Oxidation of p-aminophenol catalyzed by horseradish peroxidase and prostaglandin synthase.

p-Aminophenol oxidation is catalyzed by horseradish peroxidase. ESR spectroscopy demonstrates the formation of the p-aminophenoxy free radical, the one-electron oxidation product of p-aminophenol. The same radical is formed by alkaline autoxidation of this compound. The ultimate products of p-aminophenol oxidation are mainly polymeric; however, indophenol was isolated in low yield. Oxidation of p-aminophenol is also catalyzed by the hydroperoxidase activity of prostaglandin synthase, using ram seminal microsomal preparations as the enzyme source.