rac-α-生育酚 rac-alpha-Tocopherol

Application Notes:

Alpha-tocopherol is one of the eight forms of vitamin E and contains three methyl groups attached to the chromonal ring. Of all the forms of vitamin E, alpha-tocopherol is preferentially retained by the liver in animals and undergoes slower catabolism in cells. It has been found that alpha-tocopherol inhibits the activity of protein kinase C, an enzyme involved in cell proliferation and differentiation in smooth muscle cells, platelets, and monocytes. Other functions of alpha-tocopherol include gene regulation, up-regulation of mRNA or protein synthesis, and preventing the uptake of the harmful 7- hydroxycholesterol into cells.1 Although the antioxidant activity of alpha-tocopherol in vitro has long been established it appears that this may not be one of its primary functions in vivo.2 Vitamin E is involved in immune function, cell signaling, regulation of gene expression, and other metabolic processes. Vitamin E also inhibits lipid oxidation by donating its phenolic hydrogen to lipid free radicals.3 Antioxidant activity in vivo is normally alpha>beta>delta>gamma but the antioxidant potency may depend on various chemical and physical situations.4 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 vitamin E may delay memory loss in Down’s syndrome patients due to their protection from harmful oxidation caused by excess activity of superoxide dismutase. Vitamin E is only naturally produced in plants, algae, and some cyanobacteria and is therefore an important dietary nutrient for humans and animals.

References: 
1. R. Brigelius and M. Traber “Vitamin E: Funcion and metabolism” The FASEB Journal, Vol. 13(10) pp. 1145-1155, 1999 
2. A. Azzi “Molecular mechanism of
-tocopherol action” Free Radical Biology and Medicine, Vol. 43:1 pp. 16-21, 2007 
3. G. W. Burton and K. Ingold Autoxidation of biological molecules. 1. Antioxidant activity of vitamin E and related chain-breaking phenolic antioxidants in vitro, U. J. Am. Chem. Soc., 103, 6472-6477, 1981 
4. Anchalee Sirikhachornkit, Jai W. Shin, Irene Baroli, and Krishna K. Niyogi Replacement of
-tocopherol by  -tocopherol enhances resistance to photooxidative stress in a xanthophyll-deficient strain of Chlamydomonas reinhardtii, Eukaryotic Cell, doi:10.1128, 2009