STUDIES ON COMPOSITION,ANTIOXIDATION AND HYPOGLYCEMIC EFFECTS OF POLYSACCHARIDES FROM GREEN TEA, OOLONG TEA AND BLACK TEA NI / 营养学报

ABSTRACT

Objective: To compare tea polysaccharides(TPS) characteristics and their role in scavenging free radicals and reducing blood glucose(BG) in diabetic mice(DM). Methods: TPS was extracted from green,Oolong and black tea which were made from the same fresh leaves from Hubei,Fujian and Yunnan. Then the recovery rate of TPS, contents of neutral sugar, uronic acid and protein were analysed, and scavenging rate of -2Oand 稯H in vitro and hypoglycemic effect were also determined. Results: 1. The yield and contents of neutral sugar, uronic acid and protein of green tea TPS were the highest, and those of black tea TPS were the lowest. Oolong tea TPS acted the best in scavenging-2O and 稯H . 2. The hypoglycemic effect of TPS from Hubei tea was the best . The effect of TPS extracted from semi-fermented Oolong tea and fermented black tea was better than that of non-fermented green tea. 3. There were obvious differences in yield, free radical scavenging rate and effect of reducing BG among TPS extracted from tea in different regions. TPS extracted from Fujian tea had the best effect in reducing BG,but that from Yunnan tea had not. Conclusion: There was remarkable effect of region and process on physico-chemical characteristics,effect of scavenging radical and reducing blood sugar TSP.