Antioxidant activity of adrenergic agents derived from catechol

The ability of adrenergic catechol derivatives, including dobutamine, dopamine, and isoproterenol, to inhibit lipid peroxidation was examined. All the catechol derivatives we tested strongly inhibited lipid peroxidation. Dobutamine was a more powerful inhibitor of iron-catalyzed lipid peroxidation than the other agents, suggesting that part of the antioxidant activity of dobutamine is due to chelating iron. In addition, the catechol derivatives scavenged not only diphenylpicrylhydrazyl (DPPH) free radicals, but also 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cations and 2,2'-azobis-(2-amidinopropane)-dihydrochloride (AAPH) peroxyl radicals, indicating that the antioxidative activities of these agents are evidently due to scavenging free radicals. However, the rate constant of these catechol derivatives in scavenging hydroxyl radicals was < 10(10) M(-1) sec(-1), suggesting that they may not protect against biological damage induced by hydroxyl radicals.