(-)-Epigallocatechin gallate, a polyphenolic tea antioxidant, inhibits peroxynitrite-mediated formation of 8-oxodeoxyguanosine and 3-nitrotyrosine.
Reaction with peroxynitrite at pH 7.4 and 37 degrees C was found to increase the 8-oxodeoxyguanosine levels in calf thymus DNA 35- 38-fold. This oxidation of deoxyguanosine, as well as the peroxynitrite-mediated nitration of tyrosine to 3-nitrotyrosine, was significantly inhibited by ascorbic acid, glutathione and (-)-epigallocatechin gallate, a polyphenolic antioxidant present in tea. For 50% inhibition of the oxidation of deoxyguanosine to 8-oxodeoxyguanosine, 1.1, 7.6 or 0.25 mM ascorbate, glutathione or (-)-epigallocatechin gallate, respectively, was required. For 50% inhibition of tyrosine nitration, the respective concentrations were 1.4, 4.6 or 0.11 mM. Thus, (-)-epigallocatechin gallate is a significantly better inhibitor of both reactions than either ascorbate or glutathione. Reaction of (-)-epigallocatechin gallate with peroxynitrite alone resulted in the formation of a number of products. Ultraviolet spectra of two of these suggest that the tea polyphenol and/or its oxidation products are nitrated by peroxynitrite.
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American Health Foundation, Valhalla, New York 10595, USA.
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D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002417:Cattle; D004247:DNA / Q000737:chemistry; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry*; D010084:Oxidation-Reduction; D013662:Tea; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry
D000975:Antioxidants; D016166:Free Radical Scavengers; D009566:Nitrates; D013662:Tea; C039642:peroxynitric acid; C002744:3-nitrotyrosine; D014443:Tyrosine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D002392:Catechin; D004247:DNA; C045651:epigallocatechin gallate; D003849:Deoxyguanosine