RESUMO
Ghrelin, a gut-derived orexigenic hormone, is an endogenous ligand of the growth hormone secretagogue receptor (GHS-R). Centrally administered ghrelin has been shown to cause hunger and increase food intake in rodents. Inhibition of ghrelin actions with ghrelin antibody, peptidyl GHS-R antagonists, and antisense oligonucleosides resulted in weight loss and food intake decrease in rodents. Here we report the effects of GHS-R antagonists, some of which were potent, selective, and orally bioavailable. A structure-activity relationship study led to the discovery of 8a, which was effective in decreasing food intake and body weight in several acute rat studies.
Assuntos
Pirimidinas/farmacologia , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Animais , Células CHO , Cricetinae , Avaliação Pré-Clínica de Medicamentos , Humanos , Ligantes , Estrutura Molecular , Pirimidinas/síntese química , Pirimidinas/química , Receptores de Grelina , Estereoisomerismo , Relação Estrutura-Atividade , Fatores de TempoRESUMO
The discovery and pharmacological evaluation of potent, selective, and orally bioavailable growth hormone secretagogue receptor (GHS-R) antagonists are reported. Previously, 2,4-diaminopyrimidine-based GHS-R antagonists reported from our laboratories have been shown to be dihydrofolate reductase (DHFR) inhibitors. By comparing the X-ray crystal structure of DHFR docked with our GHS-R antagonists and GHS-R modeling, we designed and synthesized a series of potent and DHFR selective GHS-R antagonists with good pharmacokinetic (PK) profiles. An amide derivative 13d (Ca2+ flux IC50 = 188 nM, [brain]/[plasma] = 0.97 @ 8 h in rat) showed a 10% decrease in 24 h food intake in rats, and over 5% body weight reduction after 14-day oral treatment in diet-induced obese (DIO) mice. In comparison, a urea derivative 14c (Ca2+ flux IC50 = 7 nM, [brain]/[plasma] = 0.0 in DIO) failed to show significant effect on food intake in the acute feeding DIO model. These observations demonstrated for the first time that peripheral GHS-R blockage with small molecule GHS-R antagonists might not be sufficient for suppressing appetite and inducing body weight reduction.
Assuntos
Aminopiridinas/síntese química , Fármacos Antiobesidade/síntese química , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Administração Oral , Amidas/síntese química , Amidas/farmacologia , Aminopiridinas/farmacologia , Animais , Fármacos Antiobesidade/farmacologia , Depressores do Apetite/síntese química , Depressores do Apetite/farmacologia , Disponibilidade Biológica , Peso Corporal/efeitos dos fármacos , Linhagem Celular , Cristalografia por Raios X , Ingestão de Alimentos/efeitos dos fármacos , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Modelos Moleculares , Estrutura Molecular , Ratos , Ratos Sprague-Dawley , Receptores de Grelina , Relação Estrutura-Atividade , Ureia/análogos & derivados , Ureia/síntese química , Ureia/farmacologiaRESUMO
The design and synthesis of a series of 11,12-cyclic carbamate derivatives of 6-O-methylerythromycin A that are novel, nonpeptide LHRH antagonists, is described. The macrolide antagonist 1, discovered during a screen of our chemical repository, was compared to a macrocyclic peptide antagonist 2 using molecular modeling, thus providing a model for the design of more potent antagonists. Medicinal chemistry efforts to find a replacement for cladinose at position 3 of the erythronolide core provided a series of oxazolidinone carbamates that were equally as active as the cladinose-containing parent macrolides. The descladinose LHRH antagonist 14 has 1-2 nM affinity for both rat and human LHRH receptors and is a potent inhibitor of LH release (pA2 = 8.76) in vitro. In vivo, 14 was found to produce a dose-dependent suppression of LH in male castrate rats via both i.v. and p.o. dosing.
Assuntos
Eritromicina/análogos & derivados , Eritromicina/síntese química , Hormônio Liberador de Gonadotropina/antagonistas & inibidores , Hexoses/síntese química , Administração Oral , Animais , Células Cultivadas , Cricetinae , Desenho de Fármacos , Eritromicina/farmacologia , Hormônio Liberador de Gonadotropina/sangue , Hormônio Liberador de Gonadotropina/metabolismo , Hexoses/farmacologia , Humanos , Injeções Intravenosas , Masculino , Modelos Moleculares , Orquiectomia , Hipófise/citologia , Hipófise/metabolismo , Ratos , Relação Estrutura-AtividadeRESUMO
Histamine affects homeostatic mechanisms, including food and water consumption, by acting on central nervous system (CNS) receptors. Presynaptic histamine H(3) receptors regulate release of histamine and other neurotransmitters, and histamine H(3) receptor antagonists enhance neurotransmitter release. A-331440 [4'-[3-(3(R)-(dimethylamino)-pyrrolidin-1-yl)-propoxy]-biphenyl-4-carbonitrile] is a histamine H(3) receptor antagonist which binds potently and selectively to both human and rat histamine H(3) receptors (K(i)<==25 nM). Mice were stabilized on a high-fat diet (45 kcal % lard) prior to 28-day oral b.i.d. dosing for measurement of obesity-related parameters. A-331440 administered at 0.5 mg/kg had no significant effect on weight, whereas 5 mg/kg decreased weight comparably to dexfenfluramine (10 mg/kg). A-331440 administered at 15 mg/kg reduced weight to a level comparable to mice on the low-fat diet. The two higher doses reduced body fat and the highest dose also normalized an insulin tolerance test. These data show that the histamine H(3) receptor antagonist, A-331440, has potential as an antiobesity agent.
Assuntos
Fármacos Antiobesidade/farmacologia , Compostos de Bifenilo/farmacologia , Antagonistas dos Receptores Histamínicos/farmacologia , Nitrilas/farmacologia , Pirrolidinas/farmacologia , Receptores Histamínicos H3/efeitos dos fármacos , Tecido Adiposo/efeitos dos fármacos , Animais , Depressores do Apetite/farmacologia , Comportamento Animal/efeitos dos fármacos , Composição Corporal/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Cálcio/metabolismo , Clonagem Molecular , Diagnóstico por Imagem , Dieta , Gorduras na Dieta/farmacologia , Fenfluramina/farmacologia , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Humanos , Imageamento por Ressonância Magnética , Camundongos , Camundongos Endogâmicos C57BL , Ensaio Radioligante , Ratos , Redução de Peso/efeitos dos fármacosRESUMO
A-331440 [4'-[3-(3(R)-(dimethylamino)-pyrrolidin-1-yl)-propoxy]-biphenyl-4-carbonitrile], a potent and selective antagonist of histamine H3 receptors, yielded positive results in an in vitro micronucleus assay, predictive of genotoxicity in vivo. Because this compound has highly favourable properties and potential as an antiobesity agent, new compounds of this general chemical class were sought that would retain or improve upon the high potency and selectivity of A-331440 for H3 receptors, but would lack the potential for genotoxicity obtained with that compound. Our working hypothesis was that the biphenyl rings in A-331440 might contribute to interactions with DNA and thereby predispose toward genotoxicity. Toward this end, several analogues were prepared, with substituents introduced onto the biaryl ring to alter the orientation, electronegativity, and polarity of this moiety, and were tested for their radioligand binding potency and selectivity and their propensity to induce genotoxicity in the in vitro micronucleus assay. Using this strategy, novel compounds were discovered that retained or improved upon the potency and selectivity of A-331440 for H3 receptors and were devoid of genotoxicity in vitro. Of these, the simple mono- and di-fluorinated analogues (A-417022 [4'-[3-[(3R)-3-(dimethylamino)-1-pyrrolidinyl]propoxy]-3'-fluoro-1,1'-biphenyl-4-carbonitrile] and A-423579 [4'-[3-[(3R)-3-(dimethylamino)-1-pyrrolidinyl]-propoxy]-3',5'-difluoro-1,1'-biphenyl-4-carbonitrile], respectively) were found to bind to H3 receptors at least as potently as A-331440, while lacking genotoxicity in the micronucleus assay. The reason of the lack of genotoxicity of the fluorinated analogues is unclear, but is especially noteworthy in light of the general principle that fluorine and hydrogen are very similar in size. Therefore, these fluorinated analogues of A-331440 represented the most potent and potentially safest compounds for further evaluation as antiobesity leads. Preliminary findings with one of these examples, A-417022, in a mouse model of obesity are presented.
Assuntos
Fármacos Antiobesidade/farmacologia , Compostos de Bifenilo/farmacologia , Antagonistas dos Receptores Histamínicos/farmacologia , Nitrilas/farmacologia , Pirrolidinas/farmacologia , Receptores Histamínicos H3/metabolismo , Animais , Linhagem Celular , Cricetinae , Cricetulus , Modelos Animais de Doenças , Desenho de Fármacos , Antagonistas dos Receptores Histamínicos/síntese química , Camundongos , Camundongos Endogâmicos C57BL , Testes para Micronúcleos , Estrutura Molecular , Ensaio Radioligante , Relação Estrutura-Atividade , Redução de Peso/efeitos dos fármacosRESUMO
The c-Jun N-terminal kinases (JNKs) have been implicated in the development of insulin resistance, diabetes, and obesity. Genetic disruption of JNK1, but not JNK2, improves insulin sensitivity in diet-induced obese (DIO) mice. We applied RNA interference to investigate the specific role of hepatic JNK1 in contributing to insulin resistance in DIO mice. Adenovirus-mediated delivery of JNK1 short-hairpin RNA (Ad-shJNK1) resulted in almost complete knockdown of hepatic JNK1 protein without affecting JNK1 protein in other tissues. Liver-specific knockdown of JNK1 resulted in significant reductions in circulating insulin and glucose levels, by 57 and 16%, respectively. At the molecular level, JNK1 knockdown mice had sustained and significant increase of hepatic Akt phosphorylation. Furthermore, knockdown of JNK1 enhanced insulin signaling in vitro. Unexpectedly, plasma triglyceride levels were robustly elevated upon hepatic JNK1 knockdown. Concomitantly, expression of proliferator-activated receptor gamma coactivator 1 beta, glucokinase, and microsomal triacylglycerol transfer protein was increased. Further gene expression analysis demonstrated that knockdown of JNK1 up-regulates the hepatic expression of clusters of genes in glycolysis and several genes in triglyceride synthesis pathways. Our results demonstrate that liver-specific knockdown of JNK1 lowers circulating glucose and insulin levels but increases triglyceride levels in DIO mice.
Assuntos
Regulação Enzimológica da Expressão Gênica , Glucose/metabolismo , Insulina/metabolismo , Fígado/metabolismo , Proteína Quinase 8 Ativada por Mitógeno/metabolismo , Transativadores/biossíntese , Triglicerídeos/sangue , Adenoviridae/genética , Adenoviridae/metabolismo , Ração Animal , Animais , Primers do DNA/química , Camundongos , Camundongos Obesos , PPAR gama/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Fosforilação , Fatores de Transcrição , Triglicerídeos/metabolismoRESUMO
A series of potent 2-carboxychromone-based melanin-concentrating hormone receptor 1 (MCHr1) antagonists were synthesized and evaluated for hERG (human Ether-a-go-go Related Gene) channel affinity and functional blockade. Basic dialkylamine-terminated analogs were found to weakly bind the hERG channel and provided marked improvement in a functional patch-clamp assay versus previously reported antagonists of the series.
Assuntos
Amidas/farmacologia , Cromonas/farmacologia , Canais de Potássio Éter-A-Go-Go/metabolismo , Receptores do Hormônio Hipofisário/antagonistas & inibidores , Animais , Canais de Potássio Éter-A-Go-Go/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Camundongos , Obesidade/tratamento farmacológico , Técnicas de Patch-Clamp , FarmacocinéticaRESUMO
The incorporation of constrained tertiary amines into an existing class of N-benzyl-4-aminopiperidinyl chromone-based MCHr1 antagonists led to the identification of a series of chiral racemic compounds that displayed good to excellent functional potency, binding affinity, and selectivity over the hERG channel. Further separation of two distinct chiral racemic compounds into their corresponding pairs of enantiomers revealed a considerable selectivity for MCHr1 for one configuration, in addition to a striking difference in oral exposure between one pair of enantiomers in diet-induced obese mice. Oral administration of the most potent compound in this class in the same animal model led to significant reduction of fat mass in a semi-chronic model for weight loss.
Assuntos
Cromonas/síntese química , Cromonas/farmacologia , Piperidinas/síntese química , Piperidinas/farmacologia , Receptores de Somatostatina/antagonistas & inibidores , Animais , Fármacos Antiobesidade/síntese química , Fármacos Antiobesidade/farmacologia , Depressores do Apetite/farmacologia , Peso Corporal/efeitos dos fármacos , Encéfalo/metabolismo , Linhagem Celular , Dieta , Gorduras na Dieta , Canais de Potássio Éter-A-Go-Go/efeitos dos fármacos , Fenfluramina/farmacologia , Indicadores e Reagentes , Camundongos , Conformação Molecular , Bloqueadores dos Canais de Potássio/síntese química , Bloqueadores dos Canais de Potássio/farmacologia , Relação Estrutura-AtividadeRESUMO
Dexfenfluramine (DEX) and sibutramine (SIB) are effective antiobesity agents. Their effects on weight control and hormone profile have not been previously studied in diet-switched diet-induced obese (DIO) mice, in which treatment is initiated upon cessation of a low-fat diet and resumption of a high-fat diet. Furthermore, their effects on circulating ghrelin in obese humans or in animal models of obesity have not yet been reported. Male C57Bl/6J DIO mice after 16 wk on a high-fat diet (HF, 60 kcal% fat) were switched to a low-fat diet (LF, 10 kcal% fat) for 50 d. HF diet resumed concurrently with treatment for 28 d with DEX 3 and 10 mg/kg, twice a day (BID); SIB 5 mg/kg BID; or vehicle. Rapid weight regain ensued in vehicle-treated DIO mice. DEX or SIB treatment significantly blunted the body weight gain. Caloric intake was decreased acutely by DEX or SIB vs vehicle during the first 2 d treatment, but returned to control after 5 d. At the end of study, epididymal fat weight and whole body fat mass determined by DEXA scan were decreased by DEX 10 mg/kg, and whole body lean mass decreased with DEX 3 mg/kg treatment. Circulating ghrelin on d 28 was increased with either DEX 3 or 10 mg/kg treatment, while growth hormone and insulin were decreased. Leptin was also decreased in the DEX 10 mg/kg group. SIB did not significantly affect fat mass, ghrelin, growth hormone, insulin, or leptin. Mice chronically fed LF diet maintained a lower caloric intake, gained less weight and fat mass than diet-switched mice, and had higher ghrelin and lower insulin and leptin. In summary, weight regain in diet-switched DIO mice is delayed with either DEX or SIB treatment. DEX treatment of diet-switched DIO mice decreased growth hormone, insulin, leptin, fat mass, lean mass, and increased ghrelin, while SIB only decreased body weight.
Assuntos
Fármacos Antiobesidade/farmacologia , Ciclobutanos/farmacologia , Dexfenfluramina/farmacologia , Obesidade/tratamento farmacológico , Animais , Peso Corporal/efeitos dos fármacos , Dieta com Restrição de Gorduras , Grelina , Hormônio do Crescimento/sangue , Masculino , Camundongos , Obesidade/etiologia , Obesidade/prevenção & controle , Hormônios Peptídicos/sangue , Magreza/sangue , Aumento de Peso/efeitos dos fármacosRESUMO
RNA interference (RNAi) is an exciting new tool to effect acute in vivo knockdown of genes for pharmacological target validation. Testing the application of this technology to metabolic disease targets, three RNAi delivery methods were compared in two frequently utilized preclinical models of obesity and diabetes, the diet-induced obese (DIO) and B6.V-Lep
RESUMO
A series of urea-based N-1-(2-aminoethyl)-indazoles was synthesized and evaluated for melanin-concentrating hormone receptor 1 (MCHr1) antagonism in both binding and functional assays. Several compounds that acted as MCHr1 antagonists were identified, and optimization afforded a compound with excellent binding affinity, good functional potency, and oral efficacy in a chronic model for weight loss in diet-induced obese mice.