D-альфа-токоферол

Химические свойства

VITAMIN E is sometimes referred to as the antisterility vitamin, factor X (an earlier designation), chemically vitamin E is alphatocopherol. Active analogues and related compounds include: dl-α-Tocopherol; 1-α-tocopherol; esters (succinate, acetate, phosphate), and β, ζ 1, ζ 2- tocopherols. The principal physiological forms are D-a-tocopherol, tocopheronolactone, and their phosphate esters.

Использование

α-Tocopherol is the most bioactive of the naturally occurring forms of Vitamin E. Richest sources are green vegetables, grains, and oils, particularly palm, safflower and sunflower oils.

Определение

ChEBI: An alpha-tocopherol that has R,R,R configuration. The naturally occurring stereoisomer of alpha-tocopherol, it is found particularly in sunflower and olive oils.

Общее описание

α-Tocopherol is synthesized from γ-tocopherol by the action of enzyme γ-tocopherol methyltransferase. It is the major form of Vitamin E in human plasma. It is present in sunflower seed oil.

Угроза здоровью

The physiological functions of vitamin E substances include: (1) bio logical antioxidant; (2) normal growth maintenance; (3) protects unsaturated fatty acids and membrane structures; (4) aids intestinal absorption of unsaturated fatty acids; (5) maintains normal muscle metabolism; (6) maintains integrity of vascular system and central nervous system; (7) detoxifying agent; and (8) maintains kidney tubules, lungs, genital structures, liver, and red blood cell membranes.
In livestock and laboratory animals, a deficiency of vitamin E substances may cause degeneration of reproductive tissues, muscular dystrophy, encephalomalacia, and liver necrosis. Considerable research is required to fully determine supplementation of livestock diets unless typical symptoms of a deficiency appear. Symptoms have appeared where there are selenium deficiencies in the soil and where there are excessive levels of nitrates in the soil. “White muscle” is the term used to describe a condition of muscular dystrophy in cattle.

Профиль безопасности

Experimental reproductive effects. Mutation data reported. When heated to decomposition it emits acrid smoke and irritating fumes.

Методы очистки

Vitamin E is a viscous yellow oil which is distilled at high vacuum. It has max at 294nm (E1cm 1% 71). It is oxygen and light sensitive and is best stored as its stable D--acetate [58-95-7] which is purified by evaporative distillation at b 180-200o(bath temperature)/0.7mm, and has [] D 25 +3.3o (c 5.1, EtOH). It forms needles at -30o and has m 26.5-27.5o, [] D 25 +0.25o (c 10, CHCl3). [NMR: Cohen et al. Helv Chim Acta 6 4 1158 1981, Burton & Ingold Acc Chem Res 1 9 194 1986, Karrer et al. Helv Chim Acta 2 1 520 1938, Robeson J Am Chem Soc, 64 1487 1942, 65 1660 1943.] Of the eight isomers the D--isomer is the most active. [See W. Friedrich “Vitamins” Walter de Guyter Publ, Berlin 1988.] [Beilstein 17/4 V 168.]