The tocopherols are biologically active natural substances. They are n
ot only effective in vivo but also in vitro. Vitamin E is the most imp
ortant fat-soluble antioxidant (AO) in cell membranes and in vegetable
oils. The similarities and differences in the in vivo and in vitro ef
ficacy of the following tocopherols will be discussed: Tocopherol homo
logues: alpha-, beta-, gamma-, delta-tocopherol (TL); the highest vita
min E effect alpha-TL; the best AO-efficacy in vitro gamma-TL. Tocotri
enols (TT): The highest vitamin E effect alpha-TT (30% of alpha-TL); t
he best AO-efficacy in vitro gamma-TT. alpha-Tocopherol stereoisomers:
RRR-, RRS-, RSS-, SSS-, RSR-, SRS-, SRR-, SSR-alpha-TL, range of acti
vity from 1.0 to 0.21; AO-effect in vitro: equal in all 8 stereoisomer
s; ratio of activity all-rac-: RRR-alpha-tocopheryl acetate = 1:1.36 i
n multifunctional vitamin E tests with rats. Iso-alpha-tocopherol (2-p
hytyl, 2-methyl, 5, 6, 7-trimethyl, 8-chromanol): No in vivo effect (h
emolysis test); linear increasing AO-efficacy in edible oils and fats
without pro-oxidative effect in higher concentrations. Benzofuran anal
ogue of all-rac-gamma-tocopherol: Different effects in vivo dependent
upon the simultaneous realized biological parameters resorption-gestat
ion, pyruvate kinase activity and storage capacity. The tocopherols ar
e heat stable and non-toxic. Therefore, they are used as antioxidants
in food, feed, pharmaceutical and cosmetic products.