Green tea polyphenol epigallocatechin-3-gallate inhibits the expression of nitric oxide synthase and generation of nitric oxide induced by ultraviolet B in HaCaT cells.
- Author:
Xiu-zu SONG
1
;
Zhi-gang BI
;
Ai-e XU
Author Information
- Publication Type:Journal Article
- MeSH: Catechin; analogs & derivatives; pharmacology; Cells, Cultured; Gene Expression Regulation, Enzymologic; drug effects; Humans; Keratinocytes; metabolism; radiation effects; Nitric Oxide; biosynthesis; Nitric Oxide Synthase Type II; genetics; Protein Transport; drug effects; RNA, Messenger; analysis; Tea; Transcription Factor RelA; metabolism; Ultraviolet Rays; adverse effects
- From: Chinese Medical Journal 2006;119(4):282-287
- CountryChina
- Language:English
-
Abstract:
BACKGROUNDNitic oxide (NO) has been implicated in the pathogenesis of various inflammatory diseases, including sunburn and pigmentation induced by ultraviolet irradiation. Epigallocatechin-3-gallate (EGCG) is the major effective component in green tea and can protect skin from ultraviolet-induced damage. The purpose of this study was to investigate the protective mechanisms of EGCG on inducible nitric oxide synthase (iNOS) expression and NO generation by ultraviolet B (UVB) irradiation in HaCaT cells.
METHODSHaCaT cells were irradiated with UVB 30 mJ/cm 2 and pretreated with EGCG at varying concentrations. The iNOS mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR) and NO production was quantified by spectrophotometric method. The expression of NF-kappaB P65 was measured by immunofluorescence cytochemistry staining.
RESULTSThe expression of iNOS mRNA and generation of NO in HaCaT cells were increased by UVB irradiation. EGCG down regulated the UVB-induced iNOS mRNA synthesis and NO generation in a dose dependent manner. The UVB-induced ctivation and translocation of NF-kappaB were also down regulated by EGCG treatment in HaCaT cells (P < 0.01).
CONCLUSIONSGreen tea derived-EGCG can inhibit and down regulate the UVB-induced activation and translocation of NF-kappaB, expression of iNOS mRNA and generation of NO respectively, indicating EGCG may play a protective role from UVB-induced skin damage.
