title: Inhibition by uric acid of free radicals that damage biological molecules.
abstract: To clarify the antioxidative role of uric acid, its ability to scavenge carbon-centered and peroxyl radicals and its inhibitory effect on lipid peroxidation induced by various model systems were examined. Uric acid efficiently scavenged carbon-centered and peroxyl radicals derived from the hydrophilic free radical generator 2,2'-azobis-(2-amidinopropane)-dihydrochloride (AAPH). All damage to biological molecules, including protein, DNA and lipids induced by AAPH, was strongly prevented by uric acid. In contrast, alpha-tocopherol had little effect on damage to biological molecules. Lipid peroxidation by the lipophilic free radical generator 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) was little inhibited by uric acid, but not by alpha-tocopherol. Copper-induced lipid peroxidation was inhibited by uric acid and alpha-tocopherol. NADPH- and ADP-Fe(3+)-dependent microsomal lipid peroxidation was efficiently inhibited by alpha-tocopherol, but not by uric acid. Uric acid seems to scavenge free radicals in hydrophilic conditions to inhibit lipid peroxidation on the lipid-aqueous boundary, and the antioxidation is only little in lipophilic conditions.
authors.affiliation: Department of Biology, Hokkaido College of Pharmacy, Katsuraoka-cho 7-1, Otaru 0470264, Japan.
authors.forename: Sanae
authors.initials: S
authors.lastname: Muraoka
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Miura
mesh_terms: D000578:Amidines / Q000494:pharmacology*; D000818:Animals; D004347:Drug Interactions; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000037:antagonists & inhibitors; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008861:Microsomes / Q000187:drug effects* / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014527:Uric Acid / Q000494:pharmacology*
chemical_list: D000578:Amidines; D005609:Free Radicals; D016877:Oxidants; D014527:Uric Acid; C046728:2,2'-azobis(2-amidinopropane)