title: Vitamin E activity of 1-thio-alpha-tocopherol as measured by the rat curative myopathy bioassay.
abstract: The bioactivity of the acetate of the all-racemic, 1-thio analog of alpha-tocopherol (all-rac-1-thio-alpha-tocopheryl acetate) has been determined by measuring its ability to decrease plasma levels of pyruvate kinase in vitamin E deficient rats using the curative myopathy bioassay. The thio analog is only 0.22 times as active as RRR-alpha-tocopheryl acetate and is therefore approximately 0.33 times as active as all-rac-alpha-tocopheryl acetate, since the latter has been shown to be 1.47 times less active than RRR-alpha-tocopheryl acetate in the same bioassay (H. Weiser, M. Vecchi and M. Schlachter, Internat. J. Vit. Nutr. Res., 55, 149-158 (1985)). The 0.33:1.0 ratio is similar to the ratio of 0.41:1.0 measured for the in vitro antioxidant activities of the corresponding free phenols. This finding lends further support to our view that the vitamin E activity in the curative myopathy bioassay of close structural analogs of alpha-tocopherol is determined primarily by the in vitro antioxidant activity of the analog relative to alpha-tocopherol, consistent with the belief that vitamin E functions primarily as a general purpose, lipid-soluble antioxidant in mammals.
authors.affiliation: Division of Chemistry, National Research Council of Canada, Ottawa, Ontario.
authors.forename: K U
authors.initials: KU
authors.lastname: Ingold
authors.forename: G W
authors.initials: GW
authors.lastname: Burton
authors.forename: L
authors.initials: L
authors.lastname: Hughes
authors.forename: D O
authors.initials: DO
authors.lastname: Foster
authors.forename: B
authors.initials: B
authors.lastname: Robillard
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001681:Biological Assay; D008297:Male; D015394:Molecular Structure; D011770:Pyruvate Kinase / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D013237:Stereoisomerism; D024505:Tocopherols; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D014811:Vitamin E Deficiency / Q000201:enzymology*; D024502:alpha-Tocopherol / Q000031:analogs & derivatives*
chemical_list: D000975:Antioxidants; C069299:1-thio-alpha-tocopherol; D014810:Vitamin E; D011770:Pyruvate Kinase; D024502:alpha-Tocopherol; D024505:Tocopherols