Effect of diethyl maleate and glutathione on linoleate peroxidation

The antioxidant effect of diethyl maleate and reduced glutathione was studied in an in vitro peroxidizing system. Linoleate peroxidation, measured as conjugated diene formation, was not altered by diethyl maleate (2 or 4 mM), whereas the addition of reduced glutathione (1, 2 or 4 mM) elicited a marked and progressive reduction. This effect of glutathione is not modified by diethyl maleate. The inhibition of linoleate peroxidation by glutathione was found concomitantly with a decrease in the concentration of its reduced form and a corresponding increase in glutathione disulfide levels, so that the total equivalents of reduced glutathione in the system remained constant. It is concluded that diethyl maleate does not have antioxidant properties in a peroxidizing system, as found for reduced glutathione.