tocopherol

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Related to Alphatocopherol: vitamin E

tocopherol:

see vitaminvitamin,
group of organic substances that are required in the diet of humans and animals for normal growth, maintenance of life, and normal reproduction. Vitamins act as catalysts; very often either the vitamins themselves are coenzymes, or they form integral parts of coenzymes.
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Tocopherol

 

any vitamin of the E group. Tocopherols are similar in chemical structure and are contained in large quantities in vegetable oils. Eight tocopherols that have vitamin activity are known; they are designated by the Greek letters et, β, 7, and so on. Although only a tocopherol, which is the most active, was formerly considered to be vitamin E, the term subsequently came to include the entire group of natural and synthetic tocopherols, which have the activity of α-tocopherol to varying degrees (α-tocopherol was discovered in the 1920’s and was extracted in pure form in 1936; P. Karrer synthesized it chemically in 1938).

Chemically, tocopherols are derivatives of chromane (a two-ring aromatic system) combined with an isoprenoid side chain. Tocopherols are transparent, oily liquids that are soluble only in organic solvents; they remain stable upon heating. They are widespread in nature but are synthesized only by plants. Animals and man obtain them from food. The highest tocopherol content is found in the germs of cereals and in the oils extracted from them. With a normal diet, E avitaminosis and hypovitaminosis occur rarely. Insufficient intake of vitamin E in experimental animals leads to sterility, muscular dystrophy, disorders of the central nervous system, increased hemolysis, and hypothyroidism. Tocopherol deficiency causes increased permeability or complete disintegration of biological membranes, including the membranes of the mitochondria and lysosomes. It is assumed that one of the functions of tocopherols in cells is to prevent the formation of peroxides from unsaturated fatty acids—that is, to play the role of natural antioxidants. In many cases, pathological symptoms that result from a tocopherol-deficient diet may be eliminated or prevented by certain antioxidants. The biochemical functions of tocopherols are also associated with tissue respiration processes.

Tocopherols are used in medicine to treat certain nervous, skin, gynecological, and cardiovascular disorders. Supplements added to animal feeds sharply reduce miscarriages in cows and eliminate motor disorders and paralyses in young birds. Tocopherols are used as natural antioxidants to stabilize vitamins A and D and to prevent vegetable oils from becoming rancid.

REFERENCE

Shaternikov, V. A. “Vitamin E.” In Vitaminy. Moscow, 1974. Chapter 5.

N. N. ZAITSEVA

tocopherol

[tə′käf·ə‚röl]
(organic chemistry)
Any of several substances having vitamin E activity that occur naturally in certain oils; α-tocopherol possesses the highest biological activity.
References in periodicals archive ?
Effect of high-dose alphatocopherol supplementation on biomarkers of oxidative stress and inflammation and carotid atherosclerosis in patients with coronary artery disease.
Serum levels of alphatocopherol in hypertensive pregnancies.
Clinical question Does either selegiline, alphatocopherol (vitamin E), or a combination of both drugs slow the progression of Alzheimer's disease of moderate severity?
The majority of inhibitors that naturally occur in many edible plants are phenols, aromatic isothiocyanates, coumarins, flavones, diterpenes, retinoids, ascorbic acid, alphatocopherol, selenium salts and plant sterols.
When nutrition researchers at The University of Texas Southwestern Medical Center at Dallas gave volunteers daily does of 800 international units (IUs) of alphatocopherol, commonly known as vitamin E, they discovered that the oxidation rate of low-density lipoproteins (LDL) was reduced by half.
For example, ascorbic acid is another name for vitamin C; alphatocopherol is another name for vitamin E; and beta-carotene is a source of vitamin A.
The RDA for vitamin E is 8 to 10 milligrams of alphatocopherol, as determined by the National Research Council (these recommendations are revised about every five years).
Penetration and distribution of alphatocopherol, alpha- or gamma-tocotrienols applied individually onto murine skin.
3 Plasma analysis Alphatocopherol ([micro]g/dL) 636 [+ or -] 214 Beta-carotene ([micro]g/dL) 83.
gamma-tocopherol and its major metabolite, in contrast to alphatocopherol, inhibit cyclooxygenase activity in macrophages and epithelial cells.