|
Objective: To study table gallate catechin gallate (EGCG) in vitro alpha-glucosidase inhibitory activity and in vivo hypoglycemic effect, explore the mechanism of action in lowering blood sugar. Method: maltose and PNPG as substrate, glucose oxidase and PNPG method, determination of enzyme activity inhibition rate in EGCG and half inhibitory concentration (IC 50 ) value. Maltose as substrate, the establishment of evaluation system from the small intestine; measured enzyme activity inhibition rate in the reaction system and the 50% inhibitory concentration (IC 50 ) value. As a positive control drug, acarbose and compare different substrate and enzyme source of EGCG inhibition of enzyme activity. According to the Lineweaver-Burk plot method to determine the type of inhibition. Vitro experiments with over 15 kinds of Chinese herbal medicine, the size of the alpha-glucosidase inhibitory activity. (2) use of high-fat and high-sugar diet for 10 weeks of feeding, damaged rat model induced glucose regulation. Acarbose as a positive control, the oral glucose tolerance test were observed fasting blood glucose, postprandial blood glucose, insulin levels, serum total cholesterol and triglyceride changes, and insulin resistance index. The doses used were 0.2,0.7 and 1.0 g / kg.d intragastric administration of 3 days, maltose load test. 20,50,200 mg / the three kg.d dose in rats intragastrically for 6 weeks, respectively gavage 2 and 4 weeks malt glucose tolerance test, observation of EGCG on fasting blood glucose and postprandial blood glucose affected. The end of the experiment, the rats were sacrificed whichever is the liver, kidney, heart, and fat were calculated for each organ index; same time, fasting blood glucose, serum total cholesterol, triglycerides, high-density and low-density lipoprotein cholesterol, glycogen , muscle glycogen and creatinine and other indicators. Results: (1) this study ultimately determine the enzyme concentration of 0.5mg/ml and maltose concentration 0.06 mol / L in vitro and in vitro intestinal enzyme optimum reaction system; determination of EGCG on two substrate IC 50 50 . And is a non-competitive inhibitor of yeast alpha-glucosidase and its Km = 0.1518mol / L, Ki = 0.4003mg/ml,; in vitro alpha-glucosidase inhibitory activity stronger than 15 kinds of Chinese herbal medicine. ② short-term improvement glucose regulation damaged rats postprandial blood glucose and glucose tolerance is not obvious, the first two weeks, the observed protective effect. The end of the experiment, the table epigallocatechin gallate gallate, the high-dose group (50,200 mg / kg · d), fasting blood glucose, serum total cholesterol, triglycerides, low-density lipoprotein cholesterol, liver glycogen creatinine and liver and kidney weight varying degree of reduction, the body of high-density lipoprotein cholesterol was increased. Conclusion: Table gallic epigallocatechin gallate with certain alpha-glucosidase inhibitory activity in vitro, can reduce blood sugar and improve glucose tolerance. And its mechanism may play the part related to the alpha-glucosidase inhibitory activity.
|