Application of deuterated alpha-tocopherols to the biokinetics and bioavailability of vitamin E

alpha-Tocopherol, a superior chain-breaking, peroxyl radical-trapping antioxidant and the most active component of vitamin E, is elevated in liver tumor cells, contributing to their greater resistance towards lipid peroxidation compared to cells from normal tissues. Also, in regenerating rat liver the level of vitamin E has been found to fluctuate in phase with the rate of cell division. In order to study the biokinetics and mechanisms of the distribution of vitamin E in organs and within tissues of animals, deuterated forms of alpha-tocopherol have been synthesized and their uptake into blood and tissues has been measured by gas chromatography-mass spectrometry. Measurement of the competitive uptake from a mixture of the RRR- and SRR-alpha-tocopherol stereoisomers labelled with different amounts of deuterium shows that the liver exerts a strong preference for secretion of the natural (RRR) stereoisomer into the plasma. It is suggested that a tocopherol-binding protein plays a key role in this process.