Molecules

213 KiB

Open AccessCommunication

Synthesis of 5-Dialkyl(aryl)aminomethyl-8-hydroxyquinoline Dansylates as Selective Fluorescent Sensors for Fe³⁺

by Ruogu Peng, Feng Wang and Yaowu Sha

Molecules 2007, 12(5), 1191-1201; https://doi.org/10.3390/12051191 - 31 May 2007

Cited by 42 | Viewed by 9747

A series of 5-dialkyl(aryl)aminomethyl-8-hydroxyquinoline dansylates were synthesized and their fluoroionophoric properties toward representative alkali ions, alkaline earth ions and transition metal ions were investigated. Among the selected ions, Fe³⁺ caused considerable quenching of the fluorescence, while Cr³⁺ caused quenching to some [...] Read more.

A series of 5-dialkyl(aryl)aminomethyl-8-hydroxyquinoline dansylates were synthesized and their fluoroionophoric properties toward representative alkali ions, alkaline earth ions and transition metal ions were investigated. Among the selected ions, Fe³⁺ caused considerable quenching of the fluorescence, while Cr³⁺ caused quenching to some extent. The absence of any significant fluorescence quenching effects of the other ions examined, especially Fe²⁺, renders these compounds highly useful Fe³⁺-selective fluorescent sensors. Full article

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72 KiB

Open AccessArticle

Facile Synthesis of Optically Active Imidazole Derivatives

by Ales Marek, Jiri Kulhanek, Miroslav Ludwig and Filip Bures

Molecules 2007, 12(5), 1183-1190; https://doi.org/10.3390/12051183 - 30 May 2007

Cited by 29 | Viewed by 10870

Abstract

Five optically active imidazole derivatives have been synthesized via a facile 4-step reaction sequence starting from commercially available and inexpensive N-Cbz amino acids. While microwave assisted condensation was unsuccessful, the condensation of the corresponding α-bromoketones with formamidine acetate in liquid ammonia was [...] Read more.

Five optically active imidazole derivatives have been synthesized via a facile 4-step reaction sequence starting from commercially available and inexpensive N-Cbz amino acids. While microwave assisted condensation was unsuccessful, the condensation of the corresponding α-bromoketones with formamidine acetate in liquid ammonia was revealed to be a useful method for the synthesis of such imidazole derivatives. The derivatives thus prepared are structurally-related to histamine. Full article

(This article belongs to the Special Issue Heterocycles)

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135 KiB

Open AccessArticle

Stereoselective Syntheses of Fluorescent Non-Natural Aromatic Amino Acids Based on Asymmetric Michael Additions

by Heru Chen, Xianbin Zhong and Jin Wei

Molecules 2007, 12(5), 1170-1182; https://doi.org/10.3390/12051170 - 26 May 2007

Cited by 10 | Viewed by 11210

Abstract

Four fluorescent non-natural aromatic amino acids have been synthesized based on a key stereoselective Michael addition reaction. S-1-Phenylethylamine was employed as both the source of amine and the stereoselectivity controller. The overall yields were moderate (30-50%). Fluorescent properties of some of the fluorophores [...] Read more.

Four fluorescent non-natural aromatic amino acids have been synthesized based on a key stereoselective Michael addition reaction. S-1-Phenylethylamine was employed as both the source of amine and the stereoselectivity controller. The overall yields were moderate (30-50%). Fluorescent properties of some of the fluorophores were also investigated. It was found that compounds with a dimethylamino group bonded to the aromatic ring display intramolecular charge transfer fluorescence. Full article

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73 KiB

Open AccessArticle

Flavanol Derivatives from Rhizophora stylosa and Their DPPH Radical Scavenging Activity

by Dong-Li Li, Xiao-Ming Li, Ze-Yu Peng and Bin-Gui Wang

Molecules 2007, 12(5), 1163-1169; https://doi.org/10.3390/12051163 - 26 May 2007

Cited by 38 | Viewed by 14114

Abstract

A new acetylated flavanol, 3,7-O-diacetyl (–)-epicatechin (3), and seven known flavanol derivatives, (–)-epicatechin (1), 3-O-acetyl (–)-epicatechin (2), 3,3′,4′,5,7-O-pentaacetyl (–)-epicatechin (4), (+)-afzelechin (5), (+)-catechin (6), cinchonain Ib (7), and proanthocyanidin B2 (8), were isolated from the stems and twigs of [...] Read more.

A new acetylated flavanol, 3,7-O-diacetyl (–)-epicatechin (3), and seven known flavanol derivatives, (–)-epicatechin (1), 3-O-acetyl (–)-epicatechin (2), 3,3′,4′,5,7-O-pentaacetyl (–)-epicatechin (4), (+)-afzelechin (5), (+)-catechin (6), cinchonain Ib (7), and proanthocyanidin B2 (8), were isolated from the stems and twigs of the mangrove plant Rhizophora stylosa and identified. The crude extract, the different fractions and all of the purified compounds were evaluated for DPPH radical scavenging activity. Full article

(This article belongs to the Special Issue Phenolics and Polyphenolics)

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73 KiB

Open AccessArticle

Phenolic Compounds and Antimicrobial Activity of Olive (Olea europaea L. Cv. Cobrançosa) Leaves

by Ana Paula Pereira, Isabel CFR Ferreira, Filipa Marcelino, Patricia Valentão, Paula B Andrade, Rosa Seabra, Leticia Estevinho, Albino Bento and José Alberto Pereira

Molecules 2007, 12(5), 1153-1162; https://doi.org/10.3390/12051153 - 26 May 2007

Cited by 460 | Viewed by 39768

Abstract

We report the determination of phenolic compounds in olive leaves by reversed-phase HPLC/DAD, and the evaluation of their in vitro activity against several microorganisms that may be causal agents of human intestinal and respiratory tract infections, namely Gram positive (Bacillus cereus, [...] Read more.

We report the determination of phenolic compounds in olive leaves by reversed-phase HPLC/DAD, and the evaluation of their in vitro activity against several microorganisms that may be causal agents of human intestinal and respiratory tract infections, namely Gram positive (Bacillus cereus, B. subtilis and Staphylococcus aureus), Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) and fungi (Candida albicans and Cryptococcus neoformans). Seven phenolic compounds were identified and quantified: caffeic acid, verbascoside, oleuropein, luteolin 7-O-glucoside, rutin, apigenin 7-O-glucoside and luteolin 4’-O-glucoside. At low concentrations olive leafs extracts showed an unusual combined antibacterial and antifungal action, which suggest their great potential as nutraceuticals, particulalry as a source of phenolic compounds. Full article

(This article belongs to the Special Issue Phenolics and Polyphenolics)

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Open AccessArticle

Neuroprotective Activity of Triterpenoid Saponins from Platycodi radix Against Glutamate-induced Toxicity in Primary Cultured Rat Cortical Cells

by Il Hong Son, Yong Hoon Park, Sung Ik Lee, Hyun Duk Yang and Hyung-In Moon

Molecules 2007, 12(5), 1147-1152; https://doi.org/10.3390/12051147 - 25 May 2007

Cited by 34 | Viewed by 11311

Abstract

During our investigation of the neuroprotective activity of Platycodi radix we found that an aqueous extract of this folk medicine exhibited significant protection against glutamate-induced toxicity in primary cultured rat cortical cells. In order to clarify the neuroprotective mechanism(s) of this observed effect, [...] Read more.

During our investigation of the neuroprotective activity of Platycodi radix we found that an aqueous extract of this folk medicine exhibited significant protection against glutamate-induced toxicity in primary cultured rat cortical cells. In order to clarify the neuroprotective mechanism(s) of this observed effect, activity-guided isolation was performed to seek and identify active fractions and components. By such fractionation, four known triterpene saponin compounds - platycodins A, C and D and deapioplatycodin D - were isolated from the n-butanol fraction. Among these four compounds, platycodin A exhibited significant neuroprotective activities against glutamate-induced toxicity, exhibiting cell viability of about 50 %, at concentrations ranging from 0.1 μM to 10 μM. Therefore, the neuroprotective effect of Platycodi radix might be due to the inhibition of glutamate-induced toxicity by the saponin compounds it contains. Full article

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Open AccessArticle

Synthesis and Anti-tumor Activities of Novel [1,2,4]triazolo[1,5-a]pyrimidines

by Xiang-Lin Zhao, Yan-Fang Zhao, Shu-Chun Guo, Hai-Sheng Song, Ding Wang and Ping Gong

Molecules 2007, 12(5), 1136-1146; https://doi.org/10.3390/12051136 - 25 May 2007

Cited by 71 | Viewed by 11511

Abstract

A series of novel [1,2,4]triazolo[1,5-a]pyrimidine derivatives has been designed and synthesized in order to find novel anti-tumor compounds. The structures of all the compounds were confirmed by IR, ¹H-NMR, MS and elemental analysis. Their anti-tumor activities against cancer cell lines (HT-1080 and [...] Read more.

A series of novel [1,2,4]triazolo[1,5-a]pyrimidine derivatives has been designed and synthesized in order to find novel anti-tumor compounds. The structures of all the compounds were confirmed by IR, ¹H-NMR, MS and elemental analysis. Their anti-tumor activities against cancer cell lines (HT-1080 and Bel-7402) were tested by the MTT method in vitro. Among them, compound 19 displayed the best anti-tumor activity with IC₅₀ values of 12.3 μM and 6.1 μM against Bel-7402 and HT-1080 cell lines respectively. Full article

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Open AccessArticle

Synthesis of Sulfonamides and Evaluation of Their Histone Deacetylase (HDAC) Activity

by Seikwan Oh, Hyung–In Moon, Il–Hong Son and Jae–Chul Jung

Molecules 2007, 12(5), 1125-1135; https://doi.org/10.3390/12051125 - 24 May 2007

Cited by 18 | Viewed by 10166 | Correction

Abstract

A simple synthesis of sulfonamides 4–22 as novel histone deacetylase (HDAC) inhibitors is described. The key synthetic strategies involve N–sulfonylation of L–proline benzyl ester hydrochloride (2) and coupling reaction of N–sulfonyl chloride 3 with amines in high yields. It was [...] Read more.

A simple synthesis of sulfonamides 4–22 as novel histone deacetylase (HDAC) inhibitors is described. The key synthetic strategies involve N–sulfonylation of L–proline benzyl ester hydrochloride (2) and coupling reaction of N–sulfonyl chloride 3 with amines in high yields. It was found that several compounds showed good cellular potency with the most potent compound 20 exhibiting an IC₅₀ = 2.8 μM in vitro. Full article

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Open AccessArticle

Structure Elucidation of a Pyrazolo[3,4]pyran Derivative by NMR Spectroscopy

by Xuehui Liu and Yuxin Cui

Molecules 2007, 12(5), 1117-1124; https://doi.org/10.3390/12051117 - 24 May 2007

Cited by 2 | Viewed by 7960

Abstract

The structure of a representative pyrazolo[3,4]pyran derivative was determined by 1D and 2D NMR techniques. Complete ¹H and ¹³C chemical shifts for this compound are reported. Careful analysis of the HMBC (Heteronuclear Multi-Bond Correlation) spectrum helped to elucidate the configuration of [...] Read more.

The structure of a representative pyrazolo[3,4]pyran derivative was determined by 1D and 2D NMR techniques. Complete ¹H and ¹³C chemical shifts for this compound are reported. Careful analysis of the HMBC (Heteronuclear Multi-Bond Correlation) spectrum helped to elucidate the configuration of the derivative around C7 and C8. The results showed that the characteristic double-strong and double-weak cross peak pattern in the HMBC spectrum for C7 and C8 might be useful for establishing the structures of other pyrazolo[3,4]pyran derivatives. Full article

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Open AccessArticle

Synthesis and Cytotoxic Activity of Some 3-Benzyl-5-Arylidenefuran-2(5H)-ones

by Róbson Ricardo Teixeira, Luiz Cláudio Barbosa, Célia Regina Alvares Maltha, Marcelo Eça Rocha, Daniel Pereira Bezerra, Letícia Veras Costa-Lotuf, Cláudia Pessoa and Manoel Odorico Moraes

Molecules 2007, 12(5), 1101-1116; https://doi.org/10.3390/12051101 - 24 May 2007

Cited by 42 | Viewed by 9098

Abstract

3-Benzyl-furan-2(5H)-one (2a) and 3-(4-bromobenzyl)-furan-2(5H)-one (2b) were treated with TBDMSOTf and converted into the corresponding tert-butyldimethyl-silylfuran ethers. These furans were further condensed with several aromatic aldehydes affording compounds 5-14 with general 3-benzyl-5-arylidene-furan-2(5H)-one structures in 31% to 98% yields. Such compounds are analogues of the [...] Read more.

3-Benzyl-furan-2(5H)-one (2a) and 3-(4-bromobenzyl)-furan-2(5H)-one (2b) were treated with TBDMSOTf and converted into the corresponding tert-butyldimethyl-silylfuran ethers. These furans were further condensed with several aromatic aldehydes affording compounds 5-14 with general 3-benzyl-5-arylidene-furan-2(5H)-one structures in 31% to 98% yields. Such compounds are analogues of the naturally occurring nostoclide lactones, reported to present moderate cytotoxic activity. Compounds 5-14 were submitted to an in vitro bioassay against the HL-60, HCT-8, SF295 and MDA-MB-435 cancer cell lines using the MTT cytotoxicity assay. Full article

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Open AccessArticle

Biotransformations of Imbricatolic Acid by Aspergillus niger and Rhizopus nigricans Cultures

by Guillermo Schmeda-Hirschmann, Carlos Aranda, Marcela Kurina, Jaime A Rodríguez and Cristina Theoduloz

Molecules 2007, 12(5), 1092-1100; https://doi.org/10.3390/12051092 - 21 May 2007

Cited by 11 | Viewed by 10441

Abstract

Microbial transformation of imbricatolic acid (1) by Aspergillus niger afforded 1α-hydroxyimbricatolic acid (2), while transformation with Rhizopus nigricans yielded 15-hydroxy-8,17-epoxylabdan-19-oic acid (3). When the diterpene 1 was added to a Cunninghamella echinulata culture, the main products were the microbial metabolites mycophenolic [...] Read more.

Microbial transformation of imbricatolic acid (1) by Aspergillus niger afforded 1α-hydroxyimbricatolic acid (2), while transformation with Rhizopus nigricans yielded 15-hydroxy-8,17-epoxylabdan-19-oic acid (3). When the diterpene 1 was added to a Cunninghamella echinulata culture, the main products were the microbial metabolites mycophenolic acid (4) and its 3-hydroxy derivative 5. All the structures were elucidated by spectroscopic methods. The cytotoxicity of these compounds towards human lung fibroblasts and AGS cells was assessed. While 4 and 5 showed low cytotoxicity, with IC₅₀ values > 1000 μM against AGS cells and fibroblasts, 1α-hydroxyimbricatolic acid (2) presented moderate toxicity towards these targets, with IC50 values of 307 and 631 μM, respectively. The structure of 2 is presented for the first time. Full article

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Open AccessArticle

Antimicrobial Activity and Spectral, Magnetic and Thermal Studies of Some Transition Metal Complexes of a Schiff Base Hydrazone Containing a Quinoline Moiety

by Nora H Al-Sha’alan

Molecules 2007, 12(5), 1080-1091; https://doi.org/10.3390/12051080 - 21 May 2007

Cited by 76 | Viewed by 14249

Abstract

A series of new copper(II), cobalt(II), nickel(II), manganese(II), iron(III), and uranyl(VI) complexes of the Schiff base hydrazone 7-chloro-4-(benzylidene-hydrazo)quinoline (HL) were prepared and characterized. The Schiff base behaves as a monobasic bidentate ligand. Mononuclear complexes with the general composition [ML₂(Cl)_m(H [...] Read more.

A series of new copper(II), cobalt(II), nickel(II), manganese(II), iron(III), and uranyl(VI) complexes of the Schiff base hydrazone 7-chloro-4-(benzylidene-hydrazo)quinoline (HL) were prepared and characterized. The Schiff base behaves as a monobasic bidentate ligand. Mononuclear complexes with the general composition [ML₂(Cl)_m(H₂O)₂(OEt)_n]·xEtOH (M = Cu(II), Co(II), Ni(II), Mn(II), Fe(III) or UO₂(VI); m and n = 0-1; x = 1-3) were obtained in the presence of Li(OH) as a deprotonating agent. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, infrared, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry was suggested for all the complexes except the Cu(II) and UO₂(VI) ones. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, while the UO₂(VI) complex displays its favored heptacoordination. The Schiff base ligand, HL, and its complexes were tested against one strain Gram +ve bacteria (Staphylococcus aureus), Gram -ve bacteria (Escherichia coli), and Fungi (Candida albicans). The prepared metal complexes exhibited higher antibacterial activities than the parent ligand and their biopotency is discussed. Full article

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Open AccessArticle

Coordination Compounds Based on 1,2,3,4-Tetrahydro-isoquinoline-3-carboxylic Acid

by Petr Jansa, Vladimír Macháček, Petr Nachtigall, Vladimír Wsól and Markéta Svobodová

Molecules 2007, 12(5), 1064-1079; https://doi.org/10.3390/12051064 - 21 May 2007

Cited by 4 | Viewed by 9345

Abstract

Syntheses of 2,6-bis[((3S)-3-(methoxycarbonyl)-1,2,3,4-tetrahydroisoquinolin-2-yl)carbonyl]pyridine and its coordination compounds with Cu²⁺, Co²⁺, Co³⁺, or Fe³⁺ are described. By means of ¹H- and ¹³C-NMR spectra it was proved that 2,6-bis[((3S)-3-(methoxycarbonyl)-1,2,3,4-tetrahydroisoquinolin-2-yl)carbonyl]pyridine as well as its coordination compound with [...] Read more.

Syntheses of 2,6-bis[((3S)-3-(methoxycarbonyl)-1,2,3,4-tetrahydroisoquinolin-2-yl)carbonyl]pyridine and its coordination compounds with Cu²⁺, Co²⁺, Co³⁺, or Fe³⁺ are described. By means of ¹H- and ¹³C-NMR spectra it was proved that 2,6-bis[((3S)-3-(methoxycarbonyl)-1,2,3,4-tetrahydroisoquinolin-2-yl)carbonyl]pyridine as well as its coordination compound with Co³⁺ exist in the form of a mixture of three conformers, differing in the conformations at the two amide groups present. The prepared coordination compounds were tested in the enantioselective catalysis of the nitroaldol addition of nitromethane with 2-nitrobenzaldehyde or 4-nitrobenzaldehyde, and in the Michael addition of ethyl 2-oxocyclohexanecarboxylate to but-3-en-2-one. Full article

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Open AccessArticle

Antioxidant Activity of a New Aromatic Geranyl Derivative of the Resinous Exudates from Heliotropium glutinosum Phil.

by Brenda Modak, Macarena Rojas, René Torres, Jesús Rodilla and Federico Luebert

Molecules 2007, 12(5), 1057-1063; https://doi.org/10.3390/12051057 - 21 May 2007

Cited by 29 | Viewed by 12460

Abstract

Heliotropium glutinosum Phil. (Heliotropiceae) is a resinous bush that grows at a height of 2000 m in Chañaral, Chile. From the resinous exudates of Heliotropium glutinosum Phil. a new aromatic geranyl derivative: 4-methoxy-3-[(2)-7’-methyl-3’-hydroxymethyl-2’,6’-octadienyl] phenol (1) and three flavonoids: 5,3'-dihydroxy-7,4'-dimethoxyflavanone (2), 5,4'-dihydroxy-7-methoxyflavanone [...] Read more.

Heliotropium glutinosum Phil. (Heliotropiceae) is a resinous bush that grows at a height of 2000 m in Chañaral, Chile. From the resinous exudates of Heliotropium glutinosum Phil. a new aromatic geranyl derivative: 4-methoxy-3-[(2)-7’-methyl-3’-hydroxymethyl-2’,6’-octadienyl] phenol (1) and three flavonoids: 5,3'-dihydroxy-7,4'-dimethoxyflavanone (2), 5,4'-dihydroxy-7-methoxyflavanone (3) and 4'-acetyl-5-hydroxy-7-methoxyflavanone (4) were isolated and their structures were determined. Their antioxidant activity were evaluated using the bleaching of ABTS and DPPH derived cation radical methods and expressed in terms of FRE (fast reacting equivalents) and TRE (total reacting equivalents), where FRE is a good measure of the quick protection of a given compound against oxidants and TRE measures the degree of long-term protection of the antioxidant, or how effective it is against a strong oxidative stress. Full article

(This article belongs to the Special Issue Phenolics and Polyphenolics)

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Open AccessArticle

Effects of Quercetin on Mushroom Tyrosinase and B16-F10 Melanoma Cells

by Isao Kubo, Teruhiko Nitoda and Ken-ichi Nihei

Molecules 2007, 12(5), 1045-1056; https://doi.org/10.3390/12051045 - 15 May 2007

Cited by 59 | Viewed by 22193

Abstract

In searching for tyrosinase inhibitors from plants using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, quercetin was found to be partially oxidized to the corresponding o-quinone under catalysis by mushroom tyrosinase (EC 1.14.18.1). Simultaneously, L-DOPA was also oxidized to dopaquinone and [...] Read more.

In searching for tyrosinase inhibitors from plants using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, quercetin was found to be partially oxidized to the corresponding o-quinone under catalysis by mushroom tyrosinase (EC 1.14.18.1). Simultaneously, L-DOPA was also oxidized to dopaquinone and both o-quinones were further oxidized, respectively. The remaining quercetin partially formed adducts with dopaquinone through a Michael type addition. In general, flavonols form adducts with dopaquinone as long as their 3-hydroxyl group is free. Quercetin enhanced melanin production per cell in cultured murine B16-F10 melanoma cells, but this effect may be due in part to melanocytotoxicity. The concentration leading to 50% viable cells lost was established as 20 μM and almost complete lethality was observed at 80 μM. Full article

(This article belongs to the Special Issue Phenolics and Polyphenolics)

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Open AccessArticle

Lupane Triterpenoids from Acacia mellifera with Cytotoxic Activity

by Charles Mutai, Dennis Abatis, Constantinos Vagias, Dimitri Moreau, Christos Roussakis and Vassilios Roussis

Molecules 2007, 12(5), 1035-1044; https://doi.org/10.3390/12051035 - 15 May 2007

Cited by 28 | Viewed by 12094

Abstract

Three new pentacyclic triterpenoids: (20R)-3-oxolupan-30-al (1), (20S)-3-oxolupan-30-al (2) and (20R)-28-hydroxylupen-30-al-3-one (3), along with (20S)-3β-hydroxylupan-30-al (4), the latter previously described as a constituent of an epimeric mixture, were isolated from Acacia mellifera. In addition, the [...] Read more.

Three new pentacyclic triterpenoids: (20R)-3-oxolupan-30-al (1), (20S)-3-oxolupan-30-al (2) and (20R)-28-hydroxylupen-30-al-3-one (3), along with (20S)-3β-hydroxylupan-30-al (4), the latter previously described as a constituent of an epimeric mixture, were isolated from Acacia mellifera. In addition, the known metabolites 30-hydroxylup-20-(29)-en-3-one (5), 30-hydroxylup-20-(29)-en-3β-ol (6), atranorin, methyl 2,4-dihydroxy-3,6 dimethyl benzoate, sitosterol-3β-O-glucoside and linoleic acid were found in the analyzed plant species for the first time. The structures of the new metabolites were elucidated by extensive spectroscopic analyses and their relative stereochemistry was determined by NOESY experiments. The new metabolite 3 exhibited significant cytotoxic activity against the NSCLC-N6 cell line, derived from a human non-small-cell bronchopulmonary carcinoma. Full article

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Open AccessArticle

Evaluation of the Activity of the Sponge Metabolites Avarol and Avarone and their Synthetic Derivatives Against Fouling Micro- and Macroorganisms

by Maria Tsoukatou, Jean Philippe Maréchal, Claire Hellio, Irena Novaković, Srdan Tufegdzic, Dusan Sladić, Miroslav J Gašić, Anthony S Clare, Constantinos Vagias and Vassilios Roussis

Molecules 2007, 12(5), 1022-1034; https://doi.org/10.3390/12051022 - 15 May 2007

Cited by 57 | Viewed by 12338

Abstract

The sesquiterpene hydroquinone avarol (1) was isolated from the marine sponge Dysidea avara, whereas the corresponding quinone, avarone (2), was obtained by oxidation of avarol, and the significantly more lipophilic compounds [3’-(p-chloro-phenyl)avarone (3), 3’,4’-ethylenedithioavarone (4), 4’-isopropylthioavarone (5), 4’-tert-butylthioavarone [...] Read more.

The sesquiterpene hydroquinone avarol (1) was isolated from the marine sponge Dysidea avara, whereas the corresponding quinone, avarone (2), was obtained by oxidation of avarol, and the significantly more lipophilic compounds [3’-(p-chloro-phenyl)avarone (3), 3’,4’-ethylenedithioavarone (4), 4’-isopropylthioavarone (5), 4’-tert-butylthioavarone (6), 4’-propylthioavarone (7), 4’-octylthioavarone (8)] were obtained by nucleophilic addition of thiols or p-chloroaniline to avarone. All these compounds were tested, at concentrations ranging from 0.5 to 50 μg/mL, for their effect on the settlement of the cyprid stage of Balanus amphitrite, for toxicity to both nauplii and cyprids and for their growth inhibitory activity on marine bacteria (Cobetia marina, Marinobacterium stanieri, Vibrio fischeri and Pseudoalteromonas haloplanktis) and marine fungi (Halosphaeriopsis mediosetigera, Asteromyces cruciatus, Lulworthia uniseptata and Monodictys pelagica). Full article

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Open AccessArticle

Evaluation of Antioxidative Activity of Croatian Propolis Samples Using DPPH· and ABTS·⁺ Stable Free Radical Assays

by Ivona Jasprica, Mirza Bojic, Ana Mornar, Erim Besic, Kajo Bucan and Marica Medic-Saric

Molecules 2007, 12(5), 1006-1021; https://doi.org/10.3390/12051006 - 15 May 2007

Cited by 49 | Viewed by 16710

Abstract

Propolis is one of the richest sources of plant phenolics (flavonoids and phenolic acids), which are widely recognized as rather strong antioxidants. The aim of our work was to use colored stable free radical (DPPH· and ABTS·⁺) spectrophotometric and thin-layer chromatographic [...] Read more.

Propolis is one of the richest sources of plant phenolics (flavonoids and phenolic acids), which are widely recognized as rather strong antioxidants. The aim of our work was to use colored stable free radical (DPPH· and ABTS·⁺) spectrophotometric and thin-layer chromatographic (TLC) assays to study the antioxidative behavior of the phenolics (caffeic acid, galangin and pinocembrin) most commonly present in Croatian propolis samples obtained from different Croatian regions. We propose a mathematical model providing a more sophisticated interpretation of the obtained results and a new parameter named antioxidative efficiency (AOE) is introduced. The kinetic behaviour of chosen standards determined by spectrophotometric assays follows the exponential decrease of the absorption curve. Explained numerically, AOE represents the absolute value of the first derivative of an absorbance curve in the point A₀/e (where A0 is the absorbance measured at t = 0 and e is the natural logarithm base). The advantage of this newly introduced parameter is that it provides an easy and accurate mutual comparison between the rates of antioxidative efficiency of different propolis samples. A TLC assay was only applicable in the case of the DPPH· radical. Dose-response curves were described using a linear function with AOE expressed as a coefficient of the slope. The chromatographic method was shown to be very rapid, reliable and easy-to-perform. Full article

(This article belongs to the Special Issue Phenolics and Polyphenolics)

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Open AccessArticle

β-Orcinol Metabolites from the Lichen Hypotrachyna revoluta

by Panagiota Papadopoulou, Olga Tzakou, Constantinos Vagias, Panagiotis Kefalas and Vassilios Roussis

Molecules 2007, 12(5), 997-1005; https://doi.org/10.3390/12050997 - 12 May 2007

Cited by 36 | Viewed by 9142

Abstract

Four new β-orcinol metabolites, hypotrachynic acid (1), deoxystictic acid (2), cryptostictinolide (3) and 8 ́-methylconstictic acid (4) along with the metabolites 8 ́-methylstictic acid (5), 8 ́-methylmenegazziaic acid (6), stictic acid (7), 8 ́-ethylstictic acid (8) and atranorin (9), that have been previously [...] Read more.

Four new β-orcinol metabolites, hypotrachynic acid (1), deoxystictic acid (2), cryptostictinolide (3) and 8 ́-methylconstictic acid (4) along with the metabolites 8 ́-methylstictic acid (5), 8 ́-methylmenegazziaic acid (6), stictic acid (7), 8 ́-ethylstictic acid (8) and atranorin (9), that have been previously described, were isolated for the first time from the tissue extracts of the lichen Hypotrachyna revoluta (Flörke) Hale. The structures of the new metabolites were elucidated on the basis of extensive spectroscopic analyses. Radical scavenging activity (RSA) of the metabolites isolated in adequate amounts, was evaluated using luminol chemiluminescence and comparison with Trolox®. Full article

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Open AccessArticle

Synthesis and Fluorescence Properties of 5,7-Diphenylquinoline and 2,5,7-Triphenylquinoline Derived from m-Terphenylamine

by Shujian Qi, Kehui Shi, Hongyin Gao, Qiancai Liu and Hong Wang

Molecules 2007, 12(5), 988-996; https://doi.org/10.3390/12050988 - 12 May 2007

Cited by 18 | Viewed by 10194

Abstract

Synthesis of 5,7-phenylquinoline from the Skraup reaction of m-terphenyl-amine and glycerol in the presence of acid is reported. Further reaction of 5,7-diphenyl-quinoline with phenyl lithium prepared in situ led to the formation of 2,5,7-triphenyl-quinoline. All of the products and their intermediates were characterized [...] Read more.

Synthesis of 5,7-phenylquinoline from the Skraup reaction of m-terphenyl-amine and glycerol in the presence of acid is reported. Further reaction of 5,7-diphenyl-quinoline with phenyl lithium prepared in situ led to the formation of 2,5,7-triphenyl-quinoline. All of the products and their intermediates were characterized and the UV-Vis and photo-luminescence (PL) spectra of m-terphenylamine, 5,7-diphenylquinoline and 2,5,7-triphenylquinoline are also reported. Full article

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Open AccessCommunication

A New Type of NADH Model Compound: Synthesis and Enantioselective Reduction of Benzoylformates to the Corresponding Mandelates

by Jia Zhao, Nai-Xing Wang, Wu-Wei Wang, Yan-Hong Liu, Li Li, Gui-Xia Wang, Jin-Lan Yu and Xin-Liang Tang

Molecules 2007, 12(5), 979-987; https://doi.org/10.3390/12050979 - 11 May 2007

Cited by 14 | Viewed by 10664

Abstract

A new type of NADH model compound with good reactivity and enantioselectivity has been synthesized in good yields by an efficient and convenient synthetic method. The structures of these model compounds were confirmed by ¹H and ¹³C-NMR and MS. Full article

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Open AccessArticle

Synthesis, Antiviral and Antifungal Bioactivity of 2-Cyano-acrylate Derivatives Containing Phosphonyl Moieties

by Yin-Pu Lv, Xian-You Wang, Bao-An Song, Song Yang, Kai Yan, Guang-Fang Xu, Pinaki S Bhadury, Fang Liu, Lin-Hong Jin and De-Yu Hu

Molecules 2007, 12(5), 965-978; https://doi.org/10.3390/12050965 - 9 May 2007

Cited by 19 | Viewed by 10911

Abstract

Alkyl 2-cyano-3-methylthio-3-phosphonylacrylates were synthesized by the reaction of alkyl 2-cyano-3,3-dimethylthioacrylates with dialkyl phosphites. The structures of the new compounds were characterized by elemental analyses, IR, ¹H-, ¹³C- and ³¹P-NMR spectral data. These compounds were tested in vitro against pathogenic fungi, [...] Read more.

Alkyl 2-cyano-3-methylthio-3-phosphonylacrylates were synthesized by the reaction of alkyl 2-cyano-3,3-dimethylthioacrylates with dialkyl phosphites. The structures of the new compounds were characterized by elemental analyses, IR, ¹H-, ¹³C- and ³¹P-NMR spectral data. These compounds were tested in vitro against pathogenic fungi, namely, Fusarium graminearum, Cytospora mandshurica and Fusarium oxysporum. Amongst all compounds, 2d and 2t were found to be effective against the tested fungi at 50μg/mL. A half-leaf method was used to determine the in vivo protective, inactivation and curative efficacies of the title products against tobacco mosaic virus (TMV). Title compounds 2a and 2b were found to possess good in vivo curative, protection and inactivation effects against TMV with inhibitory rates at 500 mg/L of 60.0, 89.4 and 56.5 and 64.2, 84.2 and 61.2 %, respectively. To the best of our knowledge, this is the first report on the antiviral and antifungal activity of alkyl 2-cyano-3-methylthio-3-phosphonylacrylates. Full article

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Open AccessCommunication

Bis(trimethylsilyl)chromate Catalyzed Oxidations of Alcohols to Aldehydes and Ketones with Periodic Acid

by Karim Asadolah, Majid M Heravi, Rahim Hekmatshoar and Soma Majedi

Molecules 2007, 12(5), 958-964; https://doi.org/10.3390/12050958 - 5 May 2007

Cited by 14 | Viewed by 7322

Abstract

A facile, selective and high yielding bis(trimethylsilyl) chromate (BTSC) catalyzed selective oxidation of alcohols to aldehydes and ketones with periodic acid is reported. Full article

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187 KiB

Open AccessArticle

Cancer Preventive Mechanismsof the Green Tea Polyphenol (-)-Epigallocatechin-3-gallate

by Lei Chen and Hong-Yu Zhang

Molecules 2007, 12(5), 946-957; https://doi.org/10.3390/12050946 - 3 May 2007

Cited by 111 | Viewed by 18473

Abstract

Accumulating evidence indicates that consumption of tea, especially green tea, is good for preventing cancer. To elucidate the cancer preventive mechanisms of green tea, much effort has been devoted to investigating the anticancer effects of (-)-epigallocatechin-3-gallate (EGCG), the major component of green tea. [...] Read more.

Accumulating evidence indicates that consumption of tea, especially green tea, is good for preventing cancer. To elucidate the cancer preventive mechanisms of green tea, much effort has been devoted to investigating the anticancer effects of (-)-epigallocatechin-3-gallate (EGCG), the major component of green tea. It has been revealed that EGCG restrained carcinogenesis in a variety of tissues through inhibition of mitogen-activated protein kinases (MAPK), growth factor-related cell signaling, activation of activator protein 1 (AP-1) and nuclear factor-B (NF-κB), topoisomerase I, matrix metalloproteinases and other potential targets. Therefore, EGCG is a multipotent anticancer agent, which not only provides solid evidence to support the anticancer potential of green tea, but also offers new clues for discovering multiple-targeted anticancer drugs. Full article

(This article belongs to the Special Issue Phenolics and Polyphenolics)

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Open AccessArticle

Evaluation of the Antimicrobial and Antioxidant Activities of Origanum dictamnus Extracts before and after Encapsulation in Liposomes

by Olga Gortzi, Stavros Lala, Ioanna Chinou and John Tsaknis

Molecules 2007, 12(5), 932-945; https://doi.org/10.3390/12050932 - 2 May 2007

Cited by 98 | Viewed by 12448

Abstract

The antioxidant and antimicrobial activity of methanol or dichloromethane extracts of O. dictamnus, produced from wild and organic cultivated specimens, were determined. The Rancimat and malondialdehyde (MDA) by HPLC methods were used to measure the antioxidant action, in comparison with that of [...] Read more.

The antioxidant and antimicrobial activity of methanol or dichloromethane extracts of O. dictamnus, produced from wild and organic cultivated specimens, were determined. The Rancimat and malondialdehyde (MDA) by HPLC methods were used to measure the antioxidant action, in comparison with that of the common commercial antioxidants butylated hydroxytoluene (BHT) and α-tocopherol. The extracts that presented high antioxidant activity were encapsulated in liposomes and their antioxidant action was again estimated using differential scanning calorimetry (DSC). Thermaloxidative decomposition of the samples (pure liposomes and encapsulated extracts) and the modification of the main transition temperature for the lipid mixture and the splitting of the calorimetric peak in the presence of the antioxidants were also studied by the DSC method. All extracts showed antioxidant and antimicrobial activities. Their action proved superior to α-tocopherol. The methanol extract of organic cultivated O. dictamnus (240 ppm) showed higher activity than butylated hydroxytoluene. After encapsulation in liposomes the antioxidant as well as antimicrobial activities proved to be higher than those of the same extracts in pure form. Full article

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Molecules, Volume 12, Issue 5 (May 2007) – 25 articles , Pages 932-1201

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