THE CHEMISTRY AND ANTIOXIDANT PROPERTIES OF TOCOPHEROLS AND TOCOTRIENOLS

This article is a review of the fundamental chemistry of the tocophero ls and tocotrienols relevant to their antioxidant action. Despite the general agreement that a-tocopherol is the most efficient antioxidant and vitamin E homologue in vivo, there was always a considerable discr epancy in its ''absolute'' and ''relative'' antioxidant effectiveness in vitro, especially when compared to gamma-tocopherol. Many chemical, physical, biochemical, physicochemical, and other factors seem respon sible for the observed discrepancy between the relative antioxidant po tencies of the tocopherols in vivo and in vitro. This paper aims at hi ghlighting some possible reasons for the observed differences between the tocopherols (alpha-, beta-, gamma-, and delta) in relation to thei r interactions with the important chemical species involved in lipid p eroxidation, specifically trace metal ions, singlet oxygen, nitrogen o xides, and antioxidant synergists. Although literature reports related to the chemistry of the tocotrienols are quite meager, they also were included in the discussion in virtue of their structural and function al resemblance to the tocopherols.