title: Antioxidant properties of (-)-epicatechin-3-gallate and its inhibition of Cr(VI)-induced DNA damage and Cr(IV)- or TPA-stimulated NF-kappaB activation.
abstract: Electron spin resonance (ESR) spin trapping was utilized to investigate the scavenging effects on hydroxyl radicals (*OH) and superoxide radicals (O2*-) by (-)-epigallocatechin-3-gallate (EGCG), one of the major anticancer compounds in tea. The spin trap used was 5,5-dimethyl-pyrroline N-oxide (DMPO). The Fenton reaction (Fe2+ + H2O2-->Fe3+ + *OH + OH-) was used as a source of *OH radicals. EGCG efficiently scavenges *OH radicals with reaction rate of 4.62 x 10(11) M(-1)sec(-1), which is an order of magnitude higher than several well recognized antioxidants, such as ascorbate, glutathione and cysteine. It also scavenges O2*- radicals as demonstrated by using xanthine and xanthine oxidase system as a source of O2*- radicals. Through its antioxidant properties, EGCG exhibited a protective effect against DNA damage induced by Cr(VI). EGCG also inhibited activation of nuclear transcription factor NF-kappaB induced by Cr(IV) and 12-o-tetradecanoylphorbol-13-acetate (TPA). The present studies provide a mechanistic basis for the reported anticarcinogenic properties of EGCG and related tea products.
authors.affiliation: Pathology and Physiology Research Branch, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA.
authors.forename: X
authors.initials: X
authors.lastname: Shi
authors.forename: J
authors.initials: J
authors.lastname: Ye
authors.forename: S S
authors.initials: SS
authors.lastname: Leonard
authors.forename: M
authors.initials: M
authors.lastname: Ding
authors.forename: V
authors.initials: V
authors.lastname: Vallyathan
authors.forename: V
authors.initials: V
authors.lastname: Castranova
authors.forename: Y
authors.initials: Y
authors.lastname: Rojanasakul
authors.forename: Z
authors.initials: Z
authors.lastname: Dong
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002478:Cells, Cultured; D002840:Chromates / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D002857:Chromium / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects*; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D016166:Free Radical Scavengers; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism; D019169:Jurkat Cells / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000037:antagonists & inhibitors* / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D002840:Chromates; D016166:Free Radical Scavengers; D016328:NF-kappa B; D002857:Chromium; D013481:Superoxides; C074702:chromium hexavalent ion; D017665:Hydroxyl Radical; D002392:Catechin; C062669:epicatechin gallate; D013755:Tetradecanoylphorbol Acetate