Protective Effects of Polyphenol of Lotus Seed Epicarp on Oxidative Stress Damage Induced by T-BHP

Objective: The protective effect of polyphenol of lotus seed epicarp on HepG2 oxidative stress damage induced by tert-butylhydro-peroxide (T-BHP) was investigated. Method: The concentration of T-BHP with a survival rate close to 50% was selected as the concentration for establishing the oxidative damage model. To evaluate the anti-oxidative stress activity levels of polyphenol of lotus seed epicarp at different concentrations (2.5, 5, and 7.5 μg/mL), cell viability, reactive oxygen species (ROS), malondialdehyde (MDA), lactic dehydrogenase (LDH), glutathione (GSH) and antioxidant enzyme-related gene expression were used as evaluation indicators, and tea polyphenol was used as the positive control. Result: When 120 μmol/L concentration of T-BHP was established for 4 h, the cell survival rate reached 49.18%±7.55%, which met the requirements of model construction. Therefore, 120 μmol/L was selected as the modeling concentration of the oxidative damage model for subsequent experiments. The polyphenol from lotus seed epicarp significantly inhibited the decrease of cell survival rate induced by T-BHP (P<0.01). At 7.5 μg/mL, the ROS level decreased by 45.99%, the MDA decreased by 58.77%, the LDH decreased by 71.61%, and the GSH increased by 206.60% (P<0.05). The expression of antioxidant enzyme-related genes including CuZnSOD, GCLC, GPx, and GSH also gradually returned to the normal level, all in a dose-dependent manner. Conclusion: The polyphenol of lotus seed epicarp protected against the oxidative damage induced by T-BHP in HepG2 cells. The mechanism might be related to the increase of intracellular antioxidant enzyme activity and the clearance of excessive ROS.