RESUMEN
Here, we report the discovery of a new class of NPBWR1 antagonists identified from a fragment-based screen. Compound 1 (cAMP IC50 = 250 µM; LE = 0.29) emerged as an initial hit. Further optimization of 1 by SAR-by-catalogue and chemical modification produced 21a (cAMP IC50 = 30 nM; LE = 0.39) with a 6700-fold increase in potency from fragment 1. Somewhat surprisingly, Schild analysis of compound 21a suggested that in vitro inhibition of NPW-mediated effects on upon cAMP accumulation were saturable, and that compound 21a dose-dependently increased [125I]-hNPW23 dissociation rate constants from NPBWR1 in kinetic binding studies. Collectively, these data are inconsistent with a classic surmountable, orthosteric mechanism of inhibition. The benzimidazole inhibitors reported herein may therefore represent a mechanistically differentiated class of compounds with which to form a better appreciation of the pharmacology and physiological roles of this central neuropeptide system.
Asunto(s)
Bencimidazoles/farmacología , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Receptores de Neuropéptido/antagonistas & inhibidores , Animales , Bencimidazoles/síntesis química , Células CHO , Cricetulus , Descubrimiento de Drogas , Humanos , Estructura Molecular , Relación Estructura-ActividadRESUMEN
The transformation of an aryloxybutanoic acid ultra high-throughput screening (uHTS) hit into a potent and selective series of G-protein coupled receptor 120 (GPR120) agonists is reported. uHTS hit 1 demonstrated an excellent rodent pharmacokinetic profile and selectivity over the related fatty acid receptor GPR40, but only modest GPR120 potency. Optimization of the "left-hand" aryl group led to compound 6, which demonstrated a GPR120 mechanism-based pharmacodynamic effect in a mouse oral glucose tolerance test (oGTT). Further optimization gave rise to the benzofuran propanoic acid series (exemplified by compound 37), which demonstrated acute mechanism-based pharmacodynamic effects. The combination of in vivo efficacy and attractive rodent pharmacodynamic profiles suggests compounds generated from this series may afford attractive candidates for the treatment of Type 2 diabetes.
Asunto(s)
Benzofuranos/química , Benzofuranos/farmacología , Propionatos/química , Propionatos/farmacología , Receptores Acoplados a Proteínas G/agonistas , Animales , Benzofuranos/sangre , Glucemia/análisis , Glucemia/metabolismo , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Evaluación Preclínica de Medicamentos , Ensayos Analíticos de Alto Rendimiento , Humanos , Hipoglucemiantes/sangre , Hipoglucemiantes/química , Hipoglucemiantes/farmacología , Ratones , Propionatos/sangre , Receptores Acoplados a Proteínas G/metabolismoRESUMEN
MK-4256, a tetrahydro-ß-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-ß-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.
Asunto(s)
Carbolinas/química , Carbolinas/farmacología , Receptores de Somatostatina/antagonistas & inhibidores , Animales , Carbolinas/síntesis química , Perros , Relación Dosis-Respuesta a Droga , Humanos , Ratones , Estructura Molecular , Ratas , Relación Estructura-ActividadRESUMEN
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.
Asunto(s)
Metilaminas/química , Receptores de Somatostatina/química , Descubrimiento de Drogas , Humanos , Relación Estructura-ActividadRESUMEN
The imidazolyl-tetrahydro-ß-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-ß-carboline (17e, MK-1421).
RESUMEN
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.
RESUMEN
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.
RESUMEN
This letter provides the first pharmacological proof of principle that the sst3 receptor mediates glucose-stimulated insulin secretion (GSIS) from pancreatic ß-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-ß-carboline (5a), with improved ion channel selectivity and mouse pharmacokinetic properties as compared to previously described tetrahydro-ß-carboline imidazole sst3 antagonists. We demonstrated that compound 5a enhances GSIS in pancreatic ß-cells and blocks glucose excursion induced by dextrose challenge in ipGTT and OGTT models in mice. Finally, we provided strong evidence that these effects are mechanism-based in an ipGTT study, showing reduction of glucose excursion in wild-type but not sst3 knockout mice. Thus, we have shown that antagonism of sst3 represents a new mechanism with potential in treating type 2 diabetes mellitus.
RESUMEN
A structure-activity relationship study of the imidazolyl-ß-tetrahydrocarboline series identified MK-4256 as a potent, selective SSTR3 antagonist, which demonstrated superior efficacy in a mouse oGTT model. MK-4256 reduced glucose excursion in a dose-dependent fashion with maximal efficacy achieved at doses as low as 0.03 mg/kg po. As compared with glipizide, MK-4256 showed a minimal hypoglycemia risk in mice.
RESUMEN
The synthesis and evaluation of small molecule antagonists of the G protein-coupled receptor NPBWR1 (GPR7) are reported for the first time. [4-(5-Chloropyridin-2-yl)piperazin-1-yl][(1S,2S,4R)-4-{[(1R)-1-(4-methoxyphenyl)ethyl]amino}-2-(thiophen-3-yl)cyclohexyl]methanone (1) emerged as a hit from a high-throughput screen. Examination of substituents that focused on replacing the 5-chloropyridine and 4-methoxybenzylamino groups of 1 led to the identification of compounds that exhibited subnanomolar potencies as low as 660pM (9k) in the functional assay and 200pM in the binding assay (9i).
Asunto(s)
Bencilaminas/farmacología , Piperazinas/farmacología , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Receptores de Neuropéptido/antagonistas & inhibidores , Animales , Bencilaminas/síntesis química , Bencilaminas/química , Cristalografía por Rayos X , Relación Dosis-Respuesta a Droga , Humanos , Ratones , Modelos Moleculares , Estructura Molecular , Piperazina , Piperazinas/síntesis química , Piperazinas/química , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
Septum formation in Escherichia coli is a complex cascade of interactions among cell-division proteins. The tubulin-like FtsZ division protein localizes to the division site and serves a cytoskeletal role during septum formation. A novel fluorescent-based 96-well format filter assay has been developed to measure the polymerization of FtsZ. A mixture of monomers and aggregates (38 to approximately 200 KDa in range) of purified wild-type FtsZ and a fluorescently tagged derivative of FtsZ protein in stoichiometric ratio passes through a 0.2-microm filter membrane, while polymerized FtsZ is retained on the filter. Addition of the SulA protein to the assay leads to rapid disassembly of existing FtsZ polymers, demonstrating its natural regulatory effect on FtsZ under the assay conditions. This assay is sensitive (requiring 2 microM FtsZ or less) and facilitates high-throughput screening of factors affecting FtsZ polymerization.