Design, synthesis, and biological evaluation of aminopyrazine derivatives as inhibitors of mitogen-activated protein kinase-activated protein kinase 2 (MK-2).

Several series of novel non-thiourea-containing aminopyrazine derivatives were designed based on the MK-2 inhibitors 1-(2-aminopyrazin-3-yl)methyl-2-thioureas. These compounds were synthesized and evaluated for their inhibitory activity against MK-2 enzyme in vitro. Compounds with low micromolar to sub-micromolar IC50 values were identified, and several compounds were also found to be active in suppressing the lipopolysaccharide (LPS)-stimulated TNFα production in THP-1 cells with minimum shift compared to their enzyme activity.

2-[(3aR,4R,5S,7aS)-5-{(1S)-1-[3,5-bis(trifluoromethyl)phenyl]-2-hydroxyethoxy}-4-(2-methylphenyl)octahydro-2H-isoindol-2-yl]-1,3-oxazol-4(5H)-one: a potent human NK1 receptor antagonist with multiple clearance pathways.

Hydroisoindoline 2 has been previously identified as a potent, brain-penetrant NK1 receptor antagonist with a long duration of action and improved profile of CYP3A4 inhibition and induction compared to aprepitant. However, compound 2 is predicted, based on data in preclinical species, to have a human half-life longer than 40 h and likely to have drug-drug-interactions (DDI), as 2 is a victim of CYP3A4 inhibition caused by its exclusive clearance pathway via CYP3A4 oxidation in humans. We now report 2-[(3aR,4R,5S,7aS)-5-{(1S)-1-[3,5-bis(trifluoromethyl)phenyl]-2-hydroxyethoxy}-4-(2-methylphenyl)octahydro-2H-isoindol-2-yl]-1,3-oxazol-4(5H)-one (3) as a next generation NK1 antagonist that possesses an additional clearance pathway through glucuronidation in addition to that via CYP3A4 oxidation.

Discovery of Selective Small Molecule ROMK Inhibitors as Potential New Mechanism Diuretics.

The renal outer medullary potassium channel (ROMK or Kir1.1) is a putative drug target for a novel class of diuretics that could be used for the treatment of hypertension and edematous states such as heart failure. An internal high-throughput screening campaign identified 1,4-bis(4-nitrophenethyl)piperazine (5) as a potent ROMK inhibitor.

Stimulation of Glucose-Dependent Insulin Secretion by a Potent, Selective sst3 Antagonist.

This letter provides the first pharmacological proof of principle that the sst3 receptor mediates glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells. To enable these studies, we identified the selective sst3 antagonist (1R,3R)-3-(5-phenyl-1H-imidazol-2-yl)-1-(tetrahydro-2H-pyran-4-yl)-2,3,4,9-tetrahydro-1H-β-carboline (5a), with improved ion channel selectivity and mouse pharmacokinetic properties as compared to previously described tetrahydro-β-carboline imidazole sst3 antagonists. We demonstrated that compound 5a enhances GSIS in pancreatic β-cells and blocks glucose excursion induced by dextrose challenge in ipGTT and OGTT models in mice.

3-Substituted 3-(4-aryloxyaryl)-propanoic acids as GPR40 agonists.

The design, synthesis, and structure-activity relationship (SAR) for a series of β-substituted 3-(4-aryloxyaryl)propanoic acid GPR40 agonists is described. Systematic replacement of the pendant aryloxy group led to identification of potent GPR40 agonists. In order to identify candidates suitable for in vivo validation of the target, serum shifted potency and pharmacokinetic properties were determined for several compounds.

Spiroimidazolidinone NPC1L1 inhibitors. Part 2: structure-activity studies and in vivo efficacy.

Ezetimibe (Zetia®), a cholesterol-absorption inhibitor (CAI) approved by the FDA for the treatment of hypercholesterolemia, is believed to target the intestine protein Niemann-Pick C1-Like 1 (NPC1L1) or its pathway. A spiroimidazolidinone NPC1L1 inhibitor identified by virtual screening showed moderate binding activity but was not efficacious in an in vivo rodent model of cholesterol absorption. Synthesis of analogs established the structure-activity relationships for binding activity, and resulted in compounds with in vivo efficacy, including 24, which inhibited plasma cholesterol absorption by 67% in the mouse, thereby providing proof-of-concept that non-β-lactams can be effective CAIs.

Design and synthesis of a new class of malonyl-CoA decarboxylase inhibitors with anti-obesity and anti-diabetic activities.

A new series of thiazole-substituted 1,1,1,3,3,3-hexafluoro-2-propanols were prepared and evaluated as malonyl-CoA decarboxylase (MCD) inhibitors. Key analogs caused dose-dependent decreases in food intake and body weight in obese mice. Acute treatment with these compounds also led to a drop in elevated blood glucose in a murine model of type II diabetes.

Fused tricyclic pyrrolizinones that exhibit pseudo-irreversible blockade of the NK1 receptor.

Previously, we had disclosed a novel class of hNK(1) antagonists based on the 5,5-fused pyrrolidine core. These compounds displayed subnanomolar hNK(1) affinity along with good efficacy in a gerbil foot-tapping (GFT) model, but unfortunately they had low to moderate functional antagonist (IP-1) activity. To elaborate on the SAR of this class of hNK(1) compounds and to improve functional activity, we have designed and synthesized a new class of hNK(1) antagonist with a third fused ring.

Tetrahydroindolizinone NK1 antagonists.

A new class of potent NK(1) receptor antagonists with a tetrahydroindolizinone core has been identified. This series of compounds demonstrated improved functional activities as compared to previously identified 5,5-fused pyrrolidine lead structures. SAR at the 7-position of the tetrahydroindolizinone core is discussed in detail.

Substituted fused bicyclic pyrrolizinones as potent, orally bioavailable hNK1 antagonists.

Previous work on human NK(1) (hNK(1)) antagonists in which the core of the structure is a 5,5-fused pyrrolizinone has been disclosed. The structural-activity-relationship studies on simple alpha- and beta-substituted compounds of this series provided several potent and bioavailable hNK(1) antagonists that displayed excellent brain penetration as observed by their good efficacy in the gerbil foot-tapping (GFT) model assay. Several of these compounds exhibited 100% inhibition of the foot-tapping response at 0.

Discovery of 5-aryloxy-2,4-thiazolidinediones as potent GPR40 agonists.

Systematic structure-activity relationship (SAR) studies of a screening lead led to the discovery of a series of thiazolidinediones (TZDs) as potent GPR40 agonists. Among them, compound C demonstrated an acute mechanism-based glucose-lowering in an intraperitoneal glucose tolerance test (IPGTT) in lean mice, while no effects were observed in GPR40 knock-out mice.

Discovery and optimization of novel 4-[(aminocarbonyl)amino]-N-[4-(2-aminoethyl)phenyl]benzenesulfonamide ghrelin receptor antagonists.

This Letter describes optimization of ghrelin receptor antagonists and inverse agonists starting from a screening hit.

Disubstituted pyrimidines as Lck inhibitors.

We have developed a family of 4-benzimidazolyl-N-piperazinethyl-pyrimidin-2-amines that are subnanomolar inhibitors of Lck. A subset of these Lck inhibitors, with heterocyclic substituents at the benzimidazole C5, are also low-nanomolar inhibitors of cellular IL2 release.

Novel 1-(2-aminopyrazin-3-yl)methyl-2-thioureas as potent inhibitors of mitogen-activated protein kinase-activated protein kinase 2 (MK-2).

Novel 1-(2-aminopyrazin-3-yl)methyl-2-thioureas are described as inhibitors of mitogen-activated protein kinase-activated protein kinase 2 (MK-2). These compounds demonstrate potent in vitro activity against the enzyme with IC(50) values as low as 15 nM, and suppress expression of TNFalpha in THP-1 cells and in vivo in an acute inflammation model in mice. The synthesis, structure-activity relationship (SAR), and biological evaluation of these compounds are discussed.

Potent, brain-penetrant, hydroisoindoline-based human neurokinin-1 receptor antagonists.

3-[(3aR,4R,5S,7aS)-5-{(1R)-1-[3,5-bis(trifluoromethyl)phenyl]ethoxy}-4-(4-fluorophenyl)octahydro-2H-isoindol-2-yl]cyclopent-2-en-1-one (17) is a high affinity, brain-penetrant, hydroisoindoline-based neurokinin-1 (NK(1)) receptor antagonist with a long central duration of action in preclinical species and a minimal drug-drug interaction profile. Positron emission tomography (PET) studies in rhesus showed that this compound provides 90% NK(1) receptor blockade in rhesus brain at a plasma level of 67 nM, which is about 10-fold more potent than aprepitant, an NK(1) antagonist marketed for the prevention of chemotherapy-induced and postoperative nausea and vomiting (CINV and PONV). The synthesis of this enantiomerically pure compound containing five stereocenters includes a Diels-Alder condensation, one chiral separation of the cyclohexanol intermediate, an ether formation using a trichloroacetimidate intermediate, and bis-alkylation to form the cyclic amine.

Design, synthesis, and structure-activity relationship of novel CCR2 antagonists.

A series of novel 1-aminocyclopentyl-3-carboxyamides incorporating substituted tetrahydropyran moieties have been synthesized and subsequently evaluated for their antagonistic activity against the human CCR2 receptor. Among them analog 59 was found to posses potent antagonistic activity.

Selective small-molecule agonists of G protein-coupled receptor 40 promote glucose-dependent insulin secretion and reduce blood glucose in mice.

Objective: Acute activation of G protein-coupled receptor 40 (GPR40) by free fatty acids (FFAs) or synthetic GPR40 agonists enhances insulin secretion. However, it is still a matter of debate whether activation of GPR40 would be beneficial for the treatment of type 2 diabetes, since chronic exposure to FFAs impairs islet function. We sought to evaluate the specific role of GPR40 in islets and its potential as a therapeutic target using compounds that specifically activate GPR40.

Fused bicyclic pyrrolizinones as new scaffolds for human NK1 antagonists.

Previous work on human NK(1) antagonists in which the core of the structure is a substituted pyrrolidine has been disclosed. These compounds showed good binding affinity and functional IP activity, however, many did not exhibit the necessary brain penetration for good in vivo activity. The discovery and preparation of a novel 5,5-fused pyrrolidine core is presented in this paper.

Conformational studies of 3-amino-1-alkyl-cyclopentane carboxamide CCR2 antagonists leading to new spirocyclic antagonists.

In an effort to shed light on the active binding conformation of our 3-amino-1-alkyl-cyclopentane carboxamide CCR2 antagonists, we prepared several conformationally constrained analogs resulting from backbone cyclization. Evaluation of CCR2 binding affinities for these analogs gave insight into the optimal relative positions of the piperidine and benzylamide moieties while simultaneously leading to the discovery of a new, potent lead type based upon a spirocyclic acetal scaffold.

Potent heteroarylpiperidine and carboxyphenylpiperidine 1-alkyl-cyclopentane carboxamide CCR2 antagonists.

This report describes replacement of the 4-(4-fluorophenyl)piperidine moiety in our CCR2 antagonists with 4-heteroaryl piperidine and 4-(carboxyphenyl)-piperidine subunits. Some of the resulting analogs retained potency in our CCR2 binding assay and had improved selectivity versus the I(Kr) channel; poor selectivity against I(Kr) had been a liability of earlier analogs in this series.

Characterization of a novel and selective cannabinoid CB1 receptor inverse agonist, Imidazole 24b, in rodents.

We document in vitro and in vivo effects of a novel, selective cannabinoid CB(1) receptor inverse agonist, Imidazole 24b (5-(4-chlorophenyl)-N-cyclohexyl-4-(2,4-dichlorophenyl)-1-methyl-imidazole-2-carboxamide). The in vitro binding affinity of Imidazole 24b for recombinant human and rat CB(1) receptor is 4 and 10 nM, respectively. Imidazole 24b binds to human cannabinoid CB(2) receptor with an affinity of 297 nM; in vitro, it is a receptor inverse agonist at both cannabinoid CB(1) and CB(2) receptors as it causes a further increase of forskolin-induced cAMP increase.

Pyrrolidine-carboxamides and oxadiazoles as potent hNK1 antagonists.

The preparation and structure-activity-relationships of novel pyrrolidine-carboxamides and oxadiazoles are described. Compounds in this series were found to be potent hNK(1) antagonists in vitro and efficacious in vivo with minimal interactions with P(450) liver enzymes. Oxadiazole analog 22 was determined to have excellent hNK(1) binding affinity, functional activity, and a good PD response in vivo.

CCR5 blockade modulates inflammation and alloimmunity in primates.

Pharmacologic antagonism of CCR5, a chemokine receptor expressed on macrophages and activated T cells, is an effective antiviral therapy in patients with macrophage-tropic HIV infection, but its efficacy in modulating inflammation and immunity is only just beginning to be investigated. In this regard, the recruitment of CCR5-bearing cells into clinical allografts is a hallmark of acute rejection and may anticipate chronic rejection, whereas conventionally immunosuppressed renal transplant patients homozygous for a nonfunctional Delta32 CCR5 receptor rarely exhibit late graft loss. Therefore, we explored the effects of a potent, highly selective CCR5 antagonist, Merck's compound 167 (CMPD 167), in an established cynomolgus monkey cardiac allograft model.

The discovery of potent, selective, and orally bioavailable hNK1 antagonists derived from pyrrolidine.

SAR studies on amides, ureas, and vinylogous amides derived from pyrrolidine led to the discovery of several potent hNK(1) antagonists. One particular vinylogous amide (45b) had excellent potency, selectivity, pharmacokinetic profile, and functional activity in vivo. An in vivo rhesus macaque brain receptor occupancy PET study for compound 45b revealed an estimated Occ(90) approximately 300 ng/ml.

Discovery of 3-piperidinyl-1-cyclopentanecarboxamide as a novel scaffold for highly potent CC chemokine receptor 2 antagonists.

Introduction of ring restrictions to a linear aminobutyramide CC chemokine receptor 2 (CCR2) antagonist lead (2) led to the discovery of a 1,3-disubstituted cyclopentane scaffold with enhanced hCCR2 receptor binding and antagonist activity. (1S,3R)-N-[3,5-Bis(trifluoromethyl)benzyl]-1-methyl-3-[(1R,3'R)-methyl-1'H-spiro[indene-1,4'-piperidin]-1'-yl]cyclopentanecarboxamide (16) had IC50 of 1.3 nM (binding) and 0.