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Molecules, Volume 16, Issue 7 (July 2011) – 62 articles , Pages 5315-6164

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560 KiB

Open AccessArticle

Study of the Extraction Process and In Vivo Inhibitory Effect of Ganoderma Triterpenes in Oral Mucosa Cancer

by Yang Gao, Ruhui Zhang, Juan Zhang, Shang Gao, Wenxin Gao, Haifeng Zhang, Haotian Wang and Bing Han

Molecules 2011, 16(7), 5315-5332; https://doi.org/10.3390/molecules16075315 - 24 Jun 2011

Cited by 19 | Viewed by 8529

Abstract

The aim of the reported study was to optimize the extraction process for ganoderma triterpenes and to investigate the in vivo inhibitory effect of ganoderma triterpenes on the genesis and progression of oral cancer. Single-factor and orthogonal methods were used to investigate the effects of extraction solvent, solvent amount, extraction time, extraction temperature, and number of extractions, on the extraction rate for ganoderma triterpenes. A golden hamster model with cheek pouch dynamic canceration was established to receive oral treatment of ganoderma triterpenes water solution. Animals were continuously monitored, oral tissue samples were collected for histopathologic examination, and changes in the expression of VEGF (vascular endothelial growth factor) and Caspase-3 were detected by immunohistochemical methods. Optimization of the experimental conditions allowed the identification of the optimal extraction conditions: 90% ethanol as the extraction solvent, a solvent amount by the liquid-material ratio of 35 mL/g, extraction time of 2 h and extraction temperature of 80 °C. Under these conditions, the average extraction rate of ganoderma triterpenes was 1.09%. Tests in golden hamsters showed that compared with the model group during the same period, animals in the treatment group had better conditions, constantly larger number of normal cases shown by histopathologic results (P < 0.01), and consistently smaller numbers of cases with paraplasm (P < 0.05). Immunohistochemical results showed that compared with the model group, the treatment group had significantly lower (P < 0.05) rates of positive VEGF expression in the normal state, simple epithelial hyperplasia, epithelial dysplasia or squamous cell carcinoma disease stages. Caspase-3 expression showed a tendency toward a gradual increase with the worsening of disease severity in each group. Compared with the model group, the treatment group had significantly lower (P < 0.05) rates of positive Caspase-3 in the normal state, simple epithelial hyperplasia, epithelial dysplasia or squamous cell carcinoma disease grades. Using the optimized extraction process, ganoderma triterpenes could be extracted with high efficiency, and the results of animal tests showed inhibitory effects of ganoderma triterpenes on oral mucosa cancer. Full article

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464 KiB

Open AccessArticle

Neuroprotective Effects of Vanillyl Alcohol in Gastrodia elata Blume Through Suppression of Oxidative Stress and Anti-Apoptotic Activity in Toxin-Induced Dopaminergic MN9D Cells

by In Su Kim, Dong-Kug Choi and Hun Jong Jung

Molecules 2011, 16(7), 5349-5361; https://doi.org/10.3390/molecules16075349 - 24 Jun 2011

Cited by 71 | Viewed by 8812

Abstract

Gastrodia elata Blume (GE) has long been used in oriental countries as a traditional herbal medicine to relieve symptoms associated with neurological ailments such as vertigo, general paralysis and epilepsy. In this study, we have investigated the effects of GE extracts and its major bioactive components on 1-methyl-4-phenylpyridinium (MPP⁺)-treated MN9D dopaminergic cells, a classic in vitro model for Parkinson’s disease (PD). We found that vanillyl alcohol effectively inhibited the cytotoxicity and improved cell viability in MPP⁺-induced MN9D dopaminergic cells. The underlying mechanisms of vanillyl alcohol action were also studied. Vanillyl alcohol attenuated the elevation of reactive oxygen species (ROS) levels, decreased in the Bax/Bcl-2 ratio and poly (ADP-ribose) polymerase proteolysis. These results indicate that vanillyl alcohol protected dopaminergic MN9D cells against MPP⁺-induced apoptosis by relieving oxidative stress and modulating the apoptotic process and is therefore a potential candidate for treatment of neurodegenerative diseases such as Parkinson’s disease. Full article

(This article belongs to the Section Natural Products Chemistry)

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295 KiB

Open AccessArticle

Isolation of a Bis-Iodurated Tetra-THF as a Trace Product from the Oxidation of Squalene with RuO₄ and Its Double Ring Expansion to a Novel bis-THF-bis-THP Compound

by Vincenzo Piccialli, Sabrina Zaccaria, Roberto Centore, Angela Tuzi, Nicola Borbone and Giorgia Oliviero

Molecules 2011, 16(7), 5362-5373; https://doi.org/10.3390/molecules16075362 - 27 Jun 2011

Cited by 3 | Viewed by 5910

Abstract

A novel bis-iodurated polyether compound, based on an unprecedented tetra-THF backbone, has been isolated as a trace by-product of the oxidation of squalene with the catalytic system RuO₂(cat.)/NaIO₄. The double erythro configuration of the central portion of the molecule furnishes the first indirect support of the previously postulated pathway operating in the oxidative pentacyclization of the isoprenoid substrate. A bidirectional double oxidative bis-cyclization is invoked to explain the formation of this compound. The isolated substance was successfully subjected to a double rearrangement-ring expansion to give a novel bis-THF-bis-THP compound. Full article

(This article belongs to the Section Organic Chemistry)

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147 KiB

Open AccessArticle

Study of Organic Honey from the Northeast of Portugal

by Teresa Gomes, Xesús Feás, Antonio Iglesias and Leticia M. Estevinho

Molecules 2011, 16(7), 5374-5386; https://doi.org/10.3390/molecules16075374 - 27 Jun 2011

Cited by 48 | Viewed by 9571

Abstract

Concerns about traces of numerous toxic substances and authenticity have prompted consumer demand for honey that is certified as organic, based on strict ecological, natural principles and traceability. The present study aims to characterize organic honey samples (n = 73) from Northeast Portugal, with respect to floral nectar origin, physicochemical parameters and microbial safety. The phenols and flavonoids contents, often referred to as responsible for honey’s bioactive properties, were also assessed. All organic honey samples were classified as monofloral lavender (Lavandula sp.), exceeded in quality the international physicochemical standards and showed low microbiological counts (yeast, moulds and aerobic mesophiles), with negative results in respect to fecal coliforms, Salmonella and sulphite-reducing Clostridium spp. Correlation of the palynological, physicochemical and microbiological results is necessary to check the authenticity, quality and sanitation of honey. Although not required by international legislation, results of those assessments provide a complete outlook and elucidation of the organic honey’s properties, which could promote its valorisation. Full article

222 KiB

Open AccessArticle

Enantioselective Addition of Allyltin Reagents to Amino Aldehydes Catalyzed with Bis(oxazolinyl)phenylrhodium(III) Aqua Complexes

by Yukihiro Motoyama, Takatoshi Sakakura, Toshihide Takemoto, Kayoko Shimozono, Katsuyuki Aoki and Hisao Nishiyama

Molecules 2011, 16(7), 5387-5401; https://doi.org/10.3390/molecules16075387 - 27 Jun 2011

Cited by 5 | Viewed by 5583

Abstract

Bis(oxazolinyl)phenylrhodium(III) aqua complexes, (Phebox)RhX₂(H₂O) [X = Cl, Br], were found to be efficient Lewis acid catalysts for the enantioselective addition of allyl- and methallyltributyltin reagents to amino aldehydes. The reactions proceed smoothly in the presence of 5–10 mol % of (Phebox)RhX₂(H₂O) complex at ambient temperature to give the corresponding amino alcohols with modest to good enantioselectivity (up to 94% ee). Full article

(This article belongs to the Special Issue Catalytic Asymmetric Synthesis)

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301 KiB

Open AccessArticle

Synthesis of Key Fragments of Amphidinolide Q — A Cytotoxic 12-membered Macrolide

by Kohei Kawa, Akihiro Hara, Yuichi Ishikawa and Shigeru Nishiyama

Molecules 2011, 16(7), 5422-5436; https://doi.org/10.3390/molecules16075422 - 27 Jun 2011

Cited by 6 | Viewed by 5825

Abstract

b-Hydroxy aldehyde and alkyl ketone moieties were effectively synthesized as key intermediates of amphidinolide Q, a cytotoxic macrolide from the cultured dinoflagellate Amphidinium sp.. The asymmetric center of the former derivative was produced by Sharpless asymmetric epoxidation, followed by E-selective 1,4-addition to give the sp² methyl group. Derivatization of the L-ascorbic acid derivative by Evans asymmetric alkylation and Peterson olefination provided the latter intermediate. The coupling reaction of the segments was examined. Full article

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113 KiB

Open AccessArticle

In Vitro Activity of Plant Extracts and Alkaloids against Clinical Isolates of Extended-Spectrum b-Lactamase (ESBL)-Producing Strains

by Guo-Ying Zuo, Fan-Yan Meng, Jun Han, Xiao-Yan Hao, Gen-Chun Wang, Yun-Ling Zhang and Qing Zhang

Molecules 2011, 16(7), 5453-5459; https://doi.org/10.3390/molecules16075453 - 28 Jun 2011

Cited by 16 | Viewed by 5929

Abstract

The antibacterial activity of 80% ethanol extracts of 10 medicinal plants collected in Yunnan (Southwest China), was tested against clinical isolates of extended-spectrum b-lactamase (ESBL)-producing strains. Their MIC values ranged between 1.56–12.50 mg/mL. The most active plant extract was Chelidonium majus L. (MIC = 1.56 mg/mL). Two potent isoquinoline alkaloids, 8-hydroxydihydrosanguinarine and 8-hydroxydihydrochelerythrine, were identified as the major active principles through bioassay-guided fractionation and identification of the active ethyl acetate fraction from C. majus, with minimum MIC/MBC values of 15.63/62.50 mg/mL. Full article

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247 KiB

Open AccessArticle
Synthesis and Antibacterial Activities of Novel Imidazo[2,1-b]-1,3,4-thiadiazoles
by Kamal F. M. Atta, Omaima O.M. Farahat, Alaa Z. A. Ahmed and Mohamed G. Marei

Molecules 2011, 16(7), 5496-5506; https://doi.org/10.3390/molecules16075496 - 28 Jun 2011
Cited by 43 | Viewed by 8162
Abstract
2-Amino-5-(2-aryl-2H-1,2,3-triazol-4-yl)-1,3,4-thiadiazoles 2-4 have been synthesized by the reaction of 2-aryl-2H-1,2,3-triazole-4-carboxylic acids 1 with thiosemicarbazide. Their reaction with phenacyl (p-substituted phenacyl) bromides led to formation of the respective 6-aryl-2-(2-aryl-2H-1,2,3-triazol-4-yl)imidazo[2,1-b]-1,3,4-thiadiazoles 5. Reactivity of the [...] Read more.

2-Amino-5-(2-aryl-2H-1,2,3-triazol-4-yl)-1,3,4-thiadiazoles 2-4 have been synthesized by the reaction of 2-aryl-2H-1,2,3-triazole-4-carboxylic acids 1 with thiosemicarbazide. Their reaction with phenacyl (p-substituted phenacyl) bromides led to formation of the respective 6-aryl-2-(2-aryl-2H-1,2,3-triazol-4-yl)imidazo[2,1-b]-1,3,4-thiadiazoles 5. Reactivity of the latter fused ring towards reaction with different electrophilic reagents afforded the corresponding 5-substituted derivatives 6-8. The structure of the above compounds was confirmed from their spectral characteristics. Some of these compounds were found to possess slight to moderate activity against the microorganisms Staphylococcus aureus, Candida albicans, Pseudomonas aeruginosa, and Escherichia coli. Full article

(This article belongs to the Section Organic Chemistry)

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147 KiB

Open AccessArticle
Absorbable Phenylpropenoyl Sucroses from Polygala tenuifolia
by Gaimei She, Yinying Ba, Yang Liu, Hang Lv, Wei Wang and Renbing Shi

Molecules 2011, 16(7), 5507-5513; https://doi.org/10.3390/molecules16075507 - 29 Jun 2011
Cited by 14 | Viewed by 6672
Abstract
Three phenylpropenoyl sucroses – sibiricose A5 (1), A6 (2) and 3′,6-disinapoyl sucrose (3) – were isolated from the 30% EtOH extract of Polygala tenuifolia, which displayed antidepressant-like action. HPLC analysis indicated that the three phenylpropenoyl sucroses [...] Read more.

Three phenylpropenoyl sucroses – sibiricose A5 (1), A6 (2) and 3′,6-disinapoyl sucrose (3) – were isolated from the 30% EtOH extract of Polygala tenuifolia, which displayed antidepressant-like action. HPLC analysis indicated that the three phenylpropenoyl sucroses could be absorbed into serum. From the serum pharmacochemistry point of view, these three phenylpropenoyl sucroses might prevent or relieve depression. Full article

(This article belongs to the Collection Bioactive Compounds)

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168 KiB

Open AccessArticle
The Relationship of Nitrogen and C/N Ratio with Secondary Metabolites Levels and Antioxidant Activities in Three Varieties of Malaysian Kacip Fatimah (Labisia pumila Blume)
by Mohd Hafiz Ibrahim and Hawa Z.E. Jaafar

Molecules 2011, 16(7), 5514-5526; https://doi.org/10.3390/molecules16075514 - 29 Jun 2011
Cited by 45 | Viewed by 7795
Abstract
Kacip Fatimah (Labisia pumila Blume), one of the most famous and widely used herbs, especially in Southeast Asia, is found to have interesting bioactive compounds and displays health promoting properties. In this study, the antioxidant activities of the methanol extracts of leaves, [...] Read more.

Kacip Fatimah (Labisia pumila Blume), one of the most famous and widely used herbs, especially in Southeast Asia, is found to have interesting bioactive compounds and displays health promoting properties. In this study, the antioxidant activities of the methanol extracts of leaves, stems and roots of three varieties of L. pumila (var. alata, pumila and lanceolata) were evaluated in an effort to compare and validate the medicinal potential of this indigenous Malaysian herb species. The antioxidant activity determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, as well as the total amount of phenolics and flavonoids were the highest in the leaves, followed by the stems and roots in all the varieties. A similar trend was displayed by the ferric reducing antioxidant potential (FRAP) activity, suggesting that the L. pumila varieties possess high foliar antioxidant properties. At low FRAP activity concentrations, the values of the leaves’ inhibition activity in the three varieties were significantly higher than those of the stems and roots, with var. alata exhibiting higher antioxidant activities and total contents of phenolics and flavonoids compared to the varieties pumila and lanceolata. The high production of secondary metabolites and antioxidant activities in var. alata were firmly related to low nitrogen content and high C/N ratio in plant parts. The study also demonstrated a positive correlation between secondary metabolite content and antioxidant activities, and revealed that the consumption of L. pumila could exert several beneficial effects by virtue of its antioxidant activity. Full article

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250 KiB

Open AccessArticle
Microwave Assisted Synthesis of Novel Functionalized Hydantoin Derivatives and Their Conversion to 5-(Z) Arylidene-4H-imidazoles
by Sukanta Kamila, Haribabu Ankati and Edward R. Biehl

Molecules 2011, 16(7), 5527-5537; https://doi.org/10.3390/molecules16075527 - 29 Jun 2011
Cited by 10 | Viewed by 6105
Abstract
2-(Alkyl-1-yl)-1H-imidazol-5(4H)-ones 5a–n were synthesized via nucleophilic substitution of the methylsulfanyl group of the corresponding 2-(methylthio)-1H-imidazol-5(4H)-ones 3a–c with suitably substituted secondary amines. The starting 2-thioxo- imidazolidin-4-ones 2a,2b were prepared by condensation of thiohydantoin and [...] Read more.

2-(Alkyl-1-yl)-1H-imidazol-5(4H)-ones 5a–n were synthesized via nucleophilic substitution of the methylsulfanyl group of the corresponding 2-(methylthio)-1H-imidazol-5(4H)-ones 3a–c with suitably substituted secondary amines. The starting 2-thioxo- imidazolidin-4-ones 2a,2b were prepared by condensation of thiohydantoin and benzo[b]-thiophene-3-carbaldehyde or benzofuran-3-carbaldehyde under microwave irracdiation (MW) conditions. 2-Methylthio derivatives 3a–c were prepared by treatment of 2a–b with methyl iodide in the presence of aqueous sodium hydroxide. Full article

(This article belongs to the Special Issue Microwave Assisted Synthesis)

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273 KiB

Open AccessArticle
Multivariate Optimization in the Biosynthesis of a Triethanolamine (TEA)-Based Esterquat Cationic Surfactant Using an Artificial Neural Network
by Hamid Reza Fard Masoumi, Anuar Kassim, Mahiran Basri, Dzulkifly Kuang Abdullah and Mohd Jelas Haron

Molecules 2011, 16(7), 5538-5549; https://doi.org/10.3390/molecules16075538 - 29 Jun 2011
Cited by 30 | Viewed by 7683
Abstract
An Artificial Neural Network (ANN) based on the Quick Propagation (QP) algorithm was used in conjunction with an experimental design to optimize the lipase-catalyzed reaction conditions for the preparation of a triethanolamine (TEA)-based esterquat cationic surfactant. Using the best performing ANN, the optimum [...] Read more.

An Artificial Neural Network (ANN) based on the Quick Propagation (QP) algorithm was used in conjunction with an experimental design to optimize the lipase-catalyzed reaction conditions for the preparation of a triethanolamine (TEA)-based esterquat cationic surfactant. Using the best performing ANN, the optimum conditions predicted were an enzyme amount of 4.77 w/w%, reaction time of 24 h, reaction temperature of 61.9 °C, substrate (oleic acid: triethanolamine) molar ratio of 1:1 mole and agitation speed of 480 r.p.m. The relative deviation percentage under these conditions was less than 4%. The optimized method was successfully applied to the synthesis of the TEA-based esterquat cationic surfactant at a 2,000 mL scale. This method represents a more flexible and convenient means for optimizing enzymatic reaction using ANN than has been previously reported by conventional methods. Full article

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251 KiB

Open AccessCommunication
An Electrochemical Synthesis of Functionalized Arylpyrimidines from 4-Amino-6-Chloropyrimidines and Aryl Halides
by Stéphane Sengmany, Erwan Le Gall and Eric Léonel

Molecules 2011, 16(7), 5550-5560; https://doi.org/10.3390/molecules16075550 - 29 Jun 2011
Cited by 17 | Viewed by 6024
Abstract
A range of novel 4-amino-6-arylpyrimidines has been prepared under mild conditions by an electrochemical reductive cross-coupling between 4-amino-6-chloro-pyrimidines and functionalized aryl halides. The process, which employs a sacrificial iron anode in conjunction with a nickel(II) catalyst, allows the formation of coupling products in [...] Read more.

A range of novel 4-amino-6-arylpyrimidines has been prepared under mild conditions by an electrochemical reductive cross-coupling between 4-amino-6-chloro-pyrimidines and functionalized aryl halides. The process, which employs a sacrificial iron anode in conjunction with a nickel(II) catalyst, allows the formation of coupling products in moderate to high yields. Full article

(This article belongs to the Special Issue Organic Electrosynthesis)

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743 KiB

Open AccessArticle
Induction of Apoptosis in Human Promyelocytic Leukemia HL60 Cells by Panaxynol and Panaxydol
by Zhonghong Yan, Ruolin Yang, Yi Jiang, Zhihui Yang, Junrui Yang, Qian Zhao and Yang Lu

Molecules 2011, 16(7), 5561-5573; https://doi.org/10.3390/molecules16075561 - 29 Jun 2011
Cited by 28 | Viewed by 7820
Abstract
Panaxynol and panaxydol are naturally occurring polyacetylenes, isolated from the lipophilic fractions of Panax notoginseng, that exert anti-proliferative effects against malignant cells. However, to the best of our knowledge, no study concerning the inhibitory effects of the two polyacetylenes on cell growth [...] Read more.

Panaxynol and panaxydol are naturally occurring polyacetylenes, isolated from the lipophilic fractions of Panax notoginseng, that exert anti-proliferative effects against malignant cells. However, to the best of our knowledge, no study concerning the inhibitory effects of the two polyacetylenes on cell growth of human promyelocytic leukemia cells has been reported. In this paper, we examined the antiproliferation and proapoptotic effects of panaxynol and panaxydol on HL60 cells and investigated their mechanism of action. Cell growth inhibition of panaxynol and panaxydol were determined by trypan blue dye exclusion assays. Apoptosis of cells was revealed by morphological observation, analysis for nuclear DNA distribution and by annexin V-FITC/ PI staining using flow cytometry. It was found that panaxynol and panaxydol markedly inhibited proliferation of HL60 cells in a time- and dose-dependent manner via an apoptotic pathway. In concern with these ﬁndings, Western blot analysis showed proteolytic activation of PKCδ, caspase-3 activation and cleavage of poly (ADP [adenosine diphosphate]-ribose) polymerase in HL60 cells treated by panaxynol and panaxydol. In conclusion, panaxynol and panaxydol have profound effects on growth and apoptosis of HL60 cells, suggesting those substances are worthy of further exploration as potential anti-cancer agents. Full article

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500 KiB

Open AccessArticle
Intramolecular Conversions of (Aminoferrocenylpenta-1,4-dienyl)-ferrocenylcarbenes: Synthesis of Diferrocenylmono-, bi-, tricycles and Amino(diferrocenyl)hexa-1,3,5-trienes
by Elena I. Klimova, Luis A. Ortiz-Frade, Miguel A. González-Fuentes, Marcos Flores-Alamo, Leon V. Backinowsky and Marcos Martínez García

Molecules 2011, 16(7), 5574-5590; https://doi.org/10.3390/molecules16075574 - 30 Jun 2011
Cited by 5 | Viewed by 6268
Abstract
Synthesis of 3,4-diferrocenyltoluene (7), 1-morpholino- and 1-piperidino-2,3-diferrocenylbicyclo[3.1.0]hex-2-enes 8a, 8b, 1-morpholino- and 1-piperidino-7-ferrocenyl-3,4-ferrocenobicyclo[3.2.1]oct-6-enes 9a, 9b, 2- and 3-amino(diferrocenyl)-hexa-1,3,5-trienes 10a,b, 11a,b by reactions of amino(diferrocenyl)cyclopropenylium tetrafluoro-borates with 1-methylprop-2-enylmagnesium chloride at 80 °C is described. [...] Read more.

Synthesis of 3,4-diferrocenyltoluene (7), 1-morpholino- and 1-piperidino-2,3-diferrocenylbicyclo[3.1.0]hex-2-enes 8a, 8b, 1-morpholino- and 1-piperidino-7-ferrocenyl-3,4-ferrocenobicyclo[3.2.1]oct-6-enes 9a, 9b, 2- and 3-amino(diferrocenyl)-hexa-1,3,5-trienes 10a,b, 11a,b by reactions of amino(diferrocenyl)cyclopropenylium tetrafluoro-borates with 1-methylprop-2-enylmagnesium chloride at 80 °C is described. The structures of the compounds obtained were determined by IR, ¹H- and ¹³C-NMR spectroscopy and mass spectrometry. X-ray diffraction data for 1-piperidino-7-ferrocenyl-3,4-ferroceno-bicyclo[3.2.1]oct-6-ene (9b), 2-morpholino- and 2-piperidino-1,3-diferrocenyl-4-methyl-hexa-1,3,5-trienes 10a and 10b is presented. The electrochemical behaviour of compounds 7, 8a, 10a and 10b was investigated by means of cyclic voltammetry and square wave voltammetry. For 7 and 8a two electrochemical processes (I-II), attributed to the oxidation of the ferrocene moieties were found. On the other hand for compounds 10a and 10b a single electron transfer for both ferrocene groups and the electrochemical generation of the monocation and dication species were detected. Full article

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328 KiB

Open AccessArticle
Development of a Specifically Enhanced Enzyme-Linked Immunosorbent Assay for the Detection of Melamine in Milk
by Hongtao Lei, Rui Su, Simon A. Haughey, Qiang Wang, Zhenlin Xu, Jinyi Yang, Yudong Shen, Hong Wang, Yueming Jiang and Yuanming Sun

Molecules 2011, 16(7), 5591-5603; https://doi.org/10.3390/molecules16075591 - 30 Jun 2011
Cited by 39 | Viewed by 6866
Abstract
An indirect competitive enzyme-linked immunosorbent assay (icELISA) with enhanced specificity for melamine in milk was developed. Three haptens of melamine with different spacer-arms were used to prepare different plate coating antigens. It was found that the icELISA show best sensitivity and specificity to [...] Read more.

An indirect competitive enzyme-linked immunosorbent assay (icELISA) with enhanced specificity for melamine in milk was developed. Three haptens of melamine with different spacer-arms were used to prepare different plate coating antigens. It was found that the icELISA show best sensitivity and specificity to melamine when using the coating antigen prepared by coupling 3-(4,6-diamino-1,6-dihydro-1,3,5-triazin-2-ylthio)propanoic acid (Hapten C) with ovalbumin (OVA). The 50% inhibitory concentration (IC₅₀) value was 35.4 ng·mL⁻¹, the limit of detection (LOD) was 8.9 ng·mL⁻¹ and the detectable working range (20–80% inhibitory concentration) was from 14.9 to 108.5 ng·mL⁻¹, respectively. Compared to the ELISA results previously reported, the developed icELISA in the present study showed a much lower cross-reactivity to cyromazine, a fly-killing insecticide widely used in vegetables and stables. Recoveries obtained from milk samples in this study were in agreement with those obtained using the HPLC-MS method, indicating the detection performance of the icELISA could meet the requirement of the residue limit set by the Codex Alimentarius Commission. Therefore, the developed immunoassay can be applied for the analysis of melamine presented in milk. Full article

(This article belongs to the Section Organic Chemistry)

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226 KiB

Open AccessArticle
Unsymmetrical Mesoporphyrinic Complexes of Copper (II) and Zinc (II). Microwave-Assisted Synthesis, Spectral Characterization and Cytotoxicity Evaluation
by Rica Boscencu

Molecules 2011, 16(7), 5604-5617; https://doi.org/10.3390/molecules16075604 - 30 Jun 2011
Cited by 19 | Viewed by 4645
Abstract
New unsymmetrical mesoporphyrinic complexes, namely 5-(4-hydroxyphenyl)-10,15,20–tris-(4-carboxymethylphenyl)–21,23-Zn(II)-porphine and 5-(4-hydroxyphenyl)-10,15,20–tris-(4-carboxymethylphenyl)–21,23-Cu(II)-porphine, were synthesized using a microwave irradiation method. The structures of the porphyrinic complexes were confirmed using FT-IR, UV–Vis, EPR and NMR spectral data. The spectral absorption and emission properties of the porphyrinic complexes were studied [...] Read more.

New unsymmetrical mesoporphyrinic complexes, namely 5-(4-hydroxyphenyl)-10,15,20–tris-(4-carboxymethylphenyl)–21,23-Zn(II)-porphine and 5-(4-hydroxyphenyl)-10,15,20–tris-(4-carboxymethylphenyl)–21,23-Cu(II)-porphine, were synthesized using a microwave irradiation method. The structures of the porphyrinic complexes were confirmed using FT-IR, UV–Vis, EPR and NMR spectral data. The spectral absorption and emission properties of the porphyrinic complexes were studied in organic solvents of different polarities and the influence of solvent polarity on the wavelengths of the absorbance and fluorescence band maxima is described. The cytotoxicity evaluation of the porphyrinic complexes was performed on human colon adenocarcinoma cell line HT29 for different doses and incubation times. The obtained result indicates a lack of or low toxicity for both compounds, thus recommending them for further testing in light activation protocols. Full article

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223 KiB

Open AccessCommunication
Synthesis and Antifungal Activities of Some Novel Pyrimidine Derivatives
by Li Sun, Jie Wu, Lingzi Zhang, Min Luo and Dequn Sun

Molecules 2011, 16(7), 5618-5628; https://doi.org/10.3390/molecules16075618 - 30 Jun 2011
Cited by 33 | Viewed by 7053
Abstract
Three series of new pyrimidine derivatives were synthesized and their antifungal activities were evaluated in vitro against fourteen phytopathogenic fungi. The results indicated that most of the synthesized compounds possessed fungicidal activities and some of them are more potent than the control fungicides. [...] Read more.

Three series of new pyrimidine derivatives were synthesized and their antifungal activities were evaluated in vitro against fourteen phytopathogenic fungi. The results indicated that most of the synthesized compounds possessed fungicidal activities and some of them are more potent than the control fungicides. Preliminary SAR was also discussed. Full article

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246 KiB

Open AccessArticle
Pyranoxanthones from Mesua ferrea
by Soek Sin Teh, Gwendoline Cheng Lian Ee, Mawardi Rahmani, Yun Hin Taufiq-Yap, Rusea Go and Siau Hui Mah

Molecules 2011, 16(7), 5647-5654; https://doi.org/10.3390/molecules16075647 - 30 Jun 2011
Cited by 21 | Viewed by 6580
Abstract
Our phytochemical studies on the root bark extracts of Mesua ferrea have led to the isolation of two new pyranoxanthones, mesuaferrin A (1) and mesuaferrin B (2). Five other compounds – caloxanthone C (3), 1,8-dihydro-3-methoxy-6-methylanthraquinone (4 [...] Read more.

Our phytochemical studies on the root bark extracts of Mesua ferrea have led to the isolation of two new pyranoxanthones, mesuaferrin A (1) and mesuaferrin B (2). Five other compounds – caloxanthone C (3), 1,8-dihydro-3-methoxy-6-methylanthraquinone (4), β-sitosterol (5), friedelin (6) and betulinic acid (7) – were also successfully isolated. Structural elucidations of these compounds were achieved using 1D and 2D NMR and MS techniques. Full article

(This article belongs to the Section Natural Products Chemistry)

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275 KiB

Open AccessCommunication
NMR and UV Studies of 4-Thio-2′-deoxyuridine and Its Derivatives
by Xiaohui Zhang and Yao-Zhong Xu

Molecules 2011, 16(7), 5655-5664; https://doi.org/10.3390/molecules16075655 - 01 Jul 2011
Cited by 21 | Viewed by 6143
Abstract
5-Substituted-4-thio-2’-deoxyuridine nucleosides have been chemically synthesized and studied by NMR and UV spectroscopy. The results have been analyzed and discussed in connection with the previous data. The imino proton signal and the carbon signal of the thiocarbonyl group in the 5-substituted-4-thio-2’-deoxyuridines were found [...] Read more.

5-Substituted-4-thio-2’-deoxyuridine nucleosides have been chemically synthesized and studied by NMR and UV spectroscopy. The results have been analyzed and discussed in connection with the previous data. The imino proton signal and the carbon signal of the thiocarbonyl group in the 5-substituted-4-thio-2’-deoxyuridines were found to be at much lower field, offering a potential for monitoring these modified bases at the DNA level. All 4-thionucleosides have strong absorptions at around 340 nm and consequently would be useful as potential UVA-induced anticancer agents. Full article

(This article belongs to the Special Issue Nucleoside Analogues)

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Open AccessArticle
Treatment of Alcohols with Tosyl Chloride Does Not always Lead to the Formation of Tosylates
by Rui Ding, Yong He, Xiao Wang, Jingli Xu, Yurong Chen, Man Feng and Chuanmin Qi

Molecules 2011, 16(7), 5665-5673; https://doi.org/10.3390/molecules16075665 - 01 Jul 2011
Cited by 52 | Viewed by 21910
Abstract
Treatment of substituted benzyl alcohols with tosyl chloride resulted in the formation of the corresponding chlorides, not the usual tosylates. A series of experiments demonstrated that it was possible to predict whether chlorination or tosylation would occur for substituted benzyl alcohols and pyridine [...] Read more.

Treatment of substituted benzyl alcohols with tosyl chloride resulted in the formation of the corresponding chlorides, not the usual tosylates. A series of experiments demonstrated that it was possible to predict whether chlorination or tosylation would occur for substituted benzyl alcohols and pyridine methanols. Treatment of electron withdrawing group-substituted benzyl alcohols with tosyl chloride gave the corresponding chlorides in moderate yields under mild conditions, which provided a simple way to directly prepare chlorides from alcohols. Full article

(This article belongs to the Section Organic Chemistry)

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Open AccessArticle
Lianqiaoxinoside B, a Novel Caffeoyl Phenylethanoid Glycoside from Forsythia suspensa
by Hai-Xue Kuang, Yong-Gang Xia, Jun Liang, Bing-You Yang and Qiu-Hong Wang

Molecules 2011, 16(7), 5674-5681; https://doi.org/10.3390/molecules16075674 - 04 Jul 2011
Cited by 22 | Viewed by 7390
Abstract
Chemical investigation of the 70% ethanol extract of the unripe fruits of Forsythia suspensa resulted in the isolation of a novel caffeoyl phenylethanoid glycoside, lianqiaoxinoside B, together with the known compound forsythoside H. The new compound was elucidated to be 1'',2''-[β-(3,4,-dihydroxylphenyl)- [...] Read more.

Chemical investigation of the 70% ethanol extract of the unripe fruits of Forsythia suspensa resulted in the isolation of a novel caffeoyl phenylethanoid glycoside, lianqiaoxinoside B, together with the known compound forsythoside H. The new compound was elucidated to be 1'',2''-[β-(3,4,-dihydroxylphenyl)-α,β-dioxoethanol]-3''-O-caffeoyl-O-α-rhamnopyranosyl-(1→6)-O-β-glucopyranoside by extensive spectroscopic and chemical studies. Lianqiaoxinoside B and forsythoside H showed strong antioxidant and antimicrobial activities in vitro by the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS) radical-scavenging assay and plate method. This study can be further extended to exploit for the possible application of caffeoyl phenylethanoid glycosides as the alternative antioxidants and antimicrobial agents of natural origin. Full article

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Open AccessArticle
Synthesis and Anticancer Activity of Some New S-Glycosyl and S-Alkyl 1,2,4-Triazinone Derivatives
by Hosam A. Saad and Ahmed H. Moustafa

Molecules 2011, 16(7), 5682-5700; https://doi.org/10.3390/molecules16075682 - 04 Jul 2011
Cited by 36 | Viewed by 6072
Abstract
A series of S-glycosyl and S-alkyl derivatives of 4-amino-3-mercapto-6-(2-(2-thienyl)vinyl)-1,2,4-triazin-5(4H)-one (1) were synthesized using different halo compounds such as preacetylated sugar bromide, 4-bromobutylacetate, 2-acetoxyethoxy-methyl bromide, 3-chloropropanol, 1,3-dichloro-2-propanol, epichlorohydrin, allyl bromide, propargyl bromide, phthalic and succinic acids in POCl₃. The structures [...] Read more.

A series of S-glycosyl and S-alkyl derivatives of 4-amino-3-mercapto-6-(2-(2-thienyl)vinyl)-1,2,4-triazin-5(4H)-one (1) were synthesized using different halo compounds such as preacetylated sugar bromide, 4-bromobutylacetate, 2-acetoxyethoxy-methyl bromide, 3-chloropropanol, 1,3-dichloro-2-propanol, epichlorohydrin, allyl bromide, propargyl bromide, phthalic and succinic acids in POCl₃. The structures of the synthesized compounds have been deduced from their elemental analysis and spectral (IR, ¹H-NMR, and¹³C-NMR) data. Some of the synthesized compounds were screened as anticancer agents. Significant anticancer activities were observed in vitro for some members of the series, and compounds 4-Amino-3-(3-hydroxypropylthio)-6-(2-(2-thienyl)vinyl)-1,2,4-triazin-5(4H)-one (12) and 3-(4-Oxo-3-(2-(2-thienyl)vinyl)-4H-[1,3,4]thiadiazolo-[2,3-c][1,2,4]tr-iazin-7-yl)propanoic acid (18) are active cytotoxic agents against different cancer cell lines. Full article

(This article belongs to the Section Organic Chemistry)

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Two New Triterpene Glycosides with Monomethyl Malonate Groups from the Rhizome of Cimifuga foetida L.
by Li-Rong Sun, Jian Yan, Lin Zhou, Zhong-Rong Li and Ming-Hua Qiu

Molecules 2011, 16(7), 5701-5708; https://doi.org/10.3390/molecules16075701 - 05 Jul 2011
Cited by 13 | Viewed by 6524
Abstract
Two new 9,19-cycloartane triterpene glycosides 1-2, together with four known compounds—26-deoxyactein (3), actein (4), 7,8-didehydro-26-deoxyactein (5) and cimiaceroside B (6)—were isolated from the rhizome of Cimicifuga foetida. The new triterpene glycosides [...] Read more.

Two new 9,19-cycloartane triterpene glycosides 1-2, together with four known compounds—26-deoxyactein (3), actein (4), 7,8-didehydro-26-deoxyactein (5) and cimiaceroside B (6)—were isolated from the rhizome of Cimicifuga foetida. The new triterpene glycosides were identified as 23-O-methyl-24-deoxy-2'-O-(3''-methylmalonyl)-cimiaceroside B (1) and 2'-O-(3''-methylmalonyl)actein (2) based on analysis of their spectral data and chemical reactions. Full article

(This article belongs to the Section Natural Products Chemistry)

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An Effective Ostrich Oil Bleaching Technique Using Peroxide Value as an Indicator
by Uma Devi Palanisamy, Muniswaran Sivanathan, Ammu Kutty Radhakrishnan, Nagaraja Haleagrahara, Thavamanithevi Subramaniam and Gan Seng Chiew

Molecules 2011, 16(7), 5709-5719; https://doi.org/10.3390/molecules16075709 - 05 Jul 2011
Cited by 14 | Viewed by 11936
Abstract
Ostrich oil has been used extensively in the cosmetic and pharmaceutical industries. However, rancidity causes undesirable chemical changes in flavour, colour, odour and nutritional value. Bleaching is an important process in refining ostrich oil. Bleaching refers to the removal of certain minor constituents [...] Read more.

Ostrich oil has been used extensively in the cosmetic and pharmaceutical industries. However, rancidity causes undesirable chemical changes in flavour, colour, odour and nutritional value. Bleaching is an important process in refining ostrich oil. Bleaching refers to the removal of certain minor constituents (colour pigments, free fatty acid, peroxides, odour and non-fatty materials) from crude fats and oils to yield purified glycerides. There is a need to optimize the bleaching process of crude ostrich oil prior to its use for therapeutic purposes. The objective of our study was to establish an effective method to bleach ostrich oil using peroxide value as an indicator of refinement. In our study, we showed that natural earth clay was better than bentonite and acid-activated clay to bleach ostrich oil. It was also found that 1 hour incubation at a 150 °C was suitable to lower peroxide value by 90%. In addition, the nitrogen trap technique in the bleaching process was as effective as the continuous nitrogen flow technique and as such would be the recommended technique due to its cost effectiveness. Full article

(This article belongs to the Section Natural Products Chemistry)

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Licocalchone-C Extracted from Glycyrrhiza Glabra Inhibits Lipopolysaccharide-Interferon-γ Inflammation by Improving Antioxidant Conditions and Regulating Inducible Nitric Oxide Synthase Expression
by Sara Franceschelli, Mirko Pesce, Isabella Vinciguerra, Alessio Ferrone, Graziano Riccioni, Patruno Antonia, Alfredo Grilli, Mario Felaco and Lorenza Speranza

Molecules 2011, 16(7), 5720-5734; https://doi.org/10.3390/molecules16075720 - 06 Jul 2011
Cited by 61 | Viewed by 10441
Abstract
The genus Glycyrrhiza consists of about 30 species, amoung these, G. glabra is the source of several phenolic compounds, known as flavonoids, such as licoagrodin, licoagrochalcones, licoagroaurone and licochalcone C, kanzonol Y, glyinflanin B and glycyrdione A, which have shown various pharmacological [...] Read more.

The genus Glycyrrhiza consists of about 30 species, amoung these, G. glabra is the source of several phenolic compounds, known as flavonoids, such as licoagrodin, licoagrochalcones, licoagroaurone and licochalcone C, kanzonol Y, glyinflanin B and glycyrdione A, which have shown various pharmacological activities, including antitumor, antiparasitic, antileishmanial, anti-ulcer and antioxidative effects. Among these compounds, licochalcone C was isolated but its biology has not been fully examined. In our study we reproduced an inflammatory state by treating THP-1 (human myelomonocytic leukaemia) cells with pro-inflammatory stimuli, such as LPS and IFN-γ and we investigated the possible antioxidant activity of licochalcone C at a concentration of 50 μM. Our results show that treatment with licochalcone C attenuates the LPS-IFN-γ-induced inflammatory response by significantly decreasing the expression and activity of iNOS via NFκB (nuclear factor kappa-B), by influencing extracellular O₂⁻ production, and by modulating the antioxidant network activity of SOD (superoxide dismutase), CAT (catalase) and GPx (glutathione peroxidase) activity. Based on these results we hypothesize that Licochalcone C has antioxidant properties since it reduces the production of superoxide radicals and consequently reduces the activity of iNOS. Full article

(This article belongs to the Special Issue Antioxidants)

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Antioxidant Activity of Ixora parviflora in a Cell/Cell-Free System and in UV-Exposed Human Fibroblasts
by Kuo-Ching Wen, Hua-Hsien Chiu, Pei-Ching Fan, Chien-Wen Chen, Shih-Mei Wu, Jung-Hsiang Chang and Hsiu-Mei Chiang

Molecules 2011, 16(7), 5735-5752; https://doi.org/10.3390/molecules16075735 - 06 Jul 2011
Cited by 32 | Viewed by 8141
Abstract
Polyphenols and flavonoids possess a variety of biological activities including antioxidant and anti-tumor activities. Ixora parviflora is a member of the flavonoid-rich Rubiaceae family of flowering plants and used as folk medicine in India. The aim of this study was to investigate the [...] Read more.

Polyphenols and flavonoids possess a variety of biological activities including antioxidant and anti-tumor activities. Ixora parviflora is a member of the flavonoid-rich Rubiaceae family of flowering plants and used as folk medicine in India. The aim of this study was to investigate the antioxidant activity of Ixora parviflora extract (IPE) in a cell-free system and erythrocytes, and the ability of IPE to inhibit reactive oxygen species (ROS) generation in human fibroblasts (Hs68) after ultraviolet (UV) exposure. Various in vitro antioxidant assays were employed in this study. The extraction yield of IPE was 17.4 ± 3.9%, the total phenolic content of IPE was 26.2 μg gallic acid equivalent (GAE)/mg leaves dry weight and the total flavonoids content was 54.2 ± 4.4 μg quercetin equvalent (QE)/mg extract. The content of chlorogenic acid was 9.7 ± 1.2 mg/g extract. IPE at 1000 μg/mL exhibited a reducing capacity of 90.5 ± 0.6%, a 1,1-diphenyl-2-picrylhydrazy (DPPH) radical scavenging activity of 96.0 ± 0.4%, a ferrous chelating activity of 72.2 ± 3.5%, a hydroxyl radical scavenging activity of 96.8 ± 1.4%, and a hydrogen peroxide scavenging activity of 99.5 ± 3.3%. IPE at 500 μg/mL also possessed inhibitory activity against 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH)-induced hemolysis of erythrocytes (89.4 ± 1.8%) and resulted in a 52.9% reduction in ROS generation in UV-exposed fibroblasts. According to our findings, IPE is a potent antioxidant and a potential anti-photoaging agent. Full article

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Pentamethylquercetin Improves Adiponectin Expression in Differentiated 3T3-L1 Cells via a Mechanism that Implicates PPARγ together with TNF-α and IL-6
by Lei Chen, Ting He, Yi Han, Ji-Zhong Sheng, Si Jin and Man-Wen Jin

Molecules 2011, 16(7), 5754-5768; https://doi.org/10.3390/molecules16075754 - 06 Jul 2011
Cited by 33 | Viewed by 7912
Abstract
Adiponectin is an adipocyte-derived hormone that plays a pivotal role in the regulation of lipid and glucose metabolism. Up-regulation of adiponectin expression and production has been shown to benefit for metabolic disorders, including type 2 diabetes, hyperlipidemia, etc. The present study investigated whether [...] Read more.

Adiponectin is an adipocyte-derived hormone that plays a pivotal role in the regulation of lipid and glucose metabolism. Up-regulation of adiponectin expression and production has been shown to benefit for metabolic disorders, including type 2 diabetes, hyperlipidemia, etc. The present study investigated whether the novel polymethoxylated flavonoid pentamethylquercetin (PMQ), a member of polymethoxylated flavonoids family which is present in seabuckthorn (Hippophae L.) would affect adiponectin production in differentiated 3T3-L1 adipocytes. It was found that PMQ increased the adiponectin mRNA and protein expressions in adipocytes in time- and concentration-dependent manners. The PPARγ pathway plays a important roles in this effect of PMQ because blockade of PPARγ by GW9662 eliminates the PMQ-induced up-regulation of adiponectin expression. Furthermore, significant decreases of mRNA expression and secretion of TNF-α and IL-6 were also observed in PMQ-treated cells. Taken together, our study demonstrated that PMQ up-regulates adiponectin expression via a mechanism that implicates PPARγ together with TNF-α and IL-6, suggesting that PMQ might be a potential candidate for the treatment of metabolic diseases. Full article

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Use of Novel Cardanol-Porphyrin Hybrids and Their TiO₂-Based Composites for the Photodegradation of 4-Nitrophenol in Water
by Giuseppe Vasapollo, Giuseppe Mele, Roberta Del Sole, Iolanda Pio, Jun Li and Selma Elaine Mazzetto

Molecules 2011, 16(7), 5769-5784; https://doi.org/10.3390/molecules16075769 - 07 Jul 2011
Cited by 32 | Viewed by 7497
Abstract
Cardanol, a well known hazardous byproduct of the cashew industry, has been used as starting material for the synthesis of useful differently substituted “cardanol-based” porphyrins and their zinc(II), copper(II), cobalt(II) and Fe(III) complexes. Novel composites prepared by impregnation of polycrystalline TiO₂ powder [...] Read more.

Cardanol, a well known hazardous byproduct of the cashew industry, has been used as starting material for the synthesis of useful differently substituted “cardanol-based” porphyrins and their zinc(II), copper(II), cobalt(II) and Fe(III) complexes. Novel composites prepared by impregnation of polycrystalline TiO₂ powder with an opportune amount of “cardanol-based” porphyrins, which act as sensitizers for the improvement of the photo-catalytic activity of the bare TiO₂, have been used in the photodegradation in water of 4-nitrophenol (4-NP), which is a toxic and bio-refractory pollutant, dangerous for ecosystems and human health. Full article

(This article belongs to the Special Issue Tetrapyrroles, Porphyrins and Phthalocyanines)

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Design, Synthesis and Biological Activity Evaluation of Arylpiperazine Derivatives for the Treatment of Neuropathic Pain
by Yin Chen, Guan Wang, Xiangqing Xu, Bi-Feng Liu, Jianqi Li and Guisen Zhang

Molecules 2011, 16(7), 5785-5806; https://doi.org/10.3390/molecules16075785 - 07 Jul 2011
Cited by 9 | Viewed by 5775
Abstract
In this work, a series of arylpiperazine derivatives were synthesized and screened by in vivo pharmacological trials. Among the tested compounds, 2-(4-(3-(trifluoromethyl)phenyl)piperazin-1-yl)-1-phenylethanone (18) and 2-(4-(2,3-dimethylphenyl)piperazin-1-yl)-1-phenylethanone (19) exhibited potent analgesic activities in both the mice writhing and mice hot [...] Read more.

In this work, a series of arylpiperazine derivatives were synthesized and screened by in vivo pharmacological trials. Among the tested compounds, 2-(4-(3-(trifluoromethyl)phenyl)piperazin-1-yl)-1-phenylethanone (18) and 2-(4-(2,3-dimethylphenyl)piperazin-1-yl)-1-phenylethanone (19) exhibited potent analgesic activities in both the mice writhing and mice hot plate tests. They showed more than 70% inhibition relative to controls in the writhing test, and increased latency by 116.0% and 134.4%, respectively, in the hot plate test. Furthermore, compound 18 was also active in the models of formalin pain and neuropathic pain without sedative side effects. Full article

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Synthesis and Spectroscopic Characterization of Two Tetrasubstituted Cationic Porphyrin Derivatives
by Antonio E.H. Machado, Weverson R. Gomes, Diesley M.S. Araújo, Hércules S. Miglio, Leonardo T. Ueno, Rodrigo De Paula, José A.S. Cavaleiro and Newton M. Barbosa Neto

Molecules 2011, 16(7), 5807-5821; https://doi.org/10.3390/molecules16075807 - 08 Jul 2011
Cited by 12 | Viewed by 8029
Abstract
An imidazolium tetrasubstituted cationic porphyrin derivative (the free base and its Zn(II) complex) with five-membered heterocyclic groups in the meso-positions were synthesized using microwave irradiation, and the compounds obtained characterized by ¹H-NMR and mass spectrometry. We observed that under microwave irradiation [...] Read more.

An imidazolium tetrasubstituted cationic porphyrin derivative (the free base and its Zn(II) complex) with five-membered heterocyclic groups in the meso-positions were synthesized using microwave irradiation, and the compounds obtained characterized by ¹H-NMR and mass spectrometry. We observed that under microwave irradiation the yield is similar to when the synthesis is performed under conventional heating, however, the time required to prepare the porphyrins decreases enormously. In order to investigate the electronic state of these compounds, we employed UV-Vis and fluorescence spectroscopy combined with quantum chemical calculations. The results reveal the presence, in both compounds, of a large number of electronic states involving the association between the Soret and a blue-shifted band. The Soret band in both compounds also shows a considerable solvent dependence. As for emission, these compounds present low quantum yield at room temperature and no solvent influence on the fluorescence spectra was observed. Full article

(This article belongs to the Special Issue Organometallic Chemistry)

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Characterization and Determination of the Alkaloid Metabolites of Evodiae fructus in Rat Urine by Liquid Chromatography-Tandem Mass Spectrometry Detection
by Rui Yan, Qier Mu, Yin Wang, Youping Liu and Xin Di

Molecules 2011, 16(7), 5822-5832; https://doi.org/10.3390/molecules16075822 - 08 Jul 2011
Cited by 6 | Viewed by 6493
Abstract
The lack of authentic standards limits the quantitative analysis of herbal drugs in biological samples. This present work demonstrated a practicable assay of herbs and their metabolites independent of the availability of authentic standards. A liquid chromatography–electrospray ionization–mass spectrometry (LC–ESI–MS) method for the [...] Read more.

The lack of authentic standards limits the quantitative analysis of herbal drugs in biological samples. This present work demonstrated a practicable assay of herbs and their metabolites independent of the availability of authentic standards. A liquid chromatography–electrospray ionization–mass spectrometry (LC–ESI–MS) method for the qualitative and quantitative determination of the metabolites after oral administration of Evodiae fructus and Zuojinwan preparation in rat urine has been developed. Urine samples extracted with a protein precipitation procedure were separated on a C₁₈ column using a mixture of water (containing 0.1% formic acid) and acetonitrile (30:70, v/v) as mobile phase. The detection was performed by MS with electrospray ionization interface in positive selected reaction monitoring (SRM) mode. One urine sample after administration was selected as 'standard'. The method validation was carried out according to a conventional method that was calibrated by authentic standards. The fully validated method was applied to the pharmacokinetic study of the metabolites in rat urine. The results could provide evidence to explain the combination of Coptidis rhizoma and Evodiae fructus in terms of elimination. Full article

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Open AccessArticle
Two New Withanolide Lactones from Flos Daturae
by Hai-Xue Kuang, Bing-You Yang, Yong-Gang Xia and Qiu-Hong Wang

Molecules 2011, 16(7), 5833-5839; https://doi.org/10.3390/molecules16075833 - 11 Jul 2011
Cited by 38 | Viewed by 6490
Abstract
Chemical investigation of the 50% ethanol eluate fraction from a macroporous resin of flowers of Datura metel L. collected in the Jiangsu Province of China resulted in the isolation of two new withanolides, baimantuoluoline G (1) and baimantuoluoside H (2 [...] Read more.

Chemical investigation of the 50% ethanol eluate fraction from a macroporous resin of flowers of Datura metel L. collected in the Jiangsu Province of China resulted in the isolation of two new withanolides, baimantuoluoline G (1) and baimantuoluoside H (2). Their structures were elucidated as (12β,6β,22R)-1,10-seco-6,12,27-trihydroxy-26-oxo-witha-3,5,24-trienolide-1-oic acid-ε-lactone (1) and (5β,6α,12β,22R)-5,6,12,27-tetra-hydroxy-1,26-dioxo-witha-2,24-dienolide-27-O-β-glucopyranoside (2) on the basis of extensive spectroscopic analysis (1D, 2D-NMR and HRESIMS) and chemical studies. Full article

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Synthesis and Cytotoxic Activity of Some New 2,6-Substituted Purines
by Nageswara Rao Kode and Shashikant Phadtare

Molecules 2011, 16(7), 5840-5860; https://doi.org/10.3390/molecules16075840 - 11 Jul 2011
Cited by 12 | Viewed by 5975
Abstract
A seriesof twenty four acyclic unsaturated 2,6-substututed purines 5a-20b were synthesized. These compounds were evaluated for cytotoxic activity against NCI-60 DTP human tumor cell line screen at 10µMconcentration. N₉-[(Z)-4'-chloro-2'-butenyl-1'-yl]-2,6-dichloropurine(5a), N₉-[4'-chloro-2'-butynyl-1'-yl]-2,6-dichloropurine(10a), N₉-[( [...] Read more.

A seriesof twenty four acyclic unsaturated 2,6-substututed purines 5a-20b were synthesized. These compounds were evaluated for cytotoxic activity against NCI-60 DTP human tumor cell line screen at 10µMconcentration. N₉-[(Z)-4'-chloro-2'-butenyl-1'-yl]-2,6-dichloropurine(5a), N₉-[4'-chloro-2'-butynyl-1'-yl]-2,6-dichloropurine(10a), N₉-[(E)-2',3'-dibromo-4'-chloro-2'-butenyl-1'-yl]-6-methoxypurine(14)and N₉-[4'-chloro-2'-butynyl-1'-yl]-6-(4-methoxyphenyl)-purine(19)exhibited highly potent cytotoxic activity with GI₅₀ values in the 1–5 µM range for most human tumor cell lines. Other compounds exhibited moderate activity. Full article

(This article belongs to the Section Medicinal Chemistry)

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Synthesis and Biological Activities on Metal Complexes of 2,5-Diamino-1,3,4-thiadiazole Derived from Semicarbazide Hydrochloride
by Joshua A. Obaleye, Johnson F. Adediji and Matthew A. Adebayo

Molecules 2011, 16(7), 5861-5874; https://doi.org/10.3390/molecules16075861 - 12 Jul 2011
Cited by 31 | Viewed by 7276
Abstract
A bioactive ligand, 2,5-diamino-1,3,4-thiadiazole (L), derived from semicarbazide hydrochloride, and its metal complexes were prepared and characterized. The complexes were characterized using elemental, infra-red, ultraviolet/visible, magnetic moment, atomic absorption, thin layer chromatography and molar conductance measurements. The IR data revealed that [...] Read more.

A bioactive ligand, 2,5-diamino-1,3,4-thiadiazole (L), derived from semicarbazide hydrochloride, and its metal complexes were prepared and characterized. The complexes were characterized using elemental, infra-red, ultraviolet/visible, magnetic moment, atomic absorption, thin layer chromatography and molar conductance measurements. The IR data revealed that the ligand (L) behaved as a tridentate neutral ligand. It coordinated to the metal ion via sulphur and nitrogen of the amines. The molar conductance data reveal that the chelates are non-electrolytes. From the Ultraviolet/Visible spectra and magnetic moment data, the complexes were found to have octahedral geometrical structure. In vivo evaluation of the antimicrobial activities of the metal complexes and the ligands showed greater activity against some micro-organisms when compared to the parent compounds. The chelates do not show toxicity against the activities of enzymes from homogenates of liver, kidney and serum in experimental rats. Full article

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Comparative Properties of Amazonian Oils Obtained by Different Extraction Methods
by Bianca Silva Ferreira, Camila Guimarães De Almeida, Lara Pereira Faza, Angelina De Almeida, Cláudio Galuppo Diniz, Vânia Lúcia da Silva, Richard Michael Grazul and Mireille Le Hyaric

Molecules 2011, 16(7), 5875-5885; https://doi.org/10.3390/molecules16075875 - 13 Jul 2011
Cited by 81 | Viewed by 11869
Abstract
Pequi (Caryocar brasiliense Camb.), babaçu (Orbignya phalerata Mart.), buriti (Mauritia flexuosa), and passion fruit (Passiflora edulis) oils were studied to determine their antibacterial, antioxidant and cytotoxic activities, as well as their total phenol and carotenoid [...] Read more.

Pequi (Caryocar brasiliense Camb.), babaçu (Orbignya phalerata Mart.), buriti (Mauritia flexuosa), and passion fruit (Passiflora edulis) oils were studied to determine their antibacterial, antioxidant and cytotoxic activities, as well as their total phenol and carotenoid contents. The fatty acid contents were determined by GC-MS. The three types of passion fruit oils studied were refined, cold pressed or extracted from seeds in a Soxhlet apparatus. The oils thus obtained showed differences in antioxidant activity and carotenoid content, but were similar in regard to total phenols. Buriti and pequi had the highest carotenoid contents, while refined and cold pressed passion fruit oil displayed the highest antioxidant activity. Pequi oil was the only oil to display antibacterial and cytotoxic activity. Full article

(This article belongs to the Section Natural Products Chemistry)

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Friedel-Craft Acylation of ar-Himachalene: Synthesis of Acyl-ar-Himachalene and a New Acyl-Hydroperoxide
by Issam Hossini, Mohamed Anoir Harrad, Mustapha Ait Ali, Larbi El Firdoussi, Abdallah Karim, Pedro Valerga and M. Carmen Puerta

Molecules 2011, 16(7), 5886-5895; https://doi.org/10.3390/molecules16075886 - 14 Jul 2011
Cited by 7 | Viewed by 10276
Abstract
Friedel-Craft acylation at 100 °C of 2,5,9,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene [ar-himachalene (1)], a sesquiterpenic hydrocarbon obtained by catalytic dehydrogenation of α-, β- and γ-himachalenes, produces a mixture of two compounds: (3,5,5,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-2-yl)-ethanone (2, in 69% yield), with a conserved [...] Read more.

Friedel-Craft acylation at 100 °C of 2,5,9,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene [ar-himachalene (1)], a sesquiterpenic hydrocarbon obtained by catalytic dehydrogenation of α-, β- and γ-himachalenes, produces a mixture of two compounds: (3,5,5,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-2-yl)-ethanone (2, in 69% yield), with a conserved reactant backbone, and 3, with a different skeleton, in 21% yield. The crystal structure of 3 reveals it to be 1-(8-ethyl-8-hydroperoxy-3,5,5-trimethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-ethanone. In this compound O-H…O bonds form dimers. These hydrogen-bonds, in conjunction with weaker C-H…O interactions, form a more extended supramolecular arrangement in the crystal. Full article

(This article belongs to the Section Organic Chemistry)

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238 KiB

Open AccessArticle
Biocatalytic Resolution of Enantiomeric Mixtures of 1-Aminoethanephosphonic Acid
by Małgorzata Brzezińska-Rodak, Magdalena Klimek-Ochab, Ewa Żymańczyk-Duda and Paweł Kafarski

Molecules 2011, 16(7), 5896-5904; https://doi.org/10.3390/molecules16075896 - 14 Jul 2011
Cited by 21 | Viewed by 6251
Abstract
Several fungal strains, namely Bauveria bassiana, Cuninghamella echinulata, Aspergillus fumigatus, Penicillium crustosum and Cladosporium herbarum, were used as biocatalysts to resolve racemic mixtures of 1-aminoethanephosphonic acid using L/D amino acid oxidase activity. The course of reaction was analyzed by ³¹P-NMR in [...] Read more.

Several fungal strains, namely Bauveria bassiana, Cuninghamella echinulata, Aspergillus fumigatus, Penicillium crustosum and Cladosporium herbarum, were used as biocatalysts to resolve racemic mixtures of 1-aminoethanephosphonic acid using L/D amino acid oxidase activity. The course of reaction was analyzed by ³¹P-NMR in the presence of cyclodextrin used as chiral discriminating agent. The best result (42% e.e of R-isomer) was obtained with a strain of Cuninghamella echinulata. Full article

(This article belongs to the Special Issue Enzyme-Catalyzed Reactions)

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583 KiB

Open AccessArticle
HPLC Separation of All Aldopentoses and Aldohexoses on an Anion-Exchange Stationary Phase Prepared from Polystyrene-Based Copolymer and Diamine: The Effect of NaOH Eluent Concentration
by Kadumi Inoue, Kei-ichi Kitahara, Yoshihiro Aikawa, Sadao Arai and Takako Masuda-Hanada

Molecules 2011, 16(7), 5905-5915; https://doi.org/10.3390/molecules16075905 - 14 Jul 2011
Cited by 15 | Viewed by 7127
Abstract
To investigate the separations of all aldopentoses (ribose, arabinose, xylose and lyxose) and aldohexoses (glucose, galactose, allose, altrose, mannose, gulose, idose and talose) on the D₆ stationary phase prepared by the reaction of chloromethylated styrene-divinylbenzene copolymer and N,N,N [...] Read more.

To investigate the separations of all aldopentoses (ribose, arabinose, xylose and lyxose) and aldohexoses (glucose, galactose, allose, altrose, mannose, gulose, idose and talose) on the D₆ stationary phase prepared by the reaction of chloromethylated styrene-divinylbenzene copolymer and N,N,N’,N’-tetramethyl-1,6-diaminohexane, we examined the effect of varying the concentration of the NaOH eluent on the elution orders. Separations of these aldoses were achieved using a 20 mM NaOH eluent. The elution behaviors of the aldoses were probably due to not only the individual pK_a values, but also the chemical structures of the cyclic aldoses. Full article

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605 KiB

Open AccessArticle
Industrial Aplication of Catalytic Systems for n-Heptane Isomerization
by Laura Olivia Alemán-Vázquez, José Luis Cano-Domínguez, Enelio Torres-García and José Roberto Villagómez-Ibarra

Molecules 2011, 16(7), 5916-5927; https://doi.org/10.3390/molecules16075916 - 14 Jul 2011
Cited by 22 | Viewed by 9106
Abstract
The ideal gasoline must have a high pump octane number, in the 86 to 94 range, and a low environmental impact. Alkanes, as a family, have much lower photochemical reactivities than aromatics or olefins, but only the highly branched alkanes have adequate octane [...] Read more.

The ideal gasoline must have a high pump octane number, in the 86 to 94 range, and a low environmental impact. Alkanes, as a family, have much lower photochemical reactivities than aromatics or olefins, but only the highly branched alkanes have adequate octane numbers. The purpose of this work is to examine the possibilities of extending the technological alternative of paraffin isomerization to heavier feedstocks (i.e., n-heptane) using non-conventional catalytic systems which have been previously proposed in the literature: a Pt/sulfated zirconia catalyst and a molybdenum sub-oxide catalyst. Under the experimental conditions at which these catalysts have been evaluated, the molybdenum sub-oxide catalyst maintains a good activity and selectivity to isomerization after 24 h, while the Pt/sulfated zirconia catalyst shows a higher dimethylpentanes/methylhexanes ratio, probably due to a lower operating temperature, but also a high formation of cracking products, and presents signs of deactivation after 8 h. Though much remains to be done, the performance of these catalysts indicates that there are good perspectives for their industrial application in the isomerization of n-heptane and heavier alkanes. Full article

(This article belongs to the Section Molecular Diversity)

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492 KiB

Open AccessArticle
The Use of Response Surface Methodology to Optimize the Ultrasound-Assisted Extraction of Five Anthraquinones from Rheum palmatum L.
by Li-Chun Zhao, Jian Liang, Wei Li, Kun-Mu Cheng, Xianghua Xia, Xin Deng and Geng-Liang Yang

Molecules 2011, 16(7), 5928-5937; https://doi.org/10.3390/molecules16075928 - 15 Jul 2011
Cited by 49 | Viewed by 12553
Abstract
In this paper, ultrasound-assisted extraction (UAE) was applied to the extraction of anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) from Rheum palmatum L. The five anthraquinones were quantified and analyzed by high performance liquid chromatography coupled with UV detection (HPLC-UV). The extraction solvent, [...] Read more.

In this paper, ultrasound-assisted extraction (UAE) was applied to the extraction of anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) from Rheum palmatum L. The five anthraquinones were quantified and analyzed by high performance liquid chromatography coupled with UV detection (HPLC-UV). The extraction solvent, extraction temperature and extraction time parameters, the three main factors for UAE, were optimized with response surface methodology (RSM) to obtain the highest extraction efficiency. The optimal conditions were the use of 84% methanol as solvent, an extraction time of 33 min and an extraction temperature of 67 °C. Under these optimal conditions, the experimental values agreed closely with the predicted values. The analysis of variance indicated a high goodness of model fit and the success of RSM method for optimizing anthraquinones extraction in Rheum palmatum L. Full article

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440 KiB

Open AccessArticle
Synthetic Organic Electrochemistry in Ionic Liquids: The Viscosity Question
by Steven Bornemann and Scott T. Handy

Molecules 2011, 16(7), 5963-5974; https://doi.org/10.3390/molecules16075963 - 18 Jul 2011
Cited by 15 | Viewed by 7153
Abstract
Ionic liquids are obvious candidates for use in electrochemical applications due to their ionic character. Nevertheless, relatively little has been done to explore their application in electrosynthesis. We have studied the Shono oxidation of arylamines and carbamates using ionic liquids as recyclable solvents [...] Read more.

Ionic liquids are obvious candidates for use in electrochemical applications due to their ionic character. Nevertheless, relatively little has been done to explore their application in electrosynthesis. We have studied the Shono oxidation of arylamines and carbamates using ionic liquids as recyclable solvents and have noted that the viscosity of the medium is a major problem, although with the addition of sufficient co-solvent, good results and excellent recovery and recycling of the ionic liquid can be achieved. Full article

(This article belongs to the Special Issue Organic Electrosynthesis)

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549 KiB

Open AccessArticle
Integrated One-Pot Enrichment and Immobilization of Styrene Monooxygenase (StyA) Using SEPABEAD EC-EA and EC-Q1A Anion-Exchange Carriers
by Reto Ruinatscha, Rohan Karande, Katja Buehler and Andreas Schmid

Molecules 2011, 16(7), 5975-5988; https://doi.org/10.3390/molecules16075975 - 18 Jul 2011
Cited by 6 | Viewed by 6704
Abstract
A straightforward one-pot procedure combining enrichment and immobilization of recombinantely expressed FADH₂ dependent styrene monooxygenase (StyA) directly from Escherichia coli cell extracts was investigated. Sepabeads EC-EA and EC-Q1A anion-exchange carriers were employed to non-covalently adsorb StyA from the cell extracts depending on [...] Read more.

A straightforward one-pot procedure combining enrichment and immobilization of recombinantely expressed FADH₂ dependent styrene monooxygenase (StyA) directly from Escherichia coli cell extracts was investigated. Sepabeads EC-EA and EC-Q1A anion-exchange carriers were employed to non-covalently adsorb StyA from the cell extracts depending on basic parameters such as varying initial protein concentrations and pH. The protein fraction of the cell extract contained around 25% StyA. At low initial protein concentrations (2.5 mg mL⁻¹) and pH 6, the enzyme could be enriched up to 52.4% on Sepabeads EC-EA and up to 46.0% on Sepabeads EC-Q1A, accounting for an almost complete StyA adsorption from the cell extracts. Higher initial protein concentrations were necessary to exploit the high loading capacity of the beads. At 20 mg mL⁻¹, up to 37.6% of the theoretical bead loading capacity could be utilized for StyA binding using Sepabeads EC-EA, and 34.0% using Sepabeads EC-Q1A. For both carriers, protein leakage under reaction conditions could be reduced to less than 2%. During assays, the FADH₂ cofactor necessary for StyA activity was supplied by the NADH-FAD reductase component styrene monooxygenase B (StyB). StyA immobilized on Sepabeads EC-Q1A displayed twice as high styrene epoxidation rates (0.2 U mg_StyA⁻¹) as compared to Sepabeads EC-EA. This activity could be increased to 0.7 U mg_StyA⁻¹ by co-immobilizing StyB on Sepabeads EC-Q1A, which corresponds to 33% of the soluble StyA activity. Full article

(This article belongs to the Special Issue Enzyme-Catalyzed Reactions)

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460 KiB

Open AccessArticle
Three New Phytoecdysteroids Containing a Furan Ring from the Roots of Achyranthes bidentata Bl.
by Qiu-Hong Wang, Liu Yang, Hai Jiang, Zhi-Bin Wang, Bing-You Yang and Hai-Xue Kuang

Molecules 2011, 16(7), 5989-5997; https://doi.org/10.3390/molecules16075989 - 18 Jul 2011
Cited by 20 | Viewed by 8249
Abstract
Three new phytoecdysteroid compounds, named niuxixinsterone A (1), B (2) and C (3) with acetal functions in the side-chain were isolated from Achyranthes bidentata Bl. The structures were established as (20R,22R,24S)-20- [...] Read more.

Three new phytoecdysteroid compounds, named niuxixinsterone A (1), B (2) and C (3) with acetal functions in the side-chain were isolated from Achyranthes bidentata Bl. The structures were established as (20R,22R,24S)-20-O,22-O-(5′-hydroxymethyl)-furfurylidene-2β,3β,14α,25-tetrahydroxy-5β-ergost-7-en-6-one (1), (20R,22R)-20-O,22-O-(5′-hydroxymethyl)-furfurylidene-2β,3β,25-trihydroxy-14β-methyl-18-nor-5β-cholesta-7,12-dien-6-one (2) and (20R,22R,25R)-20-O,22-O-(5′-hydroxymethyl)-furfurylidene-2β, 3β,5β,14α,26-pentahydroxycholest-7-en-6-one (3) by means of spectroscopic evidence. Full article

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488 KiB

Open AccessArticle
Antioxidant Activities of Extracts and Fractions from Eupatorium lindleyanum DC
by Guilong Yan, Lilian Ji, Yuming Luo and Yonghong Hu

Molecules 2011, 16(7), 5998-6009; https://doi.org/10.3390/molecules16075998 - 19 Jul 2011
Cited by 18 | Viewed by 6047
Abstract
The antioxidant activities of water extract (WE), ethanol extract (EE), residue water extract (RWE) and petroleum ether (PF), ethyl acetate (EF), n-BuOH (BF) and water (WF) fractions of the ethanol extract from Eupatorium Lindley DC were investigated for the first time. Total [...] Read more.

The antioxidant activities of water extract (WE), ethanol extract (EE), residue water extract (RWE) and petroleum ether (PF), ethyl acetate (EF), n-BuOH (BF) and water (WF) fractions of the ethanol extract from Eupatorium Lindley DC were investigated for the first time. Total phenolics content, DPPH radical scavenging activities, superoxide radical scavenging activities, total reduction capability, and ferrous ions chelating activities were determined for all the extracts and fractions. The results showed that all the extracts and fractions exhibited antioxidant activities with different magnitudes of potency. Among all the samples, WE and RWE exhibited the best antioxidant capacities, the BF also exhibited high antioxidant abilities in all tests except for the metal chelating activity, while the other extracts and fractions were relatively weak antioxidants. The BF had the highest total phenolics contents in all extracts and fractions, and the WE and RWE were found to be rich in tannins. Furthermore, the content of total phenolics showed good correlation with DPPH radical scavenging activity, superoxide anion radical scavenging activity, and the reducing power. Phenolic composition of all the extracts and fractions was identified and quantified by HPLC. The results indicate that the extracts of E. Lindley DC might be a useful potential source of natural antioxidant ingredients. Full article

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881 KiB

Open AccessArticle
Inhibitory Effects of Constituents from Morus alba var. multicaulis on Differentiation of 3T3-L1 Cells and Nitric Oxide Production in RAW264.7 Cells
by Zhi-Gang Yang, Keiichi Matsuzaki, Satoshi Takamatsu and Susumu Kitanaka

Molecules 2011, 16(7), 6010-6022; https://doi.org/10.3390/molecules16076010 - 19 Jul 2011
Cited by 89 | Viewed by 11407
Abstract
A new arylbenzofuran, 3',5'-dihydroxy-6-methoxy-7-prenyl-2-arylbenzofuran (1), and 25 known compounds, including moracin R (2), moracin C (3), moracin O (4), moracin P (5), artoindonesianin O (6), moracin D (7), alabafuran [...] Read more.

A new arylbenzofuran, 3',5'-dihydroxy-6-methoxy-7-prenyl-2-arylbenzofuran (1), and 25 known compounds, including moracin R (2), moracin C (3), moracin O (4), moracin P (5), artoindonesianin O (6), moracin D (7), alabafuran A (8), mulberrofuran L (9), mulberrofuran Y (10), kuwanon A (11), kuwanon C (12), kuwanon T (13), morusin (14), kuwanon E (15), sanggenon F (16), betulinic acid (17), uvaol (18), ursolic acid (19), β-sitosterol (20), oxyresveratrol 2-O-β-D-glucopyranoside (21), mulberroside A (22), mulberroside B (23), 5,7-dihydroxycoumarin 7-O-β-D-glucopyranoside (24), 5,7-dihydroxycoumarin 7-O-β-D-apiofuranosyl-(1→6)-O-β-D-glucopyranoside (25) and adenosine (26), were isolated from Morus alba var. multicaulis Perro. (Moraceae). Their structures were determined by spectroscopic methods. The prenyl-flavonoids 11–14, 16, triterpenoids 17,18 and 20 showed significant inhibitory activity towards the differentiation of 3T3-L1 adipocytes. The arylbenzofurans 1–10 and prenyl-flavonoids 11–16 also showed significant nitric oxide (NO) production inhibitory effects in RAW264.7 cells. Full article

(This article belongs to the Section Natural Products Chemistry)

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1284 KiB

Open AccessArticle
Benzylidene-bis-(4-Hydroxycoumarin) and Benzopyrano-Coumarin Derivatives: Synthesis, ¹H/¹³C-NMR Conformational and X-ray Crystal Structure Studies and In Vitro Antiviral Activity Evaluations
by Davorka Završnik, Samija Muratović, Damjan Makuc, Janez Plavec, Mario Cetina, Ante Nagl, Erik De Clercq, Jan Balzarini and Mladen Mintas

Molecules 2011, 16(7), 6023-6040; https://doi.org/10.3390/molecules16076023 - 19 Jul 2011
Cited by 88 | Viewed by 12082
Abstract
We report on the synthesis of 4-hydroxycoumarin dimers 1–15 bearing an aryl substituent on the central linker and fused benzopyranocoumarin derivatives 16–20 and on their in vitro broad anti-DNA and RNA virus activity evaluations. The chemical identities and structure [...] Read more.

We report on the synthesis of 4-hydroxycoumarin dimers 1–15 bearing an aryl substituent on the central linker and fused benzopyranocoumarin derivatives 16–20 and on their in vitro broad anti-DNA and RNA virus activity evaluations. The chemical identities and structure of compounds 1–20 were deduced from their homo- and heteronuclear NMR measurements whereas the conformational properties of 5, 14 and 20 were assessed by the use of 1D difference NOE enhancements. Unequivocal proof of the stereostructure of compounds 7, 9, 16 and 18 was obtained by single crystal X-ray diffraction method. The X-ray crystal structure analysis revealed that two 4-hydroxycoumarin moieties in the 4-trifluoromethylphenyl- and 2-nitrophenyl derivatives (compounds 7 and 9, respectively) are intramolecularly hydrogen-bonded between hydroxyl and carbonyl oxygen atoms. Consequently, the compounds 7 and 9 adopt conformations in which two 4-hydroxy-coumarin moieties are anti-disposed. Antiviral activity evaluation results indicated that the 4-bromobenzylidene derivative of bis-(4-hydroxycoumarin) (compound 3) possesses inhibitory activity against HSV-1 (KOS), HSV-2 (G), vaccinia virus and HSV-1 TK^- KOS (ACV^r) at a concentration of 9–12 μM and at a minimum cytotoxic concentration (MCC) greater than 20 μM. Compounds 4–6, 8, and 20 were active against feline herpes virus (50% effective concentration, EC₅₀ = 5–8.1 μM), that is at a 4-7-fold lower concentration than the MCC. Full article

(This article belongs to the Special Issue Antivirals)

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392 KiB

Open AccessArticle
Antifeedant Diterpenoids against Tribolium castaneum from the Stems and Twigs of Ceriops tagal (Rhizophoraceae)
by Shu Shan Du, Cheng Fang Wang, Jing Li, Hai Ming Zhang, Qi Zhi Liu, Zhi Long Liu and Zhi Wei Deng

Molecules 2011, 16(7), 6060-6067; https://doi.org/10.3390/molecules16076060 - 20 Jul 2011
Cited by 22 | Viewed by 6729
Abstract
The screening of several Chinese mangrove plants for insecticidal principles showed that ethanol extract of Ceriops tagal stems and twigs possessed significant feeding deterrent activity against the red flour beetle, Tribolium castaneum (Family: Rhizophoraceae). From the ethanol extract, three feeding deterrent diterpenoids were [...] Read more.

The screening of several Chinese mangrove plants for insecticidal principles showed that ethanol extract of Ceriops tagal stems and twigs possessed significant feeding deterrent activity against the red flour beetle, Tribolium castaneum (Family: Rhizophoraceae). From the ethanol extract, three feeding deterrent diterpenoids were isolated by bioassay-guided fractionation. The compounds were identified as tagalsin A, B, and H on the basis of their phytochemical and spectral data. Tagalsin A, B, and H exhibited strong feeding deterrent activity against T. castaneum adults with EC₅₀ values of 375.3 ppm, 277.3 ppm, and 285.45 ppm, respectively. Full article

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416 KiB

Open AccessArticle
Increased Carbon Dioxide Concentration Improves the Antioxidative Properties of the Malaysian Herb Kacip Fatimah (Labisia pumila Blume)
by Mohd Hafiz Ibrahim and Hawa Z.E. Jaafar

Molecules 2011, 16(7), 6068-6081; https://doi.org/10.3390/molecules16076068 - 20 Jul 2011
Cited by 32 | Viewed by 6008
Abstract
A randomized complete randomized design (RCBD) 3 by 3 experiment was designed to investigate and distinguish the relationships among production of secondary metabolites (total phenolics, TP; total flavonoids, TF), gluthatione (GSH), oxidized gluthatione (GSSG), soluble carbohydrate and antioxidant activities of the Malaysian medicinal [...] Read more.

A randomized complete randomized design (RCBD) 3 by 3 experiment was designed to investigate and distinguish the relationships among production of secondary metabolites (total phenolics, TP; total flavonoids, TF), gluthatione (GSH), oxidized gluthatione (GSSG), soluble carbohydrate and antioxidant activities of the Malaysian medicinal herb Labisia pumila Blume under three levels of CO₂ enrichment (400, 800 and 1,200 µmol mol⁻¹) for 15 weeks. It was found that the treatment effects were solely contributed by interaction of CO₂ levels and secondary metabolites distribution in plant parts, GSH, GSHH and antioxidant activities (peroxyl radicals (ROO), superoxide radicals (O₂), hydrogen peroxide (H₂O₂) and hydroxyl radicals (OH). The records of secondary metabolites, glutahione, oxidized gluthathione and antioxidant activities in a descending manner came from the leaf enriched with 1,200 µmol/mol CO₂ > leaf 800 µmol/mol CO₂ > leaf 400 µmol/mol CO₂ > stem 1,200 µmol/mol CO₂ > stem 800 µmol/mol CO₂ > stem 400 µmol/mol CO₂ > root 1,200 µmol/mol CO₂ > root 800 µmol/mol CO₂ > root 400 µmol/mol CO₂. Correlation analyses revealed strong significant positive coefficients of antioxidant activities with total phenolics, flavonoids, GSH and GSHH indicating that an increase in antioxidative activity of L. pumila under elevated CO₂ might be up-regulated by the increase in production of total phenolics, total flavonoids, GSH, GSHH and soluble sugar. This study implied that the medicinal potential of herbal plant such as L. pumila can be enhanced under elevated CO₂, which had simultaneously improved the antioxidative activity that indicated by the high oxygen radical absorbance activity against ROO, O₂, H₂O₂, and OH radicals. Full article

469 KiB

Open AccessArticle
Bent Dinuclear Platinum(II) Halo-Bridged Carbonyl Complexes
by Daniela Belli Dell'Amico, Luca Labella and Fabio Marchetti

Molecules 2011, 16(7), 6082-6091; https://doi.org/10.3390/molecules16076082 - 20 Jul 2011
Cited by 1 | Viewed by 5545
Abstract
Crystals of trans-Pt₂(μ-X)₂X₂(CO)₂ (X = Br, I) have been grown and their molecular and crystalline structures have been solved by X-ray diffraction methods. In both cases the dinuclear molecules are bent, with a [...] Read more.

Crystals of trans-Pt₂(μ-X)₂X₂(CO)₂ (X = Br, I) have been grown and their molecular and crystalline structures have been solved by X-ray diffraction methods. In both cases the dinuclear molecules are bent, with a bending angle of 164.6° and 156.5° for the bromide and the iodide, respectively. While the structure of the bromo-derivative is reported here for the first time, a modification of trans-Pt₂(μ-I)₂I₂(CO)₂ with planar centrosymmetric molecules is known. This appears to be a rare case of a platinum(II) halo-bridged derivative structurally characterized in both bent and planar forms. Full article

(This article belongs to the Special Issue Organometallic Chemistry)

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481 KiB

Open AccessArticle
Ruthenium-Catalyzed Selective Hydrogenation of bis-Arylidene Tetramic Acids. Application to the Synthesis of Novel Structurally Diverse Pyrrolidine-2,4-diones
by Christos S. Karaiskos, Dimitris Matiadis, John Markopoulos and Olga Igglessi-Markopoulou

Molecules 2011, 16(7), 6116-6128; https://doi.org/10.3390/molecules16076116 - 20 Jul 2011
Cited by 3 | Viewed by 5456
Abstract
Catalytic hydrogenation of 3,5-bis-arylidenetetramic acids, known for their biological activity, has been developed. The chemoselective ruthenium-catalyzed reduction of the exocyclic carbon-carbon double bonds on pyrrolidine-2,4-dione ring system, containing other reducible functions, has been investigated. Depending on the substrate the yield of the hydrogenation [...] Read more.

Catalytic hydrogenation of 3,5-bis-arylidenetetramic acids, known for their biological activity, has been developed. The chemoselective ruthenium-catalyzed reduction of the exocyclic carbon-carbon double bonds on pyrrolidine-2,4-dione ring system, containing other reducible functions, has been investigated. Depending on the substrate the yield of the hydrogenation process can reach up to 95%. The structural elucidation has been established using NMR and HRMS spectral data. Full article

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870 KiB

Open AccessArticle
Synthesis and E/Z Configuration Determination of Novel Derivatives of 3-Aryl-2-(benzothiazol-2'-ylthio) Acrylonitrile, 3-(Benzothiazol-2'-ylthio)-4-(furan-2''-yl)-3-buten-2-one and 2-(1-(Furan-2''-yl)-3'-oxobut-1''-en-2-ylthio)-3-phenylquinazolin-4(3H)-one
by Fatima Al-Omran, Rafat M. Mohareb and Adel Abou El-Khair

Molecules 2011, 16(7), 6129-6147; https://doi.org/10.3390/molecules16076129 - 20 Jul 2011
Cited by 8 | Viewed by 8044
Abstract
Knoevenagel condensation of 2-(benzothiazol-2-ylthio) acetonitrile (2) with either furan-2-carbaldehyde or thiophene-2-carbaldehydes leads to E-isomers 4a–b exclusively, while the condensation of the compound 2 with benzaldehyde or para-substituted benzaldehydes with an electron-donating group afforded E/Z mixtures 4c–e with preferentially formation [...] Read more.

Knoevenagel condensation of 2-(benzothiazol-2-ylthio) acetonitrile (2) with either furan-2-carbaldehyde or thiophene-2-carbaldehydes leads to E-isomers 4a–b exclusively, while the condensation of the compound 2 with benzaldehyde or para-substituted benzaldehydes with an electron-donating group afforded E/Z mixtures 4c–e with preferentially formation of the E-isomer. Condensation of furan-2-carbaldehyde (3a) with either 1-(benzothiazol-2'-ylthio) propan-2-one (5) or 2-(2'-oxo propylthio)-3-phenyl-quinazolin-4(3H)-one (9) leads exclusively to the Z-isomers of 6 and 10, respectively. The structures of the newly synthesized compounds were elucidated by elemental analyses, ¹H-NMR and ¹³C-NMR spectra, COSY, HSQC, HMBC, NOE, MS and X-ray crystallographic investigations. Full article

(This article belongs to the Special Issue Heterocycles)

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406 KiB

Open AccessArticle
Physicochemical Characteristics and Immunomodulatory Activities of Three Polysaccharide-Protein Complexes of Longan Pulp
by Yang Yi, Sen Tai Liao, Ming Wei Zhang, John Shi, Rui Fen Zhang, Yuan Yuan Deng and Zhen Cheng Wei

Molecules 2011, 16(7), 6148-6164; https://doi.org/10.3390/molecules16076148 - 21 Jul 2011
Cited by 63 | Viewed by 8211
Abstract
Three polysaccharide-protein complexes of longan pulp (LP1-3) were isolated in this work. Their physicochemical characteristics and immunomodulatory effects on splenocytes, natural killer (NK) cells and macrophages in vitro were investigated. The carbohydrate portions of LP1-3 were principally composed of glucose, arabinose and mannose. [...] Read more.

Three polysaccharide-protein complexes of longan pulp (LP1-3) were isolated in this work. Their physicochemical characteristics and immunomodulatory effects on splenocytes, natural killer (NK) cells and macrophages in vitro were investigated. The carbohydrate portions of LP1-3 were principally composed of glucose, arabinose and mannose. LP3 displayed the maximal moisture absorption, and the thermal stability of LP2 was obviously higher than that of LP1 and LP3. All of them showed the characteristic polysaccharide and protein bands in the Fourier Transform Infrared (FTIR) spectrum. For a certain dose, all the fractions could significantly stimulate splenocyte proliferation, macrophage phagocytosis against neutral red, and NK cell cytotoxicity against YAC-1 lymphoma cell (P < 0.05). The results demonstrated that the polysaccharide-protein complexes of longan pulp have medical potential as immunotherapeutic adjuvants due to their immunomodulatory activities. Full article

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189 KiB

Open AccessReview
Generation and Detection of Levuglandins and Isolevuglandins In Vitro and In Vivo
by Ming Zhang, Wei Li and Tao Li

Molecules 2011, 16(7), 5333-5348; https://doi.org/10.3390/molecules16075333 - 24 Jun 2011
Cited by 10 | Viewed by 6288
Abstract
Levuglandins (LGs) and isolevuglandins (isoLGs), formed by rearrangement of endoperoxide intermediates generated through the cyclooxygenase and free radical induced oxidation of polyunsaturated fatty acids (PUFAs), are extraordinarily reactive, forming covalent adducts incorporating protein lysyl e-amino groups. Because they accumulate, these adducts provide a [...] Read more.

Levuglandins (LGs) and isolevuglandins (isoLGs), formed by rearrangement of endoperoxide intermediates generated through the cyclooxygenase and free radical induced oxidation of polyunsaturated fatty acids (PUFAs), are extraordinarily reactive, forming covalent adducts incorporating protein lysyl e-amino groups. Because they accumulate, these adducts provide a dosimeter of oxidative injury. This review provides an updated and comprehensive overview of the generation of LG/isoLG in vitro and in vivo and the detection methods for the adducts of LG/isoLG and biological molecules in vivo. Full article

(This article belongs to the Section Medicinal Chemistry)

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Open AccessReview
Keeping an Eye on Myocilin: A Complex Molecule Associated with Primary Open-Angle Glaucoma Susceptibility
by Farid Menaa, Carolina Ayumi Braghini, Jose Paulo Cabral De Vasconcellos, Bouzid Menaa, Vital Paulino Costa, Eugênio Santana De Figueiredo and Monica Barbosa De Melo

Molecules 2011, 16(7), 5402-5421; https://doi.org/10.3390/molecules16075402 - 27 Jun 2011
Cited by 26 | Viewed by 11134
Abstract
MYOC encodes a secretary glycoprotein of 504 amino acids named myocilin. MYOC is the first gene to be linked to juvenile open-angle glaucoma (JOAG) and some forms of adult-onset primary open-angle glaucoma (POAG). The gene was identified as an up-regulated molecule in cultured [...] Read more.

MYOC encodes a secretary glycoprotein of 504 amino acids named myocilin. MYOC is the first gene to be linked to juvenile open-angle glaucoma (JOAG) and some forms of adult-onset primary open-angle glaucoma (POAG). The gene was identified as an up-regulated molecule in cultured trabecular meshwork (TM) cells after treatment with dexamethasone and was originally referred to as trabecular meshwork-inducible glucocorticoid response (TIGR). Elevated intraocular pressure (IOP), due to decreased aqueous outflow, is the strongest known risk factor for POAG. Increasing evidence showed that the modulation of the wild-type (wt) myocilin protein expression is not causative of glaucoma while some misfolded and self-assembly aggregates of mutated myocilin may be associated with POAG in related or unrelated populations. The etiology of the disease remains unclear. Consequently, a better understanding of the molecular mechanisms underlyingPOAG is required to obtain early diagnosis, avoid potential disease progression, and develop new therapeutic strategies. In the present study, we review and discuss the most relevant studies regarding structural characterizations, expressions, molecular interactions, putative functions of MYOC gene and/or its corresponding protein in POAG etiology. Full article

(This article belongs to the Section Molecular Diversity)

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751 KiB

Open AccessReview
Recent Developments in Molecular Dynamics Simulations of Fluorescent Membrane Probes
by Luís M. S. Loura and J. P. Prates Ramalho

Molecules 2011, 16(7), 5437-5452; https://doi.org/10.3390/molecules16075437 - 27 Jun 2011
Cited by 53 | Viewed by 10249
Abstract
Due to their sensitivity and versatility, the use of fluorescence techniques in membrane biophysics is widespread. Because membrane lipids are non-fluorescent, extrinsic membrane probes are widely used. However, the behaviour of these probes when inserted in the bilayer is often poorly understood, and [...] Read more.

Due to their sensitivity and versatility, the use of fluorescence techniques in membrane biophysics is widespread. Because membrane lipids are non-fluorescent, extrinsic membrane probes are widely used. However, the behaviour of these probes when inserted in the bilayer is often poorly understood, and it can be hard to distinguish between legitimate membrane properties and perturbation resulting from probe incorporation. Atomistic molecular dynamics simulations present a convenient way to address these issues and have been increasingly used in recent years in this context. This article reviews the application of molecular dynamics to the study of fluorescent membrane probes, focusing on recent work with complex design fluorophores and ordered bilayer systems. Full article

(This article belongs to the Special Issue Fluorophores - The Fluorescent Toolbox in Biological and Biomedical Research)

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Open AccessReview
Opportunities Offered by Chiral η⁶-Arene/N-Arylsulfonyl-diamine-Ru^II Catalysts in the Asymmetric Transfer Hydrogenation of Ketones and Imines
by Jiří Václavík, Petr Kačer, Marek Kuzma and Libor Červený

Molecules 2011, 16(7), 5460-5495; https://doi.org/10.3390/molecules16075460 - 28 Jun 2011
Cited by 65 | Viewed by 10862
Abstract
Methods for the asymmetric transfer hydrogenation (ATH) of ketones and imines are still being intensively studied and developed. Of foremost interest is the use of Noyori’s [RuCl(η⁶-arene)(N-TsDPEN)] complexes in the presence of a hydrogen donor (i-PrOH, formic [...] Read more.

Methods for the asymmetric transfer hydrogenation (ATH) of ketones and imines are still being intensively studied and developed. Of foremost interest is the use of Noyori’s [RuCl(η⁶-arene)(N-TsDPEN)] complexes in the presence of a hydrogen donor (i-PrOH, formic acid). These complexes have found numerous practical applications and have been extensively modified. The resulting derivatives have been heterogenized, used in ATH in water or ionic liquids and even some attempts have been made to approach the properties of biocatalysts. Therefore, an appropriate modification of the catalyst that suits the specific requirements for the reaction conditions is very often readily available. The mechanism of the reaction has also been explored to a great extent. Model substrates, acetophenone (a ketone) and 6,7-dimethoxy-1-methyl-3,4-dihydroisoquinoline (an imine), are both reduced by this Ru catalytic system with almost perfect selectivity. However, in each case the major product is a different enantiomer (S- for an alcohol, R- for an amine when the S,S-catalyst is used), which demanded an in-depth mechanistic investigation. Full-scale molecular modelling of this system enabled us to visualize the plausible 3D structures of the transition states, allowing the proposition of a viable explanation of previous experimental findings. Full article

(This article belongs to the Special Issue Catalytic Asymmetric Synthesis)

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Open AccessReview
A Survey of Marine Natural Compounds and Their Derivatives with Anti-Cancer Activity Reported in 2010
by Marc Schumacher, Mareike Kelkel, Mario Dicato and Marc Diederich

Molecules 2011, 16(7), 5629-5646; https://doi.org/10.3390/molecules16075629 - 30 Jun 2011
Cited by 36 | Viewed by 7185
Abstract
Although considerable progress in oncology therapeutics has been achieved in the last century, cancer remains one of major death causes in the World and for this reason, the development of novel cancer drugs remains a pressing need. Natural marine compounds represent an interesting [...] Read more.

Although considerable progress in oncology therapeutics has been achieved in the last century, cancer remains one of major death causes in the World and for this reason, the development of novel cancer drugs remains a pressing need. Natural marine compounds represent an interesting source of novel leads with potent chemotherapeutic or chemo-preventive activities. In the last decades, structure-activity-relationship studies have led to the development of naturally-derived or semi-synthetic analogues with improved bioactivity, a simplified synthetic target or less toxicity. We aim here to review a selection of natural compounds with reported anticancer activity isolated of marine sources and their associated analogues published in 2010. Full article

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Open AccessReview
In Mesopore Protein Digestion: A New Forthcoming Strategy in Proteomics
by Rocco Savino, Francesca Casadonte and Rosa Terracciano

Molecules 2011, 16(7), 5938-5962; https://doi.org/10.3390/molecules16075938 - 15 Jul 2011
Cited by 23 | Viewed by 6744
Abstract
The conventional protocols for in solution or in gel protein digestion require many steps and long reaction times. The use of trypsin immobilized onto solid supports has recently captured the attention of many research groups, because these systems can speed-up protein digestion significantly. [...] Read more.

The conventional protocols for in solution or in gel protein digestion require many steps and long reaction times. The use of trypsin immobilized onto solid supports has recently captured the attention of many research groups, because these systems can speed-up protein digestion significantly. The utilization of new materials such as mesoporous silica as supports, in which enzyme and substrate are dramatically concentrated and confined in the nanospace, offers new opportunities to reduce the complexity of proteomics workflows. An overview of the procedures for in situ proteolysis of single proteins or complex protein mixtures is reported, with a special focus on porous materials used as catalysts. The challenging efforts for designing such systems aimed at mimicking the biochemistry of living cells are reviewed. Potentials, limitations and challenges of this branch of enzyme catalysis, which we indicate as in mesopore digestion, are discussed, in relation to its suitability for high-speed and high-throughput proteomics. Full article

(This article belongs to the Special Issue Catalytic Asymmetric Synthesis)

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Open AccessReview
Enzyme-Immobilized Microfluidic Process Reactors
by Yuya Asanomi, Hiroshi Yamaguchi, Masaya Miyazaki and Hideaki Maeda

Molecules 2011, 16(7), 6041-6059; https://doi.org/10.3390/molecules16076041 - 19 Jul 2011
Cited by 138 | Viewed by 12161
Abstract
Microreaction technology, which is an interdisciplinary science and engineering area, has been the focus of different fields of research in the past few years. Several microreactors have been developed. Enzymes are a type of catalyst, which are useful in the production of substance [...] Read more.

Microreaction technology, which is an interdisciplinary science and engineering area, has been the focus of different fields of research in the past few years. Several microreactors have been developed. Enzymes are a type of catalyst, which are useful in the production of substance in an environmentally friendly way, and they also have high potential for analytical applications. However, not many enzymatic processes have been commercialized, because of problems in stability of the enzymes, cost, and efficiency of the reactions. Thus, there have been demands for innovation in process engineering, particularly for enzymatic reactions, and microreaction devices represent important tools for the development of enzyme processes. In this review, we summarize the recent advances of microchannel reaction technologies especially for enzyme immobilized microreactors. We discuss the manufacturing process of microreaction devices and the advantages of microreactors compared to conventional reaction devices. Fundamental techniques for enzyme immobilized microreactors and important applications of this multidisciplinary technology are also included in our topics. Full article

(This article belongs to the Special Issue Enzyme-Catalyzed Reactions)

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Open AccessReview
The Stereochemistry of Complex Polyketide Biosynthesis by Modular Polyketide Synthases
by David H. Kwan and Frank Schulz

Molecules 2011, 16(7), 6092-6115; https://doi.org/10.3390/molecules16076092 - 20 Jul 2011
Cited by 61 | Viewed by 13355
Abstract
Polyketides are a diverse class of medically important natural products whose biosynthesis is catalysed by polyketide synthases (PKSs), in a fashion highly analogous to fatty acid biosynthesis. In modular PKSs, the polyketide chain is assembled by the successive condensation of activated carboxylic acid-derived [...] Read more.

Polyketides are a diverse class of medically important natural products whose biosynthesis is catalysed by polyketide synthases (PKSs), in a fashion highly analogous to fatty acid biosynthesis. In modular PKSs, the polyketide chain is assembled by the successive condensation of activated carboxylic acid-derived units, where chain extension occurs with the intermediates remaining covalently bound to the enzyme, with the growing polyketide tethered to an acyl carrier domain (ACP). Carboxylated acyl-CoA precursors serve as activated donors that are selected by the acyltransferase domain (AT) providing extender units that are added to the growing chain by condensation catalysed by the ketosynthase domain (KS). The action of ketoreductase (KR), dehydratase (DH), and enoylreductase (ER) activities can result in unreduced, partially reduced, or fully reduced centres within the polyketide chain depending on which of these enzymes are present and active. The PKS-catalysed assembly process generates stereochemical diversity, because carbon–carbon double bonds may have either cis- or trans- geometry, and because of the chirality of centres bearing hydroxyl groups (where they are retained) and branching methyl groups (the latter arising from use of propionate extender units). This review shall cover the studies that have determined the stereochemistry in many of the reactions involved in polyketide biosynthesis by modular PKSs. Full article

(This article belongs to the Special Issue Polyketide)

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70 KiB

Open AccessCorrection
Drozdowska D., New Solid Phase Synthesis of Distamycin Analogues. Molecules, 2011, 16, 3066-3076
by Danuta Drozdowska

Molecules 2011, 16(7), 5753; https://doi.org/10.3390/molecules16075753 - 06 Jul 2011
Cited by 8 | Viewed by 3568
Abstract
The author wishes to make the following correction to this paper [1]: The correct author’s name is: Danuta Drozdowska. [...] Full article

(This article belongs to the Section Medicinal Chemistry)

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