Reactions of the α-tocopheroxyl radical in micellar solutions studied by nanosecond laser flash photolysis

Abstract

Laser flash photolysis of α-tocopherol in methanol and in aqueous micellar solutions has been shown to produce the α-tocopheroxyl radical. The reaction between the α-tocopheroxyl radical and ascorbate in positively charged hexadecyltrimethylammonium chloride (HTAC) micelles occurred with a second order rate constant of 7.2 × 10 7 M −1·s −1, whereas in negatively charged sodium dodecyl sulphate (SDS) micelles the rats constant was only 3.8 × 10 4 M −1·s −1. The α-tocopheroxyl radical was found to be relatively long-lived in HTAC micelles ( t 1 2 ⩾ 5 min), allowing the slow disappearance of the α-tocopheroxyl radical by reaction with glutathione to be observed.