Electrocatalytic and Analytical Responses of 10-Methylphenothiazine Toward Reduced Glutathione

The electrochemical oxidation of reduced glutathione (GSH) catalyzed by 10-methylphenothiazine (MPT) at a glassy carbon electrode in 0.1 M ( Et ) 4 NClO 4 ethanol + water (1:1 v/v) solution has been studied. Addition of MPT dramatically reduces the over‐potential necessary for the oxidation of GSH and the catalytic current is affected by the concentration of the catalyst and the pH of the solution. The possible electrocatalytic reaction mechanism for the electro‐oxidation of GSH in the presence of MPT was proposed. Oxidized glutathione is the oxidation product which has been verified by thin‐layer chromatography and by melting‐point and optical rotation measurements. A nontoxic, stable, and convenient method for the measurement of GSH in the concentration range 5.0 × 10 − 6 to 1.76 × 10 − 3 M has been developed.