NORSTEROIDA — the synthetic steroids differing from natural in absence in a carbon skeleton of a molecule of one or several carbon atoms; in medicine are applied as the pharmaceuticals having anabolic or gestagenny properties; in biochemistry are used during the studying of activity or the mechanism of effect of steroid hormones.
In names H. it is specified or sequence number of the absent carbon atom during its removal from a side chain of a molecule of a steroid or angular (angular) methyl group (e.g., 19-nortestosteron), or the Latin letter designates a ring of a steroid, from to-rogo carbon atom is removed (e.g., B-norprogesteron).
The main ways of receiving N. are chemical transformation of natural steroids and directed full, i.e. without use of natural substrates, chemical synthesis. Their synthesis by recovery of an aromatic ring is widely applied to receiving practically the most important 19-norsteroid estrogen (see).
On physical. - to chemical properties H. are so similar to natural to steroids (see) that their belonging to group H. can be defined with absolute reliability studying of structure of a molecule by spectral methods, especially by methods nuclear magnetic resonance (see) and massspektrometriya (see). N significantly differ from natural steroids on hormonal activity. The removal of 19-methyl group of a molecule of steroids leading to formation of 19-norsteroid usually considerably strengthens anabolic (see. Anabolic steroids ), gestagenny (see. Progestins ) and mineralokortikoidny (see. Mineralokortikoidny hormones ) action of a steroid, but does not influence on androgenic (see. Androgens ) and glucocorticoids its action (see. Glucocorticoid hormones ), sometimes only weakening it. Removal of carbon atoms from carbon rings of a molecule of a steroid often changes hormonal activity of connection, leading to education anti-hormones (see). So, V-norprogesteron has antigestagenny activity.
The mechanism biol, N.'s actions consists in interaction with the same receptor proteins of target bodies of an organism, with to-rymi native steroids interact. The increased affinity to protein receptor at preservation biol, a steroid - a receptor complex results functions in higher hormonal activity of N. in comparison with a natural steroid of similar action; if the complex of a receptor with N. is biologically not active, blockade of a receptor results in anti-hormonal effect. In N.'s medicine in drugs of anabolic and gestagenny action as an effective agent derivatives of 19-norsteroid with additional modification of their chemical structure by etherification of alkylation, etc. for giving to the received drugs of properties of prolongation and peroral activity are generally used.
Hormonal drugs of anabolic action on the basis of 19-norsteroid have especially low androgenic effect; treat such drugs Phenobolinum (see) and retabolil (see), 17 - alpha and ethylated derivative a 19-nortestosterona — nilevar and dehydrogenated derivative a 19-nortestosterona — a triyenbolona acetate. The majority of contraceptive drugs (see. Contraceptives ) contain in quality gestagenny components 17 - alpha etilinirovannye derivatives of a 19-nortestosteron: a noretynodrel — in the drug Infecundinum, an etinodiola diacetate — in drug Bisecurinum and Norethisteronum — in drug Micronorum.
Bibliography: Akhrem A. A. and Titov of Yu. A. Himiya of 19-norsteroid, Usp. chemistry, t. 33, century 2, page 151, 1964, bibliogr.; P and in N and c to and y K. K. Anabolic steroid hormones, Probl, endocrinins., t. 20, No. 4, page 111, 1974; F from e r L. and F and z e r M. Steroids, the lane with English, page 602, 704, M., 1964; E d g-г e n R. A. a. o. Biological effects of synthetic conanes, in book: Recent progr. hormone res., ed. by G. Pincus, v. 22, p. 305, N. Y., 1966.
K. K. Pivnitsky.