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Molecules, Volume 12, Issue 3 (March 2007) – 37 articles , Pages 283-702

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72 KiB  
Article
Fast and Highly Efficient Solid State Oxidation of Thiols
by Morteza Montazerozohori, Shiva Joohari, Bahador Karami and Nasrin Haghighat
Molecules 2007, 12(3), 694-702; https://doi.org/10.3390/12030694 - 31 Mar 2007
Cited by 31 | Viewed by 11596
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 [...] Read more.
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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141 KiB  
Article
Screening Non-colored Phenolics in Red Wines using Liquid Chromatography/Ultraviolet and Mass Spectrometry/Mass Spectrometry Libraries
by Jianping Sun, Feng Liang, Yan Bin, Ping Li and Changqing Duan
Molecules 2007, 12(3), 679-693; https://doi.org/10.3390/12030679 - 30 Mar 2007
Cited by 289 | Viewed by 23402
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 [...] Read more.
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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0 pages, 406 KiB  
Article
RETRACTED: Synthesis of Gefitinib from Methyl 3-Hydroxy-4-methoxy-benzoate
by Ming Dong Li, You Guang Zheng and Min Ji
Molecules 2007, 12(3), 673-678; https://doi.org/10.3390/12030673 - 28 Mar 2007
Cited by 10 | Viewed by 12624 | Retraction
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 [...] Read more.
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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223 KiB  
Article
Identification of the Products of Oxidation of Quercetin by Air Oxygenat Ambient Temperature
by Igor G Zenkevich, Anna Yu Eshchenko, Svetlana V Makarova, Alexander G Vitenberg, Yuri G Dobryakov and Viktor A Utsal
Molecules 2007, 12(3), 654-672; https://doi.org/10.3390/12030654 - 27 Mar 2007
Cited by 129 | Viewed by 18549
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 [...] Read more.
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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152 KiB  
Article
Novel Aflatoxin Derivatives and Protein Conjugates
by Christian Cervino, Dietmar Knopp, Michael G. Weller and Reinhard Niessner
Molecules 2007, 12(3), 641-653; https://doi.org/10.3390/12030641 - 27 Mar 2007
Cited by 29 | Viewed by 12917
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, [...] Read more.
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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60 KiB  
Article
Synthesis of 5-Acetoxymethyl- and 5-Hydroxymethyl-2-vinyl-furan
by Alexander Mehner, Ana L Montero, Ricardo Martinez and Stefan Spange
Molecules 2007, 12(3), 634-640; https://doi.org/10.3390/12030634 - 26 Mar 2007
Cited by 14 | Viewed by 11632
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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69 KiB  
Article
Synthesis and in vitro Evaluation of New Benzothiazole Derivatives as Schistosomicidal Agents
by Mona A Mahran, Samia William, Fatem Ramzy and Amira M Sembel
Molecules 2007, 12(3), 622-633; https://doi.org/10.3390/12030622 - 26 Mar 2007
Cited by 72 | Viewed by 9816
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 [...] Read more.
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
124 KiB  
Article
Methyl Jasmonate and Salicylic Acid Induced Oxidative Stress and Accumulation of Phenolics in Panax ginseng Bioreactor Root Suspension Cultures
by Mohammad Babar Ali, Eun-Joo Hahn and Kee-Yoeup Paek
Molecules 2007, 12(3), 607-621; https://doi.org/10.3390/12030607 - 23 Mar 2007
Cited by 170 | Viewed by 18782
Abstract
To investigate the enzyme variations responsible for the synthesis of phenolics, 40 day-old adventitious roots of Panax ginseng were treated with 200 μM methyl jasmonate (MJ) or salicylic acid (SA) in a 5 L bioreactor suspension culture (working volume 4 L). Both treatments [...] Read more.
To investigate the enzyme variations responsible for the synthesis of phenolics, 40 day-old adventitious roots of Panax ginseng were treated with 200 μM methyl jasmonate (MJ) or salicylic acid (SA) in a 5 L bioreactor suspension culture (working volume 4 L). Both treatments caused an increase in the carbonyl and hydrogen peroxide (H2O2) contents, although the levels were lower in SA treated roots. Total phenolic, flavonoid, ascorbic acid, non-protein thiol (NPSH) and cysteine contents and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical reducing activity were increased by MJ and SA. Fresh weight (FW) and dry weight (DW) decreased significantly after 9 days of exposure to SA and MJ. The highest total phenolics (62%), DPPH activity (40%), flavonoids (88%), ascorbic acid (55%), NPSH (33%), and cysteine (62%) contents compared to control were obtained after 9 days in SA treated roots. The activities of glucose 6-phosphate dehydrogenase, phenylalanine ammonia lyase, substrate specific peroxidases (caffeic acid peroxidase, quercetin peroxidase and ferulic acid peroxidase) were higher in MJ treated roots than the SA treated ones. Increased shikimate dehydrogenase, chlorogenic acid peroxidase and β-glucosidase activities and proline content were observed in SA treated roots than in MJ ones. Cinnamyl alcohol dehydrogenase activity remained unaffected by both MJ and SA. These results strongly indicate that MJ and SA induce the accumulation of phenolic compounds in ginseng root by altering the phenolic synthesis enzymes. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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96 KiB  
Article
Characterization of Flavonoid Subgroups and Hydroxy Substitution by HPLC-MS/MS
by Dimitrios Tsimogiannis, Martina Samiotaki, George Panayotou and Vassiliki Oreopoulou
Molecules 2007, 12(3), 593-606; https://doi.org/10.3390/12030593 - 21 Mar 2007
Cited by 252 | Viewed by 23557
Abstract
HPLC-DAD coupled with mass spectrometry in the positive ionization mode was applied to study the fragmentation of twelve selected flavonoids. Compounds belonging to all the major subgroups found in common plants, i.e. flavonols, flavones, dihydroflavonols, flavanones and flavanols were studied. Compound standards were [...] Read more.
HPLC-DAD coupled with mass spectrometry in the positive ionization mode was applied to study the fragmentation of twelve selected flavonoids. Compounds belonging to all the major subgroups found in common plants, i.e. flavonols, flavones, dihydroflavonols, flavanones and flavanols were studied. Compound standards were injected into the spectrometer and produced characteristic mass spectra. The fragmentation of each compound was studied and it was shown that the dehydration andcarbon monoxide losses from the [M+H]+ ion by the members of each subgroup produced specific fragments, thus allowing the characterization of the flavonoid subgroups. Moreover, fragments resulting from fission of the C-rings are specific of each subgroup and revealed the substitution pattern of A- and B-rings. In order to verify the identifying efficiency of the positive ionization mode through these characteristic fragmentations, the unknown flavonoids of an Origanum vulgare diethyl ether extract were separated withthe HPLC system and the major peaks were successfully identified with the mass spectrometer. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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202 KiB  
Article
Proteasome and NF-κB Inhibiting Phaeophytins from the Green Alga Cladophora fascicularis
by Xinping Huang, Min Li, Bo Xu, Xiaobin Zhu, Zhiwei Deng and Wenhan Lin
Molecules 2007, 12(3), 582-592; https://doi.org/10.3390/12030582 - 21 Mar 2007
Cited by 24 | Viewed by 9706
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 [...] Read more.
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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59 KiB  
Article
Phenolic Content and Antioxidant Properties of Soybean (Glycine max (L.) Merr.) Seeds
by Djordje Malenčić, Milan Popović and Jegor Miladinović
Molecules 2007, 12(3), 576-581; https://doi.org/10.3390/12030576 - 21 Mar 2007
Cited by 102 | Viewed by 17284
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 [...] Read more.
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)
199 KiB  
Article
Symmetrically and Unsymmetrically Bridged Methylenebis(allopurinols): Synthesis of Dimeric Potential Anti-Gout Drugs
by Helmut Rosemeyer, Martina Anders and Frank Seela
Molecules 2007, 12(3), 563-575; https://doi.org/10.3390/12030563 - 21 Mar 2007
Cited by 5 | Viewed by 8210
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 [...] Read more.
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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100 KiB  
Communication
Preparative Separation and Identification of the Flavonoid Phlorhizin from the Crude Extract of Lithocarpus Polystachyus Rehd
by Huaqiang Dong, Zhengxiang Ning, Lijing Yu, Lin Li, Lichao Lin and Jianbo Huang
Molecules 2007, 12(3), 552-562; https://doi.org/10.3390/12030552 - 20 Mar 2007
Cited by 43 | Viewed by 12685
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. [...] Read more.
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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76 KiB  
Article
Microwave-promoted Facile and Efficient Preparation of N-(alkoxycarbonylmethyl) Nucleobases − Building Blocks for Peptide Nucleic Acids
by Guirong Qu, Zhiguang Zhang, Haiming Guo, Mingwei Geng and Ran Xia
Molecules 2007, 12(3), 543-551; https://doi.org/10.3390/12030543 - 19 Mar 2007
Cited by 13 | Viewed by 7665
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 [...] Read more.
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
73 KiB  
Communication
New Cytotoxic Steroid from Stachyurus imalaicus var. himalaicus
by Yun-Song Wang, Jing-Hua Yang, Shi-De Luo, Hong-Bin Zhang and Liang Li
Molecules 2007, 12(3), 536-542; https://doi.org/10.3390/12030536 - 17 Mar 2007
Cited by 4 | Viewed by 12412
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 [...] Read more.
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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259 KiB  
Review
Isoselenocyanates: A Powerful Tool for the Synthesis of Selenium-Containing Heterocycles
by Dinesh Ramesh Garud, Mamoru Koketsu and Hideharu Ishihara
Molecules 2007, 12(3), 504-535; https://doi.org/10.3390/12030504 - 17 Mar 2007
Cited by 106 | Viewed by 14841
Abstract
Selenium-containingheterocyclic compounds have been well recognized, not only because of their remarkable reactivities and chemical properties, but also because of their diverse pharmaceutical applications. In this context, isoselenocyanates have been emerged as a powerful tool for the synthesis of selenium-containing heterocycles, since they [...] Read more.
Selenium-containingheterocyclic compounds have been well recognized, not only because of their remarkable reactivities and chemical properties, but also because of their diverse pharmaceutical applications. In this context, isoselenocyanates have been emerged as a powerful tool for the synthesis of selenium-containing heterocycles, since they are easy to prepare and store and are safe to handle. In this review the recent advances in the development of synthesis methods forselenium-containing heterocycles from isoselenocyanates are presented and discussed. Full article
(This article belongs to the Special Issue Heterocycles)
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64 KiB  
Article
Facile Synthesis of Some Novel Pyrido[3', 2': 4, 5]thieno[2,3-b][1,4]thiazine-8-carboxylic Acids
by Mohammed H Al-Huniti, Mustafa M El-Abadelah, Jalal A Zahra, Salim S Sabri and Arnd Ingendoh
Molecules 2007, 12(3), 497-503; https://doi.org/10.3390/12030497 - 15 Mar 2007
Cited by 8 | Viewed by 10639
Abstract
Model tetrahydropyrido[3',2':4,5]thieno[2,3-b][1,4]thiazines 9a-c were synthesized via reductive lactamization, using sodium dithionite, of the respective 2-[(carboxyalkyl)thio]-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acids 7a-c. The latter derivatives were made via interaction of 2-chloro-7-cyclopropyl-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acid (6) with each of α–mercaptoacetic, α-mercaptopropionic, and α [...] Read more.
Model tetrahydropyrido[3',2':4,5]thieno[2,3-b][1,4]thiazines 9a-c were synthesized via reductive lactamization, using sodium dithionite, of the respective 2-[(carboxyalkyl)thio]-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acids 7a-c. The latter derivatives were made via interaction of 2-chloro-7-cyclopropyl-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acid (6) with each of α–mercaptoacetic, α-mercaptopropionic, and α-mercaptosuccinic acids and triethylamine in aqueous acetone at room temperature. The structures of 7a-7c and 9a-9c are supported by microanalytical and spectral (IR, MS, NMR) data. Compounds 9a and 9c showed potent inhibitory activity against the IGROV1 (Ovarian Cancer) cell line. Full article
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84 KiB  
Article
Effect of Extraction Conditions on Measured Total Polyphenol Contents and Antioxidant and Antibacterial Activities of Black Tea
by Nihal Turkmen, Y Sedat Velioglu, Ferda Sari and Gokce Polat
Molecules 2007, 12(3), 484-496; https://doi.org/10.3390/12030484 - 13 Mar 2007
Cited by 163 | Viewed by 20702
Abstract
Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethyl-formamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was [...] Read more.
Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethyl-formamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was found to be in the range of 0.44-114.01 mg gallic acid equivalents (GAE)/g dry weight tea, depending on the solvent used and the length of the extraction process. In general, aqueous acetone or DMF extracts displayed the highest polyphenol contents and antioxidant activity, while absolute acetone was the least efficient solvent. Antioxidant activities of tea extracts tested using the reducing power and 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods ranged from 0.09 to 1.18 and from 2.60 to 95.42 %, respectively, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations. Aqueous solvent black tea extracts also possessed antibacterial activity, depending on the solvent used and bacterial species tested. Staphylococcus aureus was found to be the most sensitive to all tea extracts, except for the methanol extract. Tea extracts were not effective against Y. enterocolitica, L. monocytogenes and E. coli O157:H7. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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171 KiB  
Review
Occurrence, Biological Activities and Synthesis of Kaurane Diterpenes and their Glycosides
by Pablo Anselmo Garcia, Alaide Braga De Oliveira and Ronan Batista
Molecules 2007, 12(3), 455-483; https://doi.org/10.3390/12030455 - 13 Mar 2007
Cited by 124 | Viewed by 17303
Abstract
This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria [...] Read more.
This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kauranediterpenes are presented, focusing on their chemical structures, occurrence in the plant kingdom and their main, recently described, biological activities. Moreover, the most significant works, published between 1964 and November 2006, which describe the total synthesis or structural transformations of some kaurane diterpenes, including either semisynthetic and/or microbiologicalmethodologies, are consisely reviewed. At this point, some general considerations on glycosides are introduced, and kaurane glycosides are presented and discussed on the basis of their toxic importance and occurrence in the plant kingdom, having focused on related aspects of their biological activities and the relationships between these activities and the structural factors of their molecules. Finally, the principal methods of glycosidation byenzymatic and chemical processes are both presented, and a few papers on the synthesis of kaurane glycosides are succinctly discussed. Full article
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159 KiB  
Article
Solventless Lactam Synthesis by Intramolecular Cyclizations of α-Iminoester Derivatives under Microwave Irradiation
by Fatima-Zohra Zradni, Jack Hamelin and Aicha Derdour
Molecules 2007, 12(3), 439-454; https://doi.org/10.3390/12030439 - 12 Mar 2007
Cited by 5 | Viewed by 10708
Abstract
We have previously reported a new synthesis of amides from esters and amines under microwave irradiation, offering much higher yields than those achieved with conventional heating [1]. We have now extended these studies to the ring closure of neat iminoesters I2, I3 and [...] Read more.
We have previously reported a new synthesis of amides from esters and amines under microwave irradiation, offering much higher yields than those achieved with conventional heating [1]. We have now extended these studies to the ring closure of neat iminoesters I2, I3 and I4-I6 to give five- and six-membered ring lactams L5, L6 and larger lactams L7-L9 (where I means imine and L means lactam), respectively, under both classical heating conditions and microwave irradiation. Full article
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54 KiB  
Article
N,N'-Ethylene-bis(benzoylacetoniminato) Copper (II), Cu(C22H22N2O2), a New Reagent for Aromatization of Hantzsch 1,4-Dihydropyridines
by Saeed Dehghanpour, Majid M Heravi and Fatemeh Derikvand
Molecules 2007, 12(3), 433-438; https://doi.org/10.3390/12030433 - 12 Mar 2007
Cited by 16 | Viewed by 7335
Abstract
A variety of Hantzsch 1,4-dihydropyridines were oxidized to their corresponding pyridines in high yields in the presence of Cu(C22H22N2O2) in refluxing acetic acid. Full article
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160 KiB  
Article
Phenolic Antioxidants Identified by ESI-MS from Yerba Maté (Ilex paraguariensis) and Green Tea (Camelia sinensis) Extracts
by Deborah H Bastos, Luciane A Saldanha, Rodrigo R Catharino, Alexandra Sawaya, Ildenize B Cunha, Patricia O Carvalho and Marcos N Eberlin
Molecules 2007, 12(3), 423-432; https://doi.org/10.3390/12030423 - 12 Mar 2007
Cited by 276 | Viewed by 31991
Abstract
Aqueous extracts of green yerba maté (Ilex paraguariensis) and green tea (Camellia sinensis) are good sources of phenolic antioxidants, as already described in the literature. The subject of this study were organic extracts from yerba maté, both green and [...] Read more.
Aqueous extracts of green yerba maté (Ilex paraguariensis) and green tea (Camellia sinensis) are good sources of phenolic antioxidants, as already described in the literature. The subject of this study were organic extracts from yerba maté, both green and roasted, and from green tea. Their phenolic profiles were characterized by direct infusion electrospray insertion mass spectrometry (ESI-MS) and their free radical scavenging activity was determined by the DPPH assay. Organic extracts containing phenolic antioxidants might be used as natural antioxidants by the food industry, replacing the synthetic phenolic additives used nowadays. Ethanolic and aqueous extracts from green yerba maté, roasted yerba maté and green tea showed excellent DPPH scavenging activity (>89%). The ether extracts from green and roasted yerba maté displayed a weak scavenging activity, different from the behavior observed for the green tea ether extract. The main phenolic compounds identified in green yerba maté water and ethanolic extracts were: caffeic acid, quinic acid, caffeoyl glucose, caffeoylquinic acid, feruloylquinic acid, dicaffeoylquinic acid and rutin. After the roasting process two new compounds were formed: caffeoylshikimic acid and dicaffeoylshikimic acid. The ethanolic extracts from yerba maté, both roasted and green, with lower content of phenolic compounds (3.80 and 2.83 mg/mL) presented high antioxidant activity and even at very low phenolic concentrations, ether extract from GT (0.07 mg/mL) inhibited DPPH over 90%. Full article
(This article belongs to the Special Issue Phenolics and Polyphenolics)
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96 KiB  
Article
N-Methyl-(R)-3-(tert-Butyl)-Sulfinyl-1,4-Dihydropyridine: A Novel NADH Model Compound
by Kun Xie, You-Cheng Liu, Yi Cui, Jian-Ge Wang, Yao Fu and Thomas C.W. Mak
Molecules 2007, 12(3), 415-422; https://doi.org/10.3390/12030415 - 12 Mar 2007
Cited by 16 | Viewed by 10268
Abstract
We have synthesized a novel chiral NADH model compound, N-methyl-(R)-3-(tert-butyl)-sulphinyl-1,4-dihydropyridine with high enantioselectivity and used it in the reduction of methyl benzoylformate, producing (S)-methyl mandelate in 95% ee. The absolute structure of its precursor, 3-(tert-butyl)sulfinyl pyridine, was determined by X-ray analysis. Full article
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149 KiB  
Article
The Synthesis and Natural Distribution of the Major Ketone Constituents in Echinacea pallida
by George A Kraus, Jaehoon Bae, Lankun Wu and Eve Wurtele
Molecules 2007, 12(3), 406-414; https://doi.org/10.3390/12030406 - 10 Mar 2007
Cited by 8 | Viewed by 6861
Abstract
The first synthesis of a series of ketones naturally occurring in E. pallida is described. The natural distribution of these ketones among different Echinacea species is also reported. Full article
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99 KiB  
Article
Functionalisation of Artemisinin and Its Ring-contracted Derivatives
by Tine Van Neck, Sarah Van Mierloo and Wim Dehaen
Molecules 2007, 12(3), 395-405; https://doi.org/10.3390/12030395 - 9 Mar 2007
Cited by 8 | Viewed by 7640
Abstract
Isoxazoline analogues of artemisinin were obtained in low yield and low diastereoselectivity from the 1,3-dipolar cycloaddition of nitrile oxides. Alternatively, starting from the aldehyde 7, a number of transformations - Wittig reaction and reduction, Henry reaction and cyanohydrin formation - were achieved in [...] Read more.
Isoxazoline analogues of artemisinin were obtained in low yield and low diastereoselectivity from the 1,3-dipolar cycloaddition of nitrile oxides. Alternatively, starting from the aldehyde 7, a number of transformations - Wittig reaction and reduction, Henry reaction and cyanohydrin formation - were achieved in significantly higher yields. In the cases where a new stereocenter was introduced this occured diastereoselectively. Full article
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55 KiB  
Article
Volatile Chemical Constituents of Piper aduncum L and Piper gibbilimbum C. DC (Piperaceae) from Papua New Guinea
by Topul Rali, Stewart W Wossa, David N Leach and Peter G Waterman
Molecules 2007, 12(3), 389-394; https://doi.org/10.3390/12030389 - 9 Mar 2007
Cited by 31 | Viewed by 12976
Abstract
Exhaustive hydro-distillation of the leaves of Piper aduncum and fruits of Piper gibbilimbum (Piperaceae) afforded colorless and pale orange colored oils in 0.35 and 0.30 % yields, respectively. Detailed chemical analysis by GC/MS indicated the volatile constituents of Piper aduncum to be composed [...] Read more.
Exhaustive hydro-distillation of the leaves of Piper aduncum and fruits of Piper gibbilimbum (Piperaceae) afforded colorless and pale orange colored oils in 0.35 and 0.30 % yields, respectively. Detailed chemical analysis by GC/MS indicated the volatile constituents of Piper aduncum to be composed of dill apiole (43.3 %), β-caryophyllene (8.2 %), piperitione (6.7 %) and α-humulene (5.1 %), whilst the oil of P. gibbilimbum is dominated by the gibbilimbols A-D (74.2 %), with the remaining major constituents being the terpenes camphene (13.6 %) and α-pinene (6.5 %). Full article
79 KiB  
Article
Phase I and Phase II Ocular Metabolic Activities and the Role of Metabolism in Ophthalmic Prodrug and Codrug Design and Delivery
by Abeer M Al-Ghananeem and Peter A Crooks
Molecules 2007, 12(3), 373-388; https://doi.org/10.3390/12030373 - 8 Mar 2007
Cited by 34 | Viewed by 14890
Abstract
While the mammalian eye is seldom considered an organ of drug metabolism, the capacity for biotransformation is present. Compared to the liver, the metabolic capabilities of the eye are minuscule; however, phase I and phase II metabolic activities have been detected in various [...] Read more.
While the mammalian eye is seldom considered an organ of drug metabolism, the capacity for biotransformation is present. Compared to the liver, the metabolic capabilities of the eye are minuscule; however, phase I and phase II metabolic activities have been detected in various ocular structures. The careful consideration of ocular tissue metabolic processes within the eye has important implications for controlling the detoxification of therapeutic agents and for providing the potential for site-specific bio-activation of certain drug molecules, thus enabling significant improvements in drug efficacy and the minimization of side-effect from either local or systemic drug delivery to the eye. Knowledge of these processes is important to prodrug and codrug development and to researchers involved in the design, delivery and metabolism of ophthalmic drugs. This present article reviews the progress in ocular prodrug and codrug design and delivery in light of ocular metabolic activities. Full article
(This article belongs to the Special Issue Prodrugs)
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159 KiB  
Article
An Efficient Synthesis of Pyrazolo[3,4-b]quinolin-3-amine and Benzo[b][1,8]naphthyridine Derivatives
by Yehya M Elkholy
Molecules 2007, 12(3), 361-372; https://doi.org/10.3390/12030361 - 8 Mar 2007
Cited by 19 | Viewed by 9686
Abstract
2-Oxo-4-phenyl-1,2,5,6,7,8-hexahydroquinoline-3-carbonitrile (10) reacted with hydrazine hydrate, phenylisothiocyanate or benzoyl chloride to give derivatives 12, 13 and 15, respectively. The latter two products were treated with hydrazine hydrate to afford pyrozole[3,4-b]quinolines derivatives 14 and 16, respectively. Compound 10 also reacted with acetonitrile [...] Read more.
2-Oxo-4-phenyl-1,2,5,6,7,8-hexahydroquinoline-3-carbonitrile (10) reacted with hydrazine hydrate, phenylisothiocyanate or benzoyl chloride to give derivatives 12, 13 and 15, respectively. The latter two products were treated with hydrazine hydrate to afford pyrozole[3,4-b]quinolines derivatives 14 and 16, respectively. Compound 10 also reacted with acetonitrile dimer or malononitrile dimer to yield benzo[b][1,8]-naphthyridine derivatives. A single crystal X-ray crystallographic analysis was performed on compound 10, confirming its structure. Full article
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95 KiB  
Article
New Diterpenoid Alkaloids from the Roots of Delphinium tiantaishanense
by Jie Li, Dong-Lin Chen, Xi-Xian Jian and Feng-Peng Wang
Molecules 2007, 12(3), 353-360; https://doi.org/10.3390/12030353 - 8 Mar 2007
Cited by 12 | Viewed by 9458
Abstract
Four new diterpenoid alkaloids: tiantaishansine (1), tiantaishannine (2), tiantaishanmine (3), and tiantaishandine (4) have been isolated from the roots of Delphinium tiantaishan. Their structures were elucidated by chemical evidence andspectral analyses, including ESI-MS, HR-EI-MS, 1D- and 2D-NMR. Full article
(This article belongs to the Special Issue Heterocycles)
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80 KiB  
Article
Synthesis of New 1,3-Disubstituted-2,3-dihydro-1H-naphth[1,2e][1,3]oxazines
by Zuhal Turgut, Emel Pelit and Adem Köycü
Molecules 2007, 12(3), 345-352; https://doi.org/10.3390/12030345 - 7 Mar 2007
Cited by 63 | Viewed by 7888
Abstract
1,3-Disubstituted-2,3-dihydro-1H-naphth[1,2-e][1,3]oxazines were prepared through the ring-closurereactions of the aminobenzylnaphthols with substituted aryl-andheteroarylaldehydes. Full article
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