Green Tea epigallocatechin-3-gallate Protects Against Oxidative Stress-Induced Nuclear Translocation of p53 and Apoptosis in Retinal Pigment Epithelial Cells, ARPE-19

Epigallocatechin-3-gallate (EGCG), the most abundant polyphenolic flavonoids in green tea has been shown to possess strong antioxidant activities. Oxidative stress causes the defect of retinal pigment epithelial (RPE) cells that contribute to several retinal diseases. Several studies have shown that increasing the body’s defenses against oxidative stress with specific antioxidants and mineral supplements could preserve the vision. Therefore, the purpose of this study was to determine the protective role of EGCG against exogenous reactive oxygen species hydrogen peroxide (H2O2)-induced cell death in ARPE-19 cells, human retinal pigment epithelial cell line. ARPE-19 cells were pretreated with EGCG in the presence/absence of H2O2. The protective effects of EGCG and the underlined mechanisms against H2O2 were evaluated. The present study demonstrated that 400 µM H2O2 significantly decreased cell viability, increased the accumulation of intracellular reactive oxygen species (ROS) and increased the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells and chromatin condensed nuclei. In addition, H2O2 induced p53 nuclear translocation, up-regulated Bax and down-regulated Bcl-2 expression thereby increased Bax/Bcl-2 ratio. These toxic effects of H2O2 were reversed by 100 µM EGCG pretreatment. These studies suggest that EGCG protects H2O2-induced cell death in ARPE-19 cells by its antioxidant property and attenuation of p53 nuclear translocation.