Biochemistry

a-tocopherol was the most biologically active, which has three methyl groups in its cycle. CH, I НО — С C CH 2 ртт pn I II I L кхГІі vrii I I I H 3 C-C C C-(CH 2 ),-CH-(CH 2 ),-CH-(CH 2 ),-CH-CH, xo / l I CH, CH, a-Tocopherol Various a-tocopherols differ from each other in the number and arrangement of methyl groups. Tocopherols are colorless oily liquids that are readily soluble in vegetable oils, alcohol, and ether. Chemically very stable, withstand heating up to 100 °C with concentrated HC1 and up to 170 °C in air; are destroyed by ultraviolet rays, but are resistant to cooking, are not destroyed by the rancidity of fats. Biological role. Vitamin E affects the function of the gonads, it is necessary for the normal course of pregnancy, it stimulates muscle activity, slows down blood coagulation, promotes the accumulation of vitamin A in the liver, and delays its oxidation. Vitamin E is a powerful antioxidant (primarily lipids). Reacting with lipid peroxide radicals and themselves being oxidized, tocopherols break the oxidation chain. The antioxidant effect of tocopherols is associated with their ability to prevent the formation of peroxides from unsaturated fatty acids, especially in cell membranes and cell structures, which ensures the preservation of their integrity and functional activity. In addition, vitamin E functions as a structural component of biological membranes. It protects membranes from oxidation forming molecular complexes with unsaturated fatty acids of phospholipids. Vitamin E is necessary for the synthesis of proteins containing thiol groups, contributes to the synthesis of coenzymes having thiol groups, especially coenzyme A. Tocopherol deficiency. A long-term deficiency of tocopherol leads to a E- vitamin deficiency, a characteristic feature of which is muscle weakness, impaired gonadal function, increased blood viscosity, impaired peripheral circulation, and destruction of red blood cells. With a lack of tocopherols, the permeability of cell membranes increases, which can lead to complete destruction of nuclei membranes, mitochondria and lysosomes. 267