A kinetic study of the generation and decomposition of some phenothiazine free radicals formed during enzymatic oxidation of phenothiazines by peroxidase-hydrogen peroxide.

A kinetic study of the oxidation of four different phenothiazines (Pts) by peroxidase-hydrogen peroxide was carried out. The free radical formed during the enzymatic oxidation suffers a non-enzymatic breakdown and the overall system was analysed and characterized. The non-enzymatic breakdown of the cation radical does not occur through a disproportionation mechanism but through a more complex mechanism. The kinetic parameters of the overall system were determined for the different Pts. These experimental data may serve in the understanding of the pharmacological action of Pts.