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A series of 1- and 4-(2-naphthylmethyl)-1H-imidazoles (3 and 4) has been synthesized and evaluated as C17,20-lyase inhibitors. Several 6-methoxynaphthyl derivatives showed potent C17,20-lyase inhibition, suppression of testosterone biosynthesis in rats and reduction in the weight of prostate and seminal vesicles in rats, whereas most of these compounds increased the liver weight after consecutive administrations. The effect on the liver weight was removed by incorporation of a hydroxy group and an isopropyl group at the methylene bridge, as seen in (S)-28d and (S)-42. Selectivity for C17,20-lyase over 11β-hydroxylase is also discussed, and (S)-42 was found to be a more than 260-fold selective inhibitor. Furthermore, (S)-42 showed a potent suppression of testosterone biosynthesis after a single oral administration in monkeys. These data suggest that (S)-42 may be a promising agent for the treatment of androgen-dependent prostate cancer. [Copyright &y& Elsevier]

To clarify whether nitric oxide (NO) modifies high K+-evoked γ-aminobutyric acid (GABA) release, we examined the effects of sodium nitroprusside, an NO donor; diethyldithiocarbamate, an NO trapper; dithiothreitol, a superoxide radical scavenger; and 1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one, a specific guanylyl cyclase inhibitor, on high (100 mM) K+-evoked GABA release from rat hippocampus in vivo using microdialysis. Perfusion with 0.5 or 5 mM sodium nitroprusside significantly reduced high K+-evoked GABA release. Co-perfusion with 0.5 mM sodium nitroprusside and 5 mM diethyldithiocarbamate or 0.5 mM 1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one significantly enhanced high K+-evoked GABA release. Co-perfusion with 0.5 mM sodium nitroprusside and 1 mM dithiothreitol tended to increase it. These results demonstrate that sodium nitroprusside reduces high K+-evoked GABA release both via an NO/cyclic GMP-dependent pathway and via an NO-dependent, but cyclic GMP-independent, pathway in rat hippocampus in vivo. [Copyright &y& Elsevier]

To clarify the functions of nitric oxide (NO) induced by either neuronal NO synthase (nNOS) or endothelial NO synthase (eNOS) after transient cerebral ischemia, we investigated the effects of l-N5-(1-iminoethyl)ornithine (l-NIO), a relatively selective eNOS inhibitor, and 7-nitroindazole (7-NI), a relatively selective nNOS inhibitor, on hippocampal dysfunction caused by cerebral ischemia. We measured mean arterial blood pressure (MABP), hippocampal blood flow, direct current (DC) potential, CA1 population spike (PS) and extracellular concentrations of glutamate from rat hippocampus after transient forebrain ischemia, which was induced by four-vessel occlusion for 10 min. l-NIO (20 mg/kg) and 7-NI (25 mg/kg) were administered intraperitoneally 20 min before ischemia. l-NIO, but not 7-NI, increased MABP before, during and after ischemia, compared with the vehicle group. 7-NI, but not l-NIO, reduced the amplitude of anoxic depolarization induced by ischemia. 7-NI recovered the PS amplitude in part 60 min after ischemia. 7-NI, but not l-NIO, reduced the ischemia-induced levels of glutamate. These results indicate that nNOS inhibition with 7-NI improves, at least in part, hippocampal dysfunction after ischemia, while eNOS inhibition with l-NIO worsens it. [Copyright &y& Elsevier]

Abstract: Endogenous androgens play a role in the development and progression of prostate cancer (PC), thus androgen suppression may offer an effective therapeutic strategy for this disease. Orteronel (TAK-700), 6-[(7S)-7-hydroxy-6,7-dihydro-5H-pyrrolo[1,2-c]imidazol-7-yl]-N-methyl-2-naphthamide, is a novel, non-steroidal, selective inhibitor of the 17,20-lyase activity of CYP17A – a key enzyme in the production of steroidal hormones – and is being developed as a therapy for PC. The purpose of this study was to elucidate the inhibitory activity of orteronel, in particular its specificity for androgen synthesis enzymes, in male rats – an androgen-synthesis model that largely reflects this pathway in humans. Orteronel inhibited 17,20-lyase activity in rats with an IC50 of 1200nM but did not inhibit 17α-hydroxylase or 11β-hydroxylase (CYP11B1) activity in rats at concentrations up to 10μM. In cellular steroidogenesis assays using rat testicular cells, orteronel suppressed testosterone and androstenedione production with an IC50 of 640nM and 210nM, respectively, but did not suppress either corticosterone or aldosterone production in rat adrenal cells at concentrations up to 30μM. In addition, serum testosterone and androstenedione levels in human chorionic gonadotropin-injected hypophysectomized rats were significantly reduced by single oral administration of orteronel at a dose of 30mg/kg (both p ≤0.01); serum corticosterone and aldosterone levels in ACTH-injected hypophysectomized rats did not result in significant differences compared with controls, following orteronel administration at doses up to 300mg/kg. Serum testosterone levels in intact male rats were significantly reduced by orteronel 4h after dosing at 100mg/kg (p ≤0.01); testosterone levels showed a tendency to recover afterward. In intact male rats, the weight of the prostate glands and seminal vesicles was decreased in a dose-dependent manner following multiple doses of orteronel at 37.5, 150, and 600mg/kg, TID for 4 days. The reversibility of orteronel was further confirmed using a human adrenocortical tumor cell line. In summary, orteronel is a selective and reversible 17,20-lyase inhibitor, and decreases the weight of androgen-dependent organs in male rats. Our data suggests that orteronel would therefore be effective for androgen-dependent disorders such as PC. [Copyright &y& Elsevier]

An efficient stereocontrolled synthesis of the potent C17,20-lyase inhibitor, (1S)-1-(1H-imidazol-4-yl)-1-(6-methoxy-2-naphthyl)-2-methyl-1-propanol 1, has been established. The stereogenic center of 1 was successfully constructed by a highly diastereoselective Grignard reaction of 2, while a subsequent imidazole ring annulation afforded 1 in an enantiomerically pure form. The procedure enables a practical synthesis of 1 that can be conveniently carried out on a multigram scale. [Copyright &y& Elsevier]

Highlights: [•] Orteronel does not directly inhibit aromatase activity. [•] At ≥3mg/kg, orteronel significantly suppresses serum estradiol in female rats. [•] In female cynomolgus monkeys, orteronel suppressed the pre-luteal estradiol surge. [•] Orteronel was specific for 17,20-lyase activity. [ABSTRACT FROM AUTHOR]

Abstract: Surgical or pharmacologic methods to control gonadal androgen biosynthesis are effective approaches in the treatment of a variety of non-neoplastic and neoplastic diseases. For example, androgen ablation and its consequent reduction in circulating levels of testosterone is an effective therapy for advanced prostate cancers. Unfortunately, the therapeutic effectiveness of this approach is often temporary because of disease progression to the ‘castration resistant’ (CRPC) state, a situation for which there are limited treatment options. One mechanism thought to be responsible for the development of CRPC is extra-gonadal androgen synthesis and the resulting impact of these residual extra-gonadal androgens on prostate tumor cell proliferation. An important enzyme responsible for the synthesis of extra-gonadal androgens is CYP17A1 which possesses both 17,20-lyase and 17-hydroxylase catalytic activities with the 17,20-lyase activity being key in the androgen biosynthetic process. Orteronel (TAK-700), a novel, selective, and potent inhibitor of 17,20-lyase is under development as a drug to inhibit androgen synthesis. In this study, we quantified the inhibitory activity and specificity of orteronel for testicular and adrenal androgen production by evaluating its effects on CYP17A1 enzymatic activity, steroid production in monkey adrenal cells and human adrenal tumor cells, and serum levels of dehydroepiandrosterone (DHEA), cortisol, and testosterone after oral dosing in castrated and intact male cynomolgus monkeys. We report that orteronel potently suppresses androgen production in monkey adrenal cells but only weakly suppresses corticosterone and aldosterone production; the IC50 value of orteronel for cortisol was ∼3-fold higher than that for DHEA. After single oral dosing, serum levels of DHEA, cortisol, and testosterone were rapidly suppressed in intact cynomolgus monkeys. In castrated monkeys treated twice daily with orteronel, suppression of DHEA and testosterone persisted throughout the treatment period. In both in vivo models and in agreement with our in vitro data, suppression of serum cortisol levels following oral dosing was less than that seen for DHEA. In terms of human CYP17A1 and human adrenal tumor cells, orteronel inhibited 17,20-lyase activity 5.4 times more potently than 17-hydroxylase activity in cell-free enzyme assays and DHEA production 27 times more potently than cortisol production in human adrenal tumor cells, suggesting greater specificity of inhibition between 17,20-lyase and 17-hydroxylase activities in humans vs monkeys. In summary, orteronel potently inhibited the 17,20-lyase activity of monkey and human CYP17A1 and reduced serum androgen levels in vivo in monkeys. These findings suggest that orteronel may be an effective therapeutic option for diseases where androgen suppression is critical, such as androgen sensitive and CRPC. [Copyright &y& Elsevier]

To clarify whether nitric oxide (NO) modifies high K(+)-evoked gamma-aminobutyric acid (GABA) release, we examined the effects of sodium nitroprusside, an NO donor; diethyldithiocarbamate, an NO trapper; dithiothreitol, a superoxide radical scavenger; and 1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one, a specific guanylyl cyclase inhibitor, on high (100 mM) K(+)-evoked GABA release from rat hippocampus in vivo using microdialysis. Perfusion with 0.5 or 5 mM sodium nitroprusside significantly reduced high K(+)-evoked GABA release. Co-perfusion with 0.5 mM sodium nitroprusside and 5 mM diethyldithiocarbamate or 0.5 mM 1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one significantly enhanced high K(+)-evoked GABA release. Co-perfusion with 0.5 mM sodium nitroprusside and 1 mM dithiothreitol tended to increase it. These results demonstrate that sodium nitroprusside reduces high K(+)-evoked GABA release both via an NO/cyclic GMP-dependent pathway and via an NO-dependent, but cyclic GMP-independent, pathway in rat hippocampus in vivo.