| Abstract | The importance of vitamin E for protecting the integrity of lipid structures in vivo is underscored by the finding that it is the major lipid-soluble, chain-breaking antioxidant found in plasma, red cells, and tissues. a-Tocopherol (a-T), the most biologically active form of vitamin E, is one of the most efficient chain-breaking antioxidants. Multigram quantities of natural and unnatural stereoisomers of a-T can be synthesized with nearly complete, selective replacement of hydrogen by deuterium in metabolically inactive, nonlabile, aromatic methyl positions. A great advantage inherent in the use of deuterated tocopherols is that, unlike radiolabeled vitamin E, the compounds may be ingested without risk. A unique application of deuterated a-T has been to use it as the sole source of dietary vitamin E for laboratory animals, allowing us to measure the long-term rate of its uptake into blood and tissues. Pancreatic cholesterol esterase and bile salts are essential for the absorption of vitamin E. |
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