蒺藜皂苷对大鼠小肠α-葡萄糖苷酶的抑制作用

目的:研究蒺藜皂苷(STT)对大鼠小肠α-葡萄糖苷酶的抑制作用及对餐后血糖水平的影响。方法:提取大鼠小肠α-葡萄糖苷酶,测定STT对其活性的抑制作用;一次性灌胃蔗糖(2 g.kg^-1)或葡萄糖(2 g.kg^-1),同时灌胃STT(100 mg.kg^-1),测定60 min后血糖水平的变化;每天一次性灌胃STT(100 mg.kg^-1),连续14 d,测定小肠α-葡萄糖苷酶活性以及灌胃蔗糖(2 g.kg^-1)60 min后血糖水平的变化。结果:0.1,1,10 mg.mL^-1的STT能够显著抑制α-葡萄糖苷酶的体外活性(P<0.001),抑制率分别为(20.83±1.66)%,(43.73±2.39)%和(52.62±2.69)%;STT显著抑制大鼠一次性灌胃蔗糖60 min后血糖水平的升高(P<0.01),变化幅度为对照的(52.61±6.24)%,但对灌胃葡萄糖没有作用;连续灌胃STT 14 d后,α-葡萄糖苷酶活性显著低于对照(P<0.05),为对照的(58.17±3.24)%,灌胃蔗糖60 min后血糖变化幅度为对照的(69.50±4.28)%(P<0.05)。结论:STT抑制大鼠餐后血糖水平的升高,是由其对小肠α-葡萄糖苷酶的抑制作用实现的。

Inhibitory effects of saponins from Tribulus terrestris on α-glucosidase in small intestines of rats

OBJECTIVE: To determine the effects of saponins from Tribulus terrestris (STT) on small intestinal a-glucosidase and postprandial blood glucose levels in rats. METHOD: The inhibitory effects of STT on a-glucosidase extracted from small intestines in rats were carried out in vitro. The blood glucose levels were measured after 60 min when sucrose (2 g x kg(-1)) or glucose (2 g x kg(-1)) was administered orally with STT (100 mg x kg(-1)). After treated with STT (100 mg x kg(-1)) for 14 d, the activities of a-glucosidase were determined daily, as well as the postprandial blood glucose levels after oraly administered sucrose (2 g x kg(-1)). RESULT: STT at concentrations of 0.1, 1 and 10 mg x mL(-1) reduced significantly the activities of alpha-glucosidase with inhibitory rates of (20.83 +/- 1.66)%, (43.73 +/- 2.39)% and (52.62 +/- 2.69)%, respectively. In facts STT (100 mg x kg(-1)) considerably decreased the blood glucose levels which was 52.61% of that of the control in rats co-administered orally with sucrose (2 g x kg(-1)). However, it showed no such effect on the rats co-administered orally with glucose (2 g x kg(-1)). After orally administered of STT for 14 d, the activity of alpha-glucosidase was significantly reduced (P < 0.05) to (58.17 +/- 3.24)% of that those in control. Meanwhile, The rats were oral administered with sucrose, the increase of postprandial blood glucose levels were (69.50 +/- 4.28)% of that in control 60 min later ( P < 0.05). CONCLUSION: It was through inhibiting the activity of a-glucosidase in small intestines that STT significantly retarded the increase in postprandial blood glucose levels in rats.