Discovery of trisubstituted cyclohexanes as potent CC chemokine receptor 2 (CCR2) antagonists

A series of trisubstituted cyclohexanes was designed, synthesized and evaluated as CC chemokine receptor 2 (CCR2) antagonists. This led to the identification of two distinct substitution patterns about the cyclohexane ring as potent and selective CCR2 antagonists. Compound 36 exhibited excellent binding (CCR2 IC₅₀ = 2.4 nM) and functional antagonism (calcium flux IC₅₀ = 2.0 nM and chemotaxis IC₅₀ = 5.1 nM).     

γ-Lactams as glycinamide replacements in cyclohexane-based CC chemokine receptor 2 (CCR2) antagonists

We describe the design, synthesis, and evaluation, of γ-lactams as glycinamide replacements within a series of di- and trisubstituted cyclohexane CCR2 antagonists. The lactam-containing trisubstituted cyclohexanes proved to be more potent than the disubstituted analogs, as trisubstituted analog, lactam 13, displayed excellent activity (CCR2 binding IC₅₀ = 1.0 nM and chemotaxis IC₅₀ = 0.5 nM) and improved metabolic stability over its parent glycinamide.     

Pyrrolidinyl phenylurea derivatives as novel CCR3 antagonists

Optimization starting with our lead compound 1 (IC₅₀ = 4.9 nM) led to the identification of pyrrolidinyl phenylurea derivatives. Further modification toward improvement of the bioavailability provided (R)-1-(1-((6-fluoronaphthalen-2-yl)methyl)pyrrolidin-3-yl)-3-(2-(2-hydroxyethoxy)phenyl)urea 32 (IC₅₀ = 1.7 nM), a potent and orally active CCR3 antagonist.     

Diazinones as P2 replacements for pyrazole-based cathepsin S inhibitors

A pyridazin-4-one fragment 4 (hCatS IC₅₀ = 170 μM) discovered through Tethering was modeled into cathepsin S and predicted to overlap in S2 with the tetrahydropyridinepyrazole core of a previously disclosed series of CatS inhibitors. This fragment served as a template to design pyridazin-3-one 12 (hCatS IC₅₀ = 430 nM), which also incorporates P3 and P5 binding elements. A crystal structure of 12 bound to Cys25Ser CatS led to the synthesis of the potent diazinone isomers 22 (hCatS IC₅₀ = 60 nM) and 27 (hCatS IC₅₀ = 40 nM).     

Isoquinoline derivatives as potent CRTH2 antagonists: Design,synthesis and SAR

In this study, we describe the synthesis and structure–activity relationship (SAR) of a series of isoquinoline chemoattractant receptor–homologous molecule expressed on Th2 cells (CRTH2) antagonists. TASP0376377 (15-20), one of the most potent compounds, showed a potent binding affinity (IC₅₀ = 19 nM) in addition to the excellent functional antagonist activity (IC₅₀ = 13 nM). Moreover, the efficacy of this compound in a chemotaxis assay (IC₅₀ = 23 nM) was in good agreement with its potency as a CRTH2 antagonist. In addition, 15-20 exhibited greater selectivity in binding to CRTH2 than to the DP1 prostanoid receptor (IC₅₀ >1 μM) or the enzymes COX-1 and COX-2 (IC₅₀ >10 μM).     

Structure-based optimization and biological evaluation of trisubstituted pyrazole as a core structure of potent ROS1 kinase inhibitors

Recently inhibition of ROS1 kinase has proven to be a promising strategy for several indications such as glioblastoma, non-small cell lung cancer (NSCLC), and cholangiocarcinoma. Our team reported trisubstituted pyrazole-based ROS1 inhibitors by which two inhibitors showed good IC₅₀ values in enzyme-based screening. To develop more advanced ROS1 inhibitors through SAR this trisubstituted pyrazole-based scaffold has been built. Consequently, 16 compounds have been designed, synthesized and shown potent IC₅₀ values in the enzymatic assay, which are from 13.6 to 283 nM. Molecular modeling studies explain how these ROS1 kinase inhibitors revealed effectively the key interactions with ROS1 ATP binding site. Among these compounds, compound 9a (IC₅₀ = 13.6 nM) has exerted 5 fold potency than crizotinib and exhibited high degree of selectivity (selectivity score value = 0.028) representing the number of non-mutant kinases with biological activity over 90% at 10 μM.     

Identification of the fused bicyclic 4-amino-2-phenylpyrimidine derivatives as novel and potent PDE4 inhibitors

2-Phenyl-4-piperidinyl-6,7-dihydrothieno[3,4-d]pyrimidine derivative (2) was found to be a new PDE4 inhibitor with moderate PDE4B activity (IC₅₀ = 150 nM). A number of derivatives with a variety of 4-amino substituents and fused bicyclic pyrimidines were synthesized. Among these, 5,5-dioxo-7,8-dihydro-6H-thiopyrano[3,2-d]pyrimidine derivative (18) showed potent PDE4B inhibitory activity (IC₅₀ = 25 nM). Finally, N-propylacetamide derivative (31b) was determined as a potent inhibitor for both PDE4B (IC₅₀ = 7.5 nM) and TNF-α production in mouse splenocytes (IC₅₀ = 9.8 nM) and showed good in vivo anti-inflammatory activity in the LPS-induced lung inflammation model in mice (ID₅₀ = 18 mg/kg). The binding mode of the new inhibitor (31e) in the catalytic site of PDE4B is presented based on an X-ray crystal structure of the ligand–enzyme complex.     

Design,synthesis and in vitro cytotoxicity evaluation of 5-(2-carboxyethenyl)isatin derivatives as anticancer agents

Forty four di- or trisubstituted novel isatin derivatives were designed and synthesized in 5–6 steps in 25–45% overall yields. Their structures were confirmed by ¹H NMR and ¹³C NMR as well as LC–MS. The anticancer activity of these new isatin derivatives against three human tumor cell lines, K562, HepG2 and HT-29, were evaluated by MTT assay in vitro. SAR studies suggested that the combination of 1-benzyl and 5-[trans-2-(methoxycarbonyl)ethen-1-yl] substitution greatly enhance their cytotoxic activity, whereas an intact carbonyl functionality on C-3 as present in the parent ring is required to such a potency. This study leads to the identification of two highly active molecules, compounds 2h (IC₅₀ = 3 nM) and 2k (IC₅₀ = 6 nM), against human leukemia K562 cells.     

Structure-guided design of new indoles as negative allosteric modulators (NAMs) of N-methyl-d-aspartate receptor (NMDAR) containing GluN2B subunit

Negative allosteric modulators (NAMs) of GluN2B-containing NMDARs provide pharmacological tools for the treatment of chronic neurodegenerative diseases. Novel NAMs have been designed on the basis of computational studies focused on the ‘hit compound’ 3. This series of indoles has been tested in competition assay. Compounds 16 and 17 were the most active ligands (IC₅₀ values of 83 nM and 71 nM, respectively) and they showed a potency close to that of reference compounds ifenprodil (1, IC₅₀ = 47 nM) and 3 (IC₅₀ = 25 nM). Furthermore, docking studies have been performed for active ligand 16 and the results were in a good agreement with biological data.     

1-(4-Phenylpiperazin-1-yl)-2-(1H-pyrazol-1-yl)ethanones as novel CCR1 antagonists

A novel series of CCR1 antagonists based on the 1-(4-phenylpiperazin-1-yl)-2-(1H-pyrazol-1-yl)ethanone scaffold was identified by screening a compound library utilizing CCR1-expressing human THP-1 cells. SAR studies led to the discovery of the highly potent and selective CCR1 antagonist 14 (CCR1 binding IC₅₀ = 4 nM using [¹²⁵I]-CCL3 as the chemokine ligand). Compound 14 displayed promising pharmacokinetic and toxicological profiles in preclinical species.     

Synthesis and biological evaluation of 5-carbamoyl-2-phenylpyrimidine derivatives as novel and potent PDE4 inhibitors

5-Carbamoyl-2-phenylpyrimidine derivative 2 has been identified as a phosphodiesterase 4 (PDE4) inhibitor with moderate PDE4B inhibitory activity (IC₅₀ = 200 nM). Modification of the carboxylic acid moiety of 2 gave N-neopentylacetamide derivative 10f, which had high in vitro PDE4B inhibitory activity (IC₅₀ = 8.3 nM) and in vivo efficacy against lipopolysaccharide (LPS)-induced pulmonary neutrophilia in mice (ID₅₀ = 16 mg/kg, ip). Furthermore, based on the X-ray crystallography of 10f bound to the human PDE4B catalytic domain, we designed 7,8-dihydro-6H-pyrido[4,3-d]pyrimidin-5-one derivative 39 which has a fused bicyclic lactam scaffold. Compound 39 exhibited excellent inhibitory activity against LPS-induced tumor necrosis factor alpha (TNF-α) production in mouse splenocytes (IC₅₀ = 0.21 nM) and in vivo anti-inflammatory activity against LPS-induced pulmonary neutrophilia in mice (41% inhibition at a dose of 1.0 mg/kg, i.t.).     

Structure activity relationships of fused bicyclic and urea derivatives of spirocyclic compounds as potent CCR1 antagonists

A series of fused bicyclic and urea derivatives of spirocyclic compounds were designed, synthesised and evaluated in vitro as potent CCR1 antagonists. In particular, 4 (7 nM), 44 (1.3 nM), 48 (0.89 nM) and 50 (0.63 nM) were the most potent hCCR1 antagonists in this series of compounds. Moreover, some of these substances demonstrated good rodent cross-over, especially 46 which exhibited very high rat CCR1 binding affinity with an IC₅₀ value of 16 nM.     

In vivo and in vitro SAR of tetracyclic MAPKAP-K2 (MK2) inhibitors. Part II

Spirocyclopropane- and spiroazetidine-substituted tetracycles 13D–E and 16A are described as orally active MK2 inhibitors. The spiroazetidine derivatives are potent MK2 inhibitors with IC₅₀ <3 nM and inhibit the release of TNFα (IC₅₀<0.3 μM) from hPBMCs and hsp27 phosphorylation in anisomycin stimulated THP-1 cells. The spirocyclopropane analogues are less potent against MK2 (IC₅₀ = 0.05–0.23 μM), less potent in cells (IC₅₀ <1.1 μM), but show good oral absorption. Compound 13E (100 mg/kg po; bid) showed oral activity in rAIA and mCIA, with significant reduction of swelling and histological score.     

Design,synthesis, and biological evaluation of 1,2,4-triazole bearing 5-substituted biphenyl-2-sulfonamide derivatives as potential antihypertensive candidates

A series of novel 1,2,4-triazole bearing 5-substituted biphenyl-2-sulfonamide derivatives were designed and synthesized to develop new angiotensin II subtype 2 (AT₂) receptor agonists as novel antihypertensive candidates. It was found that 14f (IC₅₀ = 0.4 nM) and 15e (IC₅₀ = 5.0 nM) displayed potent AT₂ receptor affinity and selectivity in binding assays. Biological evaluation in vivo suggested that 14f is obviously superior to that of reference drug losartan in RHRs, and meanwhile, 14f has no significant impact on heart rate. The interesting activities of these compounds may make them promising candidates as antihypertensive agents.     

Design,synthesis and biological evaluation of novel substituted benzoylguanidine derivatives as potent Na+/H+ exchanger inhibitors

A novel series of substituted benzoylguanidine derivatives were designed and synthesized as potent NHE1 inhibitors. Most compounds can significantly inhibit NHE1-mediated platelet swelling in a concentration-dependent manner, among which compound 5f (IC₅₀ = 3.60 nM) and 5l (IC₅₀ = 4.48 nM) are 18 and 14 times respectively more potent than cariporide (IC₅₀ = 65.0 nM). Furthermore, when tested in vivo and in vitro, compound 5f showed superior cardioprotective effects against SD rat myocardial ischemic-reperfusion injury over cariporide, representing a promising lead compound for further exploration.     

Synthesis and biological evaluation of substituted 2-phenyl-2H-indazole-7-carboxamides as potent poly(ADP-ribose) polymerase (PARP) inhibitors

A potent series of substituted 2-phenyl-2H-indazole-7-carboxamides were synthesized and evaluated as inhibitors of poly (ADP-ribose) polymerase (PARP). This extensive SAR exploration culminated with the identification of substituted 5-fluoro-2-phenyl-2H-indazole-7-carboxamide analog 48 which displayed excellent PARP enzyme inhibition with IC₅₀ = 4 nM, inhibited proliferation of cancer cell lines deficient in BRCA-1 with CC₅₀ = 42 nM and showed encouraging pharmacokinetic properties in rats compared to the lead 6.     

A novel and potent VLA-4 antagonist based on trans-4-substituted cyclohexanecarboxylic acid

During the course of our study, it was revealed that the poor pharmacokinetic properties of a series of benzoic acid derivatives such as 1 should be attributed to the diphenylurea moiety. Thus, we replaced the diphenylurea moiety in 1 with a 2-(2-methylphenylamino)benzoxazole moiety which mimics the diphenylurea structure. However, this modification resulted in a significant decrease (3, IC₅₀ = 19 nM) in VLA-4 inhibitory activity compared to 1 (IC₅₀ = 1.6 nM). To address this discrepancy, we worked on optimization of the carboxylic acid moiety in compound 3. As a result, our efforts have led to the discovery of trans-4-substituted cyclohexanecarboxylic acid derivative 11b (IC₅₀ = 2.8 nM) as a novel and potent VLA-4 antagonist. In addition, compound 11b exhibited favorable pharmacokinetic properties (CL = 3.3 ml/min/kg, F = 51%) in rats.     

Optimization of 5-vinylaryl-3-pyridinecarbonitriles as PKCθ inhibitors

Analog 8, a 3-pyridinecarbonitrile with an (E)-2-{6-[(4-methylpiperazin-1-yl)methyl]pyridin-2-yl}vinyl group at C-5, had an IC₅₀ value of 1.1 nM for the inhibition of PKCθ and potently blocked the production of IL-2 in both stimulated murine T cells (IC₅₀ = 34 nM) and human whole blood (IC₅₀ = 500 nM).     

The optimization of aminooxadiazoles as orally active inhibitors of Cdc7

A series of aminooxadiazoles was optimized for inhibition of Cdc7. Early lead isoquinoline 1 suffered from modest cell potency (cellular IC₅₀ = 0.71 μM measuring pMCM2), low selectivity against structurally related kinases, and high IV clearance in rats (CL = 18 L/h/kg). Extensive optimization resulted in azaindole 26 (Cdc7 IC₅₀ = 1.1 nM, pMCM2 IC₅₀ = 32 nM) that demonstrated robust lowering of pMCM2 in a mouse pharmacodynamic (PD) model when dosed orally. Modifications to improve the pharmacokinetic profile of this series were guided by trapping experiments with glutathione in rat hepatocytes.     

Identification of 2,3-dihydro-1H-pyrrolo[3,4-c]pyridine-derived ureas as potent inhibitors of human nicotinamide phosphoribosyltransferase (NAMPT)

Potent nicotinamide phosphoribosyltransferase (NAMPT) inhibitors containing 2,3-dihydro-1H-pyrrolo[3,4-c]pyridine-derived ureas were identified using structure-based design techniques. The new compounds displayed improved aqueous solubilities, determined using a high-throughput solubility assessment, relative to previously disclosed urea and amide-containing NAMPT inhibitors. An optimized 2,3-dihydro-1H-pyrrolo[3,4-c]pyridine-derived compound exhibited potent anti-NAMPT activity (18; BC NAMPT IC₅₀ = 11 nM; PC-3 antiproliferative IC₅₀ = 36 nM), satisfactory mouse PK properties, and was efficacious in a PC-3 mouse xenograft model. The crystal structure of another optimized compound (29; NAMPT IC₅₀ = 10 nM; A2780 antiproliferative IC₅₀ = 7 nM) in complex with the NAMPT protein was also determined.