Effects of metal ions in tea polysaccharides on their in vitro antioxidant activity and hypoglycemic activity

Total tea polysaccharides (TTPS) were extracted from two kinds of pruning leaves of tea plant and fractionated into neutral tea polysaccharides (TPSI) and acidic tea polysaccharides (TPSII) by anion exchange resin D315. Some physicochemical properties, including structure, monosaccharide composition, and molecular weight distribution, as well as the 4 in vitro antioxidant activities and inhibitory effects on α-glucosidase of above polysaccharides before and after removing metal ions were investigated. By comparing TTPS and TPSII, we found that they exhibited different antioxidant activities and inhibitory actions against α-glucosidase after their metal ions were removed. However, the in vitro antioxidant activities and inhibitory effects on α-glucosidase of TPSI were substantially improved. The study can be a certain reference for tea and soil selection. At the same time, we suggested that pruning leaves of tea plant could be treated as a potential resource for the development of polysaccharide antioxidants and hypoglycemic products.