tocopherol

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Related to Alpha tocopherol: 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 ?
Finally, compared with alpha tocopherol, gamma tocopherol appears to be more readily absorbed into endothelial cells, where it can exert its antioxidant effects to protect endothelial health.
Efficacy of fluoroqinolone in combination with alpha tocopherol to resolve nonspecific infection of reproductive tract of dairy animals.
Results: There was no significant fall in serum malondialdehyde in rats supplemented with ascorbic acid alone, however rats supplemented with alpha tocopherol or combination of ascorbic acid and alpha tocopherol revealed significant fall in serum malondialdehyde and increment in superoxide dismutase activity.
High blood levels of selenium may reduce the incidence of both BCC and SCC by about 60%, whereas serum concentrations of carotenoids or alpha tocopherol are not associated with later skin cancer incidence.
Alpha tocopherol was found to inhibit the tocotrienol's ability to suppress HMG-CoA reductase activity.
In 1997, we reported that taking only the alpha tocopherol form of vitamin E displaces critically important gamma tocopherol in the body.
Alpha tocopherol is the major form of vitamin E found in human tissues.
For the unfortunate men who received only alpha tocopherol in the SELECT study, the suppression of gamma tocopherol that occurred in their bodies presumably exposed them to higher levels of cancer-promoting byproducts of arachidonic acid.
While alpha tocopherol inhibits the production of new free radicals, gamma tocopherol is required to trap and neutralize existing free radicals.
This might account for the null effects of alpha tocopherol supplementation in Mild Cognitive Impairment and Alzheimer's Disease.