title: Protective effects of (-)-epicatechin-3-gallate on UVA-induced damage in HaCaT keratinocytes.
abstract: (-)-Epigallocatechin-3-gallate (EGCG), a constituent of green tea, has been extensively studied and shown to be a powerful antioxidant protecting skin cells against photodamage. In this study, however, we demonstrated that another gallated catechin, (-)-epicatechin-3-gallate (ECG), was also able to protect human keratinocytes against damage induced by ultraviolet A (UVA) light. We found that ECG dose-dependently inhibited UVA-induced keratinocyte death as determined by cell viability assay. Moreover, ECG had similar potency to EGCG in inhibiting UVA-induced cell death. Therefore, the mechanism of action of ECG was further investigated. As assayed by flow cytometry, UVA-induced hydrogen peroxide (H2O2) production in keratinocytes was inhibited by ECG in a concentration-dependent manner, suggesting that ECG can act as a free radical scavenger while keratinocytes were photodamaged. The scavenging effect of ECG was confirmed by the fact that ECG treatment attenuated cell damage induced by H2O2 and hypoxanthine-xanthine oxidase. In a parallel experiment, UVA-induced activation of extracellular signal-regulated kinase in keratinocytes was blocked by ECG. We provided here the first evidence that ECG is a potent protectant that protects keratinocytes from photodamage. Because ECG is abundant in green tea, we believe that this compound is beneficial for skin care.
authors.affiliation: Department of Dermatology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei County, Taiwan.
authors.forename: Chieh-Chen
authors.initials: CC
authors.lastname: Huang
authors.forename: Jai-You
authors.initials: JY
authors.lastname: Fang
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Wu
authors.forename: Han-Sun
authors.initials: HS
authors.lastname: Chiang
authors.forename: Yuan-Ju
authors.initials: YJ
authors.lastname: Wei
authors.forename: Chi-Feng
authors.initials: CF
authors.lastname: Hung
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D015603:Keratinocytes / Q000187:drug effects* / Q000528:radiation effects*; D014466:Ultraviolet Rays; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002392:Catechin; C062669:epicatechin gallate; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D014969:Xanthine Oxidase