The effects of purity of tea polysaccharides (TPS) on its five antioxidant activities and hypoglycemic activities in vitro were studied. The results showed that the higher the purity of TPS, the lower the antioxidant capacity. The purity of FTPSI is the highest (sugar content 80.72%), but its antioxidant activities were lower than those of Fujian tea polysaccharides (FTPS) and FTPSII. The antioxidant activity of tea polysaccharide is related to its protein and polyphenol content (Pearson r > .90). The protective effect of Zhejiang tea polysaccharides and FTPS on human umbilical vein endothelial cells (HUVEC) was better than that of its purified fractions. The inhibition rates of FTPSII (5 and 2 mg/ml) on α-glucosidase (32.76%) and α-amylase (-11.93%) were higher than those of FTPS and FTPSII. Purification does not change the basic structure of TPS. This study has certain reference value for the study of the antioxidant activities of TPS. Meanwhile, TPS can be used as a potential resource with hypoglycemic function. PRACTICAL APPLICATIONS: A large number of studies have shown that TPS have antioxidant activity. However, several studies considered that the antioxidant activity of TPS mainly comes from the residues of tea polyphenols. Therefore, the in vitro and cell antioxidant activities of TPS were studied in this paper. We believe that both glycoprotein and tea polyphenol are antioxidants of tea, and tea polysaccharide perform preferable effect on hypoglycemic. HUVEC cell model and four in vitro antioxidant test methods were used to study the antioxidant activities of TPS, and two enzyme inhibition activities were used to study the hypoglycemic effect of TPS, in order to provide a theoretical basis for the study of biological activity of TPS.
Keywords: antioxidant activities; hypoglycemic activities; purity; tea polysaccharides.
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