Epigallocatechin-3-gallate Protects Melanocytes From Oxidative Stress Via Induction Of Antioxidant Enzymes

Epigallocatechin-3-gallate(EGCG), the major component of green tea polyphenol, has antioxidant and anti-inflammatory effects. EGCG has been proven to effectively protected melanocytes from destruction in the mouse model of vitiligo. In this study, we investigated whether EGCG would increase phase II antioxidant enzymes including glutathione S transferase(GST), thioredoxin reductase-1(TxnRd1), superoxide dismutase(SOD), and catalase(CAT) in melanocytes. Furthermore, we estimated the intracellular signaling pathway for the induction of antioxidant enzymes mRNA expression. The results demonstrated that EGCG induced the expression of CAT, SOD2 and TxnRd1 in melanocytes after 24 h of treatment. The key regulator of antioxidant enzyme expression, Nrf2, was shown to accumulate in the nucleus after EGCG treatment. Furthermore, EGCG caused phosphorylation of p38 in a time-dependent manner. As a consequence, EGCG treatment protected melanocytes from 4-HNE-induced oxidative stress and apoptosis. Our data suggested that EGCG promotes the expression of antioxidant enzymes via inducting the phosphorylation of p38 and the expression of Nrf2 in melanocytes.