Ubiquinone protects against loss of tocopherol in rat liver microsomes and mitochondrial membranes.

Liver microsomes and submitochondrial particles (SMP) were isolated from rats fed on a vitamin E or coenzyme Q10/vitamin E enriched diet in order to clarify the antioxidant interactions between coenzyme Q10 and vitamin E. Electron spin resonance spectrometry shows that the decay of vitamin E radicals (tocopheroxy radicals) generated by the arachidonic acid/lipoxygenase oxidation system proceeded at a higher rate in vitamin E enriched microsomes and SMP than in those enriched with coenzyme Q10/vitamin E. Vitamin E levels determined by high performance liquid chromatography revealed that when subjected to enzymatic oxidation, membranes enriched with vitamin E alone were depleted of vitamin E earlier than those enriched with both coenzyme Q10 and vitamin E. These results show that coenzyme Q10 conserves vitamin E, which would help prolong membrane resistance against oxidative damage.