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

Laser flash photolysis of alpha-tocopherol in methanol and in aqueous micellar solutions has been shown to produce the alpha-tocopheroxyl radical. The reaction between the alpha-tocopheroxyl radical and ascorbate in positively charged hexadecyltrimethylammonium chloride (HTAC) micelles occurred with a second order rate constant of 7.2 x 10(7) M-1.s-1, whereas in negatively charged sodium dodecyl sulphate (SDS) micelles the rats constant was only 3.8 x 10(4) M-1.s-1. The alpha-tocopheroxyl radical was found to be relatively long-lived in HTAC micelles (t1/2 greater than or equal to 5 min), allowing the slow disappearance of the alpha-tocopheroxyl radical by reaction with glutathione to be observed.