A-Tocopherol 3-Tocopherol

Fig. 1. The four naturally occutting tocopherols (a-tocopherol, E.E.E. [59-02-9] jall-rac [2074-53-5] (1) p-tocopherol [148-03-8] (2) y-tocopherol [54-28-4] (3) 8-tocopherol [119-13-1] (4)), a-tocotrienol [1721 -51 -3] (5), and p-tocotrienol [14101-61-2] (6) where asterisks denote asymmetric centers and the...

Oil source Total tocopherols a-Tocopherol y-Tocopherol (3-Tocopherol 5-Tocopherol... 

Phenols are important antioxidants, with vitamin E being the most important endogenous phenolic membrane-bound antioxidant. Membrane levels of vitamin E are maintained through recycling of the vitamin E radical with ascorbate and thiol reductants. Vitamin E is a mixture of four lipid-soluble tocopherols, a-tocopherol being the most efiective radical quencher. The reaction of a-tocopherol with alkyl and alkylperoxyl radicals of methyl linoleate was recently reported. These are facile reactions that result in mixed dimer adducts (Yamauchi etal., 1993). 

Sunflower oil is a rich source of vitamin E. It contains, on average, 400-700 pg/g total tocopherols (Van Niekerk and Burger, 1985 Eitenmiller, 1997 Kamal-Eldin and Andersson, 1997). Total tocopherol concentration of 66 experimental breeding lines with commodity-type fatty acid compositions was 982 27 pg/g, of which >99% was a-tocopherol. a-Tocopherol was present in some lines as a minor component. The tocopherol compositions of breeding lines with adjusted fatty acid compositions were similar (Dolde et al., 1999). 

The antioxidant properties of tocopherols (such as those found in com oil) may be involved in combating atherosclerosis by preventing the oxidation of low-density lipoproteins (Saldeen et al. 1999). Another recent study indicated that the particular ratio of individual tocopherols in corn oil (a high ratio of y-tocopherol/a-tocopherol) may achieve better protection against DNA damage than a-tocopherol alone (Elmadfa and Park 1999). Others have demonstrated beneficial effects of com oil on blood pressure, platelet aggregation and diabetes (Strecker et al. 1996). 

By polarographic measurements, Baltes (1964) calculated the following normal oxidation potentials, in connection with a comparison of the antioxidant properties of the tocopherols a-tocopherol 4-754 mV P-tocophcrol 4-824 mV 7-tocopherol 4-829 mV S-tocopherol 4 886 mV. 

As a-tocopherol. a-Tocopherol includes RRR-a-tocopheroU the only form of a-tocopherol that occurs naturally in foods, and the 2R-stereoisomeric forms of a-tocopherol RRR-, RSR-, RRS-, and RSS-a-tocopherol) that occur in fortified foods and supplements. It does not include the 25 -stereoisomeric forms of o-toc< herol (SRR-, SSR-, SRS-, and 555-a-tocopherol), also found in fortified foods and... 

Figure 5 Separation of a standard mixture of tocopherols on a pentafluorophenyl re-versed-phase material. Chromatographic conditions Column, MetaChem PFP, 5 xm, 250 X 4.6 mm mobile phase, methanol water (92 8, v/v) detection, UV, 290 nm. Peak identification (from left to right) 5-tocopherol, P-tocopherol, y-tocopherol, a-tocopherol. (From Ref. 42.)... 

Berzen J, Luketic D. Stabilised polyethylene moulding materials, for implants containing polyethylene with molecular wt. 10 -10 , antioxidant, and tocopherol, a- tocopherol or Vitamin E, as stabiliser. European Patent 61S. 92S 1994. 

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