Effect of vitamin E on the secondary oxidation process of unsaturated lipids

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The secondary process of lipid peroxidation forms some toxic aldehydes. Since this process proceeds via free radical intermediates, vitamin E (alpha-tocopherol, TH) would suppress the formation of such aldehydes. We have studied the effect of TH on the hemin-catalyzed decomposition of 1-palmitoyl-2-linoleoylphosphatidylcholine hydroperoxide (PLPC-OOH) in micelles and liposomes. The hemin-catalyzed decomposition of PLPC-OOH produced hexanal as the secondary oxidation product. Although TH did not suppress the decomposition of PLPC-OOH, it suppressed the formation of hexanal. The main products of TH in micelles were TH quinone and dimer, in addition to adducts of PLPC-OOH derived free radicals (T-epoxyPLPC and TOO-epoxyPLPC). In the liposomes, the main products were TOO-epoxyPLPC and dimer, and TH quinone was produced when the liposomes were destroyed. The results indicate that TH can trap PLPC-OOH derived free radicals and suppress the formation of secondary aldehydic products.