(+)-Catechin prevents ultraviolet B-induced human keratinocyte death via inhibition of JNK phosphorylation.
High levels of (+)-catechin are found in the skin and seed of many fruits such as apples and grapes. Dietary supplementation with (+)-catechin has been demonstrated to protect epidermal cells against damage induced by ultraviolet B (UVB) radiation. However, the underlying mechanisms are not well understood yet. To determine whether (+)-catechin protects keratinocytes from UVB-induced damage, the viability of UVB- and H2O2-treated cells was determined by cell viability assay. Intracellular H2O2 level was measured by flow cytometry. UVB- or H2O2-induced signaling pathways were detected by Western blotting. The results indicated that (+)-catechin inhibited UVB- and H2O2-induced keratinocyte death. In parallel, intracellular H2O2 generation in keratinocytes irradiated by UVB was inhibited by (+)-catechin in a concentration-dependent manner. (+)-Catechin also inhibited UVB- and H2O2-induced JNK activation in keratinocytes. However, it had little inhibitory effect on UVB- and H2O2-induced ERK and p38 activation even at a higher concentration, suggesting indirectly that JNK activation is required for the induction of apoptosis in keratinocytes exposed to UVB. Finally, we compared the cytotoxicity of (+)-catechin and (-)-epigallocatechin-3-gallate (EGCG) on keratinocytes. Cell viability assay showed that (+)-catechin was relatively nontoxic at higher doses. Taken together, our results demonstrate that (+)-catechin inhibits UVB- and oxidative stress-induced H2O2 production and JNK activation and enhances human keratinocyte survival. However, although it seems that (+)-catechin and EGCG are equally effective in preventing keratinocyte death, (+)-catechin is relatively nontoxic and thus is suitable for developing as an anti-ageing agent for skin care.
Wu
Wen-Bin
WB
School of Medicine, Fu-Jen Catholic University, No. 510, Jhongjheng Rd., Sinjhuang City, Taipei County 24205, Taiwan ROC.
Chiang
Han-Sun
HS
Fang
Jia-You
JY
Chen
Shao-Kuan
SK
Huang
Chieh-Chen
CC
Hung
Chi-Feng
CF
D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology* / Q000633:toxicity; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D014466:Ultraviolet Rays
D002392:Catechin; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D048670:MAP Kinase Kinase 4