Discovery,synthesis, and structure–activity relationships of 2-aminoquinazoline derivatives as a novel class of metabotropic glutamate receptor 5 negative allosteric modulators

A virtual screening approach using various in silico methodologies led to the discovery of 2-(m-tolylamino)-7,8-dihydroquinazolin-5(6H)-one (1) as a moderately active negative allosteric modulator (NAM) of the metabotropic glutamate receptor subtype 5 (mGluR5) showing high selectivity against the subtype mGluR1. Modifications of the parent compound by rational design yielded a series of highly potent derivatives which will serve as valuable starting points for further hit-to-lead optimization efforts toward a suitable drug candidate for the treatment of l-DOPA induced dyskinesia.     

Discovery and in vitro and in vivo profiles of 4-fluoro-N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methylbenzamide as novel class of an orally active metabotropic glutamate receptor 1 (mGluR1) antagonist

We identified 4-fluoro-N-[4-[6-(isopropylamino)pyrimidin-4-yl]-1,3-thiazol-2-yl]-N-methylbenzamide 27 as a potent mGluR1 antagonist. The compound possessed excellent subtype selectivity and good PK profile in rats. It also demonstrated relatively potent antipsychotic-like effects in several animal models. Suitable for development as a PET tracer, compound 27 would have great potential for elucidation of mGluR1 functions in human.     

Discovery of 3(S)-thiomethyl pyrrolidine ERK inhibitors for oncology

Compound 5 (SCH772984) was identified as a potent inhibitor of ERK1/2 with excellent selectivity against a panel of kinases (0/231 kinases tested @ 100?nM) and good cell proliferation activity, but suffered from poor PK (rat AUC PK @10?mpk?=?0?μM?h; F%?=?0) which precluded further development. In an effort to identify novel ERK inhibitors with improved PK properties with respect to 5, a systematic exploration of sterics and composition at the 3-position of the pyrrolidine led to the discovery of a novel 3(S)-thiomethyl pyrrolidine analog 28 with vastly improved PK (rat AUC PK @10?mpk?=?26?μM?h; F%?=?70).     

Discovery and optimization of a new class of pyruvate kinase inhibitors as potential therapeutics for the treatment of methicillin-resistant Staphylococcus aureus infections

A novel series of bis-indoles derived from naturally occurring marine alkaloid 4 were synthesized and evaluated as inhibitors of methicillin-resistant Staphylococcus aureus (MRSA) pyruvate kinase (PK). PK is not only critical for bacterial survival which would make it a target for development of novel antibiotics, but it is reported to be one of the most highly connected ‘hub proteins’ in MRSA, and thus should be very sensitive to mutations and making it difficult for the bacteria to develop resistance. From the co-crystal structure of cis-3-4-dihydrohamacanthin B (4) bound to S. aureus PK we were able to identify the pharmacophore needed for activity. Consequently, we prepared simple direct linked bis-indoles such as 10b that have similar anti-MRSA activity as compound 4. Structure–activity relationship (SAR) studies were carried out on 10b and led us to discover more potent compounds such as 10c, 10d, 10k and 10m with enzyme inhibiting activities in the low nanomolar range that effectively inhibited the bacteria growth in culture with minimum inhibitory concentrations (MIC) for MRSA as low as 0.5 μg/ml. Some potent PK inhibitors, such as 10b, exhibited attenuated antibacterial activity and were found to be substrates for an efflux mechanism in S. aureus. Studies comparing a wild type S. aureus with a construct (S. aureus LAC Δpyk::Erm^R) that lacks PK activity confirmed that bactericidal activity of 10d was PK-dependant.     

3-(Pyridin-2-yl-ethynyl)benzamide metabotropic glutamate receptor 5 negative allosteric modulators: hit to lead studies

A series of 3-(pyridin-2-yl-ethynyl)benzamide negative allosteric modulators of the metabotropic glutamate receptor 5 (mGluR5 NAMs) have been prepared. Starting from HTS hit 1 (IC₅₀: 926 nM), potent mGluR5 NAMs showing excellent potencies (IC₅₀s <50 nM) and good physicochemical profiles were prepared by monitoring LipE values. One compound 26 showed excellent mGluR5 binding (K_i: 21 nM) and antagonism (IC₅₀: 8 nM), an excellent rat PK profile (CL: 12 mL/min/kg, %F: 85) and showed oral activity in a mouse 4-Plate Behavioral model of anxiety (MED: 30 mpk) and a mouse Stress Induced Hyperthermia model of anxiety (MED 17.8 mpk).     

Isoxazolopyridone derivatives as allosteric metabotropic glutamate receptor 7 antagonists

This Letter describes the synthesis and evaluation of mGluR7 antagonists in the isoxazolopyridone series. In the course of modification in this class, novel solid support synthesis of the isoxazolopyridone scaffold was developed. Subsequent chemical modification led to the identification of several potent derivatives with improved physicochemical properties compared to a hit compound 1. Among these, 2 showed good oral bioavailability and brain penetrability, suggesting that 2 may be useful for in vivo study to elucidate the role of mGluR7.     

Design,synthesis and biological evaluation of anthranilamide derivatives as potential factor Xa (fXa) inhibitors

Factor Xa (fXa) is a crucial player in various thromboembolic disorders. Inhibition of fXa can provide safe and effective antithrombotic effects. In this study, a series of anthranilamide compounds were designed by utilizing structure-based design strategies. Optimization at P1 and P4 groups led to the discovery of compound 16g: a highly potent, selective fXa inhibitor with pronounced in vitro anticoagulant activity. Moreover, 16g also displayed excellent in vivo antithrombotic activity in the rat venous thrombosis (VT) and arteriovenous shunt (AV-SHUNT) models. The bleeding risk evaluation showed that 16g had a safer profile than that of betrixaban at 1?mg/kg and 5?mg/kg dose. Additionally, 16g also exhibited satisfactory PK profiles. Eventually, 16g was selected to investigate its effect on hypoxia-reoxygenation- induced H9C2 cell viability. MTT results showed that H9C2 cell viability can be remarkably alleviated by 16g.     

7-Phenyl-pyrido[2,3-d]pyrimidine-2,4-diamines: Novel and highly selective protein tyrosine phosphatase 1B inhibitors

High throughput screening of the Roche compound collection led to the identification of diaminopyrroloquinazoline series as a novel class of PTP1B inhibitors. Structural modification of diaminopyrroloquinazoline series resulted in pyrido[2,3-d]pyrimidine-2,4-diamine series which was further optimized to give compounds 5 and 24 as potent, selective (except T-cell phosphatase) PTP1B inhibitors with good mouse PK properties.     

Carbamoyloximes as novel non-competitive mGlu5 receptor antagonists

Hit-to-lead optimization of a HTS hit led to new carbamoyloxime derivatives. After identification of an advanced hit (8d) the CYP enzyme inhibitory activity of this class of compounds was successfully eliminated. Systematic exploration of different parts of the advanced hit led us to some promising lead compounds with mGluR5 affinities comparable to that of MPEP.     

Discovery and structure–activity relationship of 1,3-cyclohexyl amide derivatives as novel mGluR5 negative allosteric modulators

A novel series of trans-1,3-cyclohexyl diamides was discovered and characterized as mGluR5 negative allosteric modulators (NAMs) lacking an alkyne moiety. Conformational constraint of one of the amide bonds in the diamide template led to a spirooxazoline template. A representative compound (24d) showed good in vitro potency, high CNS penetration and, upon subcutaneous dosing, demonstrated efficacy in the mouse marble burying test, generally used as indicative of potential anxiolytic activity.     

Discovery and biological profile of isoindolinone derivatives as novel metabotropic glutamate receptor 1 antagonists: A potential treatment for psychotic disorders

We describe here the discovery and biological profile of a series of isoindolinone derivatives as developed mGluR1 antagonists. Our combined strategy of rapid parallel synthesis and conventional medicinal optimization successfully led to N-cyclopropyl 22 and N-isopropyl isoindolinone analogs 21 and 23 with improved in vivo DMPK profiles. Moreover the most advanced analog 23 showed an oral antipsychotic-like effect at a dose of 1 mg/kg in an animal model.     

Discovery and SAR of PF-4693627, a potent,selective and orally bioavailable mPGES-1 inhibitor for the potential treatment of inflammation

Inhibition of mPGES-1, the terminal enzyme in the arachidonic acid/COX pathway to regulate the production of pro-inflammatory prostaglandin PGE2, is considered an attractive new therapeutic target for safe and effective anti-inflammatory drugs. The discovery of a novel series of orally active, selective benzoxazole piperidinecarboxamides as mPGES-1 inhibitors is described. Structure–activity optimization of lead 5 with cyclohexyl carbinols resulted in compound 12, which showed excellent in vitro potency and selectivity against COX-2, and reasonable pharmacokinetic properties. Further SAR studies of the benzoxazole ring substituents lead to a novel series of highly potent compounds with improved PK profile, including 23, 26, and 29, which were effective in a carrageenan-stimulated guinea pig air pouch model of inflammation. Based on its excellent in vitro and in vivo pharmacological, pharmacokinetic and safety profile and ease of synthesis, compound 26 (PF-4693627) was advanced to clinical studies.     

Synthesis and biological evaluation of 2-(arylethynyl)quinoline derivatives as mGluR5 antagonists for the treatment of neuropathic pain

We described here the synthesis and biological evaluation of mGluR5 antagonists containing a quinoline ring structure. Using intracellular calcium mobilization assay (FDSS assay), we identified compound 5n, showing high inhibitory activity against mGluR5. In addition, it was found that compound 5n has excellent stability profile. Finally, this compound exhibited favorable analgesic effects in spinal nerve ligation model of neuropathic pain, which is comparable to gabapentin.     

Discovery of orally efficacious RORγt inverse agonists. Part 2: Design,synthesis, and biological evaluation of novel tetrahydroisoquinoline derivatives

A series of tetrahydroisoquinoline derivatives were designed, synthesized, and evaluated for their potential as novel orally efficacious retinoic acid receptor-related orphan receptor-gamma t (RORγt) inverse agonists for the treatment of Th17-driven autoimmune diseases. We carried out cyclization of the phenylglycinamide core by structure-based drug design and successfully identified a tetrahydroisoquinoline carboxylic acid derivative 14 with good biochemical binding and cellular reporter activity. Interestingly, the combination of a carboxylic acid tether and a central fused bicyclic ring was crucial for optimizing PK properties, and the compound 14 showed significantly improved PK profile. Successive optimization of the carboxylate tether led to the discovery of compound 15 with increased inverse agonistic activity and an excellent PK profile. Oral treatment of mice with compound 15 robustly and dose-dependently inhibited IL-17A production in an IL23-induced gene expression assay.     

Synthesis and evaluation of 4-(2-fluoro-4-[11C]methoxyphenyl)-5-((2-methylpyridin-4-yl)methoxy)picolinamide for PET imaging of the metabotropic glutamate receptor 2 in the rat brain

Metabotropic glutamate receptor 2 (mGluR2) has been suggested as a therapeutic target for treating schizophrenia-like symptoms arising from increased glutamate transmission in the human forebrain. However, no reliable positron emission tomography (PET) radiotracer allowing for in vivo visualization of mGluR2 in the human brain is currently available. In this study, we synthesized 4-(2-fluoro-4-[¹¹C]methoxyphenyl)-5-((2-methylpyridin-4-yl)methoxy)picolinamide ([¹¹C]1) and evaluated its potential as a PET tracer for imaging mGluR2 in the rodent brain. Compound 1, a negative allosteric modulator (NAM) of mGluR2, showed high in vitro binding affinity (IC₅₀: 26?nM) for mGluR2 overexpressed in human cells. [¹¹C]1 was synthesized by O-[¹¹C]methylation of the phenol precursor 2 with [¹¹C]methyl iodide. After the reaction, HPLC purification and formulation, [¹¹C]1 of 7.4?±?2.8?GBq (n?=?8) was obtained from [¹¹C]carbon dioxide of 22.5?±?4.8?GBq (n?=?8) with >99% radiochemical purity and 70?±?32?GBq/μmol (n?=?8) molar activity at the end of synthesis. In vitro autoradiography for rat brains showed that [¹¹C]1 binding was heterogeneously distributed in the cerebral cortex, striatum, hippocampus, and cerebellum. This pattern is consistent with the regional distribution pattern of mGluR2 in the rodent brain. The radioactivity was significantly reduced by self- or MNI-137 (a mGluR2 NAM) blocking. Small-animal PET studies indicated a low in vivo specific binding of [¹¹C]1 in the rat brain. The brain uptake was increased in a P-glycoprotein and breast cancer resistant protein double knockout mouse, when compared to a wild-type mouse. While [¹¹C]1 presented limited potential as an in vivo PET tracer for mGluR2, we suggested that it can be used as a lead compound for developing new radiotracers with improved in vivo brain properties.     

Discovery and optimization of arylsulfonyl 3-(pyridin-2-yloxy)anilines as novel GPR119 agonists

We describe the discovery of a series of arylsulfonyl 3-(pyridin-2-yloxy)anilines as GPR119 agonists derived from compound 1. Replacement of the three methyl groups in 1 with metabolically stable moieties led to the identification of compound 34, a potent and efficacious GPR119 agonist with improved pharmacokinetic (PK) properties.     

Synthesis and SAR of 5-aryl-furan-2-carboxamide derivatives as potent urotensin-II receptor antagonists

The synthesis and biological evaluation as potential urotensin-II receptor antagonists of a series of 5-arylfuran-2-carboxamide derivatives 1, bearing a 4-(3-chloro-4-(piperidin-4-yloxy)benzyl)piperazin-1-yl group, are described. The results of a systematic SAR investigation of furan-2-carboxamides with C-5 aryl groups possessing a variety of aryl ring substituents led to identification of the 3,4-difluorophenyl analog 1y as a highly potent UT antagonist with an IC₅₀ value of 6?nM. In addition, this substance was found to display high metabolic stability, and low hERG inhibition and cytotoxicity, and to have an acceptable PK profile.     

Discovery and synthesis of tetrahydropyrimidinedione-4-carboxamides as endothelial lipase inhibitors

Endothelial lipase (EL) inhibitors have been shown to elevate HDL-C levels in pre-clinical murine models and have potential benefit in prevention and treatment of cardiovascular diseases. Modification of the 1-ethyl-3-hydroxy-1,5-dihydro-2H-pyrrol-2-one (DHP) lead, 1, led to the discovery of a series of potent tetrahydropyrimidinedione (THP) EL inhibitors. Synthesis and SAR studies including modification of the amide group, together with changes on the pyrimidinone core led to a series of arylcycloalkyl, indanyl, and tetralinyl substituted 5-amino or 5-hydroxypyrimidinedione-4-carboxamides. Several compounds were advanced to PK evaluation. Among them, compound 4a was one of the most potent with measurable EL_HDL hSerum potency and compound 3g demonstrated the best overall pharmacokinetic parameters.     

Discovery and evaluation of novel FAAH inhibitors in neuropathic pain model

Conceptual design and modification of urea moiety in chemotype PF-3845/04457845, the bench marking irreversible inhibitor of fatty acid amide hydrolase (FAAH), led to discovery of a novel nicotinamide-based lead 12a having reversible mechanism of action. Focused SAR around the pyridine heterocycle (Ar) in 12a (Tables 1 and 2) resulted into four shortlisted compounds, (?)-12a, (?)-12i, (?)-12l–m. The required (?)-enantiomers were obtained via diastereomeric resolution of a novel chiral dissymmetric intermediate 15. Based on comparative profile of FAAH potency, metabolic stability in liver microsome, liability of inhibiting major hCYP450 isoforms, rat PK, and brain penetration ability, two SAR optimized compounds, (?)-12l and (?)-12m, were selected for efficacy study in rat model of chemotherapy-induced peripheral neuropathy (CIPN). Both the compounds exhibited dose related antihyperalgesic effects, when treated with 3–30?mg/kg po for 7?days. The effects at 30?mg/kg are comparable to that of PF-04457845 (10?mg/kg) and Tramadol (40?mg/kg).     

Discovery and optimization of new oxadiazole substituted thiazole RORγt inverse agonists through a bioisosteric amide replacement approach

Starting from previously identified thiazole-2-carboxamides exemplified by compound 1/6, two new series of RORγt inverse agonists with significantly improved aqueous solubility, ADME parameters and oral PK properties were discovered. These scaffolds were identified from a bioisosteric amide replacement approach. Amongst the variety of heterocycles explored, a 1,3,4-oxadiazole led to compounds with the best overall profile for SAR development and in vivo exploration. In an ex vivo mouse PD model, concentration dependent efficacy was demonstrated and compounds 3/5 and 6/3 were profiled in a 5-day rat tolerability study.