Download Functions of Antioxidant Vitamins against Lipid Peroxidation

Foods & Food Ingredients J. Jpn., Vol. 215, No.1, 2010
Functions of Antioxidant Vitamins against Lipid Peroxidation
Ryo Yamauchi
Faculty of Applied Biological Sciences, Gifu University
1-1 Yanagido, Gifu 501-1193, Japan
Summary
Reactive oxygen species (ROS) occur in tissues and cells and can damage DNA, proteins,
carbohydrates and lipids. These deleterious reactions are controlled in part by antioxidants that
eliminate ROS and scavenge free radicals. This review describes the functions of antioxidant
vitamins and their co-operative action against lipid peroxidation. The antioxidant activity of
carotenoids is conferred by the hydrophobic chain of polyene units that can quench singlet
molecular oxygen (1O2) and stabilize lipid-peroxyl radicals, independent of their provitamin A
activity. Vitamin C (ascorbic acid) is the major water-soluble antioxidant and scavenges free
radicals directly in the aqueous phases of cells and the circulatory system. Vitamin E
(α-tocopherol) is the most abundant and efficient scavenger of lipid-peroxyl and other lipid radicals
in lipophilic circumstances. The water-soluble vitamin C can reduce the vitamin E radical and
thus support the antioxidant activity of vitamin E. Such functions can be performed also by other
appropriate reducing compounds. These interactions between redox antioxidant substances and
enzymes form an antioxidant network in the body. In addition to these antioxidant vitamins,
vitamins B2 and B6 and the reduced form of coenzyme Q (ubiquinol) may also act as antioxidants
in biological systems. The antioxidant activity of B2 is principally derived from its role as a
precursor of flavin adenine dinucleotide. Vitamin B6 compounds may function as antioxidants by
interacting with 1O2. The reduced coenzyme Q, also a resident of hydrophobic compartments,
interacts with vitamin E to regenerate its antioxidant form.