Biokinetics in humans of RRR-α-tocopherol: The free phenol, acetate ester, and succinate ester forms of vitamin E

• Published in: Free radical biology & medicine 1995-11, Vol.19 (5), p.591-598
• Main Authors: Cheeseman, Kevin H., Holley, Anne E., Kelly, Frank J., Wasil, Mohamad, Hughes, Lise, Burton, Graham
• Format: Article
• Language: English
• Subjects: Administration, Oral; alpha-Tocopherol - analogs & derivatives; Antioxidant, Biokinetics, Bioavailability, α-Tocopheryl acetate, α-Tocopheryl succinate, RRR-α-tocopherol; Antioxidants - administration & dosage; Antioxidants - pharmacokinetics; Biological Availability; Confidence Intervals; Free radicals; Gas Chromatography-Mass Spectrometry; Humans; Intestinal Absorption; Kinetics; Metabolic Clearance Rate; Reference Values; Stereoisomerism; Time Factors; Tocopherols; Vitamin E; Vitamin E - administration & dosage; Vitamin E - analogs & derivatives; Vitamin E - blood; Vitamin E - pharmacokinetics
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/0891-5849(95)00083-A

The bioavailability of RRR-α-tocopherol from the oral administration of RRR-α-tocopherol itself and its acetate and succinate esters was determined in healthy human subjects. Venous blood samples were withdrawn periodically over a 51-h period following oral administration of a gelatin capsule containing an equimolar mixture of RRR-α-tocopherol and RRR-α-tocopheryl acetate. In a second study, subjects received a capsule containing an equimolar mixture of RRR-α-tocopheryl acetate and RRR-α-tocopheryl succinate. In Study 1, RRR-α-tocopherol was absorbed at similar rates from both the free phenol, and the acetate ester and maximum plasma levels occurred at 12 h in most subjects. The extent of absorption of RRR-α-tocopherol varied considerably between subjects in absolute terms, but the relative absorption from the two forms was remarkably consistent, and a ratio of 1.0 was found for parameters of relative bioavailability in plasma. The concentration of RRR-α-tocopherol from each form was maximal at approximately 27 h in red blood cells and, as seen with the plasma data, there was a large inter-individual variability. In Study 2, there was no significant difference in the extent of absorption of RRR-α-tocopherol from the acetate ester and the succinate ester, although there was an apparently higher initial rate of absorption from the acetate ester.