Action of quinolinic and indolinonic aminoxyls as radical-scavenging antioxidants

Abstract

The kinetic studies on the actions of quinolinic and indolinonic aminoxyls in the oxidation of lipid peroxidation induced by free radicals were carried out to evaluate their antioxidant activity. These aminoxyls showed a similar reactivity toward peroxyl radical with α-tocopherol. The antioxidant efficacies of aminoxyls against oxidation of methyl linoleate in homogeneous solution were smaller than that of α-tocopherol. Hydroxylamine, a reduced form of aminoxyl, possessed a comparative antioxidant efficacy with α-tocopherol and was capable of suppressing the consumption of α-tocopherol. Aminoxyls showed more potent antioxidant activity than α-tocopherol against the oxidation of methyl linoleate micelles induced by peroxyl radical or by a combination of copper ion and hydrogen peroxide. These results suggest that quinolinic and indolinonic aminoxyls may act as potent antioxidants against lipid peroxidation, especially in the presence of a good reductant which reduces aminoxyl radicals to hydroxylamines.