bluuebunny/crossref_metadata_2025 huggingface dataset:
An Efficient Synthesis of Pyrazolo[3,4-b]quinolin-3-amine and Benzo[b][1,8]naphthyridine Derivatives
Authors: Elkholy Yehya M
Published: October 2008

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.
Phase I and Phase II Ocular Metabolic Activities and the Role of Metabolism in Ophthalmic Prodrug and Codrug Design and Delivery
Authors: Al-Ghananeem Abeer M , Crooks Peter A
Published: October 2008

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.
Volatile Chemical Constituents of Piper aduncum L and Piper gibbilimbum C. DC (Piperaceae) from Papua New Guinea
Authors: Rali Topul , Wossa Stewart W , Leach David N , Waterman Peter G
Published: October 2008

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 %).
Functionalisation of Artemisinin and Its Ring-contracted Derivatives
Authors: Van Neck Tine , Van Mierloo Sarah , Dehaen Wim
Published: October 2008

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.
The Synthesis and Natural Distribution of the Major Ketone Constituents in Echinacea pallida
Authors: Kraus George A , Bae Jaehoon , Wu Lankun , Wurtele Eve
Published: October 2008

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.
N-Methyl-(R)-3-(tert-Butyl)-Sulfinyl-1,4-Dihydropyridine: A Novel NADH Model Compound
Authors: Xie Kun , Liu You-Cheng , Cui Yi , Wang Jian-Ge , Fu Yao , Mak Thomas
Published: October 2008

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.
Phenolic Antioxidants Identified by ESI-MS from Yerba Maté (Ilex paraguariensis) and Green Tea (Camelia sinensis) Extracts
Authors: Bastos Deborah H , Saldanha Luciane A , Catharino Rodrigo R , Sawaya Alexandra , Cunha Ildenize B , Carvalho Patricia O , Eberlin Marcos N
Published: October 2008

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%.
N,N'-Ethylene-bis(benzoylacetoniminato) Copper (II), Cu(C22H22N2O2), a New Reagent for Aromatization of Hantzsch 1,4-Dihydropyridines
Authors: Dehghanpour Saeed , Heravi Majid M , Derikvand Fatemeh
Published: October 2008

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.
Solventless Lactam Synthesis by Intramolecular Cyclizations of α-Iminoester Derivatives under Microwave Irradiation
Authors: Zradni Fatima-Zohra , Hamelin Jack , Derdour Aicha
Published: October 2008

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.
Occurrence, Biological Activities and Synthesis of Kaurane Diterpenes and their Glycosides
Authors: Garcia Pablo Anselmo , De Oliveira Alaide Braga , Batista Ronan
Published: October 2008

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.
Effect of Extraction Conditions on Measured Total Polyphenol Contents and Antioxidant and Antibacterial Activities of Black Tea
Authors: Turkmen Nihal , Velioglu Y Sedat , Sari Ferda , Polat Gokce
Published: October 2008

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.
Facile Synthesis of Some Novel Pyrido[3', 2': 4, 5]thieno[2,3-b][1,4]thiazine-8-carboxylic Acids
Authors: Al-Huniti Mohammed H , El-Abadelah Mustafa M , Zahra Jalal A , Sabri Salim S , Ingendoh Arnd
Published: October 2008

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.
Isoselenocyanates: A Powerful Tool for the Synthesis of Selenium-Containing Heterocycles
Authors: Garud Dinesh Ramesh , Koketsu Mamoru , Ishihara Hideharu
Published: October 2008

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.
New Cytotoxic Steroid from Stachyurus imalaicus var. himalaicus
Authors: Wang Yun-Song , Yang Jing-Hua , Luo Shi-De , Zhang Hong-Bin , Li Liang
Published: October 2008

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.
Microwave-promoted Facile and Efficient Preparation of N-(alkoxycarbonylmethyl) Nucleobases − Building Blocks for Peptide Nucleic Acids
Authors: Qu Guirong , Zhang Zhiguang , Guo Haiming , Geng Mingwei , Xia Ran
Published: October 2008

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.
Preparative Separation and Identification of the Flavonoid Phlorhizin from the Crude Extract of Lithocarpus Polystachyus Rehd
Authors: Dong Huaqiang , Ning Zhengxiang , Yu Lijing , Li Lin , Lin Lichao , Huang Jianbo
Published: October 2008

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.
Symmetrically and Unsymmetrically Bridged Methylenebis(allopurinols): Synthesis of Dimeric Potential Anti-Gout Drugs
Authors: Rosemeyer Helmut , Anders Martina , Seela Frank
Published: October 2008

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.
Phenolic Content and Antioxidant Properties of Soybean (Glycine max (L.) Merr.) Seeds
Authors: Malenčić Djordje , Popović Milan , Miladinović Jegor
Published: October 2008

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.
Proteasome and NF-κB Inhibiting Phaeophytins from the Green Alga Cladophora fascicularis
Authors: Huang Xinping , Li Min , Xu Bo , Zhu Xiaobin , Deng Zhiwei , Lin Wenhan
Published: October 2008

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.
Characterization of Flavonoid Subgroups and Hydroxy Substitution by HPLC-MS/MS
Authors: Tsimogiannis Dimitrios , Samiotaki Martina , Panayotou George , Oreopoulou Vassiliki
Published: October 2008

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.
Methyl Jasmonate and Salicylic Acid Induced Oxidative Stress and Accumulation of Phenolics in Panax ginseng Bioreactor Root Suspension Cultures
Authors: Ali Mohammad Babar , Hahn Eun-Joo , Paek Kee-Yoeup
Published: October 2008

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.
Synthesis and in vitro Evaluation of New Benzothiazole Derivatives as Schistosomicidal Agents
Authors: Mahran Mona A , William Samia , Ramzy Fatem , Sembel Amira M
Published: October 2008

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.
Synthesis of 5-Acetoxymethyl- and 5-Hydroxymethyl-2-vinyl-furan
Authors: Mehner Alexander , Montero Ana L , Martinez Ricardo , Spange Stefan
Published: October 2008

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.
Novel Aflatoxin Derivatives and Protein Conjugates
Authors: Cervino Christian , Knopp Dietmar , Weller Michael , Niessner Reinhard
Published: October 2008

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.
Identification of the Products of Oxidation of Quercetin by Air Oxygenat Ambient Temperature
Authors: Zenkevich Igor G , Eshchenko Anna Yu , Makarova Svetlana V , Vitenberg Alexander G , Dobryakov Yuri G , Utsal Viktor A
Published: October 2008

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.
RETRACTED: Synthesis of Gefitinib from Methyl 3-Hydroxy-4-methoxy-benzoate
Authors: Li Ming , Zheng You , Ji Min
Published: October 2008

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%.
Screening Non-colored Phenolics in Red Wines using Liquid Chromatography/Ultraviolet and Mass Spectrometry/Mass Spectrometry Libraries
Authors: Sun Jianping , Liang Feng , Bin Yan , Li Ping , Duan Changqing
Published: October 2008

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.
Fast and Highly Efficient Solid State Oxidation of Thiols
Authors: Montazerozohori Morteza , Joohari Shiva , Karami Bahador , Haghighat Nasrin
Published: October 2008

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.
Investigation on the Binding of Polycyclic AromaticHydrocarbons with Soil Organic Matter: A Theoretical Approach
Authors: Saparpakorn Patchreenart , Kim Jae Hyoun , Hannongbua Supa
Published: October 2008

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants of the terrestrial environment that have been designated as Environmental Protection Agency (EPA) Priority Pollutants. In this study, molecular modeling was used to examine the physical and chemical characteristics of soil organic matter (SOM), fulvic acid (FA) and humic acid (HA), as well as their binding interactions with PAHs. The molecular structures of 18 PAHs were built by using the SYBYL 7.0 program and then fully optimized by a semiempirical (AM1) method. A molecular docking program, AutoDock 3.05, was used to calculate the binding interactions between the PAHs, and three molecular structure models including FA (Buffle’s model), HA (Stevenson’s model) and SOM (Schulten and Schnitzer’s model). The π-π interactions and H-bonding interactions were found to play an important role in the intermolecular bonding of the SOM/PAHs complexes. In addition, significant correlations between two chemical properties, boiling point (bp) and octanol/water partition coefficient (Log Kow) and final docking energies were observed. The preliminary docking results provided knowledge of the important binding modes to FA, HA and SOM, and thereby to predict the sorption behavior of PAHs and other pollutants.
Synthesis and X-ray Structure of the Inclusion Complex of Dodecamethylcucurbit[6]uril with 1,4-Dihydroxybenzene
Authors: Lu Li-Bin , Zhang Yun-Qian , Zhu Qian-Jiang , Xue Sai-Feng , Tao Zhu
Published: October 2008

The synthesis, and X-ray crystal structure of the inclusion host-guest complex of dodecamethylcucurbit[6]uril (DDMeQ[6]) with 1,4-dihydroxybenzene (DHOBEN) are reported. The complex crystallizes in the space group P21/c (No.14) with a =12.2847(4), b = 12.6895(4), c = 15.1310(4) Å, α = 74.6960(10), β = 71.4090(10), γ = 86.5090(10)° and Z = 1. A novel approach to dodecamethylcucurbit[6]uril synthesis is also described. To separate dodecamethylcucurbit[6]uril, 1,4-dihydroxybenzene is used as a guest molecule for crystallization of the fully methyl-substituted cucurbituril. The driving force for the self-assembled inclusion host-guest complex can be attributed to not only the cavity interaction of dodecamethylcucurbit[6]uril (host), but also to the hydrogen bonding between the carbonyl oxygen at the portals of the host and the hydroxy groups of the guest.
Multi-step Redox Systems with NIR-Fluorescence Based on 4H-Imidazoles
Authors: Matschke Martin , Beckert Rainer
Published: October 2008

A new class of 4H-imidazoles was synthesized starting from fused-ring aromatic dinitriles. Strong bathochromic shifts of the longest wavelength absorptions were observed in the corresponding UV/vis spectra due to a conversion of the merocyanine chromophores into cyanines/(aza)oxonoles upon protonation/deprotonation of the 4H-imidazoles. Novel boratetraazapentalenes were synthesized via a cyclization reaction with boron trifluoride. These mesoionic species bearing a cyanine chromophore not only show NIR-fluorescence, they also participate as part of a quasi-reversible multi-step redox system. Large calculated semiquinone formation constants KSEM (3x1010 to 5x1011) indicate a high thermodynamic stability of the corresponding radical anions (SEM).
Synthesis of (R)-Dihydropyridones as Key Intermediates for an Efficient Access to Piperidine Alkaloids
Authors: Tzanetou Evangelia N , Kasiotis Konstantinos M , Magiatis Prokopios , Haroutounian Serkos A
Published: October 2008

The efficient transformation of D-glucal to (2R)-hydroxymethyldihydro-pyridinone 5 in seven steps and 35 % overall yield is reported. Dihydropyridone 5 constitutes a versatile chiral building block for the synthesis of various piperidine alkaloids. In this regard, 5 was converted to piperidinol 13 and piperidinone 15, that may be further elaborated for the syntheses of (+)-desoxoprosophylline (1) and deoxymannojirimycin (3) or D-mannolactam (4), respectively.
Litchi Flavonoids: Isolation, Identification and Biological Activity
Authors: Li Jiangrong , Jiang Yueming
Published: October 2008

The current status of the isolation, identification, biological activity, utilization and development prospects of flavonoids found in litchi fruit pericarp (LFP) tissues is reviewed. LFP tissues account for approximately 15% by weight of the whole fresh fruit and are comprised of significant amount of flavonoids. The major flavonoids in ripe LFP include flavonols and anthocyanins. The major flavanols in the LFP are reported to be procyanidin B4, procyanidin B2 and epicatechin, while cyanindin-3-rutinside, cyanidin-3-glucoside, quercetin-3-rutinosde and quercetin-3-glucoside are identified as the important anthocyanins. Litchi flavanols and anthocyanins exhibit good potential antioxidant activity. The hydroxyl radical and superoxide anion scavenging activities of procyanidin B2 are greater than those of procyanidin B4 and epicatechin, while epicatechin has the highest α,α-diphenyl-β-picrylhydrazyl radical (DPPH·) scavenging activity. In addition to the antioxidant activity, LFP extract displays a dose- and time-dependent inhibitory effect on human breast cancer, which could be attributed, in part, to its inhibition of proliferation and induction of apoptosis in cancer cells through upregulation and down-regulation of multiple genes. Furthermore, various anticancer activities are observed for epicatechin, procyanidin B2, procyanidin B4 and the ethyl acetate fraction of LFP tissue extracts. Procyanidin B4 and the ethyl acetate fraction show a stronger inhibitory effect on HELF than MCF-7 proliferation, while epicatechin and procyanidin B2 have lower cytotoxicities towards MCF-7 and HELF than paclitaxel. It is therefore suggested that flavonoids from LFP might be potentially useful components for functional foods and/or anti-breast cancer drugs.
Evaluation of the Antioxidant Properties of Litchi Fruit Phenolics in Relation to Pericarp Browning Prevention
Authors: Duan Xuewu , Wu Genfu , Jiang Yueming
Published: October 2008

Phenolics were extracted from litchi fruit pericarp (LFP) tissues, purified and their antioxidant properties analyzed. LFP phenolics strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against α,α-diphenyl-β-picrylhydrazyl (DPPH·) and hydroxyl radicals and superoxide anions. The degradation of deoxyribose by hydroxyl radicals was inhibited by phenolics acting mainly as iron ion chelators, rather than by directly scavenging the radicals. Phenolics from litchi fruit pericarp were found to display similar reducing power activity as ascorbic acid. The effect of phenolic compound treatment on pericarp browning and electrolyte leakage of litchi fruit was also evaluated and it was observed that application of exogenous litchi phenolics to harvested litchi fruit significantly prevented pericarp browning and delayed increases in electrolyte leakage. These results suggest that litchi pericarp tissue phenolics could be beneficial in scavenging free radicals, maintaining membrane integrity and, thereby inhibiting pericarp browning of litchi fruit.
Chemical Composition and Antimicrobial Activity of the Essential Oil of Algerian Phlomis bovei De Noé subsp. bovei
Authors: Liolios Christos , Laouer Hocine , Boulaacheb Nacira , Gortzi Olga , Chinou Ioanna
Published: October 2008

The chemical composition of essential oil obtained by steam distillation of dried aerial parts of Phlomis bovei De Noé subsp. bovei collected from Algeria, was analyzed by GC and GC/MS. Seventy five constituents (corresponding to 86.37% of the total weight) were identified. The main components were: germacrene D, β-caryophyllene, β-bournonene, thymol and hexahydrofarnesyl acetone. Furthermore, the antimicrobial activity of the oil was evaluated against six Gram (+/-) bacteria and three pathogenic fungi, using the agar dilution technique. It was found that the oil exhibited strong antimicrobial activity against most of the tested microorganisms.
Complexes of 3dn Metal Ions with Thiosemicarbazones: Synthesis and Antimicrobial Activity
Authors: Rosu Tudor , Gulea Aurelian , Nicolae Anca , Georgescu Rodica
Published: October 2008

The chelating behavior of the thiosemicarbazone derivatives of 2-hydroxy-8-R-tricyclo[7.3.1.0.2,7]tridecane-13-one (where R = H, CH3, C6H5) towards Co(II), Ni(II) and Cu(II) has been investigated by elemental analysis, molar conductivity measurements, UV-VIS, IR, ESR spectroscopy and thermal studies. It was deduced from the experiments performed that the ligands coordinate to metal ions in different ways – neutral bidentate or mononegative bidentate – depending on the nature of R. Also, if metal acetates are used instead of metal chlorides, the ligands coordinate in a mononegative bidentate fashion, regardless of the nature of R or the thiosemicarbazone type ligand. The antimicrobial activity of the ligands and of the complexes towards samples of Acinetobacter boumanii, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was determined.
Synthesis of α,β-Unsaturated Ketones as Chalcone Analogues via a SRN1 Mechanism
Authors: Curti Christophe , Gellis Armand , Vanelle Patrice
Published: October 2008

An electron-transfer chain reaction between 2-nitropropane anion and α-bromoketones derived from nitrobenzene and nitrothiophene was demonstrated by mechanistic study and a specific convenient synthetic protocol. Thus, 2-bromo-1-(5-nitrothiophen-2-yl)ethanone or 2-bromo-1-(4-nitrophenyl)ethanone were reacted with several cyclic nitronate anions to form α,β-unsaturated ketones via a SRN1 mechanism. This new method can be used to synthesize a wide variety of chalcone analogues.
Molecularly Imprinted Polymers for 5-Fluorouracil Release in Biological Fluids
Authors: Puoci Francesco , Iemma Francesca , Cirillo Giuseppe , Picci Nevio , Matricardi Pietro , Alhaique Franco
Published: October 2008

The aim of this work was to investigate the possibility of employing Molecularly Imprinted Polymers (MIPs) as a controlled release device for 5-fluorouracil (5-FU) in biological fluids, especially gastrointestinal ones, compared to Non Imprinted Polymers (NIPs). MIPs were synthesized using methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as crosslinking agent. The capacity of the polymer to recognize and to bind the template selectively in both organic and aqueous media was evaluated. An in vitro release study was performed both in gastrointestinal and in plasma simulating fluids. The imprinted polymers bound much more 5-Fu than the corresponding non-imprinted ones and showed a controlled/sustained drug release, with MIPs release rate being indeed much more sustained than that obtained from NIPs. These polymers represent a potential valid system for drug delivery and this study indicates that the selective binding characteristic of molecularly imprinted polymers is promising for the preparation of novel controlled release drug dosage form.
Bis(4-hydroxybenzyl)sulfide: a Sulfur Compound Inhibitor of Histone Deacetylase Isolated from Root Extract of Pleuropterus ciliinervis
Authors: Son Il Hong , Lee Sung Ik , Yang Hyun Duk , Moon Hyung-In
Published: October 2008

A sulfur compound, bis(4-hydroxybenzyl)sulfide (1) was isolated from the root extract of Pleuropterus ciliinervis. Its structure was elucidated using NMR spectroscopic techniques and mass spectrometric analysis. Compound 1 showed potent inhibitory activity in a histone deacetylase (HDAC) enzyme assay. It also exhibited growth inhibitory activity on five human tumor cell lines and more sensitive inhibitory activity on the MDA-MB-231 breast tumor cell line.
Different Supramolecular Coordination Polymers of [N,N'-di(pyrazin-2-yl)-pyridine-2,6-diamine]Ni(II) with Anions and Solvent Molecules as a Result of Hydrogen Bonding
Authors: Lee Gene-Hsiang , Wang Hsin-Ta
Published: October 2008

Ni(II) complexes of N,N'–di(pyrazin–2–yl)pyridine–2,6–diamine (H2dpzpda) with different anions were synthesized and their structures were determined by X-ray diffraction. Hydrogen bonds between the amino groups and anions assembled the mononuclear molecules into different architectures. The perchlorate complex had a 1-D chain structure, whereas switching the anion from perchlorate to nitrate resulted in a corresponding change of the supramolecular structure from 1-D to 3-D. When the nitrate complex packed with the co-crystallized water, a double chain structure was formed through hydrogen bonding. The magnetic studies revealed values of g = 2.14 and D = 3.11 cm-1 for [Ni(H2dpzpda)2](ClO4)2 (1) and g = 2.18 and D = 2.19 cm-1 for [Ni(H2dpzpda)2](NO3)2 (2), respectively.
Cytotoxic Triterpenoid Saponins from the Roots of Platycodon grandiflorum
Authors: Zhang Lin , Liu Zhen-Huan , Tian Jing-Kui
Published: October 2008

Bioguided fractionation of the ethanol extracts obtained from Platycodon grandiflorum roots led to isolation of two new triterpenoid saponins, characterized as 3-O-β-D-glucopyranosyl-2β,12α,16α,23,24-pentahydroxyoleanane-28(13)-lactone (1) and 3-O-β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-2β,12α,16α,23α-tetrahydroxyoleanane-28(13)- lactone (2) by 1D- and 2D-NMR and MS techniques, as well as chemical means. Both compounds showed cytotoxic activity against human ECA-109 cells.
Identificationof Major Phenolic Compounds of Chinese Water Chestnut and their Antioxidant Activity
Authors: You Yanli , Duan Xuewu , Wei Xiaoyi , Su Xinguo , Zhao Mouming , Sun Jian , Ruenroengklin Neungnapa , Jiang Yueming
Published: October 2008

Chinese water chestnut (CWC) is one of the most popular foods among Asian people due to its special taste and medical function. Experiments were conducted to test the antioxidant activity and then determine the major phenolic compound components present in CWC. CWC phenolic extract strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against α,α-diphenyl-β-picrylhydrazyl (DPPH) radicals, superoxide anions and hydroxyl radicals, which was superior to ascorbic acid and butylated hydroxytoluene (BHT), two commercial used antioxidants. Furthermore, the CWC extract was found to have a relatively higher reducing power, compared with BHT. The major phenolic compounds present in CWC tissues were extracted, purified and identified by high-performance liquid chromatograph (HPLC) as (–)-gallocatechin gallate, (–)-epicatechin gallate and (+)-catechin gallate. This study suggests that CWC tissues exhibit great potential for antioxidant activity and may be useful for their nutritional and medicinal functions.
Molecular Complexes Based on Tetrathiafulvalene and Dialkylviologens
Authors: Rahman Bilkish , Akutsu Hiroki , Yamada Jun-ichi , Nakatsuji Shin’ichi
Published: October 2008

Three kinds of molecular complexes based on tetrathiafulvalene (TTF) and dialkylviologens were prepared and their crystal structures elucidated. While TTF-dimethylviologen complex forms a mixed stack arrangement of donors and acceptors in its crystal structure, TTF donors aggregate with long alkyl groups by CH/p and/or van der Waals interactions in a couple of TTF-heptylviologen complexes.
C(aryl)-O Bond Formation from Aryl Methanesulfonates via Consecutive Deprotection and SNAr Reactions with Aryl Halides in an Ionic Liquid
Authors: Xu Hui , Chen Yang
Published: October 2008

An efficient K3PO4-mediated synthesis of unsymmetrical diaryl ethers using the ionic liquid [Bmim]BF4 (1-butyl-3-methylimidazolium tetrafluoroborate) as solvent has been developed. The procedure involves consecutive deprotection of aryl methane-sulfonates and a nucleophilic aromatic substitution (SNAr) with activated aryl halides.
Microwave-Assisted Isolation of Essential oil of Cinnamomum iners Reinw. ex Bl.: Comparison with Conventional Hydrodistillation
Authors: Phutdhawong Weerachai , Kawaree Rungthip , Sanjaiya Samart , Sengpracha Waya , Buddhasukh Duang
Published: October 2008

Microwave-assistedhydrodistillation was used to isolate an essential oil from the leaves of Cinnamomuminers Reinw. ex Bl., and the results compared with those obtained by conventional hydrodistillation. The composition of the oil from both methods was found to be similar, and (-)-linalool was found as the main component (30-50 %). The antioxidant activity of the essential oil obtained by both methods was evaluated using DPPH, ABTS, FRAP and lipid peroxidation methods, all of which indicated the same but insignificant activity.
How Many Drugs Are Catecholics
Authors: Yang Da-Peng , Ji Hong-Fang , Tang Guang-Yan , Ren Wei , Zhang Hong-Yu
Published: October 2008

By examination of the 8659 drugs recorded in the Comprehensive Medicinal Chemistry (CMC) database, 78 catecholics (including five pyrogallolics) were identified, of which 17 are currently prescribed by FDA. Through analyzing the substitutent patterns, ClogPs and O-H bond dissociation enthalpies(BDEs) of the catecholic drugs, some molecular features that may benefit circumventing the toxicity of catecholics were revealed: i) strong electron-donating substituents are excluded; ii) ClogP 3; iii) an energy penalty exists for quinone formation. Besides, the present analyses also suggest that the clinical usage and dosage of currently prescribed catecholic drugs are of importance in designing or screening catecholic antioxidants.
Synthesis and Activity of a New Series of(Z)-3-Phenyl-2-benzoylpropenoic Acid Derivatives as Aldose Reductase Inhibitors
Authors: Wang Shao-Jie , Yan Ju-Fang , Hao Dong , Niu Xin-Wen , Cheng Mao-Sheng
Published: October 2008

During the course of studies directed towards the discovery of novel aldose reductase inhibitors for the treatment of diabetic complications, we synthesized a series of new (Z)-3-phenyl-2-benzoylpropenoic acid derivatives and tested their in vitro inhibitory activities on rat lens aldose reductase. Of these compounds, (Z)-3-(3,4-dihydroxyphenyl)-2-(4-methylbenzoyl)propenoicacid(3k) was identified as the most potent inhibitor, with an IC50 of 0.49μM. The theoretical binding mode of 3k was obtained by simulation of its docking into the active site of the human aldose reductase crystal structure.
4'-Acetamidochalcone Derivatives as Potential Antinociceptive Agents
Authors: De Campos-Buzzi Fátima , Padaratz Pâmela , Meira Aleandra Vergilina , Corrêa Rogério , Nunes Ricardo José , Cechinel-Filho Valdir
Published: October 2008

Nine acetamidochalcones were synthesized and evaluated as antinociceptive agents using the mice writhing test. Given intraperitoneally all the compounds were more effective than the two reference analgesic drugs (acetylsalicylic acid and acetaminophen) used for comparison. N-{4-[(2E)-3-(4-nitrophenyl)prop-2-enoyl]phenyl}acetamide (6) was the most effective compound and was therefore selected for more detailed studies. It caused dose-related inhibition in the writhing test, being about 32 to 34-fold more potent than the standard drugs. It was also effective in the second phase of the formalin test and the capsaicin test. These acetamidochalcones, especially compound 6, might be further used as models to obtain new and more potent analgesic drugs.
Determination of the Three-dimensional Structure of Gynoside A in Solution using NMR and Molecular Modeling
Authors: Li Qian , Yao Zhi-Hong , Shi Yan-Hong , Liu Xin , Yao Xin-Sheng , Ye Wen-Cai
Published: October 2008

The three-dimensional structure of Gynoside A, an ocotillone-type triterpenoid glycoside isolated from Gynostemma pentaphyllum, was determined in pyridine-d5 and DMSO-d6 solution through constrained molecular modeling using constraints derived from proton NMR spectra. The calculation yielded well-defined global minima. Except for some quantitative details the overall structure of Gynoside A in pyridine-d5 shared many common features with that in DMSO-d6. The structure in pyridine-d5 had lower energies than that in DMSO-d6 solution.
Effects of Different Carriers on the Production of Isoflavone Powder from Soybean Cake
Authors: Kao Tsai-Hua , Chen Bing-Huei
Published: October 2008

The objectives of this study were to use soybean cake as the raw material for the production of isoflavone powder and compare the effects of different carriers as well as drying methods on the powder quality. Results showed that with spray drying, a level of 40 % maltodextrin as carrier produced the highest yield (mass) of isoflavone powder, followed by 10 % gelatin and 1 % sodium alginate. However, a reversed trend was observed for the isoflavone content. With 1 % sodium alginate, freeze drying generated the greatest yield of isoflavone powder, followed by vacuum drying and spray drying. The isoflavone content also exhibited the same tendency. With poly-g-glutamicacid (g-PGA) as carrier, all six levels studied (0.57, 0.28, 0.14, 0.028, 0.014 and 0.003 %) were capable of forming powder containing high amounts of total isoflavone, which was comparable to that using 1% sodiumalginate by freeze drying. Both high- and low-molecular-weight g-PGA showed similar effects in terms of powder yield and isoflavone content.