EPIGALLOCATECHIN GALLATE ANTIOXIDANT EFFECT IN RETINAL PIGMENT EPITHELIAL CELLS

Abstract

Cathechins are members of the large family of polyphenols and major compounds of tea leaves. Epigallocatechin-3-gallate accounts for more than 50 % of tea catechins. Their beneficial effect for human health is well documented from epidemiological, interventional and in vitro studies as well. Most of the health benefits of catechins are related to their antioxidant properties. Retina is a tissue with high oxygen consumption and subject to the aggression of reactive oxygen species (ROS). Retinal pigment epithelium (RPE) is a monolayer of cells with crucial role in the functioning of retina. Damages of the RPE and photoreceptors are leading causes of age related macular degeneration (AMD). It has been suggested that oxidative stress play an important role in the aetiology of AMD. In this study we investigated the effect of EGCG on RPE cells viability and on cell antioxidant defence system. EGCG was delivered to the cells in different concentrations at sub confluence and incubated for 24 h. The oxidative stress was induced with 500 ?M hydrogen peroxide. The cells viability was determined by MTT assay, the inhibition of ROS generation by DCF-DA assay and the activity of glutathione peroxidise and superoxide dismutase by using commercial kits. EGCG (50-100 ?M) treatment of human RPE cells in vitro has not detrimental effects on cells viability and determined an increase of viability when oxidative stress was induced by addition of hydrogen peroxide, showing a protective effect for mithocondrial enzymes. GPx activity was decreased by EGCG but SOD activity increased, both for cells with EGCG alone and cells treated with EGCG and H2O2. EGCG has an inhibitory effect on reactive oxygen species generation in the RPE cells by inhibiting the fluorescence of DCF. A diet rich in EGCG could contribute to the antioxidant protection and could have beneficial effects in the prevention of retinal degenerative diseases.