Purification And Structure Of Anti-hyperglycemic Component From Tea Polysaccharides

Tea polysaccharides (TPS) have been documented good hypoglycemic action at home and abroad, nevertheless, few reports were involved in its structure and anti-hyperglycemia manner. Since water-soluble TPS displayed significant anti-hyperglycemic activity, TPS were extracted with water from coarse green tea leaves. Then its anti-hyperglycemic action was investigated from following aspects: scavenging of free radicals, effect on enzymes involved in carbohydrate metabolism and 3T3-L1 adipocytes. The anti-hyperglycemic components were fractionated using ion-exchange and gel columns and their structures were characterized with varieties of chemical and physical methods.First, Anthrone-Sulfuric acid Method, which was usually used to detect polysaccharide, was improved and found that using galactose as standard sugar and colorimetric analysis at 675 nm was better than that using glucose and at 620 nm. For increasing the extraction rate of TPS, the extraction parameters were optimized. Results showed that the optimum conditions for extraction of TPS were heating at 70℃for 90 min with a 1:10 ratio of tea to water, repeating three times. Under this condition, the extraction rate was 3.20 %, higher than the most extraction rate of 2.97 % in previous reports. The extracted TPS was purified with Sevag method, polyamide column chromatography and Sephadex G 50 column chromatography and obtained TPS1-1 with a 89 % purity.Then from following aspects to detect the anti-hyperglycemic effect of TPS: scavenging of free radicals, effect on enzymes involved in carbohydrate metabolism and 3T3-L1 adipocytes. Results exhibited that TPS can not stimulate the transportation of glucose into 3T3-L1 cells and scavenge free radicals in vitro, however, can increase significantly the activities of glucokinase and hexokinase in vitro, though have no obvious effect on alvine glycosidase. 1 mg/mL of TPS elevated glucokinase and hexokinase 82.97 % and 99.57 %, respectively. 10 mg/mL elevated 152.09 % and 156.10 %, respectively.For purification of the anti-hyperglycemic components, DEAE-Sepharose CL 6B was used to separate the components, which can stimulate the activities of hexokinase and glucokinase. Five components were collected and two, FA and FC, showed obvious activity. FA and FC were further isolated by Sephadex G75, and FA-1, FA-2, FC-1 and FC-2 were collected. Among the four components, FA-1 and FC-1 were detected significant stimulating activity in glucokinase and hexokinase. 1 mg/mL of FA-1 increased the activities of hexokinase and glucokinase 106.42 % and 72.92 %, respectively. 1 mg/mL of FC-1 increased the activities of...