Epigallocatechin Gallate (EGCG) Prevents H2O2-Induced Oxidative Stress in Primary Rat Retinal Pigment Epithelial Cells.

Purpose: To determine whether the green tea polyphenol epigallocatechin gallate (EGCG) could prevent H2O2-induced oxidative stress in primary rat retinal pigment epithelial cells. Methods: Primary cultures of retinal pigment epithelium (RPE) cells were established from Long-Evans newborn rats. RPE cells were pretreated with various concentrations of EGCG for 24 h before being exposed to hydrogen peroxide (H2O2) for 2 h to induce oxidative stress. Cell metabolic activity was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell death was quantified by flow cytometry using propidium iodide (PI). Results: Treatment of RPE cells with EGCG alone does not affect the cell viability up to 50 µM. Exposure of RPE cells to 600 µM H2O2 caused a significant decrease in cell viability; whereas pretreatment with 10, 25, and 50 µM EGCG significantly reduced this decrease in a dose-dependent manner. The proportion of PI-positive cells increased significantly in cultures treated with H2O2 alone; whereas pretreatment of RPE cells with 50 µM EGCG significantly reduced H2O2-induced RPE cell death. Conclusions: Our study shows that EGCG pretreatment can protect primary rat RPE cells from H2O2-induced death. This suggests potential effect of EGCG in the prevention of retinal diseases associated with H2O2-induced oxidative stress. [ABSTRACT FROM AUTHOR]