Synthesis and pharmacological evaluation of 1-alkyl-N-[(1R)-1-(4-fluorophenyl)-2-methylpropyl]piperidine-4-carboxamide derivatives as novel antihypertensive agents

We synthesized and evaluated inhibitory activity against T-type Ca(2+) channels for a series of 1-alkyl-N-[(1R)-1-(4-fluorophenyl)-2-methylpropyl]piperidine-4-carboxamide derivatives. Structure-activity relationship studies have revealed that the isopropyl substituent at the benzylic position plays an important role in exerting potent inhibitory activity, and the absolute configuration of the benzylic position was found to be opposite that of mibefradil, which was first launched as a new class of T-type Ca(2+) channel blocker. Oral administration of N-[(1R)-1-(4-fluorophenyl)-2-methylpropyl]-1-[2-(3-methoxyphenyl)ethyl]piperidine-4-carboxamide (17f) lowered blood pressure in spontaneously hypertensive rats without inducing reflex tachycardia, an adverse effect often caused by traditional L-type Ca(2+) channel blockers.

Novel 7H-pyrrolo[2,3-d]pyrimidine derivatives as potent and orally active STAT6 inhibitors

Signal transducers and activators of transcription 6 (STAT6) is an important transcription factor in interleukin (IL)-4 signaling pathway and a key regulator of the type 2 helper T (Th2) cell immune response. Therefore, STAT6 may be an excellent therapeutic target for allergic conditions, including asthma and atopic diseases. Previously, we reported 4-aminopyrimidine-5-carboxamide derivatives as STAT6 inhibitors. To search for novel STAT6 inhibitors, we synthesized fused bicyclic pyrimidine derivatives and identified a 7H-pyrrolo[2,3-d]pyrimidine derivative as a STAT6 inhibitor. Optimization of the pyrrolopyrimidine derivatives led to identification of 2-[4-(4-{[7-(3,5-difluorobenzyl)-7H-pyrrolo[2,3-d]pyrimidin-2-yl]amino}phenyl)piperazin-1-yl]acetamide (24, AS1810722) which showed potent STAT6 inhibition and a good CYP3A4 inhibition profile. Compound 24 also inhibited in vitro Th2 differentiation without affecting type 1 helper T (Th1) cell differentiation and eosinophil infiltration in an antigen-induced mouse asthmatic model after oral administration.

Synthesis and structure-activity relationships of amide derivatives of (4,4-difluoro-1,2,3,4-tetrahydro-5H-1-benzazepin-5-ylidene)acetic acid as selective arginine vasopressin V2 receptor agonists

A series of (4,4-difluoro-1,2,3,4-tetrahydro-5H-1-benzazepin-5-ylidene)acetamide derivatives was synthesized, and their structure-activity relationships were examined in order to identify potent and selective arginine vasopressin V(2) receptor agonists. Attempts to substitute other chemical groups in place of the 2-pyridilmethyl moiety of 1a led to the discovery that potent V(2) binding affinity could be obtained with a wide range of functional groups. This structural tolerance allowed for the manipulation of other attributes, such as selectivity against V(1a) receptor affinity or avoidance of the undesirable inhibition of cytochrome P450 (CYP), without losing potent affinity for the V(2) receptor. Some representative compounds obtained in this study were also found to decrease urine volume in awake rats.

Prodrug-based design, synthesis, and biological evaluation of N-benzenesulfonylpiperidine derivatives as novel, orally active factor Xa inhibitors

We describe here our investigation of a new series of orally active fXa inhibitors based on a prodrug strategy. Solid-phase parallel synthesis identified a unique series of fXa inhibitors with a substituted benzenesulfonyl group as a novel S4 binding element. This series resulted in compound 39, which exhibited potent inhibitory activity against fXa (IC50 = 13 nM) and excellent selectivity over thrombin (>7000-fold). The masking of its highly hydrophilic groups led to the creation of related prodrug 28, which demonstrated an anticoagulant effect after oral dosing.

Synthesis and biological evaluation of pyrido[3',2':4,5]furo[3,2-d]pyrimidine derivatives as novel PI3 kinase p110alpha inhibitors

4-Morpholin-4-ylpyrido[3',2':4,5]thieno[3,2-d]pyrimidine 2a was discovered in our chemical library as a novel p110alpha inhibitor with an IC(50) of 1.4 microM. By structural modification of 2a, the 2-aryl-4-morpholinopyrido[3',2':4,5]furo[3,2-d]pyrimidine derivative 10e was discovered as a p110alpha inhibitor with approximately 400-fold greater potency than 2a. Evaluation of isoform selectivity showed that 10e is a potent inhibitor of p110beta. Furthermore, 10e showed anti-proliferative activity in various cell lines, including multi-drug resistant MCF7/ADR-res cells, and was effective against HeLa human cervical tumor xenografts in nude mice.

Potent and selective TF/FVIIa inhibitors containing a neutral P1 ligand

Inhibition of tissue factor/factor VIIa complex (TF/FVIIa) is an attractive strategy for antithrombotic therapies. We began with an investigation of a non-amidine TF/FVIIa inhibitor based on a modification of amidine compound 1. Optimization of the substituents on the P1 phenyl portion of the compound 1 led to a neutral or less basic alternative for the 4-amidinophenyl moiety. By further optimization of the substituents on the central phenyl ring, a highly potent and selective TF/FVIIa inhibitor 17d was discovered.

Synthesis and biological evaluation of 4-morpholino-2-phenylquinazolines and related derivatives as novel PI3 kinase p110alpha inhibitors

A series of 4-morpholino-2-phenylquinazolines and related derivatives were prepared and evaluated as inhibitors of PI3 kinase p110alpha. In this series, the thieno[3,2-d]pyrimidine derivative 15e showed the strongest inhibitory activity against p110alpha, with an IC(50) value of 2.0 nM, and inhibited proliferation of A375 melanoma cells with an IC(50) value of 0.58 microM. Moreover, 15e was found to be selective for p110alpha over other PI3K isoforms and protein kinases, making it the first example of a selective PI3K p110alpha inhibitor.

Novel potent and selective calcium-release-activated calcium (CRAC) channel inhibitors. Part 2: Synthesis and inhibitory activity of aryl-3-trifluoromethylpyrazoles

To identify potent and selective calcium-release-activated calcium (CRAC) channel inhibitors, we examined the structure-activity relationships of the pyrazole and thiophene moieties in compound 4. Compound 25b was found to exhibit highly potent and selective inhibitory activity for CRAC channels and further modifications of the pyrazole and benzoyl moieties of compound 25b produced compound 29. These compounds were potent inhibitors of IL-2 production in vitro and also acted as inhibitors in pharmacological models of diseases resulting from T-lymphocyte activation, after oral administration.

Novel potent and selective calcium-release-activated calcium (CRAC) channel inhibitors. Part 1: synthesis and inhibitory activity of 5-(1-methyl-3-trifluoromethyl-1H-pyrazol-5-yl)-2-thiophenecarboxamides

We synthesized and evaluated a series of 5-(1-methyl-3-trifluoromethyl-1H-pyrazol-5-yl)-2-thiophenecarboxamides to identify potent inhibitors of calcium-release-activated calcium (CRAC) channels with greater selectivity than voltage-operated calcium (VOC) channels. These efforts resulted in identification of compounds 22 and 24. The former exhibits highly potent and selective CRAC channel inhibitory activity, and the latter inhibited phytohemagglutinin-induced interleukin-2 production by Jurkat T lymphocytes and concanavalin A-induced hepatitis in mice.

(+)-(2R,5S)-4-[4-Cyano-3-(trifluoromethyl)phenyl]-2,5-dimethyl-N-[6-(trifluoromethyl)pyridin-3- yl]piperazine-1-carboxamide (YM580) as an Orally Potent and Peripherally Selective Nonsteroidal Androgen Receptor Antagonist

A novel series of trans-N-aryl-2,5-dimethylpiperazine-1-carboxamide derivatives was synthesized and their androgen receptor (AR) antagonist activities and in vivo antiandrogenic effects were evaluated. Pharmacological assays indicated that compound 33 was a potent AR antagonist, and subsequent optical resolution provided (+)-(2R,5S)-4-[4-cyano-3-(trifluoromethyl)phenyl]-2,5-dimethyl-N-[6-(trifluoromethyl)pyridin-3-yl]piperazine-1-carboxamide (33a, YM580) which exhibited the most potent antiandrogenic activity. Unlike bicalutamide, compound 33a decreased the weight of rat ventral prostate in a dose-dependent manner (ED(50) = 2.2 mg/kg/day), and induced the maximum antiandrogenic effect, comparable to that of surgical castration, without significantly affecting serum testosterone levels. Compound 33a is a promising clinical candidate for prostate cancer monotherapy.

Synthetic studies on novel Syk inhibitors. Part 1: Synthesis and structure–activity relationships of pyrimidine-5-carboxamide derivatives

Spleen tyrosine kinase (Syk) is a non-receptor-type tyrosine kinase which mediates diverse responses in haematopoietic cells. Therefore, Syk is an attractive therapeutic target, and in a study of Syk inhibitors as potentially new therapeutic agents, we discovered the 4-anilinopyrimidine-5-carboxamides. Enzyme screening indicated that an aminoethylamino moiety at the 2-position of the pyrimidine ring was important for Syk inhibitory activity, and an investigation of the substituents at the 4-position revealed that an anilino moiety substituted at the meta position was preferred. These compounds showed high selectivity for Syk, compared to other kinases, such as ZAP-70, c-Src, and PKC, and exhibited good inhibitory activities against 5-HT release from RBL-cells. Among them, compound 9a inhibited the passive cutaneous anaphylaxis reaction in mice, with an ID50 of 13 mg/kg following subcutaneous administration. These results suggest that our compounds are worthy of further evaluation as new anti-allergic agents.

Synthesis and biological activity of novel 1,2-disubstituted benzene derivatives as factor Xa inhibitors

Factor Xa (fXa) is a serine protease that plays a pivotal role in the coagulation cascade. High-throughput screening of the Yamanouchi compound library yielded lead compound 1 with the ability to inhibit fXa at micromolar concentrations. To improve its fXa inhibitory activity and its oral anticoagulant activity, the linker between benzamidine and the central benzene ring was modified and a carboxyl group was introduced at the central benzene ring. The resulting compounds 40b (YM-203552), 41a (YM-202054), and 41c (YM-203558) exhibited potent fXa inhibitory activity and oral anticoagulant activity. In particular, YM-203558 exhibited the most potent oral anticoagulant activity, prolonging PT more than 3-fold at 0.5 and 2.0 h. Additionally, these compounds showed a high degree of selectivity for other serine proteases.

Synthesis and pharmacological evaluation of N-acyl-1,2,3,4-tetrahydroisoquinoline derivatives as novel specific bradycardic agents

A series of N-acyl-1,2,3,4-tetrahydroisoquinoline derivatives were synthesized and evaluated for their bradycardic activities in isolated guinea pig right atria and in urethane-anesthetized rats. These efforts resulted in identification of the compound 8a, which exhibits potent bradycardic activity with minimal influence on mean blood pressure in urethane-anesthetized rats. Oral administration of compound 8a to conscious rats revealed increased potency and prolonged duration of action when compared to Zatebradine.

Orally active factor Xa inhibitor: synthesis and biological activity of masked amidines as prodrugs of novel 1,4-diazepane derivatives

Factor Xa (fXa) is a serine protease, which plays a pivotal role in the coagulation cascade. To improve the oral anticoagulant activity of fXa inhibitors containing a 1,4-diazepane moiety as the P4 part, a prodrug strategy was examined. Among the compounds evaluated in this study, amidoxime prodrugs bearing an ester moiety, such as compounds 21 and 30, showed effective oral anticoagulant activity in mice.

Synthesis and pharmacological evaluation of piperidinoalkanoyl-1,2,3,4-tetrahydroisoquinoline derivatives as novel specific bradycardic agents

A series of piperidinoalkanoyl-1,2,3,4-tetrahydroisoquinoline derivatives were synthesized, and their bradycardic activities were investigated in the isolated right atria of guinea pigs and in conscious rats. These efforts identified the achiral compound 2f, which exhibited potent and long-lasting bradycardic activity with minimal effects on mean blood pressure in conscious rats.

Synthesis and biological activity of novel 1,4-diazepane derivatives as factor Xa inhibitor with potent anticoagulant and antithrombotic activity

Factor Xa (fXa) is a serine protease involved in the coagulation cascade, which has received great interest as a potential target for the development of new antithrombotic drugs. Herein we report a novel series of fXa inhibitors in which the 1,4-diazepane moiety was designed to interact with the S4 aryl-binding domain of the fXa active site. Compound 13 (YM-96765) showed potent fXa inhibitory activity (IC(50) = 6.8 nM) and effective antithrombotic activity without prolonging bleeding time.

Synthesis and pharmacological evaluation of 1-oxo-2-(3-piperidyl)-1,2,3,4- tetrahydroisoquinolines and related analogues as a new class of specific bradycardic agents possessing I(f) channel inhibitory activity

A series of 1-oxo-2-(3-piperidyl)-1,2,3,4-tetrahydroisoquinolines and related analogues were prepared and evaluated for their bradycardic activities in isolated right atrium and in anesthetized rats. (+/-)-6,7-Dimethoxy-2-[1-[3-(3,4-methylenedioxyphenoxy)propyl]-3-piperidyl]-1,2,3,4-tetrahydroisoquinoline (4) was chosen as a lead, and structural modifications were performed on the tetrahydroisoquinoline ring and the terminal aromatic ring. The modifications on the tetrahydroisoquinoline ring revealed that the 1-oxo-1,2,3,4-tetrahydroisoquinoline ring system was optimum structure for both in vitro potency and in vivo efficacy. Furthermore, methoxy, ethoxy, and methoxycarbonyl groups were identified as preferable substituents on the terminal aromatic ring. One of the 1-oxo-1,2,3,4-tetrahydroisoquinoline derivatives, (R)-10a, was further evaluated for its bradycardic activity and inhibitory activity against I(f) currents. Compound (R)-10a demonstrated potent bradycardic activity in rats with minimal influence on blood pressure after oral administration. The compound also showed inhibition of I(f) currents (IC(50) = 0.32 muM) in guinea pig pacemaker cells.

Syntheses and biological evaluation of novel quinuclidine derivatives as squalene synthase inhibitors

Squalene synthase (E.C. 2.5.1.21) catalyses the reductive dimerization of two molecules of farnesyl diphosphate to form squalene and is involved in the first committed step in cholesterol biosynthesis. Inhibition of this enzyme is therefore an attractive target for hypocholesterolemic strategies. A series of quinuclidine derivatives incorporating a tricyclic system was synthesized and evaluated for their ability to inhibit squalene synthase in vitro. A 9H-fluorene moiety was found to be optimal as the tricyclic system for potent inhibitory activity. Improved activity can be achieved with a conformationally constrained three-atom linkage connecting the tricyclic system with the quinuclidine nucleus. Among these compounds, (Z)-3-[2-(9H-fluoren-2-yloxy)ethylidene]-quinuclidine hydrochloride 31 was found to be a potent inhibitor of squalene synthase derived from hamster liver and human hepatoma cells with IC(50) values of 76 and 48 nM, respectively. Oral dosing of compound 31 demonstrated effective reduction of plasma non-HDL cholesterol levels in hamsters.

New thiazole derivatives as potent and selective 5-hydroxytriptamine 3 (5-HT3) receptor agonists for the treatment of constipation

The syntheses and biological evaluation of a series of novel indeno[1,2-d]thiazole derivatives are described. Several groups reported 5-HT(3) receptor agonists which were mainly evaluated for their activities on the von Bezold-Jarisch reflex (B-J reflex). We discovered that tetrahydrothiazolopyridine derivative 1b had a contractile effect on the isolated guinea pig colon with weak B-J reflex. Our efforts to find a new type of 5-HT(3) receptor agonists on the isolated guinea pig colon focused on the synthesis of a fused thiazole derivative 1d modified from 1b and reverse-fused thiazole derivatives (7-10). In this series, 10f (YM-31636) showed high affinity and selectivity for the cloned human 5-HT(3) receptor; furthermore, it showed potent and selective 5-HT(3) receptor agonistic activity. YM-31636 was examined for its effects on defecation in animals, thus evaluating the compound as an agent against constipation.

YM-254890, a novel platelet aggregation inhibitor produced by Chromobacterium sp. QS3666

A novel platelet aggregation inhibitor, YM-254890, was isolated from the culture broth of strain QS3666. This strain was isolated from a soil sample collected at Okutama, Tokyo, Japan, and was identified as Chromobacterium sp. by morphological and physiological criteria. YM-254890 was purified from the culture supernatant by solvent extraction, ODS and silica gel flash chromatography, followed by preparative HPLC. YM-254890 inhibited ADP-induced platelet aggregation in human platelet-rich plasma with an IC50 value below 0.6 microM by blocking the P2Y1 receptor-signal transduction pathway.

Design, synthesis and biological activity of YM-60828 derivatives. Part 2: potent and orally-bioavailable factor Xa inhibitors based on benzothiadiazine-4-one template

Compound YM-60828 was previously characterized in our laboratory as a potent, selective and orally-bioavailable Factor Xa (FXa) inhibitor. The L-shape conformation of this compound in the active site of FXa was recognized as an important factor in displaying its FXa inhibitory activity. This led to the exploration of conformationally restricted cyclic scaffolds bearing a similar active conformation. The current study investigated a novel series of benzothiadiazine-4-one based compounds as FXa inhibitors. Structure-activity relationship (SAR) investigations revealed some potent FXa inhibitors that were selected for further in vitro and ex vivo anticoagulant studies. Among them, compound 6j (YM-169920) was proved to be most effective anticoagulant in this series. The synthesis and SAR in addition to docking studies of this class of inhibitors are described.

Design, synthesis and biological activity of YM-60828 derivatives: potent and orally-bioavailable factor Xa inhibitors based on naphthoanilide and naphthalensulfonanilide templates

Factor Xa (FXa) is a serine protease which plays a pivotal role in the coagulation cascade. The inhibition of FXa has received great interest as a potential target for the development of new antithrombotic drug. Herein we describe a series of novel 7-amidino-2-naphthoanilide and 7-amidino-2-naphthalensulfonanilide derivatives which are potent FXa inhibitors. These scaffolds are rigid and are allowed to adopt an L-shape conformation which was estimated as the active conformation based on a docking study of YM-60828 with FXa. Optimization of the side chain at the central aniline nitrogen of 7-amidino-2-naphthoanilide has led to several potent and orally active FXa inhibitors. 5h (YM-169964), the best compound of these series, showed potent FXa inhibitory activity (IC(50)=3.9nM) and effectively prolonged prothrombin time by 9.6-fold ex vivo at an oral dose of 3mg/kg in squirrel monkeys.

N-Methylbenzanilide derivatives as a novel class of selective V(1A) receptor antagonists

During our efforts to develop a novel class of selective V(1A) receptor antagonists, the N-methylbenzanilide structure was applied to a 4,4-difluoro-1-benzazepine derivative, 4, which is a selective V(1A) receptor antagonist. Further structural modifications gave 16a with high V(1A) affinity and V(2)/V(1A) selectivity (K(i)=5.71 nM, V(2)/V(1A)=140) and potent V(1A) receptor antagonist activity (ID(50)=0.0080 mg/kg iv).

Novel malonamide derivatives as alpha v beta 3 antagonists. Syntheses and evaluation of 3-(3-indolin-1-yl-3-oxopropanoyl)aminopropanoic acids on vitronectin interaction with alpha v beta 3

In attempt to find novel integrin alphavbeta3 antagonists, we selected SC65811 and its guanidine analogue (1) as lead compounds. Modification of the glycine part of SC65811 led to a new series of malonamide derivatives that exhibited alphavbeta3 inhibitory activity. Among them, (R,S)-3-[3-[6-(3-benzylureido)indolin-1-yl]-3-oxopropanoylamino]-3- (pyridin-3-yl)propanoic acid (43a) showed not only potent activity with an IC50 value of 3.0 nM but also good selectivity for alphavbeta3 relative to alphaIIbbeta3, alpha5beta1, and alphavbeta5 with IC50 values of 19,000, 11,000, and 14 nM, respectively. Furthermore, optimization of 43a led to the most potent alphavbeta3 antagonist, (R,S)-3-(3-[6-[(4,5-dihydro-1H-imidazol-2-yl)amino]indolin-1-yl]-3-oxopropanoylamino)-3-(quinolin-3-yl)propanoic acid (431) with an IC50 value of 0.42 nM. The synthesis and the structure-activity relationships of these malonamide derivatives are presented.