RESUMO
Recent studies have demonstrated the antiproliferative and cytotoxic effects of aza-steroids and steroidal sapogenins on human cancer cell lines. The scientific community has shown a growing interest in these compounds as drug candidates for cancer treatment. In the current work, we report the synthesis of new diosgenin oxime derivatives as potential antiproliferative agents. From (25 R)-5α-spirost-3,5,6-triol (1), a diosgenin derivative, ketones 2, 3, 4, and 9 were obtained and used as precursors of the new oximes. A condensation reaction was carried out between the steroidal ketones (2, 3, 4, and 9) with hydroxylamine hydrochloride in 2,4,6-trimethylpyridine to produce five spirostanic oximes (four of them are not reported before) with a 42-96% yield. Also, a new spirostanic α, ß-unsaturated cyanoketone was synthesized via Beckmann fragmentation using thionyl chloride with a 62% yield. Furthermore, we proposed a reaction mechanism with the aim of explaining such transformation.
Assuntos
Antineoplásicos , Diosgenina , Humanos , Cianocetona , Diosgenina/farmacologia , Esteroides/farmacologia , Antineoplásicos/farmacologia , Oximas/farmacologia , Cetonas/farmacologiaRESUMO
Several studies indicate that wild free-living vertebrates seasonally regulate plasma glucocorticoids. However, not only glucocorticoids but also the amount of receptors is important in determining biological responses. In this context, seasonal regulation of glucocorticoid receptor (GR) is crucial to modulate the response to glucocorticoids. Rhinella arenarum is an anuran exhibiting seasonal variations in plasma glucocorticoids and also in the number of binding sites (B(max)) of the testicular cytosolic GR. In this work, we evaluated if the annual pattern of GR protein in the testis varies seasonally and, by an in vitro approach, the role of glucocorticoids, androgens, and melatonin in the regulation of the GR B(max) and protein level. For this purpose, testes were treated with two physiological concentrations of melatonin (40 and 200 pg/ml), with or without luzindole (melatonin-receptor antagonist); with testosterone, cyanoketone (inhibitor of steroidogenesis) or casodex (androgen-receptor antagonist); or with dexamethasone or RU486 (GR antagonist). After treatments, B(max) and protein level were determined by the binding of [(3)H]dexamethasone and Western blot, respectively. Results showed that GR protein decreases in the winter. The in vitro treatment with melatonin produced a biphasic effect on the B(max) with the lowest concentration decreasing this parameter by a receptor-mediated mechanism. However, melatonin had no effect on the GR protein level. Conversely, a high concentration of dexamethasone up-regulated the GR protein and androgens neither changed the B(max) nor the protein level. These findings suggest that seasonal changes in plasma melatonin and glucocorticoids modulate the effect of glucocorticoids in the testis of R. arenarum.
Assuntos
Bufo marinus/metabolismo , Glucocorticoides/metabolismo , Receptores de Glucocorticoides/metabolismo , Testículo/metabolismo , Anilidas/farmacologia , Animais , Sítios de Ligação , Western Blotting/veterinária , Cianocetona/farmacologia , Dexametasona/farmacologia , Regulação da Expressão Gênica , Glucocorticoides/sangue , Técnicas In Vitro , Cinética , Masculino , Melatonina/metabolismo , Melatonina/farmacologia , Mifepristona/farmacologia , Nitrilas/farmacologia , Distribuição Aleatória , Receptores de Glucocorticoides/genética , Estações do Ano , Testículo/efeitos dos fármacos , Testosterona/metabolismo , Testosterona/farmacologia , Compostos de Tosil/farmacologia , Triptaminas/farmacologiaRESUMO
Testis fragments from Bufo arenarum were incubated with [7(n)-(3)H]pregnenolone (P5), [1,2-(3)H]dehydroepiandrosterone (DHEA) and [1,2,6.7-(3)H]testosterone (T), and different steroid-biosynthesis inhibitors. The inhibitors used were: cyanoketone (CNK), spironolactone (SPNL) and finasteride (FIN). CNK significantly increased the recovery of 3beta-hydroxy-5-ene steroids while SPNL reduced the metabolism of P5 and the production of C19-steroids. The metabolism of C19-substrates was only modified by CNK, which reduced the transformation of DHEA without modifying the metabolism of T. To determine the degree of inhibition exerted by the inhibitors used, the activities of the enzymes were estimated as the percentage of their contribution to the total steroid metabolism. CNK strongly inhibited the activity of hydroxysteroid dehydrogenase/isomerase if its contribution was estimated using both P5 and DHEA. If the analysis was made considering both activities associated to cytochrome P450 17chi-hydroxylase, C17-20 lyase (P450c17), it became evident that SPNL inhibited both of them. The percent contribution of 17beta-hydroxysteroid dehydrogenase (17betaHSD) activity diminished in the presence of CNK only if it was estimated considering P5 and DHEA metabolism. SPNL produced a significant inhibition of 17betaHSD when its contribution was estimated considering P5 metabolism. However, SPNL was insufficient if DHEA or T were considered. The effect of SPNL on the contribution of 17betaHSD could be due to the reduction of C19-substrates. The activity of 5chi-reductase was inhibited by CNK only if results from P5 and DHEA were considered.
Assuntos
Antagonistas de Androgênios/farmacologia , Androgênios/biossíntese , Bufonidae/metabolismo , Cianocetona/farmacologia , Inibidores Enzimáticos/farmacologia , Finasterida/farmacologia , Espironolactona/farmacologia , Testículo/metabolismo , 17-Hidroxiesteroide Desidrogenases/metabolismo , Animais , Colestenona 5 alfa-Redutase , Desidroepiandrosterona/farmacologia , Masculino , Oxirredutases/metabolismo , Pregnenolona/farmacologia , Esteroide 17-alfa-Hidroxilase/metabolismo , Testosterona/farmacologiaRESUMO
This study employed an in vitro system to identify potential steroidal mediators of spermiation in Bufo arenarum. Testicular fragments were incubated for 2 h at 28 degrees. Spermiation was induced by 10 IU human chorionic gonadotropin (hCG) and the effect of different inhibitors of steroid biosynthesis was analyzed. Cyanoketone (10(-5)-10(-6) M), an inhibitor of 3-oxo-4-ene steroid biosynthesis, did not block hCG-inducing activity even when biosynthesis of 3-oxo-4-ene steroids and its reduced metabolites was inhibited by 95%. Aminogluthetimide at a concentration that inhibited testosterone biosynthesis (10(-4) and 10(-5) M) did not alter hCG actions. Similar results were obtained with spironolactone, an inhibitor of 17alpha-hydroxylase/17-20 lyase activity. No spermiation-inducing activity was found with different steroids (progesterone, 17-hydroxypregnenolone, 17, 20alpha/beta-dihydroxy-4-pregnene-3-one, estradiol, testosterone, etc.). It is concluded that spermiation induced by hCG is not steroid mediated in B. arenarum.
Assuntos
Bufo arenarum/fisiologia , Gonadotropina Coriônica/farmacologia , Espermatogênese/efeitos dos fármacos , Esteroides/biossíntese , 3-Hidroxiesteroide Desidrogenases/antagonistas & inibidores , Aminoglutetimida/farmacologia , Androgênios/farmacologia , Animais , Enzima de Clivagem da Cadeia Lateral do Colesterol/antagonistas & inibidores , Cianocetona/farmacologia , Inibidores Enzimáticos/farmacologia , Masculino , Progesterona/farmacologia , Espironolactona/farmacologia , Esteroide 17-alfa-Hidroxilase/antagonistas & inibidores , Esteroides/antagonistas & inibidores , Esteroides/farmacologia , Testículo/efeitos dos fármacos , Testículo/metabolismo , Testosterona/biossínteseRESUMO
The first section of this publication summarizes early work according to which 5 beta-pregnanedione is an important metabolite of progesterone in the early stages of the chick embryo's adrenal steroidogenesis, then decreasing gradually as corticosteroidogenesis increases. In the second section a model is described in which adrenal 3 beta-ol hydroxylase-isomerase of the 17-day-old chicken is suppressed pharmacologically, this suppression being correlated with that of the synthesis of aminoevulinic acid (ALA), the first and rate-limiting step of the heme pathway. 5 beta-Pregnanedione (10(-7)-10(-6) M) restored ALA synthesis in this inhibited model to normal values. The effect of 5 beta-pregnanedione was specific since other steroids tested: progesterone; 5 alpha-pregnanedione; corticosterone or estradiol, did not stimulate ALA. Since heme formation by steroidogenic glands contributes to the synthesis of cytochrome P450 rather than hemoglobin, 5 beta-pregnanedione was also assayed as a stimulator of this enzyme system and was found to increase cytochrome P450 in adrenals and testes but not in the liver. In view of these results a hypothesis is advanced according to which 5 beta-reduced progestagens and androgens stimulate cytochrome P450 formation, i.e. the synthesis of progesterone and higher hydroxylated steroids, by steroidogenic glands in the event of an excessive precursor reduction.