Standardisation of Gymnema sylvestre R.Br. by high-performance thin-layer chromatography: an improved method

An improved high-performance thin-layer chromatographic (HPTLC) method for the standardisation of Gymnema sylvestre is reported. The method involves the initial hydrolysis of gymnemic acids, the active ingredients, to a common aglycone followed by the quantitative estimation of gymnemagenin. The present method rectifies an error found in an HPTLC method reported recently.     

Three-dimensional structure of gurmarin,a sweet taste-suppressing polypeptide

Summary The solution structure of gurmarin was studied by two-dimensional proton NMR spectroscopy at 600 MHz. Gurmarin, a 35-amino acid residue polypeptide recently discovered in an Indian-originated tree Gymnema sylvestre, selectively suppresses the neural responses of rat to sweet taste stimuli. Sequence-specific protons. The three-dimensional solution structure was determined by simulated-annealing calculations on the basis of 135 interproton distance constraints derived from NOEs, six distance constraints for three hydrogen bonds and 16 dihedral angle constraints derived from coupling constants. A total of 10 structures folded into a well-defined structure with a triple-stranded antiparallel -sheet. The average rmsd values between any two structures were 1.65±0.39 Å for the backbone atoms (N, C, C) and 2.95±0.27 Å for all heavy atoms. The positions of the three disulfide bridges, which could not be deterermined chemically, were estimated to be Cys³–Cys¹⁸, Cys¹⁰–Cys²³ and Cys¹⁷–Cys³³ on the basis of the NMR distance constraints. This disulfide bridge pattern in gurmarin turned out to be analogous to that in -conotoxin and Momordica charantia trypsin inhibitor-II, and the topology of folding was the same as that in -conotoxin.Abbreviations DQF-COSY double-quantum-filtered correlated spectroscopy - HOHAHA homonuclear Hartmann-Hahn spectroscopy - NOESY nuclear Overhauser enhancement spectroscopy - ppm parts per million; rmsd, root-mean-square deviation - TSP 3-(trimethylsilyl)-2,2,3,3-tetradeutero-propionate     

云南匙羹藤的化学成分

从云南匙羹藤(Gymnema yunnanense Tsiang)的粗甙酸水解产物中分离得到6个C_(21)甾体甙元。其中一个新甙元,命名为吉马甙元(gymnemarsgenin),经光谱数据和化学反应证明其结构为12-β-氧-苯甲酰-20-氧-肉桂珊瑚甙元。     

In vitro micropropagation of Gymnema sylvestre – A multipurpose medicinal plant

The nature of the explant, seedling age, medium type, plant growth regulators, complex extracts (casein hydrolysate, coconut milk, malt extract and yeast extract) and antioxidants (activated charcoal, ascorbic acid, citric acid and polyvinylpyrrolidone) markedly influenced in vitro propagation of Gymnema sylvestre. A maximum number of shoots (57.2) were induced from 30 day old seedling axillary node explants on Murashige and Skoog (MS) medium containing 6-benzyladenine (1 mg l⁻¹), kinetin (0.5 mg l⁻¹), 1-napthalene acetic acid (0.1 mg l⁻¹), malt extract (100 mg l⁻¹) and citric acid (100 mg l⁻¹). High frequency of rooting was obtained in axillary node explant derived shoots (50%) on half strength MS medium supplemented with IBA (3 mg l⁻¹). The plantlets, thus developed, were hardened and successfully established in natural soil. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of <Emphasis Type="Italic">Gymnema montanum</Emphasis> leaves on red blood cell resistance to oxidative stress in experimental diabetes

The aim of the present study was to evaluate the protective effect of Gymnema montanum on red blood cell (RBC) membrane in diabetic rats during lipid peroxidation. Ethanol extract of G. montanum leaves (GLEt) was administered orally to alloxan-induced diabetic rats for 3 weeks, and the effects on blood glucose, insulin, lipid peroxidation markers, thiobarbituric acid reactive substances, hydroperoxides in plasma and antioxidant enzymes including superoxide dismutase, catalase and glutathione peroxidase activities in erythrocytes were studied. Administration of GLEt to diabetic animals at doses of 50, 100, and 200 mg/kg body weight lowered elevated blood glucose levels by 24, 35, and 66%, respectively, relative to untreated diabetic rats. In comparison, treatment with the known antidiabetic drug, glibenclamide (600 μg/kg body weight) decreased blood glucose concentrations by 51%. Plasma insulin concentrations were increased in the diabetic rat by 73% with GLEt (200 mg/kg body weight) and 45% with glibenclamide (600 μg/kg body weight). Although a significant decrease in the lipid peroxidation markers was observed in plasma on treatment with GLEt and glibenclamide, the RBC antioxidant levels were increased significantly in diabetic rats. Furthermore, erythrocytes from the GLEt-treated animals were found to be more resistant to H₂O₂-induced peroxidation than that of untreated diabetic animals. The chemical characterization of the polyphenolics of the extract showed the presence of gallic acid (5.29% w/w), resveratrol (2.2% w/w), and quercetin (16.6% w/w). The results of this study suggest that G. montanum may be useful for the control, management, and prevention of oxidative stress associated with diabetes.     

Two new triterpenoid saponins from Gymnema sylvestre

Two new oleanane-type triterpenoid saponins, gymnemoside-W1 and W2, together with seven known compounds were isolated from the leaves of Gymnema sylvestre R. Br. By means of spectral and chemical analysis, the structures of the new compounds were elucidated as 16 β-hydroxyl olean-12-en-3-O-[β-D-glucopyranosyl (1→6)-β.D-glucopyranosyl]-28-O-β-D-glucopyranoside(1) and 16 β,21 β,28-trihydroxyl-olean-12-ene-3-O-glucoronopyranoside (2). The EtOHIH2O extracts of this plant were shown to be able to inhibit glucose absorption in rats.     

匙羹藤叶中匙羹藤酸的含量测定

匙羹藤叶中匙羹藤酸的含量测定＠秦民坚＠叶文才＠张健＠田中俊弘￥中国药科大学￥岐阜药科大学匙羹藤;匙羹藤酸;含量测定匙羹藤叶中匙羹藤酸的含量测定秦民坚叶文才张健田中俊弘（中国药科大学,南京２１００３８）（岐阜药科大学,岐阜５０２日本）Ｄｅｔｅｒｍｉｎａｔｉｏ...     

Extraction and quantification of gymnemic acids through gymnemagenin from callus cultures of Gymnema sylvestre

The phyto-constituents of Gymnema sylvestre are used in the treatment of diabetes and obesity. The present work reports on the extraction of gymnemic acid through gymnemagenin from callus cultures of G. sylvestre. Components were separated on pre-coated silica gel 60 GF254 plates with chloroform:methanol (8:2) and scanned using a densitometric scanner at 205 nm in the near-UV region. Linearity of determination of gymnemagenin was observed in the range 2-10 microg. The average percentage recovery of gymnemagenin from leaf callus extracts was 98.9+/-0.3.     

匙羹藤组织培养条件优化研究

以匙羹藤无菌种子苗为外植体,通过预备实验确定基本培养基后,采用完全实验和正交设计相结合的方法,研究植物生长调节剂两因素配合和多因素组合(NAA、TDZ、2-ip、IAA、6-BA和KT)对匙羹藤芽体诱导及继代培养的影响。结果显示,匙羹藤组织培养最适的基本培养基为N68;N68+NAA0.05mg/L+2-ip0.4mg/L+TDZ0.001mg/L利于芽体增殖,可用于继代培养;N68+NAA0.05mg/L+TDZ0.005mg/L促进植株长根,可用于生根培养。