Effect Of Tea Polyphenols And Its Main Components On Insulin Secretion

Tea has a role for prevention and treatment on diabetes, mainly due to the presence of tea polyphenols. The prevention mechanism of tea polyphenols on diabetes is not very clear, which becomes a research focus in recent years. Because tea polyphenols is a mixture, this paper investigated how tea polyphenols and its main components effect on glucose-stimulated insulin secretion, and explained its mechanism of prevention and treatment of diabetes preliminary.Firstly, we investigated the effect of tea polyphenols as a whole on glucose-stimulated insulin secretion and Ca2+ concentration in islets. Then tea polyphenols was separated by high performance liquid chromatography and identified the biological active ingredients which can be absorbed by islets. Lastly the effect of the biological activities on glucose-stimulated insulin secretion, and the interaction between the main bioactive components were investigated. And we found:(1) When the glucose concentration was 2.8mmol/L,8.3mmol/L,16.7mmol/L respectively, the polyphenols could increase the secretion of insulin andthe Ca2+ concentration in the islets, and they can be more significant when glucose concentrations is low (2.8mmol/L). (2) After co-incubation with islets, the absorption capacity of EGCG and ECG, was over 80%, which were significantly higher than the other components (ranging from 16% to 43%), so we cansure that EGCG and ECG are two main biological active ingredients of tea polyphenols. (3) When the glucose concentration was 2.8mmol/L,8.3mmol/L,16.7mmol/L respectively, EGCG and ECG could increase the secretion of insulin and the it can be more significant when glucose concentrations is low (2.8mmol/L). And the absorption capacities of EGCG and ECG, are not subject to influence each other, in other word, EGCG and ECG had different action sites on islets.