THE EFFECT OF GLUTATHIONE ON THE VITAMIN-E REQUIREMENT FOR INHIBITION OF LIVER MICROSOMAL LIPID-PEROXIDATION

Vitamin E dependent inhibition of rat liver microsomal lipid peroxidation in an NADPH and ADP-Fe+3 containing system occurred at lower vitamin E concentrations in the presence of glutathione (GSH). Using microsomes from rats fed a vitamin E deficient diet, vitamin E was shown to be rquired for inhibition. Inhibition also required the presence of a storage labile microsomal component, since no inhibition was observed when using microsomes that had been stored for one moth. This observation provides evidence that direct reduction of reversibly oxidized vitamin E by GSH does not appear to contribute significantly to inhibition of peroxidation. During GSH and vitamin E dependent inhibition of lipid peroxidation, vitamin E (reduced form) concentrations remained constant, indicating that GSH maintained vitamin E concentrations. Without GSH, vitamin E concentrations dropped rapidly. By adding vitamin E to microsomes, it was found that inhibition of lipid peroxidation in the presence of GSH occurred at about five-fold less vitamin E than in the absence of GSH. Inhibition at these lower levels of vitamin E was 85-90% complete. Results indicate that GSH can be used to maintain vitamin E (reduced form) concentrations, thereby lowering the concentration of vitamin E necessary to inhibit microsomal lipid peroxidation. © 1990 American Oil Chemists' Society.