Discovery of 1,8-naphthyridin-2-one derivative as a potent and selective sphingomyelin synthase 2 inhibitor.

Sphingomyelin synthase 2 (SMS2) has attracted attention as a drug target for the treatment of various cardiovascular and metabolic diseases. The modification of a high throughput screening hit, 2-quinolone 10, enhanced SMS2 inhibition at nanomolar concentrations with good selectivity against SMS1. To improve the pharmaceutical properties such as passive membrane permeability and aqueous solubility, adjustment of lipophilicity was attempted and 1,8-naphthyridin-2-one 37 was identified as a potent and selective SMS2 inhibitor. A significant reduction in hepatic sphingomyelin levels following repeated treatment in mice suggested that compound 37 could be an effective in vivo tool for clarifying the role of SMS2 enzyme and developing the treatment for SMS2-related diseases.

Design, synthesis, and biological evaluation of 4-phenylpyrrole derivatives as novel androgen receptor antagonists.

A series of 4-phenylpyrrole derivatives D were designed, synthesized, and evaluated for their potential as novel orally available androgen receptor antagonists therapeutically effective against castration-resistant prostate cancers. 4-Phenylpyrrole compound 1 exhibited androgen receptor (AR) antagonistic activity against T877A and W741C mutant-type ARs as well as wild-type AR. An arylmethyl group incorporated into compound 1 contributed to enhancement of antagonistic activity. Compound 4n, 1-{[6-chloro-5-(hydroxymethyl)pyridin-3-yl]methyl}-4-(4-cyanophenyl)-2,5-dimethyl-1H-pyrrole-3-carbonitrile exhibited inhibitory effects on tumor cell growth against the bicalutamide-resistant LNCaP-cxD2 cell line as well as the androgen receptor-dependent JDCaP cell line in a mouse xenograft model. These results demonstrate that this series of pyrrole compounds are novel androgen receptor antagonists with efficacy against prostate cancer cells, including castration-resistant prostate cancers such as bicalutamide-resistant prostate cancer.

17,20-lyase inhibitors. Part 4: design, synthesis and structure-activity relationships of naphthylmethylimidazole derivatives as novel 17,20-lyase inhibitors.

A novel series of naphthylmethylimidazole derivatives and related compounds have been investigated as selective 17,20-lyase inhibitors. Optimization of the substituent at the 6-position on the naphthalene ring was performed to yield a methylcarbamoyl derivative, which exhibited potent inhibitory activity against human 17,20-lyase and promising selectivity (>200-fold) for 17,20-lyase over CYP3A4. Further modifications of the methylcarbamoyl derivative led to the discovery of the corresponding tricyclic compound, which showed highly potent activity against human 17,20-lyase (IC(50) 19 nM) and good selectivity (>1000-fold) for inhibition of 17,20-lyase over CYP3A4. Additional biological evaluation revealed that the tricyclic compound had potent in vivo efficacy in monkeys and favorable pharmacokinetic profiles when administered in rats. Asymmetric synthesis of the selective tricyclic inhibitor was also achieved using a chiral α-hydroxy ketone.

17,20-Lyase inhibitors. Part 3: Design, synthesis, and structure-activity relationships of biphenylylmethylimidazole derivatives as novel 17,20-lyase inhibitors.

A novel series of biphenylylmethylimidazole derivatives and related compounds were synthesized as inhibitors of 17,20-lyase, a key enzyme in the production of steroid hormones, and their biological activities were evaluated. In an attempt to identify potent and selective inhibitors of 17,20-lyase over the related CYP3A4 enzyme, a homology model for human 17,20-lyase was developed using the X-ray crystallographic structure of the mammalian CYP2C5 enzyme. With the aid of molecular modeling, optimization of the biphenyl moiety was performed to give an acetamide derivative, which was resolved by HPLC to give the active (-)-enantiomer. The obtained active enantiomer showed not only potent inhibition of both rat and human 17,20-lyase,with IC(50) values of 14 and 26 nM, respectively, but also excellent selectivity (>300-fold) for inhibition of 17,20-lyase over CYP3A4. Moreover, the active enantiomer significantly reduced both serum testosterone and DHEA concentrations in a monkey model after single oral administration. Asymmetric synthesis of the active enantiomer was also developed via a chiral intermediate using a diastereoselective Grignard reaction.

Discovery of orteronel (TAK-700), a naphthylmethylimidazole derivative, as a highly selective 17,20-lyase inhibitor with potential utility in the treatment of prostate cancer.

A novel naphthylmethylimidazole derivative 1 and its related compounds were identified as 17,20-lyase inhibitors. Based on the structure-activity relationship around the naphthalene scaffold and the results of a docking study of 1a in the homology model of 17,20-lyase, the 6,7-dihydro-5H-pyrrolo[1,2-c]imidazole derivative (+)-3c was synthesized and identified as a potent and highly selective 17,20-lyase inhibitor. Biological evaluation of (+)-3c at a dose of 1mg/kg in a male monkey model revealed marked reductions in both serum testosterone and dehydroepiandrosterone concentrations. Therefore, (+)-3c (termed orteronel [TAK-700]) was selected as a candidate for clinical evaluation and is currently in phase III clinical trials for the treatment of castration-resistant prostate cancer.

Discovery of 3,5-Diphenyl-4-methyl-1,3-oxazolidin-2-ones as Novel, Potent, and Orally Available Δ-5 Desaturase (D5D) Inhibitors.

The discovery and optimization of Δ-5 desaturase (D5D) inhibitors are described. Investigation of the 1,3-oxazolidin-2-one scaffold was inspired by a pharmacophore model constructed from the common features of several hit compounds, resulting in the identification of 3,5-diphenyl-1,3-oxazolidin-2-one 5h as a novel lead showing potent in vitro activity. Subsequent optimization focused on the modification of two metabolic sites, which provided (4S,5S)-5i, a derivative with improved metabolic stability. Moreover, adding a substituent into the upper phenyl moiety further enhanced the intrinsic activity, which led to the discovery of 5-[(4S,5S)-5-(4fluorophenyl)-4-methyl-2-oxo-1,3-oxazolidin-3-yl]benzene-1,3-dicarbonitrile (4S,5S)-5n, endowed with excellent D5D binding affinity, cellular activity, and high oral bioavailability in a mouse. It exhibited robust in vivo hepatic arachidonic acid/dihomo-γ-linolenic acid ratio reduction (a target engagement marker) in an atherosclerosis mouse model. Finally, an asymmetric synthetic procedure for this compound was established.

Identification of benzoxazin-3-one derivatives as novel, potent, and selective nonsteroidal mineralocorticoid receptor antagonists.

Mineralocorticoid receptor (MR) blockade has come into focus as a promising approach for the treatment of cardiovascular diseases such as hypertension and congestive heart failure. In order to identify a novel class of nonsteroidal MR antagonists that exhibit significant potency and good selectivity over other steroidal hormone receptors, we designed a novel series of benzoxazin-3-one derivatives and synthesized them from 6-(7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-yl)-2H-1,4-benzoxazin-3(4H)-one (1a), high-throughput screening (HTS) hit compound. Our design was based on a crystal structure of an MR/compound complex and a docking model. In the course of lead generation from 1a, a 1,2-diaryl framework was characterized as a key structure with high binding affinity. On the basis of scaffold hopping and optimization studies, benzoxazin-3-one derivatives possessing 1-phenyl-3-trifluoromethylpyrazol-5-yl moiety at the 6-position were identified as a novel series of potent and selective MR antagonists. Among these compounds, 6-[1-(4-fluoro-2-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-5-yl]-2H-1,4-benzoxazin-3(4H)-one (14n) showed highly potent activity and good selectivity and also exhibited a significant antihypertensive effect in deoxycorticosterone acetate-salt hypertensive rats. On the basis of these results, compound 14n was progressed for further pharmacological evaluation.

C(17,20)-lyase inhibitors. Part 2: design, synthesis and structure-activity relationships of (2-naphthylmethyl)-1H-imidazoles as novel C(17,20)-lyase inhibitors.

A series of 1- and 4-(2-naphthylmethyl)-1H-imidazoles (3 and 4) has been synthesized and evaluated as C(17,20)-lyase inhibitors. Several 6-methoxynaphthyl derivatives showed potent C(17,20)-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 C(17,20)-lyase over 11beta-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.

C17,20-lyase inhibitors I. Structure-based de novo design and SAR study of C17,20-lyase inhibitors.

Novel nonsteroidal C(17,20)-lyase inhibitors were synthesized using de novo design based on its substrate, 17 alpha-hydroxypregnenolone, and several compounds exhibited potent C(17,20)-lyase inhibition. However, in vivo activities were found to be short-lasting, and in order to improve the duration of action, a series of benzothiophene derivatives were evaluated. As a result, compounds 9h, (S)-9i, and 9k with nanomolar enzyme inhibition (IC(50)=4-9 nM) and 9e (IC(50)=27 nM) were identified to have powerful in vivo efficacy with extended duration of action. The key structural determinants for the in vivo efficacy were demonstrated to be the 5-fluoro group on the benzothiophene ring and the 4-imidazolyl moiety. Superimposition of 9k and 17 alpha-hydroxypregnenolone demonstrated their structural similarity and enabled rationalization of the pharmacological results. In addition, selected compounds were also identified to be potent inhibitors of human enzyme with IC(50) values of 20-30 nM.

TAK-599, a novel N-phosphono type prodrug of anti-MRSA cephalosporin T-91825: synthesis, physicochemical and pharmacological properties.

Crystalline 1 (TAK-599) is a novel N-phosphono prodrug of anti-methicillin-resistant Staphylococcus aureus (MRSA) cephalosporin 2a (T-91825) that has high affinity for penicillin-binding protein (PBP) 2' (IC(50); 0.90 microg/mL) and shows potent in vitro anti-MRSA activity (MIC against MRSA N133; 1.56 microg/mL), comparable to that of vancomycin (1.56 microg/mL). Although 2a had insufficient water solubility (2.3 mg/mL) for parenteral administration, 1 showed excellent water solubility (>100 mg/mL, pH 7) as well as good chemical stability in the solid state and solution. In pharmacokinetic studies, when 1 was administered intravenously to rats and monkeys, it was rapidly converted into 2a in the blood. These results show that 1 (TAK-599) is a highly promising parenteral cephalosporin targeted for MRSA infection.