Tocopherols

Tocopherols are involved in immune function, cell signaling, regulation of gene expression, and other metabolic processes. They also inhibit lipid oxidation by donating their phenolic hydrogen to lipid free radicals.1 Antioxidant activity in vivo is normally alpha>beta>delta>gamma but the antioxidant potency may depend on various chemical and physical situations.2 The ortho-methyl substitution of the chroman head plays a vital role in the antioxidant activity of tocopherols while the phytyl tail is very important for proper positioning in the biomembranes. The antioxidant properties of tocopherols may delay memory loss in Down’s syndrome patients due to their protection from harmful oxidation caused by excess activity of superoxide dismutase. Tocopherols are only naturally produced in plants, algae, and some cyanobacteria and are therefore important dietary nutrients for humans and animals.

References:

  1. G. W. Burton and K. Ingold "Autoxidation of biological molecules. 1. Antioxidant activity of vitamin E and related chain-breaking phenolic antioxidants in vitro," J. Am. Chem. Soc., Vol. 103 pp. 6472-6477, 1981
  2. A. Sirikhachornkit, et al., "Replacement of alpha-tocopherol by beta-tocopherol enhances resistance to photo-oxidative stress in a xanthophyll-deficient strain of Chlamydomonas reinhardtii" Eukaryotic Cell, Vol. 8(11) pp. 1648-57, 2009