From Big Medical Encyclopedia

STEROIDS — a numerous class of the natural, physiologically active connections containing a carbon skeleton of the hydrogenated tsiklopentanofenantren. Treat S. sex hormones (see), corticosteroids (see), sterols (see), bile acids (see), cardiac glycosides (see), vitamins of group D (see. Calciferols ), steroid saponins (see) and steroid alkaloids (see).

the Constitutional formula of a holestanol — the typical representative of steroids. The numbering system of provisions in a molecule of a steroid is shown: And, In and With — the condensed six-membered rings, D — pentatomic ring.

S.'s most are secondary alcohol and represent solid crystal matters, almost water-insoluble and quite well soluble in organic solvents. Various deputies are usually attached to the main cyclic group C. having different degree of a saturation; carbon atoms in the 10th and 13th provisions in all S.' molecules except for estrogen have methyl groups (fig). To carbon atom in the 3rd situation it is attached IT - or WITH - group, the carbon chain of various length is attached to carbon atom in the 17th situation: at corticosteroids it consists of 2 carbon atoms, at cardiac glycosides — from 4, at bilious to - t — from 5, at sterols — from 8 — 9. Almost all S. have one or several ON-GROUP and therefore can be called hydroxysteroids.

Pages are formed in animal and vegetable organisms, most of them possesses high biol. activity. Serves as the classical representative of a class C. at animals cholesterol (see), from to-rogo are formed steroid hormones (see) and bilious to - you. The sex hormones produced by ovaries belong to steroid hormones — is oestrogenic (see) and seed bubbles — androgens (see), and also corticosteroids (see), synthesized by adrenal glands. The molting hormone of insects belongs to steroid hormones also ekdizon. This S. is found also in plants. In large numbers ekdizon is poison for insects and, apparently, serves as means of their scaring away at plants. Nek-rye S., formed at amphibians and erinaceouses, are quite strong neuroparalytic poisons (batrakhotoksin, bufotoksin, goloturin And).

At the higher plants steroid glycosides — the saponins having properties of detergents are eurysynusic. The steroid alkaloids produced by plants make big group of connections, nitrogen atoms are attached to a steroid kernel to-rykh in different provisions. The solanidine which is present at a green peel and escapes of potatoes and doing them very poisonous belongs to number of steroid alkaloids. Contains in leaves of tomatoes tomatidin, having antibiotic properties. The alkaloid to-nessin emitted from a bush of Holarrhena is applied in India to treatment of amoebic dysentery. Ways of a biogenesis of saponins and steroid alkaloids are still insufficiently clear.

Bibliography: Metsler D. Biochemistry, the lane with English, t. 2, page 578, M., 1980; R about - e r t from D highways and To and with e r and about M. Fundamentals of organic chemistry, the lane with English, t. 2, page 558, M., 1978; Fizer L. and F and z e p M. Steroids, the lane with English, M., 1964; Heftman E. M. Biochemistry of steroids, the lane with English, M., 1972, bibliogr.

N. A. Yudayev.