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With the emergence and rapid spreading of NDM-1 and existence of clinically relevant VIM-1 and IMP-1, discovery of pan inhibitors targeting metallo-beta-lactamases (MBLs) became critical in our battle against bacterial infection. Concurrent with our fragment and high-throughput screenings, we performed a knowledge-based search of known metallo-beta-lactamase inhibitors (MBLIs) to identify starting points for early engagement of medicinal chemistry. A class of compounds exemplified by

GPR40 (FFAR1 or FFA1) is a G protein-coupled receptor, primarily expressed in pancreatic islet β-cells and intestinal enteroendocrine cells. When activated by fatty acids, GPR40 elicits increased insulin secretion from islet β-cells only in the presence of elevated glucose levels. Towards this end, studies were undertaken towards discovering a novel GPR40 Agonist whose mode of action is via Positive Allosteric Modulation of the GPR40 receptor (AgoPAM). Efforts were made to identify a suitable GPR40 AgoPAM tool molecule to investigate mechanism of action and de-risk liver toxicity of GPR40 AgoPAMs due to reactive acyl-glucuronide (AG) metabolites.

GPR40 is a G-protein-coupled receptor expressed primarily in pancreatic islets and intestinal L-cells that has been a target of significant recent therapeutic interest for type II diabetes. Activation of GPR40 by partial agonists elicits insulin secretion only in the presence of elevated blood glucose levels, minimizing the risk of hypoglycemia. GPR40 agoPAMs have shown superior efficacy to partial agonists as assessed in a glucose tolerability test (GTT). Herein, we report the discovery and optimization of a series of potent, selective GPR40 agoPAMs. Compound 24 demonstrated sustained glucose lowering in a chronic study of Goto Kakizaki rats, showing no signs of tachyphylaxis for this mechanism.

A novel series of benzo-[1,2,4]-triazolo-[1,4]-oxazepine GPR142 agonists are described. The series was designed to address the suboptimal PK (pharmacokinetic) and off-target profile of a class of N-aryl-benzo-[1,4]-oxazepine-4-carboxamides, represented by 1, that were identified from a high-throughput screen of the Merck compound collection for GPR142 agonists. This work led to the discovery of 3-phenoxy-benzo-[1,2,4]-triazolo-[1,4]-oxazepine 47, a potent GPR142 agonist with an off-target and PK profile suitable for in vivo studies. This compound and a related analogue 40 were shown to be active in mouse oral glucose tolerance tests (OGTTs). Furthermore, a GPR142 knock-out mouse OGTT study with compound 40 provides evidence that its glucose-lowering effect is mediated by GPR142.

GPR40 (FFA1) is a fatty acid receptor whose activation results in potent glucose lowering and insulinotropic effects in vivo. Several reports illustrate that GPR40 agonists exert glucose lowering in diabetic humans. To assess the mechanisms by which GPR40 partial agonists improve glucose homeostasis, we evaluated the effects of MK-2305, a potent and selective partial GPR40 agonist, in diabetic Goto Kakizaki rats. MK-2305 decreased fasting glucose after acute and chronic treatment. MK-2305-mediated changes in glucose were coupled with increases in plasma insulin during hyperglycemia and glucose challenges but not during fasting, when glucose was normalized. To determine the mechanism(s) mediating these changes in glucose metabolism, we measured the absolute contribution of precursors to glucose production in the presence or absence of MK-2305. MK-2305 treatment resulted in decreased endogenous glucose production (EGP) driven primarily through changes in gluconeogenesis from substrates entering at the TCA cycle. The decrease in EGP was not likely due to a direct effect on the liver, as isolated perfused liver studies showed no effect of MK-2305 ex vivo and GPR40 is not expressed in the liver. Taken together, our results suggest MK-2305 treatment increases glucose stimulated insulin secretion (GSIS), resulting in changes to hepatic substrate handling that improve glucose homeostasis in the diabetic state. Importantly, these data extend our understanding of the underlying mechanisms by which GPR40 partial agonists reduce hyperglycemia.

Antagonism of somatostatin subtype receptor 3 (sstr3) has emerged as a potential treatment of Type 2 diabetes. Unfortunately, the development of our first preclinical candidate, MK-4256, was discontinued due to a dose-dependent QTc (QT interval corrected for heart rate) prolongation observed in a conscious cardiovascular (CV) dog model. As the fate of the entire program rested on resolving this issue, it was imperative to determine whether the observed QTc prolongation was associated with hERG channel (the protein encoded by the human Ether-à-go-go-Related Gene) binding or was mechanism-based as a result of antagonizing sstr3. We investigated a structural series containing carboxylic acids to reduce the putative hERG off-target activity. A key tool compound, 3A, was identified from this SAR effort. As a potent sstr3 antagonist, 3A was shown to reduce glucose excursion in a mouse oGTT assay. Consistent with its minimal hERG activity from in vitro assays, 3A elicited little to no effect in an anesthetized, vagus-intact CV dog model at high plasma drug levels. These results afforded the critical conclusion that sstr3 antagonism is not responsible for the QTc effects and therefore cleared a path for the program to progress.

GPR142 has been identified as a potential glucose-stimulated insulin secretion (GSIS) target for the treatment of type 2 diabetes mellitus (T2DM). A class of triazole GPR142 agonists was discovered through a high throughput screen. The lead compound 4 suffered from poor metabolic stability and poor solubility. Lead optimization strategies to improve potency, efficacy, metabolic stability, and solubility are described. This optimization led to compound 20e, which showed significant reduction of glucose excursion in wild-type but not in GPR142 deficient mice in an oral glucose tolerance test (oGTT) study. These studies provide strong evidence that reduction of glucose excursion through treatment with 20e is GPR142-mediated, and GPR142 agonists could be used as a potential treatment for type 2 diabetes.

A QSAR model for predicting passive permeability (Papp ) was derived from Papp values measured in the LLC-PK1 cell line. The QSAR method and descriptor set that performed best in terms of cross-validation was random forest with a combination of AP, DP, and MOE_2D descriptors. The QSAR model was used to predict the Caco-2 cell permeability for 313 compounds described in the literature with good success. We find that passive permeability for different cell lines can be predicted with similar molecular properties and descriptors. It is shown that the variation in experimental measurements of Papp is smaller than the error in QSAR predictions indicating that predictions are not quantitatively perfect, although qualitatively useful. We get better predictions if the training set is large and diverse, rather than smaller and more internally consistent. This is because prediction accuracy falls off quickly with decreasing similarity to the training set and it is therefore better to have as large a training set as possible. While single physical parameters are not as good as a full QSAR model in predicting Papp , logD seems the most important parameter. Intermediate values of logD are associated with higher Papp .

MK-4256, a tetrahydro-β-carboline sstr3 antagonist, was discontinued due to a cardiovascular (CV) adverse effect observed in dogs. Additional investigations revealed that the CV liability (QTc prolongation) was caused by the hERG off-target activity of MK-4256 and was not due to sstr3 antagonism. In this Letter, we describe our extensive SAR effort at the C3 position of the tetrahydro-β-carboline structure. This effort resulted in identification of 5-fluoro-pyridin-2-yl as the optimal substituent on the imidazole ring to balance sstr3 activity and the hERG off-target liability.

We report an efficient method for the synthesis of β-carbolines from α-siloxy α,β-unsaturated esters, which are accessible from a variety of aldehydes and ketones.

The design, synthesis, and binding activity of ring constrained analogs of the acyclic cannabinoid-1 receptor (CB1R) inverse agonist taranabant 1 are described. The initial inspiration for these taranabant derivatives was its conformation 1a, determined by 1H NMR, X-ray, and molecular modeling. The constrained analogs were all much less potent than their acyclic parent structure. The results obtained are discussed in the context of a predicted binding of 1 to a homology model of CB1R.

The purpose of this study was to characterize the alpha(4)beta(1) receptor (CD49d/CD29, very late antigen-4, VLA-4) on circulating equine leukocytes and to evaluate the intrinsic potency of an alpha(4)beta(1) receptor antagonist (Compound B) in the horse. Ultimately, these studies would allow us to determine the suitability of treating recurrent airway obstruction (RAO; heaves) affected horses by blocking the cellular recruitment of lymphocytes and neutrophils into the lung. The data demonstrates the alpha(4)beta(1) integrin is present on horse lymphocytes and neutrophils (fluorescence-assisted cell sorter, FACS) and can bind low molecular weight alpha(4)beta(1) antagonists (Compounds A and B) with high affinity. K(D) values for the binding of Compound A to non-activated alpha(4)beta(1) on isolated horse PBMCs (peripheral blood mononuclear cells) and activated neutrophils were 17 pM and 27 pM, respectively. Compound B was identified as a suitable antagonist for performing a series of in vivo experiments. Compound B was found to possess excellent potency in horse whole blood, possessing IC(50) and IC(90) values of 39 pM and 172 pM, respectively. This represents a 3.9-fold molar excess of drug over the alpha(4)beta(1) concentration in blood. Following oral administration of Compound B (5 mg/kg) to beagle dogs and rhesus monkeys, rapid and sustained alpha(4)beta(1) receptor occupancy (80%) was achieved and maintained for a period of 24 h. When Compound B was administered intravenously to the horse, by either a slow or rapid infusion at a dose of 0.3 mg/kg, receptor blockade of80% was observed out to 24 h with a concomitant leukocytosis. We believe that Compound B possesses suitable intrinsic and pharmacological properties to be evaluated clinically in horses affected by RAO.

Extremely potent very late antigen-4 (VLA-4) antagonists with picomolar, whole blood activity and slow dissociation rates were discovered by incorporating an amino substituent on the proline fragment of the initial lead structure. This level of potency against the unactivated form of VLA-4 was shown to be sufficient to overcome the poor pharmacokinetic profiles typical of this class of VLA-4 antagonists, and sustained activity as measured by receptor occupancy was achieved in preclinical species after oral dosing.

A novel series of 1-sulfonyl-4-acylpiperazines as selective cannabinoid-1 receptor (CB1R) inverse agonists was discovered through high throughput screening (HTS) and medicinal chemistry lead optimization. Potency and in vivo properties were systematically optimized to afford orally bioavailable, highly efficacious, and selective CB1R inverse agonists that caused food intake suppression and body weight reduction in diet-induced obese rats and dogs. It was found that the receptor binding assay predicted in vivo efficacy better than functional antagonist/inverse agonist activities. This observation expedited the structure-activity relationship (SAR) analysis and may have implications beyond the series of compounds presented herein.

The in vitro and in vivo evaluation of the selective, high affinity (human CB1 IC(50) 0.49 nM) inverse agonist CB1R tracer [(11)C]CB-119, a close analog of the previously disclosed [(18)F]MK-9470, was undertaken.[(11)C]CB-119 was synthesized with high specific activity by alkylation of a phenolic precursor with [(11)C]methyl iodide. In vitro autoradiographic studies using rhesus brain slices were carried out using [(3)H]CB-119, and in vivo imaging studies were carried out using [(11)C]CB-119 in rhesus monkeys under baseline and blocked conditions.Autoradiographic studies in rhesus brain showed the expected distribution pattern for CB1R with highest binding in the cerebral cortex, cerebellum, caudate/putamen, globus pallidus, substantia nigra, and hippocampus. Lower binding was seen in the posterior hypothalamus, ventral tegmental area, and periventricular gray area, and the lowest binding was in the thalamic nuclei. The binding of [(3)H]CB-119 was fully blocked by the addition of 10 microM CB-119. Rhesus positron emission tomography imaging studies showed very good brain uptake and a distribution pattern consistent with that seen in the autoradiographic studies. The kinetics of tracer uptake was slow. The brain uptake was blocked by pretreatment with taranabant, a CB1R inverse agonist. The specific signal (total/nonspecific) in rhesus putamen at 90 min was approximately 6:1.[(11)C]CB-119 is a suitable tracer for imaging central CB1 receptors.

Through alternative splicing, the human cannabinoid CB(1) receptor gene encodes three variants of protein products (hCB(1), hCB(1a), and hCB(1b)) that differ in amino acid sequence at the N terminus of the receptors. By semi-quantitative PCR from human adult and fetal brain mRNA, we demonstrated that the transcript encoding hCB(1) is the major transcript, and estimated that those of hCB(1a) and hCB(1b) represent fewer than 5% of the total human cannabinoid CB(1) receptor transcripts. We characterized the three variants stably expressed in CHO cells. In the contrary to the study by Ryberg et al. (FEBS Lett 579[1], 259-64), we did not find substantial difference among the three variants according to the binding affinity, functional potency, and efficacy of meth-anandamide, 2-arachidonoyl glycerol, virodhamine, Noladin ether, docosatetraenylethanolamide, CP55940, AM251, and compound 35e (an acyclic class human CB(1) receptor inverse agonist similar to MK-0364). The functional significance of different human cannabinoid CB(1) receptor variants remains to be clarified.

The integrin VLA-4 is implicated in several inflammatory disease states. In search of non-peptidic antagonists of VLA-4, rotational constraints were imposed on the amide bond of prototypical N-sulfonylated dipeptide VLA-4 antagonists. By judicious structural modification of the side chains, trisubstituted imidazoles with moderate binding potencies were obtained, for example, 19, VLA-4 IC50 = 237 nM.

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. Oral administration of Imidazole 24b blocked CP-55940-induced hypothermia, demonstrating cannabinoid CB 1 receptor antagonist efficacy in vivo . Using ex vivo autoradiography, Imidazole 24b resulted in dose-dependent increases in brain cannabinoid CB 1 receptor occupancy (RO) at 2h post-dosing in rats, indicating that ∼ 50% receptor occupancy is sufficient for attenuation of receptor agonist-induced hypothermia. Imidazole 24b administered to C57Bl/6 mice and to dietary-induced obese (DIO) Sprague–Dawley rats attenuated overnight food intake with a minimal effective dose of 10 mg/kg, p.o. Administration had no effect in cannabinoid CB 1 receptor-deficient mice. DIO rats were dosed orally with vehicle, Imidazole 24b (1, 3 or 10 mg/kg), or dexfenfluramine (3 mg/kg) for 2 weeks. At 3 mg/kg, Imidazole 24b reduced cumulative food intake, leading to a non-significant decrease in weight gain. Imidazole 24b at 10 mg/kg and dexfenfluramine treatment inhibited food intake and attenuated weight gain. These findings suggest that selective cannabinoid CB 1 receptor inverse agonists such as Imidazole 24b have potential for the treatment of obesity.

Silver oxide used in stoichiometric amounts promoted the direct functionalization of tert -alkyl bromides and provided the desired adducts in 39–96% isolated yield. Reaction of tert -bromides with carboxylic acids yielded esters, with alcohols and phenols yielded alkyl and aryl ethers, with amines and anilines yielded selectively mono-alkylated amines and anilines, and with a C-nucleophile yielded an all-carbon quaternary hydrocarbon. The method was applied to a sequential alkylation of a primary amine with two different alkyl bromides yielding selectively a tertiary amine with three different substituents in one-pot.

Sulfonamide analogues of the potent CB1R inverse agonist taranabant were prepared and optimized for potency and selectivity for CB1R. They were variably more potent than the corresponding amide analogues. The most potent representative 22 had good pharmacokinetic and brain levels, but was modestly active in blocking CB1R agonist-mediated hypothermia.

Herein we report a high yielding one-pot ‘green’ synthesis of 3-substituted-5-carbonylmethyl-1,2,4-oxadiazoles from readily available β-keto esters and amidoximes under simple and convenient solvent-free conditions. No additional base is needed. The reaction likely goes through an acyl ketene intermediate.

VLA-4 is implicated in several inflammatory and autoimmune disease states. A series of cyclic beta-amino acids (beta-aa) was studied as VLA-4 antagonists. Binding affinity was highly dependent on the dihedral angle (phi) between the amino and the carboxyl termini of the beta-aa. Compound 5 m where the beta-aa is embedded in a bicycle possesses the most preferred phi (120 degrees). It is a potent and bioavailable VLA-4 antagonist (VCAM-Ig alpha4beta1 IC50 = 54 nM, rat po F = 49%).

We report SAR studies on a novel non-peptidic somatostatin receptor 3 (SSTR3) agonist lead series derived from (4-phenyl-1H-imidazol-2-yl)methanamine. This effort led to the discovery of a highly potent low molecular weight SSTR3 agonist 5c (EC50=5.2 nM, MW=359). The results from molecular overlays of 5c onto the L-129 structure indicate good alignment, and two main differences of the proposed overlays of the antagonist MK-4256 onto the conformation of 5c lead to inversion of antagonism to agonism.

The discovery of novel acyclic amide cannabinoid-1 receptor inverse agonists is described. They are potent, selective, orally bioavailable, and active in rodent models of food intake and body weight reduction. A major focus of the optimization process was to increase in vivo efficacy and to reduce the potential for formation of reactive metabolites. These efforts led to the identification of compound 48 for development as a clinical candidate for the treatment of obesity.

A ‘one-pot’ procedure for synthesis of α-1,2,4-oxadiazolo esters from malonic diesters and amidoximes under solvent-free conditions is described. It is likely that this reaction goes through a ketene intermediate generated from the malonic diester by elimination of a molecule of alcohol.

The imidazolyl-tetrahydro-β-carboline class of sstr3 antagonists have demonstrated efficacy in a murine model of glucose excursion and may have potential as a treatment for type 2 diabetes. The first candidate in this class caused unacceptable QTc interval prolongation in oral, telemetrized cardiovascular (CV) dogs. Herein, we describe our efforts to identify an acceptable candidate without CV effects. These efforts resulted in the identification of (1R,3R)-3-(4-(5-fluoropyridin-2-yl)-1H-imidazol-2-yl)-1-(1-ethyl-pyrazol-4-yl)-1-(3-methyl-1,3,4-oxadiazol-3H-2-one-5-yl)-2,3,4,9-tetrahydro-1H-β-carboline (17e, MK-1421).

Through a directed screening of a combinatorial library containing carboxylic acids, N-sulfonylated dipeptides were identified as leads in the Merck Research Laboratories VLA-4 antagonist program. Further optimization quickly identified subnanomolar compounds with varying degrees of specificity over the related integrin alpha4beta7. Various metabolic liabilities were identified and addressed. However, the pharmacokinetic properties of nearly all compounds in this class were unacceptable. Other leads were identified with apparent good oral bioavailability, but these were generally associated with very high plasma protein binding and a loss of potency. The mechanism of high plasma clearance was identified in the rat as the organic acid transporter, mrp-2. Compounds were identified that were not substrates of mrp-2, but they still suffered from poor oral bioavailability. Finally, a shift in strategy to identifying VLA-4 antagonists that would be suitable as candidates for inhalation therapy resulted in the preparation of compounds with exception tight binding properties. These compounds were superior to BIO-1211 in the ovalbumin-sensitized mouse model of eosinophil trafficking to the lung. One particular compound had an exceptionally long off-rate with a KD < or = 2 pM. The evolution of the structure activity relationships in our laboratories and strategies for improving potencies and pharmacokinetic profiles are the subject of this review.

VLA-4 (alpha(4)beta(1), very late activating antigen-4), a key cell surface integrin plays an important role in inflammation by promoting leukocyte attachment and extravasation from the vasculature into the peripheral tissues. As such, VLA-4 antagonists may be useful in the treatment, prevention, and suppression of diseases where cell adhesion and migration are important such as asthma, rheumatoid arthritis, and multiple sclerosis. Herein, we report on the discovery, synthesis, and biological evaluation of amidines as small molecule antagonists of VLA-4.

A series of isonicotinoyl-(L)-aminophenylalanine derivatives was prepared and evaluated as VLA-4 antagonists. These compounds exhibit subnanomolar binding affinity to VLA-4 and significant off-rates. The interplay between off-rate, protein binding and pharmacokinetics is discussed.

An α4β1/α4β7 dual antagonist, 35S-compound 1, was used as a model ligand to study the effect of divalent cations on the activation state and ligand binding properties of α4 integrins. In the presence of 1 mM each Ca2+/Mg2+, 35S-compound 1 bound to several cell lines expressing both α4β1 and α4β7, but 2 S -[(1-benzenesulfonyl-pyrrolidine-2 S -carbonyl)-amino]-4-[4-methyl-2 S -(methyl-{2-[4-(3- o -tolyl-ureido)-phenyl]-acetyl}-amino) pentanoylamino]-butyric acid (BIO7662), a specific α4β1 antagonist, completely inhibited 35S-compound 1 binding, suggesting that α4β1 was responsible for the observed binding. 35S-Compound 1 bound RPMI-8866 cells expressing predominantly α4β7 with a K D of 1.9 nM in the presence of 1 mM Mn2+, and binding was inhibited only 29% by BIO7662, suggesting that the probe is a potent antagonist of activated α4β7. With Ca2+/Mg2+, 35S-compound 1 bound Jurkat cells expressing primarily α4β1 with a K D of 18 nM. In contrast, the binding of 35S-compound 1 to Mn2+-activated Jurkat cells occurred slowly, reaching equilibrium by 60 min, and failed to dissociate within another 60 min. The ability of four α4β1/α4β7 antagonists to block binding of activated α4β1 or α4β7 to vascular cell adhesion molecule-1 or mucosal addressin cell adhesion molecule-1, respectively, or to 35S-compound 1 was measured, and a similar rank order of potency was observed for native ligand and probe. Inhibition of 35S-compound 1 binding to α4β1 in Ca2+/Mg2+ was used to identify nonselective antagonists among these four. These studies demonstrate that α4β1 and α4β7 have distinct binding properties for the same ligand, and binding parameters are dependent on the state of integrin activation in response to different divalent cations.

A nonpeptidyl small molecule antagonist, compound A, to nonactivated very late antigen-4 (VLA4) was examined in lung inflammation induced by a single dose of ovalbumin challenge. Compound A presented a good pharmacokinetic property, when given intratracheally, and the blood cells from such pharmacokinetic study showed good receptor occupancy of the compound for approximately 8 hours. Compound A was then tested in an ovalbumin-induced airway inflammation model by intranasal or intravenous route of administration. There was a dose-dependent inhibition of eosinophilia in the bronchiolar lavage fluid, when compound A was given intranasally but not when it was given intravenously. For comparison, antibody to VLA4 and another compound, BIO1211, which reacts only with activated VLA4, were examined in this system. Immunohistochemical analyses of the lung tissue substantiated the findings in the bronchiolar lavage fluid. Specific staining of the major basic protein of eosinophils showed peribronchiolar infiltration of eosinophils. Some of these eosinophils were also positive for nitrotyrosine, suggesting activation of eosinophils in the lung interstitium. There was deposition of major basic protein and nitrotyrosine at the base of the perivascular endothelium, indicative of degranulation of eosinophils in the area. After intranasal treatment with compound A, eosinophils in the lungs and their activation products were substantially decreased, documenting its effectiveness in inhibiting lung inflammation.

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.

A series of substituted N-(3,5-dichlorobenzenesulfonyl)-( l )-prolyl- and ( l )-azetidyl-β-biaryl β-alanine derivatives was prepared as selective and potent VLA-4 antagonists. The 2,6-dioxygenated biaryl substitution pattern is important for optimizing potency. Oral bioavailability was variable and may be a result of binding to circulating plasma proteins.

A series of potent N-(aralkyl-, arylcycloalkyl-, and heteroaryl-acyl)-4-biphenylalanine VLA-4 antagonists was prepared by rapid analogue methods using solid-phase chemistry. Further optimization led to several highly potent compounds (IC(50)1 nM). Evaluation of rat pharmacokinetic revealed generally high clearance.

The alpha(4) integrin, alpha(4)beta(7), plays an important role in recruiting circulating lymphocytes to the gastrointestinal tract, where its ligand mucosal addressin cell adhesion molecule-1 (MAdCAM-1) is preferentially expressed on high endothelial venules (HEVs). Dual antagonists of alpha(4)beta(1) and alpha(4)beta(7), N-(2,6-dichlorobenzoyl)-(L)-4-(2',6'-bis-methoxyphenyl)phenylalanine (TR14035) and N-(N-[(3,5-dichlorobenzene)sulfonyl]-2-(R)-methylpropyl)-(D)-phenylalanine (compound 1), were tested for their ability to block the binding of alpha(4)beta(7)-expressing cells to soluble ligand in suspension and under in vitro and in vivo shear flow. Compound 1 and TR14035 blocked the binding of human alpha(4)beta(7) to an (125)I-MAdCAM-Ig fusion protein with IC(50) values of 2.93 and 0.75 nM, respectively. Both compounds inhibited binding of soluble ligands to alpha(4)beta(1) or alpha(4)beta(7) on cells of human or rodent origin with similar potency. Under shear flow in vitro, TR14035 and compound 1 blocked binding of human alpha(4)beta(7)-expressing RPMI-8866 cells or murine mesenteric lymph node lymphocytes to MAdCAM-Ig with IC(50) values of 0.1 and 1 microM, respectively. Intravital microscopy was used to quantitate alpha(4)-dependent adhesion of fluorescent murine lymphocytes in Peyer's patch HEVs. When cells were prestimulated with 2 mM Mn(2+) to activate alpha(4)beta(7) binding to ligand, anti-alpha(4) monoclonal antibody (mAb) [10 mg/kg (mpk) i.v.] blocked adhesion by 95%, and anti-beta(1) mAb did not block adhesion, demonstrating that this interaction was dependent on alpha(4)beta(7). TR14035 blocked adhesion to HEVs [ED(50) of 0.01-0.1 mpk i.v.], and compound 1 blocked adhesion by 47% at 10 mpk i.v. Thus, alpha(4)beta(7)/alpha(4)beta(1) antagonists blocked alpha(4)beta(7)-dependent adhesion of lymphocytes to HEVs under both in vitro and in vivo shear flow.

Given the proposed involvement of VLA-4 in inflammatory processes, a program to identify orally active VLA-4 antagonists was initiated. Herein, we report the discovery of a N -tetrahydrofuroyl-( l )-phenylalanine derivative ( 17 ) and related analogues as potent VLA-4 antagonists with good oral bioavailability.

Integrins alpha9beta1 and alpha4beta1 form a distinct structural class, but while alpha4beta1 has been subjected to extensive study, alpha9beta1 remains poorly characterized. We have used the small molecule N-(benzenesulfonyl)-(L)-prolyl-(L)-O-(1-pyrrolidinylcarbonyl)tyrosine (3) to investigate the biochemical properties of alpha9beta1 and directly compare these properties with those of alpha4beta1. Compound 3 has a high affinity for both integrins with K(D) values of 1000-fold difference in the affinity of the integrins for VCAM-1, which binds alpha4beta1with an apparent K(D) of 10 nM and alpha9beta1 with an apparent K(D) of >10 microM. Differences were also seen in the binding of alpha9beta1 and alpha4beta1 to osteopontin. Compound 3 competed effectively for the binding of VCAM-1 and osteopontin to both integrins. While these studies show many similarities in the biochemical properties of alpha9beta1 and alpha4beta1, they identify important differences in their structure and function that can be exploited in the design of selective alpha9beta1 and alpha4beta1 inhibitors.

A series of substituted N-(3,5-dichlorobenzenesulfonyl)-L-prolyl- and alpha-methyl-L-prolyl-phenylalanine derivatives was prepared as VLA-4/VCAM antagonists. The compounds showed excellent potency with a wide variety of neutral, polar, electron withdrawing or donating groups on the phenylalanine ring (IC50 approximately 1 nM). Heteroaryl ring substitution for phenylalanine was also well tolerated. Pharmacokinetic studies in rat were performed on a representative set of compounds in both series.

A combinatorial library of 28 pools of 180 compounds (345 diastereomers) was designed and prepared in support of the delineation of the SAR of two prototypical VLA-4 antagonists. Deconvolution of the active pools led to the identification of three novel series of VLA-4 antagonists with low nanomolar potencies.

The alpha(4)beta(1) and alpha(4)beta(7) integrins are implicated in several inflammatory disease states. Systematic SAR studies of an alpha(4)beta(1)-specific arylsulfonyl-Pro-Tyr lead led to the identification of a new alpha(4)beta(7) binding site, best captured by O-carbamates of Tyr for this structural class. Several compounds showed a 200- to 400-fold improvement in alpha(4)beta(7) binding affinity while maintaining subnanomolar alpha(4)beta(1) activity, for example 2l, VCAM-Ig alpha(4)beta(1) IC(50)=0.13 nM, VCAM-Ig alpha(4)beta(7) IC(50)=1.92 nM.

N-(3,5-Dichlorophenylsulfonyl)-(R)-thioprolyl biarylalanine 10a has been identified as a potent and specific antagonist of the α4β1 integrin. Altering the configuration of thioproline from R to S led to a series of dual antagonists of α4β1 and α4β7, and the N-acetyl analogue 8b was found to be the most potent dual antagonist. A binding site model for α4β1 and α4β7 is proposed to explain the structure–activity relationship.

A novel class of small-molecule, highly potent, and subtype-selective somatostatin SST3 agonists was discovered through modification of a SST3 antagonist. As an example, (1R,2S)-9 demonstrated not only potent in vitro SST3 agonist activity but also in vivo SST3 agonist activity in a mouse oral glucose tolerance test (OGTT). These agonists may be useful reagents for studying the physiological roles of the SST3 receptor and may potentially be useful as therapeutic agents.

Directed screening of a carboxylic acid-containing combinatorial library led to the discovery of potent inhibitors of the integrin VLA-4. Subsequent optimization by solid-phase synthesis afforded a series of sulfonylated dipeptide inhibitors with structural components that when combined in a single hybrid molecule gave a sub-nanomolar inhibitor as a lead for medicinal chemistry. Preliminary metabolic studies led to the discovery of substituted biphenyl derivatives with low picomolar activities. SAR and pharmacokinetic characterization of this series are presented.

Deprotection of Boc groups in the presence of tert -butyl esters was achieved by using concentrated H 2 SO 4 (1.5–3.0 equiv.) in t BuOAc or MeSO 3 H (1.5–3.0 equiv.) in t BuOAc:CH 2 Cl 2 (4:1 v/v). The yields ranged from 70 to 100% for a variety of amino acid and dipeptide substrates.

Enantioselective alkylation of chiral amide enolates derived from L-prolinol with β-branched chiral iodides afforded good yields of hydroxy amide adducts, which were elaborated in four steps to give C-carboxyalkyl dipeptide inhibitors of stromelysin-1 (MMP-3).

We have identified a series of potent, orally bioavailable, non-peptidyl, triarylimidazole and triarylpyrrole glucagon receptor antagonists. 2-(4-Pyridyl)-5-(4-chlorophenyl)-3-(5-bromo-2-propyloxyphenyl)p yrr ole (L-168,049), a prototypical member of this series, inhibits binding of labeled glucagon to the human glucagon receptor with an IC50 = 3. 7 +/- 3.4 nM (n = 7) but does not inhibit binding of labeled glucagon-like peptide to the highly homologous human glucagon-like peptide receptor at concentrations up to 10 microM. The binding affinity of L-168,049 for the human glucagon receptor is decreased 24-fold by the inclusion of divalent cations (5 mM). L-168,049 increases the apparent EC50 for glucagon stimulation of adenylyl cyclase in Chinese hamster ovary cells expressing the human glucagon receptor and decreases the maximal glucagon stimulation observed, with a Kb (concentration of antagonist that shifts the agonist dose-response 2-fold) of 25 nM. These data suggest that L-168,049 is a noncompetitive antagonist of glucagon action. Inclusion of L-168, 049 increases the rate of dissociation of labeled glucagon from the receptor 4-fold, confirming that the compound is a noncompetitive glucagon antagonist. In addition, we have identified two putative transmembrane domain residues, phenylalanine 184 in transmembrane domain 2 and tyrosine 239 in transmembrane domain 3, for which substitution by alanine reduces the affinity of L-168,049 46- and 4. 5-fold, respectively. These mutations do not alter the binding of labeled glucagon, suggesting that the binding sites for glucagon and L-168,049 are distinct.

Further development of N-carboxyalkyl dipeptide inhibitors of stromelysin-1 (MMP-3) led to the discovery of C-carboxyalkyl dipeptide analogs with improved oral bioavailability. An in vivo assay of human MMP-3 mediated degradation of a macromolecular substrate in an extravascular space is described and inhibition studies are reported.

The matrix metalloproteinase stromelysin-1 (MMP-3) is inhibited more strongly by peptidyl phosphinic acid 7 than by its corresponding phosphonamidate and phosphonate analogs. Extending a benzyl group at P′ 1 to a phenylethyl group in 8 further increases the potency (K i = 1.4 nM). Enhanced potency with an extended substituent into the P 3 region was observed.