Chemical Composition and Effects on Carbohydrate Metabolism of Chloroform Fraction of Coix lachryma-jobi (L) Stem ExtractT.H. Phung, H.A. Nguyen, Q.C. Nguyen, T.D. Nguyen, and T.H. Nguyen
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Coix lachryma-jobi (L) seeds have been studied and used widely in many Asian countries as a mothermilk secretagogue or for nutrition, the stems are often considered as waste products, few studies on pharmaceutical benefits of Coix lachryma-jobi (L) stems were reported. A survey on usage of herbal medicines for the treatment of diabetes mellitus showed that Coix lachryma-jobi (L) stems are principal in some diabetes recipes of several Vietnamese ethnic communities. In our preliminary studies, Coix lachryma-jobi (L) stem ethanol extract and its chloroform fraction had hypoglycemic effect on streptozocine (STZ)-induced hyperglycemic mice. In this study, the chloroform fraction had no impact on blood glucose level and gluconeogenic enzyme activities of normoglycemic mice. On STZ-induced hyperglycemic mice, the fraction significantly reduced blood glucose level (p<0.01) as well as gluconeogenic enzyme activities such as G6Pase and F1,6BPase (p<0.05). Two compounds were isolated from the chloroform fraction and identified as β-sitosterol and stigmasterol both of which had been reported as hypoglycemic substances by various authors. This is the first time these compounds are reported as the constituents of Coix lachrymal-jobi (L) stem. Such results proved the hypoglycemic effect and helped to reveal partly the mechanism of Coix lachrymal-jobi (L) stem in treatment of diabetes mellitus.
Keyword:
Coix lachryma-jobi, Blood glucose level, Gluconeogenesis, Stem, Phytosterols
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