Modeling of the Interaction of Flavanoids with GABA (A) Receptor Using PRECLAV (Property-Evaluation by Class Variables)

Quantitative Structure-Activity Relationship (2D-QSAR) models for binding affinity constants (log Ki) of 78 flavanoid ligands towards the benzodiazepine site of GABA (A) receptor complex were estimated using the PRECLAV (Property-Evaluation by Class Variables) program. The best MLR equation with nine PRECLAV descriptors has R2 = 0.843 and R2C = 0.782. Attempt is also made for obtaining 2D-QSAR model using NCSS software. The comparison of the results indicated that the PRECLAV method is very efficient in detecting structure-activity correlation with good predictive power.

Flavanone and flavonoid hydroxylase genes regulate fiber color formation in naturally colored cotton

Using naturally colored cotton(NCC)can eliminate dyeing,printing and industrial processing,and reduce sewage discharge and energy consumption.Proanthocyanidins(PAs),the primary coloration components in brown fibers,are polyphenols formed by oligomers or polymers of flavan-3-ol units derived from anthocyanidins.Three essential structural genes for flavanone and flavonoid hydroxylation encoding flavanone-3-hydroxylase(F3H),flavonoid 3’-hydroxylase(F3’H)and flavonoid 3’5’-hydroxylase(F3’5’H)are initially committed in the flavonoid biosynthesis pathway to produce common precursors.The three genes were all expressed predominantly in developing fibers of NCCs,and their expression patterns varied temporally and spatially among NCC varieties.In GhF3Hi,GhF3’Hi and GhF3’5’Hi silenced lines of NCC varieties XC20 and ZX1,the expression level of the three genes decreased in developing cotton fiber,negatively correlated with anthocyanidin content and fiber color depth.Fiber color depth and type in RNAi lines changed with endogenous gene silencing efficiency and expression pattern,the three hydroxylase genes functioned in fiber color formation.GhF3H showed functional differentiation among NCC varieties and GhF3’H acted in the accumulation of anthocyanin in fiber.Compared with GhF3’H,GhF3’5’H was expressed more highly in brown fiber with a longer duration of expression and caused lighter color of fibers in GhF3’5’H silenced lines.These three genes regulating fiber color depth and type could be used to improve these traits by genetic manipulation.

Hypoglycemic and anti-hyperglycemic study of Gynura procumbens leaf extracts

Objective:To study the antidiabetic activity of Gynura procumbens(G.procumbens)used in the traditional management of diabetes in Southern Asia.Methods:G.procumbens leaves were extracted sequentially with graded percentage of ethanol in water(95%,75%,50%,25%and 0%),and the extracts were tested for antidiabetic activity using acute(7 h),subcutaneous glucose tolerance test and sub-chronic(14 d)test in non-diabetic and streptozotocin-induced diabetic rats.The extracts were further subjected to phytochemical studies.Results:In acute dose(1 g/kg),the extracts significantly lowered fasting blood glucose(FBG)in streptozotocin-induced diabetic rats(P<0.05).However,the FBG-lowering effect of the 25%extract compared to the other extracts,was rapid(47%after 2 h)and the highest:53%,53%and 60%in the 3rd,5th,and 7th h,respectively(P<0.05),comparable only to the effect of metformin.Furthermore,the extracts suppressed peak FBG in subcutaneous glucose tolerance test,but only the 0%and 25%extracts,and metformin sustained the decrease until the 90th min(P<0.05).Moreover,in the 14 days study,the 25%extract exerted the highest FBG-lowering effect,namely 49.38%and 65.43%on days 7 and 14,respectively(P<0.05),similar to the effect of metformin(46.26%and 65.42%).Total flavanoid and phenolic contents in the extracts were found to decrease with increase in polarity of extraction solvents.The composition of reference compounds(chlorogenic acid,rutin,astragalin and kaempferol-3-O-nrtinoside)followed a similar trend.Conclusions:G.procumbens contains antidiabetic principles,most extracted in 25%ethanol.Interaction among active components appears to determine the antidiabetic efficacy,achieved likely by a metformin-like mechanism.

Medicinal activities of the leaves of Musa sapientum var.sylvesteris in vitro

Objective:This study is to investigate the medicinal value of methanolic extiact of the leaves of Musa sapientum var.sylvesteris in Bangladesh.Methods:Several biochemical assays,thin layer chormatogarphy and ultra-violet spectroscopy were used to detect the presence of various types of compounds in this extract.Antioxidant effects were measured by DPPH scavenging assay,total reducing assay and hydrogen peroxide scavenging assay.Receptor binding activities and hydrogen peroxide induced hemolysis assay were performed by hemagglutination assay and hemolysis assay using erythrocytes.Disk diffusion assay was performed to show the antibacterial effect of the extract.Results:Alethanolic extract of the leaves showed antioxidant and antibacterial activity in ritro.The extract showed hemaglutination inhibition activities and hydrogen peroxide induced hemolysis inhibition activity of human red blood cells.Conclusion:Musa sapientum var.sylvesteris can be an useful medicinal plant.

First total synthesis of (±)-malaysianone A and (±)-tanariflavanones B

A concise approach for the frst total synthesis of two naturally occurring flavanoids,（）-malaysianone A（1）and（）-tanariflavanones B（2）,has been accomplished with total yields of 12.9%and 10.4%,respectively.The key steps were regioselective deprotection and regioselective synthesis of 5-formaldehyde-8-hydroxy-2-[40-methyl-30-penteneyl]-dihydro-1-benzopyran（8）.

Comparative evaluation of the medicinal activities of methanolic extract of seeds,fruit pulps and fresh juice of Syzygium cumini in vitro

Objective:To establish the health benefits of Syzgium cumin to discover functional components present in the seeds,fruit pulps and fresh juice of this fruit grown in Bangladesh.Methods:Thin layer chromatography and ultra-violet spectroscopy were used to detect the presence of various types of compound in seeds and juice.Antioxidant effects were measured by DPPH scavenging assay and total reducing assay.Receptor binding activities was performed by hemagglutination inhibition assay.Anti-inflammatory assay and hydrogen peroxide induced hemolysis assay was also investigated.Disc diffusion assay was performed to show the antibacterial effect using Gram positive,Gram negative strains of bacteria and fungi.Results:Methanolic extract of the seeds showed stronger antioxidant,hydrogen peroxide induced hemolysis activities,hemagglutination inhibition activities and membrane stabilization activities than those of fresh juice.However,fresh juice showed stronger antibacterial and antifungal activities than those of methanolic seed extract.The seed contains higher amount of polyphenols and flavanoids than those of fruit juice.Conclusions:Therefore,fruit juice,fruit pulp and seed of Syzygium cumini contain medicinal active components in different ratios.

Flavonoids from Litchi(Litchi chinensis Sonn.) Seeds and Their Inhibitory Activities on α-Glucosidase

With the bioactivity-guided method,a new flavanone glycoside,together with nine known flavonoids were isolated from 50% aqueous ethanol of litchi（Litchi chinensis Sonn.） seeds.The chemical structure of the new compound was elucidated via 1D and 2D nuclear magnetic resonance（NMR） techniques and mass spectrometry to be （2S）-pinocembrin-7-O-（6＂-O-α-L-arabinosyl-β-D-glucopyranoside）（1）,and the nine known compounds were determined to be quercetin（2）,phlorhizin（3）,pinocembrin-7-O-glucoside（4）,kaempferol-7-O-β-D-glucopyranoside（5）,onychin（6）,nairutin（7）,narcissin（8）,pinocembrin-7-O-[（6＂-O-β-D-glucopyranoside）-β-D-glucopyranoside]（9） and pinocembrin-7-O-[（2＂,6＂-di-O-α-L-rhamnopyranosyl）-β-D-glucopyranoside]（10）.Some of the isolated flavonoids were tested for their inhibitory effects on α-glucosidase.And compounds 2 and 3 showed stronger inhibitory activity than positive control.

Synthesis of New 7-O-Modified Chrysin Derivatives and Their Anti-proliferative and Apoptotic Effects on Human Gastric Carcinoma MGC-803 Cells

Two series of 7-O-modified chrysin derivatives were prepared from 7-O-carboxymethy! chrysin（2a）, 7-O-carboxypropylchrysin（2b） and short-chain alcohols by using 1-ethyl-3-（3-dimethylaminopropyl）carbodiimide hydrochloride（EDCI）, N-hydroxybenzotriazole（HOBt） and 4-dimethylamiopryidine（DMAP） as coupling reagents. Taking cisplatin as a reference substance, their anti-proliferative activities in vitro against human gastric carcinoma MGC-803 cells were evaluated by the standard 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl-2H-tetrazolium bromide （MTT） method. The results show that among the compounds tested, hepty 4-（5-hydroxy-4-oxo-2-phenyl-4H- chromen-7-yloxy） acetate（3f） displayed the most potent growth-inhibitory effect on MGC-803 cells with half maximal inhibitory concentration（ICso） value of 3.23 pmol/L. The preliminary mechanism of inhibitory effect of compound 3f was also detected by flow cytometry（FCM）, and the compound exerted anti- cancer activity via inducing the apoptosis of MGC-803 cells in a dose dependent manner, which suggested that compound 3f would be a potential anti-cancer agent.