Antioxidant Activity of Ubiquinol in Solution and Phosphatidylcholine Liposome

Abstract

The antioxidant activities of ubiquinol and ubiquinone were measured in the free radical-mediated oxidations of methyl linoleate in solution and phosphatidylcholine liposomes in aqueous dispersion. Ubiquinol-10 suppressed the oxidation of methyl linoleate in hexane, although its reactivity toward peroxyl radical was about 10 times less than that of α-tocopherol. Ubiquinone-10, on the contrary, did not show any antioxidant activity. On the other hand, ubiquinol-10 inhibited the oxidation of phosphatidylcholine liposomal membranes as efficiently as α-tocopherol When both ubiquinol-10 and α-tocopherol were present, ubiquinol-10 decreased first and α-tocopherol decreased after all ubiq-uinol-10 was consumed in both solution and liposomes. These results and electron spin resonance (ESR) study suggest that ubiquinol-10 regenerates a-tocopherol by reducing a-tocopheroxyl radical. © 1990, Center for Academic Publications Japan. All rights reserved.