Nakamura Y, Tsumura Y, Tonogai Y, Shibata T
Division of Food Chemistry, National Institute of Health Sciences, Osaka Branch, 1-1-43, Hoenzaka, Chuo-ku, Osaka, 540-0006, Japan.
J Nutr. 1999 Jun;129(6):1214-22. doi: 10.1093/jn/129.6.1214.
Gymnemic acids are the saponins with a triterpenoid structure contained in Gymnema sylvestre leaves and have the hypoglycemic effects. In spite of the cholesterol-binding properties of saponins, the effect of gymnemic acids on cholesterol metabolism has not been elucidated to date. We investigated the effects of gymnemic acids on fecal steroid excretion in rats. Three kinds of extracts from Gymnema sylvestre leaves, extract (GSE), acid precipitate (GSA) and column fractionate (GSF), of which the gymnemagenin (an aglycone of gymnemic acids) concentrations are 58.87, 161.6, and 363.3 mg/g respectively, were used for the experiments. These were administered to rats orally at the dose of 0.05-1.0 g/kg for 22 d. Rats were given free access to water and nonpurified diet without cholesterol, and the differences in fecal excretion of steroids and gymnemic acids were investigated. Although there were no significant effects of GSE, GSA and GSF decreased body weight gain and food intakes in a dose-dependent manner (P < 0.01). GSF (1.0 g/kg) significantly increased fecal excretion of neutral steroids and bile acids in a dose-dependent manner (P < 0.05), especially those of cholesterol and cholic acid (CA)-derived bile acids. The increases in fecal steroid excretion of cholesterol, total neutral steroids, total bile acids and CA-related bile acids were acute and significantly correlated with fecal gymnemagenin levels (r2 = 0.2316-0.9861, P < 0. 05). These results demonstrated for the first time that a high dose of gymnemic acids increases fecal cholesterol and CA-derived bile acid excretion. Further studies are needed to clarify the effect of gymnemic acids on cholesterol metabolism.
匙羹藤酸是匙羹藤叶中含有的具有三萜结构的皂苷，具有降血糖作用。尽管皂苷具有结合胆固醇的特性，但匙羹藤酸对胆固醇代谢的影响至今尚未阐明。我们研究了匙羹藤酸对大鼠粪便类固醇排泄的影响。使用了匙羹藤叶的三种提取物，即提取物（GSE）、酸沉淀（GSA）和柱分级分离物（GSF），其中匙羹藤皂苷元（匙羹藤酸的苷元）浓度分别为58.87、161.6和363.3mg/g用于实验。将这些提取物以0.05 - 1.0g/kg的剂量口服给予大鼠，持续22天。大鼠可自由饮水并食用不含胆固醇的非纯化饮食，研究类固醇和匙羹藤酸粪便排泄的差异。尽管GSE、GSA和GSF对体重增加和食物摄入量没有显著影响，但呈剂量依赖性降低（P < 0.01）。GSF（1.0g/kg）以剂量依赖性方式显著增加中性类固醇和胆汁酸的粪便排泄（P < 0.05），尤其是胆固醇和胆酸（CA）衍生的胆汁酸。胆固醇、总中性类固醇、总胆汁酸和CA相关胆汁酸的粪便类固醇排泄增加是急性的，并且与粪便匙羹藤皂苷元水平显著相关（r2 = 0.2316 - 0.9861，P < 0.05）。这些结果首次证明高剂量的匙羹藤酸会增加粪便胆固醇和CA衍生的胆汁酸排泄。需要进一步研究以阐明匙羹藤酸对胆固醇代谢的影响。
