Figure 1
From: Oxidative stress and its biomarkers in systemic lupus erythematosus
Main sources of free radical generation and their catabolism. Highly reactive superoxide anions are mainly produced in mitochondrial, xanthine oxidase and NADPH-oxidase. Superoxide anions can either react with nitric oxide to generate the strong oxidant peroxynitrite, or be degraded by superoxide dismutase into the less reactive species hydrogen peroxide. Hydrogen peroxide can then be catabolized by glutathione peroxidase or catalase reaction, react with Fe2+ to form hydroxyl radicals via the Fenton reaction, or be degraded by the myeloperoxydase, another source of hydroxyl radicals.