Novel Steroidal Inhibitors of Human Cytochrome P45017α (17α-Hydroxylase-C17,20-lyase): Potential Agents for the Treatment of Prostatic Cancer

Article abstract of DOI:10.1021/jm00013a022

Steroidal compounds having a 17-(3-pyridyl) substituent together with a 16,17-double bond have been synthesized, using a palladium-catalyzed cross-coupling reaction of a 17-enol triflate with diethyl(3-pyridyl)borane, which are potent inhibitors of human testicular 17α-hydroxylase-C_17,20-lyase.The requirement for these structural features is stringent: compounds having 2-pyridyl (9), 4-pyridyl (10), or 2-pyridylmethyl (11) substituents instead of the 3-pyridyl substituent were either poor inhibitors or noninhibitory.Reduction of the 16,17-double bond to give 17β-pyridyl derivatives diminished potency with 3-pyridyl substitution (3<*>27; IC50 for lyase, 2.9<*>23 nM) but increased it with a 4-pyridyl substituent present (10<*>28; IC50 1 μM<*>53 nM).In contrast, a variety of substitution patterns in rings A-C of the steroid skeleton afforded inhibitors having potencies similar to those most closely related structurally to the natural substrates pregnenolone and progesterone, respectively 17-(3-pyridyl)androsta-5,16-dien-3β-ol (3, K_iapp < 1 nM; IC50 for lyase, 2.9 nM) and 17-(3-pyridyl)androsta-4,16-dien-3-one (15; IC50 for lyase, 2.1 nM).Thus compounds having variously aromatic ring A (18), saturated rings A/B (21,22), and oxygenated ring C (26) exhibited IC50 values for lyase (1.8-3.0 nM) falling within a 2-fold range.The most potent compounds are candidates for development as drugs for the treatment of hormone-dependent prostatic carcinoma.