Norsteroid
Norsteroids are a structural class of steroids that have had an atom or atoms removed, biosynthetically or synthetically, from positions of branching off of rings or side chains, or from within rings of the steroid ring system. For instance, 19-norsteroids constitute an important class of natural and synthetic steroids derived by removal of the methyl group of the natural product progesterone; the equivalent change between testosterone and 19-nortestosterone is illustrated below.Examples
Norsteroid examples include: 19-norpregnane, desogestrel, ethylestrenol, etynodiol diacetate, ethinylestradiol, gestrinone, levonorgestrel, norethisterone, norgestrel, norpregnatriene, quinestrol, 19-norprogesterone, Nomegestrol acetate, 19-nortestosterone, and norethisterone acetate.
