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Biopotency of -Tocopherols as Determined by Curative Myopathy Bioassay in the Rat

Department of Clinical Nutrition, Hoffmann-LaRoche Inc., Nutley, NJ 07110

The decrease in plasma pyruvate kinase activity after administration of various tocopherols to vitamin E-deficient rats provided the basis for a 3-point parallelslope assay for vitamin E activity. Based on 6 replicate assays, RRR--tocopheryl acetate (RRR--TA) was 141% as active as all-rac--tocopheryl acetate (all-rac--TA). This confirms many previous reports with other bioassays and is in agreement with the unit-weight relationships assigned by The National Formulary. 2-ambo--Tocopheryl acetate was 97% as active as all-rac--TA indicating that only the configuration of the 2-position on the chromanol ring is important in determining the biological activity of -tocopherol.

KEY WORDS: • vitamin E • curative myopathy bioassay • RRR--tocopheryl acetate • all-rac--tocopheryl acetate • 2-ambo--tocopheryl acetate • relative potency

Manuscript received 13 August 1981.