RESUMO
The 17beta-hydroxysteroid dehydrogenases (17beta-HSDs) are involved in the last step of the biosynthesis of sex steroids from cholesterol. This family of steroidogenic enzymes constitutes an interesting target in the control of the concentration of estrogens and androgens. Among the isoforms of 17beta-HSD, type II preferentially catalyzes the oxidation of estradiol (E(2)), testosterone (T), dihydrotestosterone (DHT), and 20alpha-dihydroprogesterone (20alpha-DHP). Based on structure-activity relationship studies, we have developed steroidal spirolactones as inhibitors of type II 17beta-HSD using different steroid nuclei: a C18-steroid (lactones 1 and 10), an antiestrogenic nucleus (lactone 2), and a C19-steroid (lactone 28). We know these inhibitors are selective for type II 17beta-HSD as no or only weak inhibition was observed for types I and III. They also have no proliferative (androgenic) activity on androgen sensitive (AR(+)) Shionogi cells whereas their proliferative (estrogenic) activity on estrogen sensitive (ER(+)) ZR-75-1 cells depends on the nature of the steroid nucleus. Lactones 1 and 10 are weak estrogens, while lactones 2 and 28 do not exert estrogenic activity, in fact lactone 2 is an antiestrogen. Lactones 1, 2, 10 and 28 were also tested in an identical assay with a series of enzyme substrates, C19-steroid diols, and known inhibitors, for the oxidation of testosterone and estradiol into androstenedione and estrone, respectively. From this comparative study, the best inhibitors of type II 17beta-HSD (oxidase activity) were identified, but none of them were clearly more potent than the hydroxylated (reduced) forms of enzyme substrates, E2, T, and DHT. Such inhibitors remain, however, useful tools to, (1) further elucidate the role of type II 17beta-HSD, and (2) regulate the level of active estrogens, androgens and progesterone.
Assuntos
17-Hidroxiesteroide Desidrogenases/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Isoenzimas/antagonistas & inibidores , 17-Hidroxiesteroide Desidrogenases/genética , Linhagem Celular , Di-Hidrotestosterona/metabolismo , Inibidores Enzimáticos/química , Estradiol/química , Estradiol/metabolismo , Feminino , Humanos , Isoenzimas/genética , Rim , NADP/farmacologia , Placenta/enzimologia , Proteínas Recombinantes/antagonistas & inibidores , Espironolactona/química , Espironolactona/farmacologia , Esteroides/química , Esteroides/farmacologia , Relação Estrutura-Atividade , Testosterona/metabolismo , TransfecçãoRESUMO
Five dehydrated compounds obtained from a tert-butyldimethylsilylchloride/imidazole or an aqueous hydrochloric acid treatment of 17 alpha-butyl-3-O-methyl estradiol in refluxing solvent were purified and characterized. Three compounds were obtained from a direct vicinal proton elimination, the two others from a vicinal elimination after migration of methyl-18. Depending on the treatment, the proportions of dehydrated compounds are different. In addition, a general profile of experimental conditions providing a similar mixture of dehydrated compounds was also established for this steroid-hindered 17 beta-tertiary alcohol.