Free radical metabolite of uric acid.
Uric acid has previously been shown to act as a water-soluble antioxidant. Although the antioxidant activity of uric acid has been attributed to its ability to scavenge free radicals, the one-electron uric acid oxidation product of such a scavenging reaction has not been detected. It order to determine whether a free radical metabolite of uric acid could be formed via one-electron redox processes, we oxidized uric acid with potassium permanganate, horseradish peroxidase/hydrogen peroxide, and hematin/hydrogen peroxide systems. With the use of the rapid-mixing, continuous-flow electron spin resonance technique, we were able to detect the urate anion free radical in all three radical-generating systems. Based on N15-isotopic-labeling experiments, we show that the unpaired electron of this radical is located primarily on the five-membered ring of the purine structure. We were also able to demonstrate that this radical could be scavenged by ascorbic acid.
Maples
K R
KR
Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709.
Mason
R P
RP
D001205:Ascorbic Acid; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006427:Hemin; D006735:Horseradish Peroxidase; D006861:Hydrogen Peroxide; D010084:Oxidation-Reduction; D011196:Potassium Permanganate; D014527:Uric Acid / Q000378:metabolism*
D005609:Free Radicals; D011196:Potassium Permanganate; D014527:Uric Acid; D006427:Hemin; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D001205:Ascorbic Acid