Protective effects of (-)-epicatechin-3-gallate on UVA-induced damage in HaCaT keratinocytes.
(-)-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.
Huang
Chieh-Chen
CC
Department of Dermatology, Shin Kong Wu Ho-Su Memorial Hospital, Taipei County, Taiwan.
Fang
Jai-You
JY
Wu
Wen-Bin
WB
Chiang
Han-Sun
HS
Wei
Yuan-Ju
YJ
Hung
Chi-Feng
CF
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
D000975:Antioxidants; D002392:Catechin; C062669:epicatechin gallate; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D014969:Xanthine Oxidase