Antioxidant activity of uric acid and 3-N-ribosyluric acid with unsaturated fatty acids and erythrocyte membranes.

Uric acid and 3-N-ribosyluric acid have been proposed to be important antioxidants in human plasma and in the bovine erythrocyte, respectively. In this study both of these compounds at 0.2 mM protected linolenate and arachidonate from air oxidation in the presence of 5 microM copper sulfate. The unsaturated fatty acids were protected when the urates were added at the beginning of the incubation or at 12 and 24 h of incubation for linolenate and at 3, 6, and 12 h for arachidonate. Both urates protected human and bovine erythrocyte membranes from peroxidation by t-butylhydroperoxide. These data support the proposal that urates are important antioxidants and free radical scavengers.