Effect of Vitamin E Deficiency on Ubiquinone Levels in Rat and Rabbit Liver

Isolation of a trimer of α-tocopherol from mammalian liver

Evidence is presented for the formation in mammalian liver of a trimeric metabolite of alpha-tocopherol. This compound has been shown to be identical to a trimer produced by oxidation of alpha-tocopherol with alkaline K(3)Fe(CN)(6). In addition, confirmation was obtained for the occurrence in vivo of a dimeric metabolite reported previously. These compounds, together with tocopheryl-p-quinone, are postulated to arise from reactions with lipid-free radicals or peroxides in the course of the antioxidant action of vitamin E.

The analysis of alpha-tocopherol and ubiquinone in rat liver

1. A comparative study has been made of five methods of saponifying normal and vitamin E-deficient rat liver and subsequently measuring ubiquinone and α-tocopherol. 2. Losses of ubiquinone and α-tocopherol occur under certain conditions, and three of the methods were judged to be unsatisfactory. Recoveries of α-tocopherol are nearly quantitative under the conditions of ToŠić & Moore (1945), but methods that use large reaction times or weaker alkali destroy tocopherol, and over 50 % loss can be encountered. Ubiquinone does not seem as sensitive to the time of reaction, but is sensitive to the concentration of alkali and amount of water present during saponification.