RESUMO
Alpha-Lipoic acid is involved in the oxidative decarboxylation of ketoacids as a constituent of enzyme complexes in which it is covalently bound to the epsilon- amino group of lysine residues. It is employed as a therapeuthic agent in alcoholic and diabetic polyneuropathies and in chronic and toxic liver damage. Lipoic acid is effective in preventing oxidative damage in a series of oxidative stress situation. In vivo lipoic acid treatment (100 mg/kg) inhibited chemiluminescence overshoot after ischemia-reperfusion in the rat intestine. lipoic acid (50 to 150 mg/kg) also inhibited xanthine dehydrogenase to xanthine oxidase conversion in rat intestine homogenate. In vitro, lipoic acid inhibited buttermilk and rat liver xanthine oxidase activity and xanthine dehydrogenase to xanthine oxidase conversion in rat liver and intestine homogenates. Lineweaver-Burk and Dixon plots indicate that lipoic acid is a competitive inhibitor of xanthine oxidase with respect to xanthine.