TOCOPHEROLS - ANTIOXIDANTS IN NATURE

The tocopherols are biologically active natural substances. They are not only effective in vivo but also in vitro. Vitamin E is the most important fat-soluble antioxidant (AO) in cell membranes and in vegetable oils. The similarities and differences in the in vivo and in vitro efficacy of the following tocopherols will be discussed: Tocopherol homologues: alpha-, beta-, gamma-, delta-tocopherol (TL); the highest vitamin E effect alpha-TL; the best AO-efficacy in vitro gamma-TL. Tocotrienols (TT): The highest vitamin E effect alpha-TT (30% of alpha-TL); the best AO-efficacy in vitro gamma-TT. alpha-Tocopherol stereoisomers: RRR-, RRS-, RSS-, SSS-, RSR-, SRS-, SRR-, SSR-alpha-TL, range of activity from 1.0 to 0.21; AO-effect in vitro: equal in all 8 stereoisomers; ratio of activity all-rac-: RRR-alpha-tocopheryl acetate = 1:1.36 in multifunctional vitamin E tests with rats. Iso-alpha-tocopherol (2-phytyl, 2-methyl, 5, 6, 7-trimethyl, 8-chromanol): No in vivo effect (hemolysis test); linear increasing AO-efficacy in edible oils and fats without pro-oxidative effect in higher concentrations. Benzofuran analogue of all-rac-gamma-tocopherol: Different effects in vivo dependent upon the simultaneous realized biological parameters resorption-gestation, pyruvate kinase activity and storage capacity. The tocopherols are heat stable and non-toxic. Therefore, they are used as antioxidants in food, feed, pharmaceutical and cosmetic products.