiles can be released from nonvolatile glycosideprecursors, these compounds can be considered as a hidden potential source ofantioxidant substances and may contribute to the
[...] Read more.
The results obtained show that Bosnian pine is richin glycosidically bound volatile compounds with strong free radical scavengingproperties. Since volatiles can be released from nonvolatile glycosideprecursors, these compounds can be considered as a hidden potential source ofantioxidant substances and may contribute to the total free radical scavengingability of Bosnian pine. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Reactive Oxygen Species Scavenging Activity of Flavone Glycosides from Melilotus neapolitana
Molecules 2007, 12(2), 263-270; doi:10.3390/12020263
Received: 21 January 2007 / Revised: 13 February 2007 / Accepted: 27 February 2007 / Published: 28 February 2007
Cited by 15 | PDF Full-text (78 KB) | HTML Full-text | XML Full-text
Abstract
One new and six known flavone glycosides were isolated from the MeOH extract of Melilotus neapolitana Ten. The new compound, identified as 7-O-β-D-gluco-pyranosyloxy-4',5-dihydroxy-3-[O-α-L-rhamnopyranosyl-(1→6)-3-O-β-D-glucopyrano-syloxy]flavone (1) by 1D and 2D NMR techniques and mass spectra, was isolated along with kaempferol-3-O-rutinoside (2), kaempferol-3-O-glucoside (3), rutin (4),
[...] Read more.
One new and six known flavone glycosides were isolated from the MeOH extract of Melilotus neapolitana Ten. The new compound, identified as 7-O-β-D-gluco-pyranosyloxy-4',5-dihydroxy-3-[O-α-L-rhamnopyranosyl-(1→6)-3-O-β-D-glucopyrano-syloxy]flavone (1) by 1D and 2D NMR techniques and mass spectra, was isolated along with kaempferol-3-O-rutinoside (2), kaempferol-3-O-glucoside (3), rutin (4), quercetin-3-O-glucoside (5), isorhamnetin-3-O-rutinoside (6), and isorhamnetin-3-O-glucoside (7). The antioxidant and radical scavenging activities of these compounds and the whole crude methanol extract were evaluated. The organic extract can inhibit MDA marker’s synthesis by 57%. All the metabolites displayed good reducing power, with the kaempferol (2,3) and isorhamnetin derivatives (6,7) being less active than the corresponding quercetin derivatives 4,5. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle A Novel Antioxidant Phenyl Disaccharide from Populus tremula Knotwood
Molecules 2007, 12(2), 205-217; doi:10.3390/12020205
Received: 8 January 2007 / Revised: 15 February 2007 / Accepted: 18 February 2007 / Published: 19 February 2007
Cited by 3 | PDF Full-text (157 KB) | HTML Full-text | XML Full-text
Abstract
The complete characterization of two compounds obtained from the acetoneextract of Populus tremula knotwood has been was achieved using LC-DAD-MS,MS/MS, IR and NMR. The new compounds were unequivocally identified as a mixtureof the ester isomers of the (E) and (Z) p-coumarate of 1-O-rutinose.
[...] Read more.
The complete characterization of two compounds obtained from the acetoneextract of Populus tremula knotwood has been was achieved using LC-DAD-MS,MS/MS, IR and NMR. The new compounds were unequivocally identified as a mixtureof the ester isomers of the (E) and (Z) p-coumarate of 1-O-rutinose. The isomers showedthe capacity to inhibit lipid peroxidation induced by tert-butylhydroperoxide and to trapperoxyl radicals, as determined by a chemiluminescence method. These new phenyldisaccharides also showed a significant ORAC (oxygen radical absorbance capacity)value, i.e. 11.7 μM TE (Trolox Equivalents). Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Radical-scavenging Activity of Natural Methoxyphenols vs. Synthetic Ones using the Induction Period Method
Molecules 2007, 12(2), 130-138; doi:10.3390/12020130
Received: 22 January 2007 / Revised: 31 January 2007 / Accepted: 1 February 2007 / Published: 3 February 2007
Cited by 10 | PDF Full-text (110 KB) | HTML Full-text | XML Full-text
Abstract
The radical-scavenging activities of the synthetic antioxidants 2-allyl-4-X-phenol (X=NO2, Cl, Br, OCH3, COCH3, CH3, t-(CH3)3, C6H5) and 2,4-dimethoxyphenol, and the natural antioxidants eugenol and isoeugenol, were
[...] Read more.
The radical-scavenging activities of the synthetic antioxidants 2-allyl-4-X-phenol (X=NO2, Cl, Br, OCH3, COCH3, CH3, t-(CH3)3, C6H5) and 2,4-dimethoxyphenol, and the natural antioxidants eugenol and isoeugenol, were investigated using differential scanning calorimetry (DSC) by measuring their anti-1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activity and the induction period for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO). 2-Allyl-4-methoxyphenol and 2,4-dimethoxy-phenol scavenged not only oxygen-centered radicals (PhCOO.) derived from BPO, but also carbon-centered radicals (R.) derived from the AIBN and DPPH radical much more efficiently, in comparison with eugenol and isoeugenol. 2-Allyl-4-methoxyphenol may be useful for its lower prooxidative activity. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Inhibitory Effects of 5,6,7-Trihydroxyflavones on Tyrosinase
Molecules 2007, 12(1), 86-97; doi:10.3390/12010086
Received: 8 December 2006 / Revised: 24 January 2007 / Accepted: 24 January 2007 / Published: 29 January 2007
Cited by 24 | PDF Full-text (138 KB) | HTML Full-text | XML Full-text
Abstract
Baicalein (1), 6-hydroxyapigenin (6), 6-hydroxygalangin (13) and 6-hydroxy-kaempferol (14), which are naturally occurring flavonoids from a set of 14 hydroxy-flavones tested, exhibited high inhibitory effects on tyrosinase with respect to L-DOPA,while each of the 5,6,7-trihydroxyflavones 1, 6, 13 or 14 acted as a
[...] Read more.
Baicalein (1), 6-hydroxyapigenin (6), 6-hydroxygalangin (13) and 6-hydroxy-kaempferol (14), which are naturally occurring flavonoids from a set of 14 hydroxy-flavones tested, exhibited high inhibitory effects on tyrosinase with respect to L-DOPA,while each of the 5,6,7-trihydroxyflavones 1, 6, 13 or 14 acted as a cofactor tomonophenolase. Moreover, 6-hydroxykaempferol (14) showed the highest activity andwas a competitive inhibitor of tyrosinase compared to L-DOPA. 5,6,7-Trihydroxyflavones 1, 6, 13 or 14 showed also high antioxidant activities. Hence, weconclude that the 5,6,7-trihydroxy-flavones are useful as good depigmentation agentswith inhibitory effects in addition to their antioxidant properties. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Antioxidant Activity and Total Phenols in Different Extracts of Four Staphylea L. Species
Molecules 2007, 12(1), 98-102; doi:10.3390/12010098
Received: 1 December 2006 / Revised: 9 January 2007 / Accepted: 16 January 2007 / Published: 29 January 2007
Cited by 11 | PDF Full-text (47 KB) | HTML Full-text | XML Full-text
Abstract
Staphylea L. is a deciduous ornamental shrub that possesses significant cytotoxic and antibacterial activity, although the chemical composition of its extracts and the identity of the structures responsible for these biological activities are not yet known. In this study we have determined the
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Staphylea L. is a deciduous ornamental shrub that possesses significant cytotoxic and antibacterial activity, although the chemical composition of its extracts and the identity of the structures responsible for these biological activities are not yet known. In this study we have determined the total phenolic content in chloroform and ethyl acetate extracts of four Staphylea species: Staphylea colchica Stev., S. elegans Zab., S. holocarpa Hemsl. and S. pinnata L.. The antioxidant potential (DPPH radical and peroxynitrite scavenging activity) of these extracts was also determined and a correlation between the phenolic content and antioxidant activities of the ethyl acetate extracts has been found. Ethyl acetate extracts were more active and one of them, obtained from S. colchica Stev., possessed the highest activity. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)

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Open AccessReview Sequestration and Transport of Lignin Monomeric Precursors
Molecules 2011, 16(1), 710-727; doi:10.3390/molecules16010710
Received: 23 November 2010 / Revised: 13 January 2011 / Accepted: 17 January 2011 / Published: 18 January 2011
Cited by 28 | PDF Full-text (202 KB)
Abstract
Lignin is the second most abundant terrestrial biopolymer after cellulose. It is essential for the viability of vascular plants. Lignin precursors, the monolignols, are synthesized within the cytosol of the cell. Thereafter, these monomeric precursors are exported into the cell wall, where they
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Lignin is the second most abundant terrestrial biopolymer after cellulose. It is essential for the viability of vascular plants. Lignin precursors, the monolignols, are synthesized within the cytosol of the cell. Thereafter, these monomeric precursors are exported into the cell wall, where they are polymerized and integrated into the wall matrix. Accordingly, transport of monolignols across cell membranes is a critical step affecting deposition of lignin in the secondarily thickened cell wall. While the biosynthesis of monolignols is relatively well understood, our knowledge of sequestration and transport of these monomers is sketchy. In this article, we review different hypotheses on monolignol transport and summarize the recent progresses toward the understanding of the molecular mechanisms underlying monolignol sequestration and transport across membranes. Deciphering molecular mechanisms for lignin precursor transport will support a better biotechnological solution to manipulate plant lignification for more efficient agricultural and industrial applications of cell wall biomass. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Phenolic Compounds in Brassica Vegetables
Molecules 2011, 16(1), 251-280; doi:10.3390/molecules16010251
Received: 19 October 2010 / Revised: 6 December 2010 / Accepted: 28 December 2010 / Published: 30 December 2010
Cited by 169 | PDF Full-text (313 KB)
Abstract
Phenolic compounds are a large group of phytochemicals widespread in the plant kingdom. Depending on their structure they can be classified into simple phenols, phenolic acids, hydroxycinnamic acid derivatives and flavonoids. Phenolic compounds have received considerable attention for being potentially protective factors against
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Phenolic compounds are a large group of phytochemicals widespread in the plant kingdom. Depending on their structure they can be classified into simple phenols, phenolic acids, hydroxycinnamic acid derivatives and flavonoids. Phenolic compounds have received considerable attention for being potentially protective factors against cancer and heart diseases, in part because of their potent antioxidative properties and their ubiquity in a wide range of commonly consumed foods of plant origin. The Brassicaceae family includes a wide range of horticultural crops, some of them with economic significance and extensively used in the diet throughout the world. The phenolic composition of Brassica vegetables has been recently investigated and, nowadays, the profile of different Brassica species is well established. Here, we review the significance of phenolic compounds as a source of beneficial compounds for human health and the influence of environmental conditions and processing mechanisms on the phenolic composition of Brassica vegetables. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessReview Biosynthesis of Anthocyanins and Their Regulation in Colored Grapes
Molecules 2010, 15(12), 9057-9091; doi:10.3390/molecules15129057
Received: 19 October 2010 / Accepted: 7 December 2010 / Published: 9 December 2010
Cited by 126 | PDF Full-text (504 KB)
Abstract
Anthocyanins, synthesized via the flavonoid pathway, are a class of crucial phenolic compounds which are fundamentally responsible for the red color of grapes and wines. As the most important natural colorants in grapes and their products, anthocyanins are also widely studied for their
[...] Read more.
Anthocyanins, synthesized via the flavonoid pathway, are a class of crucial phenolic compounds which are fundamentally responsible for the red color of grapes and wines. As the most important natural colorants in grapes and their products, anthocyanins are also widely studied for their numerous beneficial effects on human health. In recent years, the biosynthetic pathway of anthocyanins in grapes has been thoroughly investigated. Their intracellular transportation and accumulation have also been further clarified. Additionally, the genetic mechanism regulating their biosynthesis and the phytohormone influences on them are better understood. Furthermore, due to their importance in the quality of wine grapes, the effects of the environmental factors and viticulture practices on anthocyanin accumulation are being investigated increasingly. The present paper summarizes both the basic information and the most recent advances in the study of the anthocyanin biosynthesis in red grapes, emphasizing their gene structure, the transcriptional factors and the diverse exterior regulation factors. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Supramolecular Self-Assembled Chaos: Polyphenolic Lignin’s Barrier to Cost-Effective Lignocellulosic Biofuels
Molecules 2010, 15(12), 8641-8688; doi:10.3390/molecules15118641
Received: 15 October 2010 / Revised: 22 November 2010 / Accepted: 25 November 2010 / Published: 29 November 2010
Cited by 45 | PDF Full-text (552 KB)
Abstract
Phenylpropanoid metabolism yields a mixture of monolignols that undergo chaotic, non-enzymatic reactions such as free radical polymerization and spontaneous self-assembly in order to form the polyphenolic lignin which is a barrier to cost-effective lignocellulosic biofuels. Post-synthesis lignin integration into the plant cell wall
[...] Read more.
Phenylpropanoid metabolism yields a mixture of monolignols that undergo chaotic, non-enzymatic reactions such as free radical polymerization and spontaneous self-assembly in order to form the polyphenolic lignin which is a barrier to cost-effective lignocellulosic biofuels. Post-synthesis lignin integration into the plant cell wall is unclear, including how the hydrophobic lignin incorporates into the wall in an initially hydrophilic milieu. Self-assembly, self-organization and aggregation give rise to a complex, 3D network of lignin that displays randomly branched topology and fractal properties. Attempts at isolating lignin, analogous to archaeology, are instantly destructive and non-representative of in planta. Lack of plant ligninases or enzymes that hydrolyze specific bonds in lignin-carbohydrate complexes (LCCs) also frustrate a better grasp of lignin. Supramolecular self-assembly, nano-mechanical properties of lignin-lignin, lignin-polysaccharide interactions and association-dissociation kinetics affect biomass deconstruction and thereby cost-effective biofuels production. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessReview Monocyclic Phenolic Acids; Hydroxy- and Polyhydroxybenzoic Acids: Occurrence and Recent Bioactivity Studies
Molecules 2010, 15(11), 7985-8005; doi:10.3390/molecules15117985
Received: 19 October 2010 / Revised: 3 November 2010 / Accepted: 4 November 2010 / Published: 8 November 2010
Cited by 92 | PDF Full-text (242 KB)
Abstract
Among the wide diversity of naturally occurring phenolic acids, at least 30 hydroxy- and polyhydroxybenzoic acids have been reported in the last 10 years to have biological activities. The chemical structures, natural occurrence throughout the plant, algal, bacterial, fungal and animal kingdoms, and
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Among the wide diversity of naturally occurring phenolic acids, at least 30 hydroxy- and polyhydroxybenzoic acids have been reported in the last 10 years to have biological activities. The chemical structures, natural occurrence throughout the plant, algal, bacterial, fungal and animal kingdoms, and recently described bioactivities of these phenolic and polyphenolic acids are reviewed to illustrate their wide distribution, biological and ecological importance, and potential as new leads for the development of pharmaceutical and agricultural products to improve human health and nutrition. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Factors Affecting Polyphenol Biosynthesis in Wild and Field Grown St. John’s Wort (Hypericum perforatum L. Hypericaceae/Guttiferae)
Molecules 2009, 14(2), 682-725; doi:10.3390/molecules14020682
Received: 28 December 2008 / Revised: 22 January 2009 / Accepted: 6 February 2009 / Published: 11 February 2009
Cited by 42 | PDF Full-text (782 KB) | HTML Full-text | XML Full-text
Abstract
The increasing diffusion of herbal products is posing new questions: why are products so often different in their composition and efficacy? Which approach is more suitable to increase the biochemical productivity of medicinal plants with large-scale, low-cost solutions? Can the phytochemical profile of
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The increasing diffusion of herbal products is posing new questions: why are products so often different in their composition and efficacy? Which approach is more suitable to increase the biochemical productivity of medicinal plants with large-scale, low-cost solutions? Can the phytochemical profile of a medicinal plant be modulated in order to increase the accumulation of its most valuable constituents? Will polyphenol-rich medicinal crops ever be traded as commodities? Providing a proactive answer to such questions is an extremely hard task, due to the large number of variables involved: intraspecific chemodiversity, plant breeding, ontogenetic stage, post-harvest handling, biotic and abiotic factors, to name but a few. An ideal path in this direction should include the definition of optimum pre-harvesting and post-harvesting conditions and the availability of specific Good Agricultural Practices centered on secondary metabolism enhancement. The first steps to be taken are undoubtedly the evaluation and the organization of scattered data regarding the diverse factors involved in the optimization of medicinal plant cultivation, in order to provide an interdisciplinary overview of main possibilities, weaknesses and drawbacks. This review is intended to be a synopsis of the knowledge on this regard focused on Hypericum perforatum L. (Hypericaceae/Guttiferae) secondary metabolites of phenolic origin, with the aim to provide a reference and suggest an evolution towards the maximization of St. John's Wort bioactive constituents. Factors considered emerged not only from in-field agronomic results, but also from physiological, genetical, biotic, abiotic and phytochemical data that could be scaled up to the application level. To increase quality for final beneficiaries, growers’ profits and ultimately transform phenolic-rich medicinal crops into commodities, the emerging trend suggests an integrated and synergic approach. Agronomy and genetics will need to develop their breeding strategies taking account of the suggestions of phytochemistry, biochemistry, pharmacognosy and pharmacology, without losing sight of the economic balance of the production. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Phenolics: Occurrence and Immunochemical Detection in Environment and Food
Molecules 2009, 14(1), 439-473; doi:10.3390/molecules14010439
Received: 30 November 2008 / Revised: 6 January 2009 / Accepted: 12 January 2009 / Published: 19 January 2009
Cited by 21 | PDF Full-text (311 KB) | HTML Full-text | XML Full-text | Correction | Supplementary Files
Abstract
Phenolic compounds may be of natural or anthropogenic origin and be present in the environment as well as in food. They comprise a large and diverse group of compounds that may be either beneficial or harmful for consumers. In this review first a
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Phenolic compounds may be of natural or anthropogenic origin and be present in the environment as well as in food. They comprise a large and diverse group of compounds that may be either beneficial or harmful for consumers. In this review first a non-exhausting overview of interesting phenolics is given, in particular with regards to their presence in environment and food. For some of these compounds, beneficial, toxicological and/or optionally endocrine disrupting activities will be presented. Further, immunochemical detection and/or isolation methods developed will be discussed, including advantages and disadvantages thereof in comparison with conventional analytical methods such as HPLC, GC, MS. A short overview of new sensor-like methods will also be included for present and future application. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Methodologies for the Extraction of Phenolic Compounds from Environmental Samples: New Approaches
Molecules 2009, 14(1), 298-320; doi:10.3390/molecules14010298
Received: 26 November 2008 / Revised: 24 December 2008 / Accepted: 4 January 2009 / Published: 9 January 2009
Cited by 91 | PDF Full-text (195 KB) | HTML Full-text | XML Full-text
Abstract
Phenolic derivatives are among the most important contaminants present in the environment. These compounds are used in several industrial processes to manufacture chemicals such as pesticides, explosives, drugs and dyes. They also are used in the bleaching process of paper manufacturing. Apart from
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Phenolic derivatives are among the most important contaminants present in the environment. These compounds are used in several industrial processes to manufacture chemicals such as pesticides, explosives, drugs and dyes. They also are used in the bleaching process of paper manufacturing. Apart from these sources, phenolic compounds have substantial applications in agriculture as herbicides, insecticides and fungicides. However, phenolic compounds are not only generated by human activity, but they are also formed naturally, e.g., during the decomposition of leaves or wood. As a result of these applications, they are found in soils and sediments and this often leads to wastewater and ground water contamination. Owing to their high toxicity and persistence in the environment, both, the US Environmental Protection Agency (EPA) and the European Union have included some of them in their lists of priority pollutants. Current standard methods of phenolic compounds analysis in water samples are based on liquid–liquid extraction (LLE) while Soxhlet extraction is the most used technique for isolating phenols from solid matrices. However, these techniques require extensive cleanup procedures that are time-intensive and involve expensive and hazardous organic solvents, which are undesirable for health and disposal reasons. In the last years, the use of news methodologies such as solid-phase extraction (SPE) and solid-phase microextraction (SPME) have increased for the extraction of phenolic compounds from liquid samples. In the case of solid samples, microwave assisted extraction (MAE) is demonstrated to be an efficient technique for the extraction of these compounds. In this work we review the developed methods in the extraction and determination of phenolic derivatives in different types of environmental matrices such as water, sediments and soils. Moreover, we present the new approach in the use of micellar media coupled with SPME process for the extraction of phenolic compounds. The advantages of micellar media over conventional extractants are reduction of organic solvent, low cost, easy handling and shorter time procedures. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Chemical Synthesis of Proanthocyanidins in Vitro and Their Reactions in Aging Wines
Molecules 2008, 13(12), 3007-3032; doi:10.3390/molecules13123007
Received: 15 November 2008 / Revised: 26 November 2008 / Accepted: 27 November 2008 / Published: 4 December 2008
Cited by 21 | PDF Full-text (573 KB) | HTML Full-text | XML Full-text
Abstract
Proanthocyanidins are present in many fruits and plant products like grapes and wine, and contribute to their taste and health benefits. In the past decades of years, substantial progresses has been achieved in the identification of composition and structure of proanthocyanidins, but the
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Proanthocyanidins are present in many fruits and plant products like grapes and wine, and contribute to their taste and health benefits. In the past decades of years, substantial progresses has been achieved in the identification of composition and structure of proanthocyanidins, but the debate concerning the existence of an enzymatic or nonenzymatic mechanism for proanthocyanidin condensation still goes on. Substantial attention has been paid to elucidating the potential mechanism of formation by means of biomimetic and chemical synthesis in vitro. The present paper aims at summarizing the research status on chemical synthesis of proanthocyanidins, including non-enzymatic synthesis of proanthocyanidin precursors, chemical synthesis of proanthocyanidins with direct condensation of flavanols and stereoselective synthesis of proanthocyanidins. Proanthocyanidin-involved reactions in aging wines are also reviewed such as direct and indirect reactions among proanthocyanidins, flavanols and anthocyanins. Topics for future research in this field are also put forward in this paper. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessReview Biosynthesis and Genetic Regulation of Proanthocyanidins in Plants
Molecules 2008, 13(10), 2674-2703; doi:10.3390/molecules13102674
Received: 11 August 2008 / Revised: 21 October 2008 / Accepted: 23 October 2008 / Published: 28 October 2008
Cited by 57 | PDF Full-text (886 KB) | HTML Full-text | XML Full-text
Abstract
Proanthocyanidins (PAs), also known as condensed tannins, are a group of polyphenolic secondary metabolites synthesized in plants as oligomers or polymers of flavan-3-ol units via the flavonoid pathway. Due to their structural complexity and varied composition, only in the recent years has the
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Proanthocyanidins (PAs), also known as condensed tannins, are a group of polyphenolic secondary metabolites synthesized in plants as oligomers or polymers of flavan-3-ol units via the flavonoid pathway. Due to their structural complexity and varied composition, only in the recent years has the study on the biosynthesis and regulation of PAs in plants taken off, although some details of the synthetic mechanism remain unclear. This paper aims to summarize the status of research on the structures of PAs in plants, the genes encoding key enzymes of biosynthetic pathway, the transport factors, the transcriptional regulation of PA biosynthesis and the genetic manipulation of PAs. The problems of this field were also discussed, including the nature of the final “enzyme” which catalyzes the polymerization reaction of PAs and the possible mechanism of how the elementary units of flavanols are assembled in vivo. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessReview Anti-carcinogenic Effects of the Flavonoid Luteolin
Molecules 2008, 13(10), 2628-2651; doi:10.3390/molecules13102628
Received: 17 September 2008 / Revised: 17 October 2008 / Accepted: 21 October 2008 / Published: 22 October 2008
Cited by 117 | PDF Full-text (330 KB) | HTML Full-text | XML Full-text
Abstract
Luteolin is a flavonoid which is part of our daily nutrition in relatively low amounts (less than 1 mg/day). Nevertheless, some epidemiological studies suggest an inverse correlation between luteolin intake and the risk of some cancer types. Luteolin displays specific anti-inflammatory and anti-carcinogenic
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Luteolin is a flavonoid which is part of our daily nutrition in relatively low amounts (less than 1 mg/day). Nevertheless, some epidemiological studies suggest an inverse correlation between luteolin intake and the risk of some cancer types. Luteolin displays specific anti-inflammatory and anti-carcinogenic effects, which can only partly be explained by its anti-oxidant and free radical scavenging capacities. Luteolin can delay or block the development of cancer cells in vitro and in vivo by protection from carcinogenic stimuli, by inhibition of tumor cell proliferation, by induction of cell cycle arrest and by induction of apoptosis via intrinsic and extrinsic signaling pathways. When compared to other flavonoids, luteolin was usually among the most effective ones, inhibiting tumor cell proliferation with IC50 values between 3 and 50 μM in vitro and in vivo by 5 to 10 mg/kg i.p., intragastric application of 0.1–0.3 mg/kg/d, or as food additive in concentrations of 50 to 200 ppm. Luteolin has been shown to penetrate into human skin, making it also a candidate for the prevention and treatment of skin cancer. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessReview Advances of Modern Chromatographic and Electrophoretic Methods in Separation and Analysis of Flavonoids
Molecules 2008, 13(10), 2521-2544; doi:10.3390/molecules13102521
Received: 18 August 2008 / Revised: 30 September 2008 / Accepted: 7 October 2008 / Published: 16 October 2008
Cited by 37 | PDF Full-text (298 KB) | HTML Full-text | XML Full-text
Abstract
Flavonoids, one of the largest groups of secondary metabolites, are widespread in vegetable crops such as herbs, fruits, vegetables, grains, seeds and derived foods such as juices, wines, oils, etc. They receive considerable attention due to their biological and physiological importance. Hundreds
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Flavonoids, one of the largest groups of secondary metabolites, are widespread in vegetable crops such as herbs, fruits, vegetables, grains, seeds and derived foods such as juices, wines, oils, etc. They receive considerable attention due to their biological and physiological importance. Hundreds of publications on the analysis of flavonoids have appeared over the past decade. Traditional and more advanced techniques have come to prominence for sample preparation, separation, detection, and identification. This review intends to provide an updated, concise overview on the recent development and trends of separation, identification and quantification for flavonoids by modern chromatographic and spectrophotometric analytical techniques, including gas chromatography (GC), liquid chromatography (LC), and capillary electrophoresis (CE). The sample preparation before analysis is also briefly summarized. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Polyphenols in Cocoa and Cocoa Products: Is There a Link between Antioxidant Properties and Health?
Molecules 2008, 13(9), 2190-2219; doi:10.3390/molecules13092190
Received: 16 August 2008 / Revised: 29 August 2008 / Accepted: 2 September 2008 / Published: 16 September 2008
Cited by 52 | PDF Full-text (272 KB) | HTML Full-text | XML Full-text
Abstract
Cocoa and cocoa products have received much attention due to their significant polyphenol contents. Cocoa and cocoa products, namely cocoa liquor, cocoa powder and chocolates (milk and dark chocolates) may present varied polyphenol contents and possess different levels of antioxidant potentials. For the
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Cocoa and cocoa products have received much attention due to their significant polyphenol contents. Cocoa and cocoa products, namely cocoa liquor, cocoa powder and chocolates (milk and dark chocolates) may present varied polyphenol contents and possess different levels of antioxidant potentials. For the past ten years, at least 28 human studies have been conducted utilizing one of these cocoa products. However, questions arise on which of these products would deliver the best polyphenol contents and antioxidant effects. Moreover, the presence of methylxanthines, peptides, and minerals could synergistically enhance or reduce antioxidant properties of cocoa and cocoa products. To a greater extent, cocoa beans from different countries of origins and the methods of preparation (primary and secondary) could also partially influence the antioxidant polyphenols of cocoa products. Hence, comprehensive studies on the aforementioned factors could provide the understanding of health-promoting activities of cocoa or cocoa products components. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessReview Flavonoids: Hemisynthesis, Reactivity, Characterization and Free Radical Scavenging Activity
Molecules 2007, 12(9), 2228-2258; doi:10.3390/12092228
Received: 29 May 2007 / Revised: 17 September 2007 / Accepted: 18 September 2007 / Published: 26 September 2007
Cited by 58 | PDF Full-text (544 KB) | HTML Full-text | XML Full-text
Abstract
Phenolic compounds form one of the main classes of secondary metabolites. They display a large range of structures and they are responsible for the major organoleptic characteristics of plant-derived-foods and beverages, particularly color and taste properties and they also contribute to the nutritional
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Phenolic compounds form one of the main classes of secondary metabolites. They display a large range of structures and they are responsible for the major organoleptic characteristics of plant-derived-foods and beverages, particularly color and taste properties and they also contribute to the nutritional qualities of fruits and vegetables. Phenolic compounds are also highly unstable compounds which undergo numerous enzymatic and chemical reactions during postharvest food storage and processing thus adding to the complexity of plant polyphenol composition. Among these compounds flavonoids constitute one of the most ubiquitous groups of all plant phenolics. Owing to their importance in food organoleptic properties and in human health, a better understanding of their structures, their reactivity and chemical properties in addition to the mechanisms generating them appears essential to predict and control food quality. The purpose of this work is an overview of our findings concerning the hemisynthesis, the reactivity and the enzymatic oxidation of some flavonoids and shed light on the mechanisms involved in some of these processes and the structures of the resulting products. The free radical scavenging activity of some of the synthesized compounds is also presented and a structure-activity relationship is discussed. The first part of this review concerns the synthesis and structural characterization of modified monomeric flavanols. The use of these compounds as precursor for the preparation of natural and modified dimeric procyanidin derivatives was then explored through different coupling reactions. The full characterization of the synthesized compounds was achieved by concerted use of NMR and ESI-MS techniques. The free radical scavenging activity of some of the synthesized compounds was investigated. The second part of this review concerns the enzymatic oxidation of several flavonols by Trametes versicolor laccase. Most of the major oxidation products have been isolated as pure compounds and their structures unambiguously established through spectroscopic methods. Correlation between the structure of the oxidation product and the substitution pattern of the starting materials allows mechanistic features of this transformation to be elucidated. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessReview Phenolic Molecules in Virgin Olive Oils: a Survey of Their Sensory Properties, Health Effects, Antioxidant Activity and Analytical Methods. An Overview of the Last Decade Alessandra
Molecules 2007, 12(8), 1679-1719; doi:10.3390/12081679
Received: 9 June 2007 / Revised: 2 August 2007 / Accepted: 2 August 2006 / Published: 6 August 2007
Cited by 358 | PDF Full-text (262 KB) | HTML Full-text | XML Full-text
Abstract
Among vegetable oils, virgin olive oil (VOO) has nutritional and sensory characteristics that to make it unique and a basic component of the Mediterranean diet. The importance of VOO is mainly attributed both to its high content of oleic acid a balanced contribution
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Among vegetable oils, virgin olive oil (VOO) has nutritional and sensory characteristics that to make it unique and a basic component of the Mediterranean diet. The importance of VOO is mainly attributed both to its high content of oleic acid a balanced contribution quantity of polyunsaturated fatty acids and its richness in phenolic compounds, which act as natural antioxidants and may contribute to the prevention of several human diseases. The polar phenolic compounds of VOO belong to different classes: phenolic acids, phenyl ethyl alcohols, hydroxy-isochromans, flavonoids, lignans and secoiridoids. This latter family of compounds is characteristic of Oleaceae plants and secoiridoids are the main compounds of the phenolic fraction. Many agronomical and technological factors can affect the presence of phenols in VOO. Its shelf life is higher than other vegetable oils, mainly due to the presence of phenolic molecules having a catechol group, such as hydroxytyrosol and its secoiridoid derivatives. Several assays have been used to establish the antioxidant activity of these isolated phenolic compounds. Typical sensory gustative properties of VOO, such as bitterness and pungency, have been attributed to secoiridoid molecules. Considering the importance of the phenolic fraction of VOO, high performance analytical methods have been developed to characterize its complex phenolic pattern. The aim of this review is to realize a survey on phenolic compounds of virgin olive oils bearing in mind their chemical-analytical, healthy and sensory aspects. In particular, starting from the basic studies, the results of researches developed in the last ten years will be focused. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Flavonoid Composition of Citrus Juices
Molecules 2007, 12(8), 1641-1673; doi:10.3390/12081641
Received: 22 June 2007 / Revised: 30 July 2006 / Accepted: 31 July 2007 / Published: 3 August 2007
Cited by 205 | PDF Full-text (369 KB) | HTML Full-text | XML Full-text
Abstract
In the early nineties the presence of flavonoids in Citrus juices began to attract the attention of a number of researchers, as a result of their biological and physiological importance. This short review will explore two different aspects. The first part will focus
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In the early nineties the presence of flavonoids in Citrus juices began to attract the attention of a number of researchers, as a result of their biological and physiological importance. This short review will explore two different aspects. The first part will focus on analytical techniques for the characterization of juices from different Citrus fruits regarding their flavonoid content (even if present in only trace amounts), concentrating on the most widely used methods (LC-MS and LC-MS-MS). The second part analyzes data reported in the literature regarding the composition of Citrus juices. The main components that have been detected so far are flavanone-O-glycosides and flavone-O- or -C-glycosides. The presence of such derivatives in various hand-squeezed and industrial juices is discussed, with special emphasis on their correlation to different species. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Functional Analysis of Polyphenol Oxidases by Antisense/Sense Technology
Molecules 2007, 12(8), 1569-1595; doi:10.3390/12081569
Received: 30 May 2007 / Revised: 19 July 2007 / Accepted: 19 July 2007 / Published: 27 July 2007
Cited by 64 | PDF Full-text (391 KB) | HTML Full-text | XML Full-text
Abstract
Polyphenol oxidases (PPOs) catalyze the oxidation of phenolics to quinones, the secondary reactions of which lead to oxidative browning and postharvest losses of many fruits and vegetables. PPOs are ubiquitous in angiosperms, are inducible by both biotic and abiotic stresses, and have been
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Polyphenol oxidases (PPOs) catalyze the oxidation of phenolics to quinones, the secondary reactions of which lead to oxidative browning and postharvest losses of many fruits and vegetables. PPOs are ubiquitous in angiosperms, are inducible by both biotic and abiotic stresses, and have been implicated in several physiological processes including plant defense against pathogens and insects, the Mehler reaction, photoreduction of molecular oxygen by PSI, regulation of plastidic oxygen levels, aurone biosynthesis and the phenylpropanoid pathway. Here we review experiments in which the roles of PPO in disease and insect resistance as well as in the Mehler reaction were investigated using transgenic tomato (Lycopersicon esculentum) plants with modified PPO expression levels (suppressed PPO and overexpressing PPO). These transgenic plants showed normal growth, development and reproduction under laboratory, growth chamber and greenhouse conditions. Antisense PPO expression dramatically increased susceptibility while PPO overexpression increased resistance of tomato plants to Pseudomonas syringae. Similarly, PPO-overexpressing transgenic plants showed an increase in resistance to various insects, including common cutworm (Spodoptera litura (F.)), cotton bollworm (Helicoverpa armigera (Hübner)) and beet army worm (Spodoptera exigua (Hübner)), whereas larvae feeding on plants with suppressed PPO activity had higher larval growth rates and consumed more foliage. Similar increases in weight gain, foliage consumption, and survival were also observed with Colorado potato beetles (Leptinotarsa decemlineata (Say)) feeding on antisense PPO transgenic tomatoes. The putative defensive mechanisms conferred by PPO and its interaction with other defense proteins are discussed. In addition, transgenic plants with suppressed PPO exhibited more favorable water relations and decreased photoinhibition compared to nontransformed controls and transgenic plants overexpressing PPO, suggesting that PPO may have a role in the development of plant water stress and potential for photoinhibition and photooxidative damage that may be unrelated to any effects on the Mehler reaction. These results substantiate the defensive role of PPO and suggest that manipulation of PPO activity in specific tissues has the potential to provide broad-spectrum resistance simultaneously to both disease and insect pests, however, effects of PPO on postharvest quality as well as water stress physiology should also be considered. In addition to the functional analysis of tomato PPO, the application of antisense/sense technology to decipher the functions of PPO in other plant species as well as for commercial uses are discussed. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Comparative Evaluation of Various Total Antioxidant Capacity Assays Applied to Phenolic Compounds with the CUPRAC Assay
Molecules 2007, 12(7), 1496-1547; doi:10.3390/12071496
Received: 30 June 2007 / Revised: 17 July 2007 / Accepted: 18 July 2007 / Published: 19 July 2007
Cited by 346 | PDF Full-text (266 KB) | HTML Full-text | XML Full-text
Abstract
It would be desirable to establish and standardize methods that can measure the total antioxidant capacity level directly from vegetable extracts containing phenolics. Antioxidant capacity assays may be broadly classified as electron transfer (ET)− and hydrogen atom transfer (HAT)−based assays. The majority of
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It would be desirable to establish and standardize methods that can measure the total antioxidant capacity level directly from vegetable extracts containing phenolics. Antioxidant capacity assays may be broadly classified as electron transfer (ET)− and hydrogen atom transfer (HAT)−based assays. The majority of HAT assays are kinetics-based, and involve a competitive reaction scheme in which antioxidant and substrate compete for peroxyl radicals thermally generated through the decomposition of azo compounds. ET−based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes colour when reduced. ET assays include the ABTS/TEAC, CUPRAC, DPPH, Folin-Ciocalteu and FRAP methods, each using different chromogenic redox reagents with different standard potentials. This review intends to offer a critical evaluation of existing antioxidant assays applied to phenolics, and reports the development by our research group of a simple and low-cost antioxidant capacity assay for dietary polyphenols, vitamins C and E, and human serum antioxidants, utilizing the copper(II)-neocuproine reagent as the chromogenic oxidizing agent, which we haved named the CUPRAC (cupric ion reducing antioxidant capacity) method. This method offers distinct advantages over other ET−based assays, namely the selection of working pH at physiological pH (as opposed to the Folin and FRAP methods, which work at alkaline and acidic pHs, respectively), applicability to both hydrophilic and lipophilic antioxidants (unlike Folin and DPPH), completion of the redox reactions for most common flavonoids (unlike FRAP), selective oxidation of antioxidant compounds without affecting sugars and citric acid commonly contained in foodstuffs and the capability to assay –SH bearing antioxidants (unlike FRAP). Other similar ET–based antioxidant assays that we have developed or modified for phenolics are the Fe(III)− and Ce(IV)−reducing capacity methods. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Flavonoids and Strigolactones in Root Exudates as Signals in Symbiotic and Pathogenic Plant-Fungus Interactions
Molecules 2007, 12(7), 1290-1306; doi:10.3390/12071290
Received: 29 May 2007 / Revised: 20 June 2007 / Accepted: 3 July 2007 / Published: 5 July 2007
Cited by 116 | PDF Full-text (123 KB) | HTML Full-text | XML Full-text
Abstract
Secondary plant compounds are important signals in several symbiotic and pathogenic plant-microbe interactions. The present review is limited to two groups of secondary plant compounds, flavonoids and strigolactones, which have been reported in root exudates. Data on flavonoids as signaling compounds are available
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Secondary plant compounds are important signals in several symbiotic and pathogenic plant-microbe interactions. The present review is limited to two groups of secondary plant compounds, flavonoids and strigolactones, which have been reported in root exudates. Data on flavonoids as signaling compounds are available from several symbiotic and pathogenic plant-microbe interactions, whereas only recently initial data on the role of strigolactones as plant signals in the arbuscular mycorrhizal symbiosis have been reported. Data from other plant-microbe interactions and strigolactones are not available yet. In the present article we are focusing on flavonoids in plant-fungalinteractions such as the arbuscular mycorrhizal (AM) association and the signaling between different Fusarium species and plants. Moreover the role of strigolactones in the AM association is discussed and new data on the effect of strigolactones on fungi, apart from arbuscular mycorrhizal fungi (AMF), are provided. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessReview Litchi Flavonoids: Isolation, Identification and Biological Activity
Molecules 2007, 12(4), 745-758; doi:10.3390/12040745
Received: 14 March 2007 / Revised: 26 March 2007 / Accepted: 28 March 2007 / Published: 11 April 2007
Cited by 40 | PDF Full-text (106 KB) | HTML Full-text | XML Full-text
Abstract
The current status of the isolation, identification, biological activity, utilization and development prospects of flavonoids found in litchi fruit pericarp (LFP) tissues is reviewed. LFP tissues account for approximately 15% by weight of the whole fresh fruit and are comprised of significant amount
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The current status of the isolation, identification, biological activity, utilization and development prospects of flavonoids found in litchi fruit pericarp (LFP) tissues is reviewed. LFP tissues account for approximately 15% by weight of the whole fresh fruit and are comprised of significant amount of flavonoids. The major flavonoids in ripe LFP include flavonols and anthocyanins. The major flavanols in the LFP are reported to be procyanidin B4, procyanidin B2 and epicatechin, while cyanindin-3-rutinside, cyanidin-3-glucoside, quercetin-3-rutinosde and quercetin-3-glucoside are identified as the important anthocyanins. Litchi flavanols and anthocyanins exhibit good potential antioxidant activity. The hydroxyl radical and superoxide anion scavenging activities of procyanidin B2 are greater than those of procyanidin B4 and epicatechin, while epicatechin has the highest α,α-diphenyl-β-picrylhydrazyl radical (DPPH·) scavenging activity. In addition to the antioxidant activity, LFP extract displays a dose- and time-dependent inhibitory effect on human breast cancer, which could be attributed, in part, to its inhibition of proliferation and induction of apoptosis in cancer cells through upregulation and down-regulation of multiple genes. Furthermore, various anticancer activities are observed for epicatechin, procyanidin B2, procyanidin B4 and the ethyl acetate fraction of LFP tissue extracts. Procyanidin B4 and the ethyl acetate fraction show a stronger inhibitory effect on HELF than MCF-7 proliferation, while epicatechin and procyanidin B2 have lower cytotoxicities towards MCF-7 and HELF than paclitaxel. It is therefore suggested that flavonoids from LFP might be potentially useful components for functional foods and/or anti-breast cancer drugs. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)

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