title: Scavenging of peroxynitrite by a phenolic/peroxidase system prevents oxidative damage to DNA.
abstract: We examined the ability of horseradish peroxidase (HRP), an analog of human myeloperoxidase, to protect DNA against oxidative damage caused by peroxynitrite in the presence of chlorogenic acid (CGA), a naturally occurring polyphenol. Chlorogenic acid inhibits the formation of single strand breaks in supercoiled pBR322 DNA by acting as a scavenger of peroxynitrite. Horseradish peroxidase markedly enhances the extent of DNA protection by catalyzing the decomposition of peroxynitrite in the presence of CGA. Horseradish peroxidase alone does not inhibit peroxynitrite-induced DNA strand breaks, indicating that CGA is required as an electron donor to regenerate the active enzyme. The apparent second order rate constant for the HRP-mediated oxidation of CGA in the presence of peroxynitrite at pH 6.9 is 3.4 x 10(7) M(-1) s(-1). This high rate suggests that CGA and other dietary polyphenols might efficiently scavenge peroxynitrite in peroxidase-containing systems in vivo.
authors.affiliation: Biodynamics Institute, Louisiana State University, Baton Rouge 70803-1800, USA. scgrace@unix1.sncc.lsu.edu
authors.forename: S C
authors.initials: SC
authors.lastname: Grace
authors.forename: M G
authors.initials: MG
authors.lastname: Salgo
authors.forename: W A
authors.initials: WA
authors.lastname: Pryor
mesh_terms: D002726:Chlorogenic Acid / Q000737:chemistry / Q000494:pharmacology*; D004247:DNA / Q000737:chemistry; D004249:DNA Damage; D016166:Free Radical Scavengers; D006735:Horseradish Peroxidase / Q000378:metabolism; D007700:Kinetics; D009566:Nitrates / Q000737:chemistry*; D010084:Oxidation-Reduction; D010957:Plasmids
chemical_list: D016166:Free Radical Scavengers; D009566:Nitrates; C039642:peroxynitric acid; D002726:Chlorogenic Acid; D004247:DNA; D006735:Horseradish Peroxidase