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Molecules, Volume 12, Issue 3 (March 2007), Pages 283-702

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Open AccessArticle Fast and Highly Efficient Solid State Oxidation of Thiols
Molecules 2007, 12(3), 694-702; https://doi.org/10.3390/12030694
Received: 22 January 2007 / Revised: 13 February 2007 / Accepted: 26 February 2007 / Published: 31 March 2007
Cited by 26 | PDF Full-text (72 KB) | HTML Full-text | XML Full-text
Abstract
A fast and efficient solid state method for the chemoselective room temperature oxidative coupling of thiols to afford their corresponding disulfides using inexpensive and readily available moist sodiumperiodate as the reagent is described. The reaction was applicable to a variety of thiols giving
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A fast and efficient solid state method for the chemoselective room temperature oxidative coupling of thiols to afford their corresponding disulfides using inexpensive and readily available moist sodiumperiodate as the reagent is described. The reaction was applicable to a variety of thiols giving high yields after short reaction times. Comparison of yield/time ratios of this method with some of those reported in the literature shows the superiority of this reagent over others under these conditions. Full article
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Open AccessArticle Screening Non-colored Phenolics in Red Wines using Liquid Chromatography/Ultraviolet and Mass Spectrometry/Mass Spectrometry Libraries
Molecules 2007, 12(3), 679-693; https://doi.org/10.3390/12030679
Received: 13 December 2006 / Revised: 24 March 2007 / Accepted: 29 March 2007 / Published: 30 March 2007
Cited by 148 | PDF Full-text (141 KB) | HTML Full-text | XML Full-text
Abstract
Liquid chromatography/ultraviolet (LC/UV) and mass spectrometry/mass spectrometry (MS/MS) libraries containing 39 phenolic compounds were established by coupling a LC and an ion trap MS with an electrospray ionization (ESI) source, operated in negative ion mode. As a result, the deprotonated [M-H]- molecule was
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Liquid chromatography/ultraviolet (LC/UV) and mass spectrometry/mass spectrometry (MS/MS) libraries containing 39 phenolic compounds were established by coupling a LC and an ion trap MS with an electrospray ionization (ESI) source, operated in negative ion mode. As a result, the deprotonated [M-H]- molecule was observed for all the analyzed compounds. Using MS/MS hydroxybenzoic acid and hydroxycinnamic acids showed a loss of CO2 and production of a [M-H-44] - fragment and as expected, the UV spectra of these two compounds were affected by their chemical structures. For flavonol and flavonol glycosides, the spectra of their glycosides and aglycones produced deprotonated [M-H]- and [A-H]- species, respectively, and their UV spectra each presented two major absorption peaks. The UV spectra and MS/MS data of flavan-3-ols and stilbenes were also investigated. Using the optimized LC/MS/MS analytical conditions, the phenolic extracts from six representative wine samples were analyzed and 31 phenolic compounds were detected, 26 of which were identified by searching the LC/UV and MS/MS libraries. Finally, the presence of phenolic compounds was confirmed in different wine samples using the LC/UV and LC/MS/MS libraries. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Synthesis of Gefitinibfrom Methyl 3-Hydroxy-4-methoxy-benzoate
Molecules 2007, 12(3), 673-678; https://doi.org/10.3390/12030673
Received: 9 March 2007 / Revised: 22 March 2007 / Accepted: 23 March 2007 / Published: 28 March 2007
Cited by 5 | PDF Full-text (60 KB) | HTML Full-text | XML Full-textRetraction
Abstract
This paper reports a novel synthesis of gefitinib starting from methyl3-hydroxy-4-methoxybenzoate. The process starts with alkylation of the starting material, followed by nitration, reduction, cyclization, chlorination and two successive amination reactions. The intermediates andtarget molecule were characterized by 1H-NMR, 13C-NMR, MSand
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This paper reports a novel synthesis of gefitinib starting from methyl3-hydroxy-4-methoxybenzoate. The process starts with alkylation of the starting material, followed by nitration, reduction, cyclization, chlorination and two successive amination reactions. The intermediates andtarget molecule were characterized by 1H-NMR, 13C-NMR, MSand the purities of all these compounds were determined by HPLC. This novelsynthetic route produced overall yields as high as 37.4%. Full article
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Open AccessArticle Identification of the Products of Oxidation of Quercetin by Air Oxygenat Ambient Temperature
Molecules 2007, 12(3), 654-672; https://doi.org/10.3390/12030654
Received: 13 January 2007 / Revised: 22 March 2007 / Accepted: 25 March 2007 / Published: 27 March 2007
Cited by 62 | PDF Full-text (223 KB) | HTML Full-text | XML Full-text
Abstract
Oxidation of quercetin by air oxygen takes place in water and aqueous ethanol solutions under mild conditions, namely in moderately-basic media (pH ∼ 8-10) at ambient temperature and in the absence of any radical initiators, without enzymatic catalysis or irradiation of the reaction
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Oxidation of quercetin by air oxygen takes place in water and aqueous ethanol solutions under mild conditions, namely in moderately-basic media (pH ∼ 8-10) at ambient temperature and in the absence of any radical initiators, without enzymatic catalysis or irradiation of the reaction media by light. The principal reaction products are typical of other oxidative degradation processes of quercetin, namely 3,4-dihydroxy-benzoic (proto-catechuic) and 2,4,6-trihydroxybenzoic (phloroglucinic) acids, as well as the decarboxylation product of the latter – 1,3,5-trihydroxybenzene (phloroglucinol). In accordance with the literature data, this process involves the cleavage of the γ-pyrone fragment (ring C) of the quercetin molecule by oxygen, with primary formation of 4,6-dihydroxy-2-(3,4-dihydroxybenzoyloxy)benzoic acid (depside). However under such mild conditions the accepted mechanism of this reaction (oxidative decarbonylation with formation of carbon monoxide, CO) should be reconsidered as preferably an oxidative decarboxylation with formation of carbon dioxide, CO2. Direct head-space analysis of the gaseous components formed during quercetin oxidation in aqueous solution at ambient temperature indicates that the ratio of carbon dioxide/carbon monoxide in the gas phase after acidification of the reaction media is ca. 96:4 %. Oxidation under these mild conditions is typical for other flavonols having OH groups at C3 (e.g., kaempferol), but it is completely suppressed if this hydroxyl group is substituted by a glycoside fragment (as in rutin), or a methyl substituent. An alternative oxidation mechanism involving the direct cleavage of the C2-C3 bond in the diketo-tautomer of quercetin is proposed. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Novel Aflatoxin Derivatives and Protein Conjugates
Molecules 2007, 12(3), 641-653; https://doi.org/10.3390/12030641
Received: 14 March 2007 / Revised: 25 March 2007 / Accepted: 26 March 2007 / Published: 27 March 2007
Cited by 22 | PDF Full-text (152 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Aflatoxins, a group of structurally related mycotoxins, are well known for their toxic and carcinogenic effects in humans and animals. Aflatoxin derivatives and protein conjugates are needed for diverse analytical applications. This work describes a reliable and fast synthesis of novel aflatoxin derivatives,
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Aflatoxins, a group of structurally related mycotoxins, are well known for their toxic and carcinogenic effects in humans and animals. Aflatoxin derivatives and protein conjugates are needed for diverse analytical applications. This work describes a reliable and fast synthesis of novel aflatoxin derivatives, purification by preparative HPLC and characterisation by ESI-MS and one- and two-dimensional NMR. Novel aflatoxin bovine serum albumin conjugates were prepared and characterised by UV absorption and MALDI-MS. These aflatoxin protein conjugates are potentially interesting as immunogens for the generation of aflatoxin selective antibodies with novel specificities. Full article
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Open AccessArticle Synthesis of 5-Acetoxymethyl- and 5-Hydroxymethyl-2-vinyl-furan
Molecules 2007, 12(3), 634-640; https://doi.org/10.3390/12030634
Received: 8 March 2007 / Revised: 23 March 2007 / Accepted: 23 March 2007 / Published: 26 March 2007
Cited by 8 | PDF Full-text (60 KB) | HTML Full-text | XML Full-text
Abstract
5-Acetoxymethyl- and 5-hydroxymethyl-2-vinylfuran were synthesized by two routes. The first route starts from 2-methylfuran and the second from furfuryl acetate. The latter route, involving successive Vilsmeier-Haack and Wittig reactions, is suitable for producing 5-acetoxymethyl-2-vinylfuran and 5-hydroxymethyl-2 vinylfuran in 68% and 60%yields, respectively. Full article
(This article belongs to the Special Issue Heterocycles)
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Open AccessArticle Synthesis and in vitro Evaluation of New Benzothiazole Derivatives as Schistosomicidal Agents
Molecules 2007, 12(3), 622-633; https://doi.org/10.3390/12030622
Received: 9 November 2006 / Revised: 21 March 2007 / Accepted: 23 March 2007 / Published: 26 March 2007
Cited by 45 | PDF Full-text (258 KB)
Abstract
A series of benzothiazol-2-yl-dithiocarbamates 3a-d along with their copper complexes 4a-c were synthesized via the reaction of suitable alkyl, aralkyl or heteroaryl halides with the sodium salt of benzothiazol-2-yl-dithiocarbamic acid, followed by complexation with copper sulphate. N-(4-Acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl)-N-benzothiazol-2-yl-acetamides 7a-c were synthesized by cyclization of
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A series of benzothiazol-2-yl-dithiocarbamates 3a-d along with their copper complexes 4a-c were synthesized via the reaction of suitable alkyl, aralkyl or heteroaryl halides with the sodium salt of benzothiazol-2-yl-dithiocarbamic acid, followed by complexation with copper sulphate. N-(4-Acetyl-5-aryl-4,5-dihydro-1,3,4-thiadiazol-2-yl)-N-benzothiazol-2-yl-acetamides 7a-c were synthesized by cyclization of the appropriate thiosemicarbazones 6a-c in acetic anhydride. Selected compounds were screened for in vitro schistosomicidal activity against Schistosoma mansoni at three different dosage levels (10, 50 and 100 μg/ mL). Three of these products, 4a-c, showed schistosomicidal activity similar to praziquantel, with 100% worm mortality at 10 μg/mL. These compounds would constitute a new class of potent schistosomicidal agents. Full article
Open AccessArticle Methyl Jasmonate and Salicylic Acid Induced Oxidative Stress and Accumulation of Phenolics in Panax ginseng Bioreactor Root Suspension Cultures
Molecules 2007, 12(3), 607-621; https://doi.org/10.3390/12030607
Received: 24 January 2007 / Revised: 13 March 2007 / Accepted: 18 March 2007 / Published: 23 March 2007
Cited by 80 | PDF Full-text (124 KB) | HTML Full-text | XML Full-text
Abstract
To investigate the enzyme variations responsible for the synthesis of phenolics, 40 day-old adventitious roots of Panax ginseng were treated with 200 μM methyl jasmonate (MJ) or salicylic acid (SA) in a 5 L bioreactor suspension culture (working volume 4 L). Both treatments
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To investigate the enzyme variations responsible for the synthesis of phenolics, 40 day-old adventitious roots of Panax ginseng were treated with 200 μM methyl jasmonate (MJ) or salicylic acid (SA) in a 5 L bioreactor suspension culture (working volume 4 L). Both treatments caused an increase in the carbonyl and hydrogen peroxide (H2O2) contents, although the levels were lower in SA treated roots. Total phenolic, flavonoid, ascorbic acid, non-protein thiol (NPSH) and cysteine contents and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical reducing activity were increased by MJ and SA. Fresh weight (FW) and dry weight (DW) decreased significantly after 9 days of exposure to SA and MJ. The highest total phenolics (62%), DPPH activity (40%), flavonoids (88%), ascorbic acid (55%), NPSH (33%), and cysteine (62%) contents compared to control were obtained after 9 days in SA treated roots. The activities of glucose 6-phosphate dehydrogenase, phenylalanine ammonia lyase, substrate specific peroxidases (caffeic acid peroxidase, quercetin peroxidase and ferulic acid peroxidase) were higher in MJ treated roots than the SA treated ones. Increased shikimate dehydrogenase, chlorogenic acid peroxidase and β-glucosidase activities and proline content were observed in SA treated roots than in MJ ones. Cinnamyl alcohol dehydrogenase activity remained unaffected by both MJ and SA. These results strongly indicate that MJ and SA induce the accumulation of phenolic compounds in ginseng root by altering the phenolic synthesis enzymes. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Characterization of Flavonoid Subgroups and Hydroxy Substitution by HPLC-MS/MS
Molecules 2007, 12(3), 593-606; https://doi.org/10.3390/12030593
Received: 15 January 2007 / Revised: 13 March 2007 / Accepted: 14 March 2007 / Published: 21 March 2007
Cited by 106 | PDF Full-text (96 KB) | HTML Full-text | XML Full-text
Abstract
HPLC-DAD coupled with mass spectrometry in the positive ionization mode was applied to study the fragmentation of twelve selected flavonoids. Compounds belonging to all the major subgroups found in common plants, i.e. flavonols, flavones, dihydroflavonols, flavanones and flavanols were studied. Compound standards were
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HPLC-DAD coupled with mass spectrometry in the positive ionization mode was applied to study the fragmentation of twelve selected flavonoids. Compounds belonging to all the major subgroups found in common plants, i.e. flavonols, flavones, dihydroflavonols, flavanones and flavanols were studied. Compound standards were injected into the spectrometer and produced characteristic mass spectra. The fragmentation of each compound was studied and it was shown that the dehydration andcarbon monoxide losses from the [M+H]+ ion by the members of each subgroup produced specific fragments, thus allowing the characterization of the flavonoid subgroups. Moreover, fragments resulting from fission of the C-rings are specific of each subgroup and revealed the substitution pattern of A- and B-rings. In order to verify the identifying efficiency of the positive ionization mode through these characteristic fragmentations, the unknown flavonoids of an Origanum vulgare diethyl ether extract were separated withthe HPLC system and the major peaks were successfully identified with the mass spectrometer. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Proteasome and NF-κB Inhibiting Phaeophytins from the Green Alga Cladophora fascicularis
Molecules 2007, 12(3), 582-592; https://doi.org/10.3390/12030582
Received: 18 February 2007 / Revised: 18 March 2007 / Accepted: 21 March 2007 / Published: 21 March 2007
Cited by 12 | PDF Full-text (202 KB) | HTML Full-text | XML Full-text
Abstract
Chemical examination of the green alga Cladophora fascicularis resulted in the isolation and characterization of a new porphyrin derivative, porphyrinolactone (1), along with five known phaeophytins 2-6 and fourteen sterols and cycloartanes. The structure of 1 was determined on the basis of spectroscopic
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Chemical examination of the green alga Cladophora fascicularis resulted in the isolation and characterization of a new porphyrin derivative, porphyrinolactone (1), along with five known phaeophytins 2-6 and fourteen sterols and cycloartanes. The structure of 1 was determined on the basis of spectroscopic analyses and by comparison of its NMR data with those of known phaeophytins. Compounds 1-6 displayed moderate inhibition of tumor necrosis factor alpha (TNF-α) induced nuclear factor-κB (NF-κB) activation, while 2 and 4 displayed potential inhibitory activity toward proteasome chymotripsin-like activation. The primary structure-activity relationship was also discussed. Full article
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Open AccessArticle Phenolic Content and Antioxidant Properties of Soybean (Glycine max (L.) Merr.) Seeds
Molecules 2007, 12(3), 576-581; https://doi.org/10.3390/12030576
Received: 13 February 2007 / Revised: 6 March 2007 / Accepted: 14 March 2007 / Published: 21 March 2007
Cited by 59 | PDF Full-text (59 KB) | HTML Full-text | XML Full-text
Abstract
The contents and antioxidant ability of various classes of phenolic compounds present in the seeds of twenty soybean hybrids were evaluated. Total phenolics, tannins and proanthocyanidins were determined spectrophotometrically, after extraction of seeds with 70% aqueous acetone. In addition, the flavonoid contents were
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The contents and antioxidant ability of various classes of phenolic compounds present in the seeds of twenty soybean hybrids were evaluated. Total phenolics, tannins and proanthocyanidins were determined spectrophotometrically, after extraction of seeds with 70% aqueous acetone. In addition, the flavonoid contents were determined. The antioxidant activity of aqueous acetone extracts was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity assay. The highest contents of total phenolics were found in Serbian cultivar 1511 and Chinese cultivar LN92-7369, which also displayed the highest total antioxidant activity. Conversely, genotypes poor in phenolics also showed low levels of DPPH-radical scavenging activity. The results suggested that besides protein and oil contents, the phenolic contents should be also considered as an important characteristic feature of soybean seeds, and as a potential selection criterion for antioxidant activity in soybean. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
Open AccessArticle Symmetrically and Unsymmetrically Bridged Methylenebis(allopurinols): Synthesis of Dimeric Potential Anti-Gout Drugs
Molecules 2007, 12(3), 563-575; https://doi.org/10.3390/12030563
Received: 9 March 2007 / Revised: 19 March 2007 / Accepted: 19 March 2007 / Published: 21 March 2007
Cited by 2 | PDF Full-text (199 KB) | HTML Full-text | XML Full-text
Abstract
Liquid-liquid phase transfer alkylation of 4-methoxy-pyrazolo[3,4-d]-pyrimidine (1a) with a dichloromethane/dibromomethane mixture (3:1, v/v) gave the regioisomeric methylenebis(heterocycles) 3a–5a. These were converted by dilute aqueous sodium hydroxide containing dimethylsulfoxide (DMSO) at concentrations between 0 and 60 vol-% into the methylenebis(allopurinols) 3b–5b by
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Liquid-liquid phase transfer alkylation of 4-methoxy-pyrazolo[3,4-d]-pyrimidine (1a) with a dichloromethane/dibromomethane mixture (3:1, v/v) gave the regioisomeric methylenebis(heterocycles) 3a–5a. These were converted by dilute aqueous sodium hydroxide containing dimethylsulfoxide (DMSO) at concentrations between 0 and 60 vol-% into the methylenebis(allopurinols) 3b–5b by nucleophilic SNAr reactions at C(4). The effect of DMSO on the reaction kinetics was investigated. Full article
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Open AccessCommunication Preparative Separation and Identification of the Flavonoid Phlorhizin from the Crude Extract of Lithocarpus Polystachyus Rehd
Molecules 2007, 12(3), 552-562; https://doi.org/10.3390/12030552
Received: 6 February 2007 / Revised: 13 March 2007 / Accepted: 13 March 2007 / Published: 20 March 2007
Cited by 27 | PDF Full-text (100 KB) | HTML Full-text | XML Full-text
Abstract
The flavonoid phlorhizin is abundant in the leaves of Sweet Tea(ST, Lithocarpus Polystachyus Rehd). Phlorhizinwas preparatively separated and purified from a crude ST extract containing 40% total flavonoids by static adsorption and dynamic desorption on ADS-7 macroporous resin and neutral alumina column chromatography.
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The flavonoid phlorhizin is abundant in the leaves of Sweet Tea(ST, Lithocarpus Polystachyus Rehd). Phlorhizinwas preparatively separated and purified from a crude ST extract containing 40% total flavonoids by static adsorption and dynamic desorption on ADS-7 macroporous resin and neutral alumina column chromatography. Only water and ethanol were used as solvents and eluants throughout the whole separation and purification process. Using a phlorhizin standard as the reference compound, the target compound separated from the crude ST extracts was analyzed by thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and electrosprayionization mass spectrometry (EIS-MS) and identified as 99.87% pure (by HPLC-UV) phlorhizin. The results showed that 10g of the targetcompound could be obtained from 40g of the crude extracts in a single operation, indicating a 40% recovery. Therefore, this represents an efficientand environmentally-friendly technology for separating and purifying phlorhizinfrom ST leaves. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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Open AccessArticle Microwave-promoted Facile and Efficient Preparation of N-(alkoxycarbonylmethyl) Nucleobases − Building Blocks for Peptide Nucleic Acids
Molecules 2007, 12(3), 543-551; https://doi.org/10.3390/12030543
Received: 13 December 2006 / Revised: 11 February 2007 / Accepted: 17 February 2007 / Published: 19 March 2007
Cited by 7 | PDF Full-text (76 KB) | HTML Full-text | XML Full-text
Abstract
A simple, rapid, and regioselective approach for the synthesis of N-(methoxy-carbonylmethyl)- and N-(n-propoxycarbonylmethyl) nucleobases was developed. By using DMF as the solvent and in the presence of K2CO3 as the base, all the desired products were obtained in moderate yields
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A simple, rapid, and regioselective approach for the synthesis of N-(methoxy-carbonylmethyl)- and N-(n-propoxycarbonylmethyl) nucleobases was developed. By using DMF as the solvent and in the presence of K2CO3 as the base, all the desired products were obtained in moderate yields within 8 min under microwave irradiation. Full article
Open AccessCommunication New Cytotoxic Steroid from Stachyurus imalaicus var. himalaicus
Molecules 2007, 12(3), 536-542; https://doi.org/10.3390/12030536
Received: 20 December 2006 / Revised: 11 February 2007 / Accepted: 17 February 2007 / Published: 17 March 2007
Cited by 3 | PDF Full-text (73 KB) | HTML Full-text | XML Full-text
Abstract
A phytochemical study of the ethanolic extract of Stachyurus imalaicus var. himalaicus was undertaken and as a result a new polyoxygenated steroid, named stachsterol ((20S)-20, 25-dihydroxy-4-cholesten-3-one, 1) and three known ecdysteroids, 20-hydroxyecdysone (2), 20-hydroxyecdysone-20, 22-monoacetonide (3) and polypodine B-20,22-monoacetonide (4), were isolated. Their
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A phytochemical study of the ethanolic extract of Stachyurus imalaicus var. himalaicus was undertaken and as a result a new polyoxygenated steroid, named stachsterol ((20S)-20, 25-dihydroxy-4-cholesten-3-one, 1) and three known ecdysteroids, 20-hydroxyecdysone (2), 20-hydroxyecdysone-20, 22-monoacetonide (3) and polypodine B-20,22-monoacetonide (4), were isolated. Their structures were elucidated by spectroscopic methods, including UV, NMR, MS and HR-MS. The purified product 1 was found to have in vitro cytotoxic activity against human Hela cell lines with an IC50 value of 2.5 μg/mL. This is the first time that phytoecdysteroids have been found in the genus Stachyurus. Full article
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