RESUMEN
Nicotinic acid (niacin) induces beneficial changes in serum lipoproteins and has been associated with beneficial cardiovascular effects. Niacin reduces low-density lipoprotein, increases high-density lipoprotein, and decreases triglycerides. It is well established that activation of the seven-transmembrane G(i)-coupled receptor GPR109A on Langerhans cells results in release of prostaglandin D2, which mediates the well-known flushing side effect of niacin. Niacin activation of GPR109A on adipocytes also mediates the transient reduction of plasma free fatty acid (FFA) levels characteristic of niacin, which has been long hypothesized to be the mechanism underlying the changes in the serum lipid profile. We tested this "FFA hypothesis" and the hypothesis that niacin lipid efficacy is mediated via GPR109A by dosing mice lacking GPR109A with niacin and testing two novel, full GPR109A agonists, MK-1903 and SCH900271, in three human clinical trials. In mice, the absence of GPR109A had no effect on niacin's lipid efficacy despite complete abrogation of the anti-lipolytic effect. Both MK-1903 and SCH900271 lowered FFAs acutely in humans; however, neither had the expected effects on serum lipids. Chronic FFA suppression was not sustainable via GPR109A agonism with niacin, MK-1903, or SCH900271. We conclude that the GPR109A receptor does not mediate niacin's lipid efficacy, challenging the long-standing FFA hypothesis.
Asunto(s)
Ácidos Grasos/metabolismo , Niacina/farmacología , Receptores Acoplados a Proteínas G/metabolismo , Receptores Nicotínicos/metabolismo , Animales , Relación Dosis-Respuesta a Droga , Ácidos Grasos/sangre , Humanos , Lipólisis/efectos de los fármacos , Lipoproteínas/sangre , Masculino , Ratones , Ratones Endogámicos C57BL , Niacina/administración & dosificación , Pirazoles/farmacología , Receptores Acoplados a Proteínas G/agonistasRESUMEN
G-protein coupled receptor (GPCR) GPR109a is a molecular target for nicotinic acid and is expressed in adipocytes, spleen, and immune cells. Nicotinic acid has long been used for the treatment of dyslipidemia due to its capacity to positively affect serum lipids to a greater extent than other currently marketed drugs. We report a series of tricyclic pyrazole carboxylic acids that are potent and selective agonists of GPR109a. Compound R,R-19a (MK-1903) was advanced through preclinical studies, was well tolerated, and presented no apparent safety concerns. Compound R,R-19a was advanced into a phase 1 clinical trial and produced a robust decrease in plasma free fatty acids. On the basis of these results, R,R-19a was evaluated in a phase 2 study in humans. Because R,R-19a produced only a weak effect on serum lipids as compared with niacin, we conclude that the beneficial effects of niacin are most likely the result of an undefined GPR109a independent pathway.
Asunto(s)
Ácidos Grasos no Esterificados/sangre , Pirazoles/uso terapéutico , Receptores Acoplados a Proteínas G/agonistas , Animales , Humanos , Hipolipemiantes/farmacocinética , Hipolipemiantes/uso terapéutico , Masculino , Niacina/farmacología , Pirazoles/síntesis química , Pirazoles/farmacocinética , Ratas , Receptores Acoplados a Proteínas G/efectos de los fármacos , Receptores Nicotínicos/efectos de los fármacos , Estereoisomerismo , Vasodilatadores/farmacologíaRESUMEN
The Mas receptor is a class I G-protein-coupled receptor that is expressed in brain, testis, heart, and kidney. The intracellular signaling pathways activated downstream of Mas are still largely unknown. In the present study, we examined the expression pattern and signaling of Mas in the heart and assessed the participation of Mas in cardiac ischemia-reperfusion injury. Mas mRNA and protein were present in all chambers of human hearts, with cardiomyocytes and coronary arteries being sites of enriched expression. Expression of Mas in either HEK293 cells or cardiac myocytes resulted in constitutive coupling to the G(q) protein, which in turn activated phospholipase C and caused inositol phosphate accumulation. To generate chemical tools for use in probing the function of Mas, we performed a library screen and chemistry optimization program to identify potent and selective nonpeptide agonists and inverse agonists. Mas agonists activated G(q) signaling in a dose-dependent manner and reduced coronary blood flow in isolated mouse and rat hearts. Conversely, treatment of isolated rat hearts with Mas inverse agonists improved coronary flow, reduced arrhythmias, and provided cardioprotection from ischemia-reperfusion injury, an effect that was due, at least in part, to decreased cardiomyocyte apoptosis. Participation of Mas in ischemia-reperfusion injury was confirmed in Mas knockout mice, which had reduced infarct size relative to mice with normal Mas expression. These results suggest that activation of Mas during myocardial infarction contributes to ischemia-reperfusion injury and further suggest that inhibition of Mas-G(q) signaling may provide a new therapeutic strategy directed at cardioprotection.
Asunto(s)
Cardiotónicos/farmacología , Circulación Coronaria/efectos de los fármacos , Subunidades alfa de la Proteína de Unión al GTP Gq-G11/metabolismo , Infarto del Miocardio/prevención & control , Daño por Reperfusión Miocárdica/prevención & control , Miocardio/metabolismo , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Receptores Acoplados a Proteínas G/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Animales , Animales Recién Nacidos , Apoptosis/efectos de los fármacos , Cardiotónicos/química , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Agonismo Inverso de Drogas , Activación Enzimática , Células HEK293 , Humanos , Fosfatos de Inositol/metabolismo , Ratones , Ratones Noqueados , Estructura Molecular , Infarto del Miocardio/genética , Infarto del Miocardio/metabolismo , Infarto del Miocardio/patología , Infarto del Miocardio/fisiopatología , Daño por Reperfusión Miocárdica/genética , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Daño por Reperfusión Miocárdica/fisiopatología , Miocardio/patología , Proto-Oncogenes Mas , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Factores de Tiempo , Transfección , Fosfolipasas de Tipo C/metabolismo , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
Serotonin, which is stored in platelets and is released during thrombosis, activates platelets via the 5-HT(2A) receptor. 5-HT(2A) receptor inverse agonists thus represent a potential new class of antithrombotic agents. Our medicinal program began with known compounds that displayed binding affinity for the recombinant 5-HT(2A) receptor, but which had poor activity when tested in human plasma platelet inhibition assays. We herein describe a series of phenyl pyrazole inverse agonists optimized for selectivity, aqueous solubility, antiplatelet activity, low hERG activity, and good pharmacokinetic properties, resulting in the discovery of 10k (APD791). 10k inhibited serotonin-amplified human platelet aggregation with an IC(50) = 8.7 nM and had negligible binding affinity for the closely related 5-HT(2B) and 5-HT(2C) receptors. 10k was orally bioavailable in rats, dogs, and monkeys and had an acceptable safety profile. As a result, 10k was selected further evaluation and advanced into clinical development as a potential treatment for arterial thrombosis.
Asunto(s)
Arterias/efectos de los fármacos , Benzamidas/química , Benzamidas/farmacología , Descubrimiento de Drogas/métodos , Agonismo Inverso de Drogas , Morfolinas/química , Morfolinas/farmacología , Pirazoles/química , Pirazoles/farmacología , Agonistas del Receptor de Serotonina 5-HT2 , Trombosis/tratamiento farmacológico , Animales , Benzamidas/metabolismo , Benzamidas/farmacocinética , Perros , Femenino , Humanos , Concentración 50 Inhibidora , Masculino , Morfolinas/metabolismo , Morfolinas/farmacocinética , Agregación Plaquetaria/efectos de los fármacos , Pirazoles/metabolismo , Pirazoles/farmacocinética , Ratas , Receptor de Serotonina 5-HT2A/metabolismo , Relación Estructura-Actividad , Especificidad por Sustrato , Trombosis/metabolismoRESUMEN
GPR41 and GPR42 are two closely related genes that are part of a cluster of four adjacent G protein-coupled receptors (GPCRs) (GPR40, 41, 42, and 43) localized on human chromosome 19. There are only six nucleotide and amino acid differences between GPR41 and GPR42. High sequence homology between these two genes suggests that they are the result of a recent duplication event. Mutagenesis studies have previously shown that amino acid 174 is important for functional signaling since conversion of R174 (found in GPR41) to W174 (found in GPR42) silences the response to short chain fatty acids, raising the possibility that GPR42 might be an inactive pseudogene. In the present study, we present evidence showing that the six amino acid differences, including that R/W174 are polymorphisms rather than gene-specific differences between GPR41 and GPR42. Most importantly, of the 202 GPR42 alleles that were genotyped, 123 (61%) had arginine at amino acid 174, suggesting that GPR42 could potentially be a functional gene in a significant fraction of the human population and should therefore not be categorically characterized as an inactive pseudogene. In addition, a second copy of GPR40 was found to localize between GPR41 and GPR42 genes in human and chimp, suggesting that the duplication event that generated GPR42 in human and chimp might have involved a 12.5 kb DNA fragment that also contains GPR40. This second copy of the GPR40 gene is a pseudogene since it has diverged extensively from GPR40 and does not contain an open reading frame.
Asunto(s)
Polimorfismo Genético , Seudogenes , Receptores Acoplados a Proteínas G/genética , Secuencia de Bases , Secuencia de Consenso , Humanos , Datos de Secuencia Molecular , Regiones Promotoras Genéticas , Receptores Acoplados a Proteínas G/químicaRESUMEN
We have evaluated the receptor pharmacology, antiplatelet activity, and vascular pharmacology of APD791 [3-methoxy-N-(3-(1-methyl-1H-pyrazol-5-yl)-4-(2-morpholinoethoxy)phenyl)benzamide] a novel 5-hydroxytryptamine 2A (5-HT(2A)) receptor antagonist. APD791 displayed high-affinity binding to membranes (K(i) = 4.9 nM) and functional inverse agonism of inositol phosphate accumulation (IC(50) = 5.2 nM) in human embryonic kidney cells stably expressing the human 5-HT(2A) receptor. In competition binding assays, APD791 was greater than 2000-fold selective for the 5-HT(2A) receptor versus 5-HT(2C) and 5-HT(2B) receptors, and was inactive when tested against a wide panel of other G-protein-coupled receptors. APD791 inhibited 5-HT-mediated amplification of ADP-stimulated human and dog platelet aggregation (IC(50) = 8.7 and 23.1 nM, respectively). Similar potency was observed for inhibition of 5-HT-stimulated DNA synthesis in rabbit aortic smooth muscle cells (IC(50) = 13 nM) and 5-HT-mediated vasoconstriction in rabbit aortic rings. Oral administration of APD791 to dogs resulted in acute (1-h) and subchronic (10-day) inhibition of 5-HT-mediated amplification of collagen-stimulated platelet aggregation in whole blood. Two active metabolites, APD791-M1 and APD791-M2, were generated upon incubation of APD791 with human liver microsomes and were also indentified in dogs after oral administration of APD791. The affinity and selectivity profiles of both metabolites were similar to APD791. These results demonstrate that APD791 is an orally available, high-affinity 5-HT(2A) receptor antagonist with potent activity on platelets and vascular smooth muscle.
Asunto(s)
Benzamidas/química , Benzamidas/farmacología , Plaquetas/efectos de los fármacos , Morfolinas/química , Morfolinas/farmacología , Músculo Liso Vascular/fisiología , Activación Plaquetaria/fisiología , Pirazoles/química , Pirazoles/farmacología , Receptor de Serotonina 5-HT2A/fisiología , Antagonistas del Receptor de Serotonina 5-HT2 , Antagonistas de la Serotonina/farmacología , Administración Oral , Animales , Aorta/efectos de los fármacos , Aorta/fisiología , Benzamidas/farmacocinética , Plaquetas/fisiología , Línea Celular , Estudios Cruzados , Perros , Relación Dosis-Respuesta a Droga , Femenino , Haplorrinos , Humanos , Masculino , Morfolinas/farmacocinética , Músculo Liso Vascular/efectos de los fármacos , Activación Plaquetaria/efectos de los fármacos , Pirazoles/farmacocinética , Conejos , Ratas , Receptor de Serotonina 5-HT2A/sangre , Antagonistas de la Serotonina/administración & dosificación , Antagonistas de la Serotonina/sangre , Antagonistas de la Serotonina/farmacocinética , Especificidad de la EspecieRESUMEN
A series of 5-N,N-disubstituted-5-aminopyrazole-3-carboxylic acids were prepared and found to act as highly potent and selective agonists of the G-Protein Coupled Receptor (GPCR) GPR109b, a low affinity receptor for niacin and some aromatic d-amino acids. Little activity was observed at the highly homologous higher affinity niacin receptor, GPR109a.
Asunto(s)
Ácidos Carboxílicos/síntesis química , Receptores Acoplados a Proteínas G/agonistas , Animales , Aterosclerosis/tratamiento farmacológico , Células CHO , Ácidos Carboxílicos/farmacología , Química Farmacéutica/métodos , Cricetinae , Cricetulus , Diseño de Fármacos , Dislipidemias/tratamiento farmacológico , Humanos , Ligandos , Lipoproteínas HDL/química , Lipoproteínas LDL/química , Modelos Químicos , Niacina/química , Pirazoles/farmacología , Receptores Acoplados a Proteínas G/metabolismo , Receptores NicotínicosRESUMEN
Regulation of cellular metabolism by the citric acid cycle occurs in the mitochondria. However, the citric acid cycle intermediate succinate was shown recently to be a ligand for the G-protein-coupled receptor GPR91. Here, we describe a role for succinate and its receptor in the stimulation of hematopoietic progenitor cell (HPC) growth. GPR91 mRNA and protein expression were detected in human bone marrow CD34+ progenitor cells, as well as in erythroid and megakaryocyte cultures and the erythroleukemic cell line TF-1. Treatment of these cell cultures with succinate resulted in increased proliferation rates. The proliferation response of TF-1 cells was pertussis toxin (PTX)-sensitive, suggesting a role for Gi signaling. Proliferation was also blocked when TF-1 cells were transfected with small interfering RNA specific for GPR91. Succinate stimulated activation of the Erk MAPK pathway and inositol phosphate accumulation in a PTX-sensitive manner. Pretreatment of TF-1 cells with the Erk1/2 kinase (MEK) inhibitor PD98059 blocked the proliferation response. Succinate treatment additionally protected TF-1 cells from cell death induced by serum deprivation. Finally, in vivo administration of succinate was found to elevate the levels of hemoglobin, platelets, and neutrophils in a mouse model of chemotherapy-induced myelosuppression. These results suggest that succinate-GPR91 signaling is capable of promoting HPC development.
Asunto(s)
Células Madre Hematopoyéticas/efectos de los fármacos , Receptores Acoplados a Proteínas G/metabolismo , Transducción de Señal , Ácido Succínico/farmacología , Animales , Antígenos CD34/metabolismo , Línea Celular , Proliferación Celular , Células Madre Hematopoyéticas/metabolismo , Humanos , Ligandos , Sistema de Señalización de MAP Quinasas , Masculino , Ratones , Ratones Endogámicos BALB C , ARN Mensajero/metabolismoRESUMEN
The discovery and profiling of 3-(1H-tetrazol-5-yl)-1,4,5,6-tetrahydro-cyclopentapyrazole (5a, MK-0354), a partial agonist of GPR109a, is described. Compound 5a retained the plasma free fatty acid lowering effects in mice associated with GPR109a agonism, but did not induce vasodilation at the maximum feasible dose. Moreover, preadministration of 5a blocked the flushing effect induced by nicotinic acid but not that induced by PGD2. This profile made 5a a suitable candidate for further study for the treatment of dyslipidemia.
Asunto(s)
Hipolipemiantes/farmacología , Pirazoles/farmacocinética , Receptores Acoplados a Proteínas G/agonistas , Tetrazoles/farmacocinética , Adipocitos/efectos de los fármacos , Animales , Ácidos Grasos no Esterificados/sangre , Humanos , Hipolipemiantes/síntesis química , Hipolipemiantes/uso terapéutico , Lipólisis/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Pirazoles/síntesis química , Receptores Nicotínicos , Tetrazoles/síntesis química , Vasodilatación/efectos de los fármacosRESUMEN
We have evaluated the anti-platelet and vascular pharmacology of AR246686, a novel 5-hydroxytryptamine2A (5-HT2A) receptor antagonist. AR246686 displayed high affinity binding to membranes of HEK cells stably expressing recombinant human and rat 5-HT2A receptors (Ki=0.2 nM and 0.4 nM, respectively). Functional antagonism (IC50=1.9 nM) with AR246686 was determined by inhibition of ligand-independent inositol phosphate accumulation in the 5-HT2A stable cell line. We observed 8.7-fold and 1360-fold higher affinity of AR246686 for the 5-HT2A receptor vs. 5-HT2C and 5-HT2B receptors, respectively. AR246686 inhibited 5-HT-induced amplification of ADP-stimulated human platelet aggregation (IC50=21 nM). Similar potency was observed for inhibition of 5-HT stimulated DNA synthesis in rat aortic smooth muscle cells (IC(50)=10 nM) and 5-HT-mediated contraction in rat aortic rings. Effects of AR246686 on arterial thrombosis and bleeding time were studied in a rat model of femoral artery occlusion. Oral dosing of AR246686 to rats resulted in prolongation of time to occlusion at 1 mg/kg, whereas increased bleeding time was observed at a dose of 20 mg/kg. In contrast, both bleeding time and time to occlusion were increased at the same dose (10 mg/kg) of clopidogrel. These results demonstrate that AR246686 is a high affinity 5-HT2A receptor antagonist with potent activity on platelets and vascular smooth muscle. Further, oral administration results in anti-thrombotic effects at doses that are free of significant effects on traumatic bleeding time.
Asunto(s)
Vasos Sanguíneos/efectos de los fármacos , Fibrinolíticos/farmacología , Compuestos de Fenilurea/farmacología , Receptor de Serotonina 5-HT2A/efectos de los fármacos , Antagonistas de la Serotonina/farmacología , Anfetaminas/metabolismo , Animales , Aorta Torácica/efectos de los fármacos , Tiempo de Sangría , Plaquetas/efectos de los fármacos , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , ADN/biosíntesis , ADN/genética , Fibrinolíticos/farmacocinética , Humanos , Fosfatos de Inositol/metabolismo , Masculino , Músculo Liso Vascular/efectos de los fármacos , Agregación Plaquetaria/efectos de los fármacos , Unión Proteica , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes/química , Serotonina/metabolismo , Vasoconstricción/efectos de los fármacosRESUMEN
BACKGROUND: Development of niacin-like agents that favorably affect lipids with an improved flushing profile would be beneficial. OBJECTIVE: To evaluate a niacin receptor partial agonist, MK-0354, in Phase I and II studies. METHODS: The pharmacokinetic/pharmacodynamic effects of single and multiple doses (7 days) of MK-0354 (300-4000 mg) were evaluated in two Phase I studies conducted in healthy men. A Phase II study assessed the effects of MK-0354 2.5 g once daily on lipids during 4 weeks in 66 dyslipidemic patients. RESULTS: MK-0354 single doses up to 4000 mg and multiple doses (7 days) up to 3600 mg produced robust dose-related reductions in free fatty acid (FFA) over 5 hours. Single doses of MK-0354 300 mg and extended release-niacin (Niaspan) 1 g produced comparable reductions in FFA. Suppression of FFA following 7 daily doses of MK-0354 was similar to that after a single dose. In the Phase II study, MK-0354 2.5 g produced little flushing but no clinically meaningful effects on lipids (placebo-adjusted percent change: high-density lipoprotein cholesterol, 0.4%, 95% confidence interval -5.2 to 6.0; low-density lipoprotein cholesterol, -9.8%, 95% confidence interval -16.8 to -2.7; triglyceride, -5.8%, 95% confidence interval -22.6 to 11.9). CONCLUSION: Treatment with MK-0354 for 7 days resulted in plasma FFA suppression with minimal cutaneous flushing. However, 4 weeks of treatment with MK-0354 failed to produce changes in high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, or triglycerides.
RESUMEN
A series of 3-nitro-4-substituted-aminobenzoic acids were prepared and found to act as potent and highly selective agonists of the orphan human GPCR GPR109b, a low affinity receptor for niacin. No activity was observed at the closely homologous high affinity niacin receptor, GPR109a. A second series, comprising 6-amino-substituted nicotinic acids was, also prepared and several analogues showed comparable activity to the nitroaryl series.
Asunto(s)
Benzoatos/química , Ácidos Nicotínicos/química , Receptores Acoplados a Proteínas G/agonistas , Animales , Benzoatos/agonistas , Benzoatos/metabolismo , Células CHO , Cricetinae , Cricetulus , Humanos , Niacina/metabolismo , Ácidos Nicotínicos/agonistas , Ácidos Nicotínicos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores Acoplados a Proteínas G/fisiología , Receptores Nicotínicos/metabolismo , Receptores Nicotínicos/fisiología , Relación Estructura-ActividadRESUMEN
A series of 5-alkyl pyrazole-3-carboxylic acids were prepared and found to act as potent and selective agonists of the human GPCR, GPR109a, the high affinity nicotinic acid receptor. No activity was observed at the highly homologous low affinity niacin receptor, GPR109b. A further series of 4-fluoro-5-alkyl pyrazole-3-carboxylic acids were shown to display similar potency. One example from the series was shown to have improved properties in vivo compared to niacin.
Asunto(s)
Ácidos/química , Flúor/química , Agonistas Nicotínicos/química , Agonistas Nicotínicos/farmacología , Pirazoles/química , Pirazoles/farmacología , Receptores Acoplados a Proteínas G/agonistas , Animales , Ácidos Grasos/metabolismo , Ligandos , Masculino , Ratones , Estructura Molecular , Agonistas Nicotínicos/síntesis química , Pirazoles/síntesis química , Ratas , Receptores Acoplados a Proteínas G/metabolismo , Receptores Nicotínicos/metabolismo , Relación Estructura-ActividadRESUMEN
A strategy for lead identification of new agonists of GPR109a, starting from known compounds shown to activate the receptor, is described. Early compound triage led to the formulation of a binding hypothesis and eventually to our focus on a series of pyrazole acid derivatives. Further elaboration of these compounds provided a series of 5,5-fused pyrazoles to be used as lead compounds for further optimization.
Asunto(s)
Ácidos Heterocíclicos/química , Química Farmacéutica/métodos , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/química , Receptores Nicotínicos/química , Adipocitos/metabolismo , Animales , AMP Cíclico/metabolismo , Diseño de Fármacos , Humanos , Cinética , Modelos Químicos , Niacina/química , Pirazoles/química , Ratas , Bazo/metabolismoRESUMEN
Nicotinic acid remains the most effective therapeutic agent for the treatment and prevention of atherosclerosis resulting from low high density lipoprotein cholesterol. The therapeutic actions of nicotinic acid are mediated by GPR109A, a Gi protein-coupled receptor, expressed primarily on adipocytes, Langerhans cells, and macrophage. Unfortunately, a severe, cutaneous flushing side effect limits its use and patient compliance. The mechanism of high density lipoprotein elevation is not clearly established but assumed to be influenced by an inhibition of lipolysis in the adipose. The flushing side effect appears to be mediated by the release of prostaglandin D2 from Langerhans cells in the skin. We hypothesized that the signal transduction pathways mediating the anti-lipolytic and prostaglandin D2/flushing pathways are distinct and that agonists may be identified that are capable of selectively eliciting the therapeutic, anti-lipolytic pathway while avoiding the activation of the parallel flush-inducing pathway. We have identified a number of GPR109A pyrazole agonists that are capable of fully inhibiting lipolysis in vitro and in vivo and not only fail to elicit a flushing response but can antagonize the ability of nicotinic acid to elicit a flush response in vivo. In contrast to flushing agonists, exposure of cells expressing GPR109A to the non-flushing agonists fails to induce internalization of the receptor or to activate ERK 1/2 mitogen-activated protein kinase phosphorylation.
Asunto(s)
Regulación de la Expresión Génica , Agonistas Nicotínicos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores Nicotínicos/metabolismo , Tejido Adiposo/metabolismo , Animales , Células CHO , Células COS , Chlorocebus aethiops , Cricetinae , Cricetulus , Masculino , Ratones , Ratones Endogámicos C57BL , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Modelos Químicos , Prostaglandina D2/metabolismo , Ratas , Receptores Acoplados a Proteínas G/química , Receptores Nicotínicos/químicaRESUMEN
Recently identified GPCRs, GPR109a and GPR109b, the high and low affinity receptors for niacin, may represent good targets for the development of HDL elevating drugs for the treatment of atherosclerosis. Acifran, an agonist of both receptors, has been tested in human subjects, yet until recently very few analogs had been reported. We describe a series of acifran analogs prepared using newly developed synthetic pathways and evaluated as agonists for GPR109a and GPR109b, resulting in identification of compounds with improved activity at these receptors.
Asunto(s)
Furanos/síntesis química , Niacina/metabolismo , Receptores Acoplados a Proteínas G/agonistas , Línea Celular , AMP Cíclico/biosíntesis , Furanos/química , Furanos/farmacología , Humanos , Niacina/farmacología , Receptores Acoplados a Proteínas G/metabolismo , Receptores Nicotínicos/metabolismo , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
Nicotinic acid, used for atherosclerosis treatment, has an adverse effect of skin flushing. The flushing mechanism, thought to be caused by the release of prostaglandin D(2) (PGD(2)), is not well understood. We aimed to identify which cells mediate the flushing effect. Nicotinic acid receptor (GPR109A) gene expression was assessed in various tissues and cell lines. Cells expressing GPR109A mRNA were further assayed for PGD(2) release in response to nicotinic acid. Of all samples, only skin was able to release PGD(2) upon stimulation with nicotinic acid. The responsive cells were localized to the epidermis, and immunocytochemical studies revealed the presence of GPR109A on epidermal Langerhans cells. CD34+ cells isolated from human blood and differentiated into Langerhans cells (hLC-L) also showed GPR109A expression. IFNgamma treatment increased both mRNA and plasma membrane expression of GPR109A. IFNgamma-stimulated hLC-Ls released PGD(2) in response to nicotinic acid in a dose-dependant manner (effector concentration for half-maximum response=1.2 mM+/-0.7). Acifran, a structurally distinct GPR109A ligand, also increased PGD(2) release, whereas isonicotinic acid, a nicotinic acid analog with low affinity for GPR109A, had no effect. These results suggest that nicotinic acid mediates its flushing side effect by interacting with GPR109A on skin Langerhans cells, resulting in release of PGD(2).
Asunto(s)
Rubor/inducido químicamente , Hipolipemiantes/farmacología , Células de Langerhans/efectos de los fármacos , Células de Langerhans/metabolismo , Niacina/farmacología , Prostaglandina D2/metabolismo , Animales , Células Cultivadas , Humanos , Técnicas In Vitro , Masculino , Ratones , Ratones Endogámicos C57BL , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Receptores Nicotínicos/genética , Receptores Nicotínicos/metabolismo , Piel/metabolismo , Distribución TisularRESUMEN
1-Substituted benzotriazole carboxylic acids have been identified as the first reported examples of selective small-molecule agonists of the human orphan G-protein-coupled receptor GPR109b (HM74), a low-affinity receptor for the HDL-raising drug niacin. No activity was observed at the highly homologous high-affinity niacin receptor GPR109a (HM74A). The high degree of selectivity was attributed to a difference in the amino acid sequence adjacent to a key arginine-ligand interaction allowing somewhat larger ligands to be tolerated by GPR109b.
Asunto(s)
Ácidos Carboxílicos/síntesis química , Hipolipemiantes/síntesis química , Receptores Acoplados a Proteínas G/agonistas , Triazoles/síntesis química , Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Sitios de Unión , Ácidos Carboxílicos/química , Ácidos Carboxílicos/farmacología , AMP Cíclico/biosíntesis , Humanos , Hipolipemiantes/química , Hipolipemiantes/farmacología , Ligandos , Lipólisis/efectos de los fármacos , Niacina/farmacología , Receptores Nicotínicos , Relación Estructura-Actividad , Triazoles/química , Triazoles/farmacologíaRESUMEN
A novel series of substituted N-[3-(1,1,2,2-tetrafluoroethoxy)benzyl]-N-(3-phenoxyphenyl)-trifluoro-3-amino-2-propanols is described which potently and reversibly inhibit cholesteryl ester transfer protein (CETP). Starting from the initial lead 1, various substituents were introduced into the 3-phenoxyaniline group to optimize the relative activity for inhibition of the CETP-mediated transfer of [3H]-cholesteryl ester from HDL donor particles to LDL acceptor particles either in buffer or in human serum. The better inhibitors in the buffer assay clustered among compounds in which the phenoxy group was substituted at the 3, 4, or 5 positions. In general, small lipophilic alkyl, haloalkyl, haloalkoxy, and halogen moieties increased potency relative to 1, while analogues containing electron-donating or hydrogen bond accepting groups exhibited lower potency. Compounds with polar or strong electron-withdrawing groups also displayed lower potency. Replacement of the phenoxy ring in 1 with either simple aliphatic or cycloalkyl ethers as well as basic heteroaryloxy groups led to reduced potency. From the better compounds, a representative series 4a-i was prepared as the chirally pure R(+) enantiomers, and from these, the 4-chloro-3-ethylphenoxy analogue was identified as a potent inhibitor of CETP activity in buffer (4a, IC50 0.77 nM, 59 nM in human serum). The simple R(+) enantiomer 4a represents the most potent acyclic CETP inhibitor reported. The chiral synthesis and biochemical characterization of 4a are reported along with its preliminary pharmacological assessment in animals.
Asunto(s)
Compuestos de Anilina/síntesis química , Proteínas Portadoras/antagonistas & inhibidores , Ésteres del Colesterol/metabolismo , Glicoproteínas , Hipolipemiantes/síntesis química , Propanolaminas/síntesis química , Administración Oral , Compuestos de Anilina/farmacocinética , Compuestos de Anilina/farmacología , Animales , Proteínas de Transferencia de Ésteres de Colesterol , Ésteres del Colesterol/sangre , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Cricetinae , Humanos , Hipolipemiantes/farmacocinética , Hipolipemiantes/farmacología , Lipoproteínas , Mesocricetus , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Propanolaminas/farmacocinética , Propanolaminas/farmacología , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
A novel series of substituted N-benzyl-N-phenyl-trifluoro-3-amino-2-propanols are described that reversibly inhibit cholesteryl ester transfer protein (CETP). Starting with screening lead 22, various structural features were explored with respect to inhibition of the CETP-mediated transfer of [(3)H]cholesterol from high-density cholesterol donor particles to low-density cholesterol acceptor particles. The free hydroxyl group of the propanol was required for high potency, since acylation or alkylation reduced activity. High inhibitory potency was also associated with 3-ether moieties in the aniline ring, and the highest potencies were exhibited by 3-phenoxyaniline analogues. Activity was substantially reduced by oxidation or substitution in the methylene of the benzylic group, implying that the benzyl ring orientation was important for activity. In the benzylic group, substitution at the 3-position was preferred over either the 2- or the 4-positions. Highest potencies were observed with inhibitors in which the 3-benzylic substituent had the potential to adopt an out of plane orientation with respect to the phenyl ring. The best 3-benzylic substituents were OCF(2)CF(2)H (42, IC(50) 0.14 microM in buffer, 5.6 microM in human serum), cyclopentyl (39), 3-iso-propoxy (27), SCF(3) (67), and C(CF(3))(2)OH (36). Separation of 42 into its enantiomers unexpectedly showed that the minor R(+) enantiomer 1a was 40-fold more potent (IC(50) 0.02 microM in buffer, 0.6 microM in human serum) than the major S(-) enantiomer 1b, demonstrating that the R-chirality at the propanol 2-position is key to high potency in this series. The R(+) enantiomer 1a represents the first reported acyclic CETP inhibitor with submicromolar potency in plasma. A chiral synthesis of 1a is reported.