茶多糖降糖作用机制

目的研究茶多糖的降糖作用机制。方法用比色法测定茶多糖对。一葡萄糖苷酶（EC3．2．1．20）和α-淀粉酶（EC3．2．1．1）的抑制活性，用快速过滤法观察茶多糖对兔小肠刷状缘囊泡葡萄糖转运活性的影响。结果茶多糖显示较强的α-葡萄糖苷酶抑制活性，其α-葡萄糖苷酶的半抑制浓度（IC50）值为3．2g／L；茶多糖对。淀粉酶的抑制活性则较弱，浓度为为1g／L时，其对α-淀粉酶的抑制率为10％；茶多糖同时明显降低兔小肠刷状缘囊泡葡萄糖转运能力，其半抑制浓度（IC50）值为15g/L。结论茶多糖可抑制α-葡萄糖苷酶及α-淀粉酶活力和小肠刷状缘囊泡葡萄糖转运能力，从而可延缓小肠对糖的消化吸收。

Study on hypoglycemic mechanism of tea polysaccharide

Objective To study the hypoglycemic mechanism of tea polysaccharide.Methods The inhibitory activities of tea polysaccharide against alpha-glucosidase(EC 3.2.1.20)and alpha-amylase(EC 3.2.1.1)were tested by colorimetric method,glucose uptake into brush border membrane vehicles were determined by rapid filtration method.Results In alpha-glucosidase inhibitory assay,tea polysaccharide showed potent inhibitory activity with IC50value of 3.2g/L;while inhibitory effect of tea polysaccharide on alpha-amylase was low,the inhibitory activity were about 10% at the concentration of 1 g/L.Tea polysaccharide also significantly decreased glucose transport potency of brush border membrane vehicle of rabbit small intestine with IC50 value of 15g/L.Conclusion Tea polysaccharide can inhibit alpha-glucosidase and alpha-amylase activities and glucose uptake into brush border membrane vehicles,therefore can delay carbohydrate digestion and absorption.