токоферол

Химические свойства

Viscous oils. Soluble in fats; insoluble in water. Stable to heat in the absence of oxygen, to strong acids, and to visible light; unstable to UV light, alkalies, and oxidation.

Использование

Fat-soluble vitamin E, which is a light yellow oil readily degradable by heat. As a vitamin, it is essential for normal muscle growth and prevents vitamin A destruction by deterioration. It also functions as an antioxidant. It prevents the oxidation of certain fatty acids and is stable unless the food becomes rancid. Vegetable oils contain a higher concentration of natural antioxidants, including tocopherols, than animal fats and are thus more stable. Tocopherol is obtained from vegetable oils, beans, eggs, and milk. It is also termed alpha-tocopherol.

Определение

(vitamin E). Any of a group of related substances (α-, β-, γ-, andΔ-tocopherol) that constitute vitamin E. The α-form (which occurs naturally as the d-isomer) is the most potent. Occurs naturally in plants, especially wheat germ. All are derivatives of dihydrobenzo-γ-pyran and differ from each other only in the number and position of methyl groups. Vitamin E is required by certain rodents for normal reproduction. Muscular and central nervous system depletion along with generalized edema are deficiency symptoms in all animals. It is not required as a dietary supplement for humans.

Подготовка

Tocopherol is synthesised in two ways. One is to extract it from natural plant sources and the other is to obtain it by chemical synthesis. The following are the chemical synthesis routes:
The most important natural raw materials for production of tocopherols by extraction are deodoriser sludges, which are distillates obtained in the deodorisation of vegetable oils. Such distillates contain sterols, sterol esters and triacylglycerols, as well as tocopherols and tocotrienols. The concentration of tocopherols depends on the deodorisation parameters (temperature, vacuum, quantity of injected steam and equipment) but their amount is lower than 10%, usually 8–9 %, of unsaponifiable matter present. Separation of tocopherol from the other distilled compounds is possible by several methods: (1) by esterification with a lower alcohol, washing and vacuum distillation; (2) by saponification, or (3) by fractional liquid–liquid extraction. The concentrates obtained in this way may be purified further by molecular distillation, extraction, crystallisation, or combinations of these procedures.
The tocopherol concentrates recommended as antioxidants are mixtures with relatively high contents of γ-tocopherol and δ-tocopherol (being obtained from soybean oil), but α-tocopherol is also present. The total tocopherol concentration usually lies between 30 and 80%. The rest is constituted of triacylglycerols.

Фармаколо?гия

The antioxidant effects of tocopherol can be translated into different changes at the pharmacodynamic level. In vitro studies have shown that this antioxidant activity can produce modification in protein kinase C (PKC) which will later be translated into an inhibition of cell death. Some other derivate effects are the anti-inflammatory properties of tocopherol which can be related to the modulation of cytokines or prostaglandins, prostanoids and thromboxanes.

Токсикология

Tocopherol is considered as non-toxic but if very high doses are administered, there are reports of hemorrhagic activity. Reproductive and developmental toxicity tests are negative. These negative results were also observed in the analysis of mutagenicity and carcinogenicity.