Comparative study on the action of tocopherols and tocotrienols as antioxidant: chemical and physical effects

Abstract

α-Tocopherol is known as the most abundant and active form of vitamin E homologues in vivo, but recently the role of other forms of vitamin E has received renewed attention. The antioxidant properties were compared for α-, β-, γ- and δ-tocopherols and tocotrienols. The following results were obtained: (1) the corresponding tocopherols and tocotrienols exerted the same reactivities toward radicals and the same antioxidant activities against lipid peroxidation in solution and liposomal membranes; (2) tocopherols gave more significant physical effect than tocotrienols on the increase in rigidity at the membrane interior; (3) tocopherols and tocotrienols showed similar mobilities within the membranes, but tocotrienols were more readily transferred between the membranes and incorporated into the membranes than tocopherols; (4) α-tocopherol and α-tocotrienol, but not the other forms, reduced Cu( II) to give Cu( I) together with α-tocopheryl and α-tocotrienyl quinones, respectively and exerted prooxidant effect in the oxidation of methyl linoleate in SDS micelles.