Simultaneous Tests of Theaflavin-3,3′-digallate as an Anti-Diabetic Drug in Human Hepatoma G2 Cells and Zebrafish (Danio rerio)

Theaflavin-3,3′-digallate (TF3) is the most important theaflavin monomer in black tea. TF3 was proved to reduce blood glucose level in mice and rats. However, the elaborate anti-diabetic mechanism was not well elucidated. In this work, human hepatoma G2 (HepG2) cells and zebrafish (Danio rerio) were used simultaneously to reveal anti-diabetic effect of TF3. The results showed that TF3 could effectively rise glucose absorption capacity in insulin-resistant HepG2 cells and regulate glucose level in diabetic zebrafish. The hypoglycemic effect was mediated through down-regulating phosphoenolpyruvate carboxykinase and up-regulating glucokinase. More importantly, TF3 could significantly improve β cells regeneration in diabetic zebrafish at low concentrations (5 μg/mL and 10 μg/mL), which meant TF3 had a strong anti-diabetic effect. Obviously, this work provided the potential benefit of TF3 on hypoglycemic effect, regulating glucose metabolism enzymes, and protecting β cells. TF3 might be a promising agent for combating diabetes.