Abstract
The antioxidative activities of vitamin E analogues were believed to be weak in foods systems to prevent oxidative deterioration or autoxidation of oils and fats. But, recent results have shown that α-tocopherol is consumed very rapidly during autoxidation of lipids or oils and fats, because it has high reactivity with oxygen radicals comparing with any other natural and synthetic antioxidants. So, α-tocopherol is present in biomembranes and organisms as the predominant antioxidant. Among vitamin E analogues α-tocopherol has the highest biological activity due to its excellent antioxidative activity. Also, vitamin E has good reactivity to quench singlet oxygen. Recently, biopotencies of stereo-isomers of natural α-tocopherol are discussed among researchers. RRR-α-tocopherol is believed to have the highest activity than other isomers of α-tocopherol.α-Tocopherol is transported with lipoproteins in blood such as LDL-and HDL-lipoproteins. A possible incorporation route into cells from blood is binding with LDL-receptors. In almost tissues and organs of RRR-α-tocopherol overdosed rats except liver upper concentrations of α-tocopherol are present, although upper limit values are depending on tissues properties. So, the low risk of hyper-vitamin E-dosis is due to such as low incorporation capacity of all of organs and tissues. But, since in liver the concentration of α-tocopherol increased with logarithmic relation with dose level and has no upper limit of α-tocopherol concentration, this phenomenon might cause a risk of extremely high intake of vitamin E in human such as daily intake over 10 gramms order.
