Biological activity of all-rac-a-tocopherol and RRR-a-tocopherol determined by three different rat bioassays.

The biological activity of 2 R, 4' R, 8' R-(RRR)-a-tocopherol and all-rac-a-tocopherol has been determined by 3 different bioassays: Resorption-gestation test, red blood cell hemolysis test and rat liver storage test. Expressed in relation to all-rac-a-tocopheryl acetate is found by the resorption-gestation test with the doses given in vegetable oil potency ratios of 0.79 for all-rac-a-tocopherol and 1.06 for RRR-a-tocopherol, by the red blood cell hemolysis test ratios of 0.85 for all-rac-a-tocopherol and 1.13 for RRR-a-tocopherol and by the rat liver storage test ratios of 1.03 for all-rac-a-tocopherol and 1.32 for RRR-a-tocopherol. Furthermore is by the resorption-gestation test found a potency ratio of 0.90 between RRR-a-tocopheryl succinate and all-rac-a-tocopheryl acetate. By the evaluation of these figures, most weight must be added to the results from the resorption-gestation test, as it involves the most complex biological mechanism of the 3 methods. The potency ratios found in this investigation are significantly lower than the currently accepted potency ratios of 1.10 between all-rac-a-tocopherol and all-rac-a-tocopheryl acetate, 1.49 between RRR-a-tocopherol and all-rac-a-tocopheryl acetate and 1.21 between RRR-a-tocopheryl succinate and all-rac-a-tocopheryl acetate (all values calculated from their corresponding acetate by multiplication with the ratio of the molecular weight), but the potency ratio between RRR-a-tocopherol and all-rac-a-tocopherol calculated from the 3 different bioassays does not deviate significantly from the currently accepted value of 1.36. It seems necessary to reconsider the biological activity of all-rac-a-tocopherol and RRR-a-tocopherol, and it is suggested to use a potency ratio of 0.80 between all-rac-a-tocopherol and all-rac-a-tocopheryl acetate and 1.0 between RRR-a-tocopherol and all-rac-a-tocopheryl acetate.