Design,synthesis, and biological evaluation of novel biphenyl-4-carboxamide derivatives as orally available TRPV1 antagonists

A new series of transient receptor potential vanilloid type 1 (TRPV1) antagonists were designed and synthesized from N-(3-hydroxyphenyl)-2-(piperidin-1-ylmethyl)biphenyl-4-carboxamide hydrochloride (8). SAR studies identified (R)-N-(1-methyl-2-oxo-1,2,3,4-tetrahydro-7-quinolyl)-2-[(2-methylpyrrolidin-1-yl)methyl]biphenyl-4-carboxamide hydrochloride (ASP8370, 7), as a compound with high aqueous solubility, satisfactory stability in human liver microsomes, and reduced CYP3A4 inhibition. ASP8370 was selected as a clinical development candidate with significant ameliorative effects on neuropathic pain. SAR studies also revealed the structural mechanisms underlying the switching between TRPV1 antagonism and agonism.     

Design, synthesis, and SAR of 2-dialkylamino-4-arylpyrimidines as potent and selective corticotropin-releasing factor(1) (CRF(1)) receptor antagonists

A series of 2-dialkylamino-4-phenylpyrimidines (7) was designed and synthesized as CRF(1) antagonists. SAR studies of this series resulted in the discovery of potent and selective antagonists 7b and 7n bearing a 4-(2,4,6-trisubstituted-phenyl) ring and a bulky 2-(N-bis(cyclopropane)methyl-N-propyl)amino group.     

4-Amino-5-vinyl-3(2H)-pyridazinones and analogues as potent antinociceptive agents: Synthesis, SARs, and preliminary studies on the mechanism of action

A series of 4-amino-5-vinyl-3(2H)-pyridazinones and analogues were synthesized and their antinociceptive effect was evaluated in the mouse abdominal constriction model. Several of the novel compounds showed ED(50) values in the range 6-20mg/kg/sc and demonstrated to be able to completely protect all the treated animals from the effect of the noxious stimulus at 30 mg/kg/sc. SAR studies confirmed the essential role played by an amino or substituted amino function at position 4 and by a vinyl group at position 5 of the diazine system.     

Novel, potent and selective anilinoquinazoline and anilinopyrimidine inhibitors of p38 MAP kinase

SAR studies led to the identification of 4-(3-benzoylamino-6-methyl-anilino)quinazolines as potent and selective inhibitors of p38 MAP kinase. Further optimisation led to the identification of a series of 4-(3-benzoylamino-6-methyl-anilino)pyrimidines as potent inhibitors of the p38 MAP kinase signalling pathway in vitro and in vivo.     

Synthesis and biological evaluation of methanesulfonamide analogues of rofecoxib: Replacement of methanesulfonyl by methanesulfonamido decreases cyclooxygenase-2 selectivity

A new group of 3-(4-substituted-phenyl)-4-(4-methylsulfonamidophenyl)-2(5H)furanones in which the methylsulfonyl (MeSO(2)) COX-2 pharmacophore present in rofecoxib was replaced by a methanesulfonamido (MeSO(2)NH) moiety, and where the substituent at the para-position of the C-3 phenyl ring was simultaneously varied (H, F, Cl, Br, Me, OMe), were evaluated to determine the combined effects of steric and electronic substituent properties upon COX-1 and COX-2 inhibitory potency and COX isozyme selectivity. Structure-activity relationship (SAR) studies showed that compounds having a neutral (H), or electronegative halogen (F, Cl, Br), substituent at the para-position of the C-3 phenyl ring inhibited both COX-1 and COX-2 with COX-2 selectivity indexes in the 3.1-39.4 range. In contrast, compounds having an electron-donating Me or OMe substituent were selective inhibitors of COX-2 (COX-1 IC(50)>100 microM). These SAR data indicate the 3-aryl-4-(4-methylsulfonamidophenyl)-2(5H)furanone scaffold provides a suitable template to design COX inhibitors with variable COX-2 selectivity indexes.     

Subtype selective NMDA receptor antagonists: evaluation of some novel alkynyl analogues

A benzylpiperidine analogue with an acetylenic linker, 5-(3-[4-(4-fluorobenzyl)-piperidin-1-yl]-prop-1-ynyl)-1,3-dihydrobenzimidazol-2-one (3), was identified as a chemical lead with excellent activity at the NR1A/2B receptor (IC50=3 nM). Efforts to optimize this activity led to focused modifications around the structural motif of 3. The synthesis and SAR studies are discussed.     

Discovery of substituted 4-anilino-2-(2-pyridyl)pyrimidines as a new series of apoptosis inducers using a cell- and caspase-based high throughput screening assay. Part 1: structure-activity relationships of the 4-anilino group

A series of 4-anilino-2-(2-pyridyl)pyrimidines has been discovered as a new class of potent inducers of apoptosis using a cell-based HTS assay. Compound 5a was found to arrest T47D cells in G2/M and induced apoptosis. SAR studies showed that a small and electron-donating group at the meta-position of the anilino ring is important for activity. A 20-fold increase in potency, from hit compound 4-(3-methoxyanilino)-2-(2-pyridinyl)-6-(trifluoromethyl)pyrimidine (5a) to lead compound 4-(2,5-dimethoxyanilino)-2-(2-pyridinyl)-6-(trifluoromethyl)pyrimidine (5l), was obtained through the SAR studies. Compound 5l is highly active with an EC50 value of 18 nM in the caspase activation assay in T47D breast cells. Interestingly, 5a and other meta-mono-substituted compounds were active against T47D cells but were not active against H1299 and HT29 cells, while 5l and other 2,5-disubstituted compounds were active against all the three cells. In a tubulin polymerization assay, compound 5l inhibited tubulin polymerization with an IC50 value of < 0.5 microM, while 5a was not active up to 50 microM.     

Synthesis, SAR, and Evaluation of 4-[2,4-Difluoro-5-(cyclopropylcarbamoyl)phenylamino]pyrrolo[2,1-f][1,2,4]triazine-based VEGFR-2 kinase inhibitors

Introduction of the 2,4-difluoro-5-(cyclopropylcarbamoyl)phenylamino group at the C-4 position of the pyrrolo[2,1-f][1,2,4] triazine scaffold led to the discovery of a novel sub-series of inhibitors of VEGFR-2 kinase activity. Subsequent SAR studies on the 1,3,5-oxadiazole ring appended to the C-6 position of this new sub-family of pyrrolotriazines resulted in the identification of low nanomolar inhibitors of VEGFR-2. Antitumor efficacy was observed with compound 37 against L2987 human lung carcinoma xenografts in athymic mice.     

Discovery of 4-aryl-4H-chromenes as a new series of apoptosis inducers using a cell- and caspase-based high-throughput screening assay. 2. Structure-activity relationships of the 7- and 5-, 6-, 8-positions

As a continuation of our efforts to discover and develop the apoptosis inducing 4-aryl-4H-chromenes as novel anticancer agents, we explored the SAR of 4-aryl-4H-chromenes with modifications at the 7- and 5-, 6-, 8-positions. It was found that a small hydrophobic group, such as NMe2, NH2, NHEt, and OMe, is preferred at the 7-position. Di-substitution at either the 5,7-positions or the 6,7-positions generally led to a large decrease in potency. Di-substitution at the 7,8-positions, in general, was found to result in potent compounds. 7-NMe2, 7-NHEt, 7-OMe, and 7,8-di-NH2 analogs were found to have similar SAR for the 4-aryl group, and several 7-substituted and 7,8-di-substituted analogs were found to have similar potencies as the lead compound MX58151 (2a) both as caspase activators and inhibitors of cell proliferation.     

N-(3-phenylsulfonyl-3-piperidinoyl)-phenylalanine derivatives as potent,selective VLA-4 antagonists

The SAR of 1-sulfonyl-cyclopentyl carboxylic acid amides, ligands for the VLA-4 integrin, was investigated. This effort resulted in the identification of N-(3-phenylsulfonyl-3-piperidinoyl)-(L)-4-(2',6'-dimethoxyphenyl)phenylalanine 52 as a potent, selective VLA-4 antagonist (IC(50)=90 pM). Expansion of the SAR demonstrated that this structural unit can be used to identify a diverse series of sub-nanomolar antagonists.     

Synthesis and structure-activity relationships of thieno[2,3-d]pyrimidine-2,4-dione derivatives as potent GnRH receptor antagonists

The synthesis and SAR studies of thieno[2,3-d]pyrimidine-2,4-diones as human GnRH receptor antagonists to treat reproductive diseases are discussed. It was found that the 2-(2-pyridyl)ethyl group on the 5-aminomethyl functionality of the core structure was a key feature for good receptor binding activity. SAR study of the 6-(4-aminophenyl) group suggests that hydrophobic substituents were preferred. The best compound from this series had binding affinity (K(i)) of 0.4 nM to the human GnRH receptor.     

Indoline and piperazine containing derivatives as a novel class of mixed D(2)/D(4) receptor antagonists. Part 1: identification and structure-activity relationships

Optimization of the lead compound 2-[-4-(4-chloro-benzyl)-piperazin-1-yl]-1-(2,3-dihydro-indol-1-yl)-ethanone 1 by systematic structure-activity relation (SAR) studies lead to two potent compounds 2-[-4-(4-chloro-benzyl)-piperazin-1-yl]-1-(2-methy-2,3-dihydro-indol-1-yl)-ethanone 2n and 2-[-4-(4-chloro-benzyl)-piperazin-1-yl]-1-(2-methy-2,3-dihydro-indol-1-yl)-ethanone 7b. Their related synthesis was also reported.     

The discovery of potent,orally bioavailable pyrimidine-5-carbonitrile-6-alkyl CXCR2 receptor antagonists

A hit-to-lead optimisation programme was carried out on the Novartis archive screening hit, pyrimidine 2-((2,6-dichlorobenzyl)thio)-5-isocyano-6-phenylpyrimidin-4-ol 4, resulting in the discovery of CXCR2 receptor antagonist 2-((2,3-difluorobenzyl)thio)-6-(2-(hydroxymethyl)cyclopropyl)-5-isocyanopyrimidin-4-ol 24. The SAR was investigated by systematic variation of the aromatic group at c-6, the linker between c-2 and the halogenated ring, and the c-5 nitrile moiety.     

A comparison of sucrose,saline, and saline with egg-yolk diluents on the cryopreservation of cane toad (Bufo marinus) sperm

Previous studies on cane toad (Bufo marinus; Bufonidae; Anura) sperm cryopreservation were extended to compare the effects of cryopreservation in established sucrose (non-ionic) diluents with cryopreservation in ionic diluents containing amphibian Ringer solutions (with and without egg-yolk). In addition, methanol was tested as a cryoprotectant for B. marinus sperm for the first time. Twenty-seven cryoprotective solutions were trialled, with each containing one of the three diluents [10% (w/v) sucrose, simplified amphibian Ringer (SAR) or SAR/egg-yolk], with one of the three cryoprotectants (Me(2)SO, glycerol, or methanol) at one of the three concentrations (10%, 15%, or 20% v/v). Sperm were collected by maceration of testes into cryoprotective solutions with post-thaw recovery assessed as the percentage of motile sperm and the degree (vigour) of motility. Percentage motility was the most sensitive measure of post-thaw recovery. The recovery of motility was lowest in Ringer (SAR) diluents and highest in sucrose diluents, with improved motility in SAR diluents when egg-yolk was added. Methanol was the poorest cryoprotectant and Me(2)SO the most effective. Methanol at high concentrations was shown to support recovery in sucrose diluent but not in SAR, although its effectiveness in SAR was improved by egg-yolk. Overall, the efficacy of diluents in supporting a high percentage of sperm recovery was in declining order: sucrose>SAR/egg-yolk>SAR diluents, and with cryoprotectants: Me(2)SO>glycerol>methanol. In conclusion, SAR offers less potential as a diluent than sucrose, presumably due to the presence of inorganic ions.     

Modulators of the human CCR5 receptor. Part 3: SAR of substituted 1-[3-(4-methanesulfonylphenyl)-3-phenylpropyl]-piperidinyl phenylacetamides

SAR and PK studies led to the identification of N-(1-{(3R)-3-(3,5-difluorophenyl)-3-[4-methanesulfonylphenyl] propyl}piperidin-4-yl)-N-ethyl-2-[4-methanesulfonylphenyl]acetamide as a highly potent and selective ligand for the human CCR5 chemokine receptor with good oral pharmacokinetic properties.     

Pyrazolopyridines as a novel structural class of potent and selective PDE4 inhibitors

Optimisation of a high-throughput screening hit resulted in the discovery of 4-(substituted amino)-1-alkyl-pyrazolo[3,4-b]pyridine-5-carboxamides as potent and selective inhibitors of Phosphodiesterase 4 (PDE4). Herein, we describe early SAR studies around this novel template highlighting preferred substituents and rationalization of SAR through X-ray crystal structures of analogues bound to the PDE4 active site. Pyrazolopyridine 20a was found to be a potent and selective PDE4 inhibitor which also inhibits LPS induced TNF-α production from isolated human peripheral blood mononuclear cells and has an encouraging rat PK profile suitable for oral dosing.     

Pyrazole related nucleosides 5. Synthesis and biological activity of 2'-deoxy-2',3'-dideoxy- and acyclo-analogues of 4-iodo-1-beta-D-ribofuranosyl-3-carboxymethyl pyrazole (IPCAR)

Continuing our studies on the structure-activity relationships (SAR) of 4-iodo-1-beta-D-ribofuranosyl-3-carboxymethyl pyrazole (IPCAR), the ribofuranosyl moiety has been substituted with acyclic chains, namely 1-[(2-hydroxyethoxy)methyl]- and 1-[(1,3-dihydroxy-2-propoxy)methyl]-pyrazole derivatives (4, 5 and 8, 9 respectively), with the 2'-deoxy-beta-D-ribofuranosyl group (12 and 13) and finally with the 2',3'-dideoxy-D-glycero-pentofuranosyl-moiety (16 and 17). None of the new compounds display any interesting biological activity.     

The discovery of a potent and selective lethal factor inhibitor for adjunct therapy of anthrax infection

A potent and selective anthrax LF inhibitor 40, (2R)-2-[(4-fluoro-3-methylphenyl)sulfonylamino]-N-hydroxy-2-(tetrahydro-2H-pyran-4-yl)acetamide, was identified through SAR study of a high throughput screen lead. It has an IC50 of 54 nM in the enzyme assay and an IC50 of 210 nM in the macrophage cytotoxicity assay. Compound 40 is also effective in vivo in several animal model studies.     

Phenylaminopyrimidines as inhibitors of Janus kinases (JAKs)

A series of phenylaminopyrimidines has been identified as inhibitors of Janus kinases (JAKs). Development of this initial series led to the potent JAK2/JAK1 inhibitor CYT387 (N-(cyanomethyl)-4-[2-[[4-(4-morpholinyl)phenyl]amino]-4-pyrimidinyl]-benzamide). Details of synthesis and SAR studies of these compounds are reported.