RESUMO
Antagonism of the bradykinin B(1) receptor represents a potential treatment for chronic pain and inflammation. Novel antagonists incorporating alpha-hydroxy amides were designed that display low-nanomolar affinity for the human bradykinin B(1) receptor and good bioavailability in the rat and dog. In addition, these functionally active compounds show high passive permeability and low susceptibility to phosphoglycoprotein mediated efflux, predictive of good CNS exposure.
Assuntos
Amidas/farmacologia , Antagonistas de Receptor B1 da Bradicinina , Amidas/química , Amidas/farmacocinética , Animais , Disponibilidade Biológica , Barreira Hematoencefálica , Inibidores das Enzimas do Citocromo P-450 , Cães , Meia-Vida , Humanos , Ratos , Ratos Sprague-Dawley , Relação Estrutura-AtividadeRESUMO
Antagonism of the bradykinin B1 receptor represents a potential treatment for chronic pain and inflammation. Novel antagonists were designed that display low-nanomolar affinity for the human bradykinin B1 receptor and good bioavailability in the rat.
Assuntos
Amidas/síntese química , Analgésicos/síntese química , Anti-Inflamatórios não Esteroides/síntese química , Antagonistas de Receptor B1 da Bradicinina , Ciclopropanos/síntese química , Piridinas/síntese química , Amidas/química , Amidas/farmacologia , Analgésicos/química , Analgésicos/farmacologia , Animais , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/farmacologia , Disponibilidade Biológica , Ciclopropanos/química , Ciclopropanos/farmacologia , Desenho de Fármacos , Humanos , Conformação Molecular , Piridinas/química , Piridinas/farmacologia , Ratos , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
This study used behavioural and in vivo electrophysiological paradigms to examine the effects of systemic and spinal administration of a bradykinin B1 receptor antagonist, compound X, on acute nociceptive responses in the rat. In behavioural experiments, compound X significantly increased the latency to withdraw the hindpaw from a radiant heat source after both intravenous and intrathecal administration, without affecting motor performance on the rotarod. In electrophysiological experiments, both intravenous and direct spinal administration of compound X attenuated the responses of single dorsal horn neurones to noxious thermal stimulation of the hindpaw. These data show that the antinociceptive effects of a bradykinin B1 receptor antagonist are mediated, at least in part, at the level of the spinal cord and suggest a role for spinal bradykinin B1 receptors in acute nociception.
Assuntos
Amidas/farmacocinética , Antagonistas de Receptor B1 da Bradicinina , Naftalenos/farmacocinética , Medição da Dor/métodos , Pirrolidinas/farmacocinética , Medula Espinal/efeitos dos fármacos , Amidas/administração & dosagem , Animais , Carragenina/administração & dosagem , Carragenina/toxicidade , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Eletrofisiologia/métodos , Pé , Membro Posterior , Temperatura Alta/efeitos adversos , Hiperalgesia/etiologia , Hiperalgesia/fisiopatologia , Hiperalgesia/prevenção & controle , Hipersensibilidade/etiologia , Hipersensibilidade/fisiopatologia , Injeções Intravenosas , Injeções Espinhais , Masculino , Morfina/farmacologia , Naftalenos/administração & dosagem , Nociceptores/efeitos dos fármacos , Nociceptores/fisiologia , Desempenho Psicomotor/efeitos dos fármacos , Pirrolidinas/administração & dosagem , Ratos , Ratos Sprague-Dawley , Medula Espinal/fisiologiaRESUMO
Bradykinin B1 receptor antagonists embody a potentially novel approach for the treatment of chronic pain and inflammation. A series of 2,3-diaminopyridine B1 antagonists was optimized to have sub-nanomolar affinity and good pharmacokinetic properties. Lead compounds were shown to exhibit good efficacy in rabbit in vivo models of pain and inflammation.
Assuntos
Aminopiridinas/síntese química , Analgésicos/síntese química , Anti-Inflamatórios não Esteroides/síntese química , Antagonistas de Receptor B1 da Bradicinina , Aminopiridinas/química , Aminopiridinas/farmacologia , Analgésicos/química , Analgésicos/farmacologia , Animais , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/farmacologia , Cães , Meia-Vida , Inflamação/tratamento farmacológico , Medição da Dor , Coelhos , Ratos , Especificidade da Espécie , Relação Estrutura-AtividadeRESUMO
Antagonism of the bradykinin B(1) receptor was demonstrated to be a potential treatment for chronic pain and inflammation. Novel benzodiazepines were designed that display subnanomolar affinity for the bradykinin B(1) receptor (K(i) = 0.59 nM) and high selectivity against the bradykinin B(2) receptor (K(i) > 10 microM). In vivo efficacy, comparable to morphine, was demonstrated for lead compounds in a rodent hyperalgesia model.
Assuntos
Benzodiazepinas/síntese química , Antagonistas dos Receptores da Bradicinina , Animais , Benzodiazepinas/química , Benzodiazepinas/farmacologia , Células CHO , Cricetinae , Humanos , Hiperalgesia/induzido quimicamente , Hiperalgesia/tratamento farmacológico , Ensaio Radioligante , Ratos , Ratos Sprague-Dawley , Receptor B1 da Bradicinina , Receptor B2 da Bradicinina , Relação Estrutura-AtividadeRESUMO
Compound A (N-[2-[4-(4,5-dihydro-1H-imidazol-2-yl)phenyl]ethyl]-2-[(2R)-1-(2-napthylsulfonyl)-3-oxo-1,2,3,4-tetrahydroquinoxalin-2-yl]acetamide) is a member of a new class of aryl sulfonamide dihydroquinoxalinone bradykinin B1 receptor antagonists that should be useful pharmacological tools. Here we report on some of the pharmacological properties of compound A as well as the characterization of [35S]compound A as the first nonpeptide bradykinin B1 receptor radioligand. Compound A inhibited tritiated peptide ligand binding to the cloned human, rabbit, dog, and rat bradykinin B1 receptors expressed in CHO cells with Ki values of 0.016, 0.050, 0.56, and 29 nM, respectively. It was inactive at 10 microM in binding assays with the cloned human bradykinin B2 receptor. In functional antagonist assays with the cloned bradykinin B1 receptors, compound A inhibited agonist-induced signaling with activities consistent with the competition binding results, but had no antagonist activity at the bradykinin B2 receptor. Compound A was also found to be a potent antagonist in a rabbit aorta tissue bath preparation and to effectively block des-Arg9 bradykinin depressor responses in lipopolysaccharide-treated rabbit following intravenous administration. The binding of [35S]compound A was evaluated with the cloned bradykinin B1 receptors. In assays with human, rabbit, and dog receptors, [35S]compound A labeled a single site with Kd values of 0.012, 0.064, and 0.37 nM, respectively, and with binding site densities equivalent to those obtained using the conventional tritiated peptide ligands. Binding assays with the cloned rat bradykinin B1 receptor were not successful, presumably due to the low affinity of the ligand for this species receptor. There was no specific binding of the ligand detected in CHO cells expressing the human bradykinin B2 receptor. In assays with the cloned human bradykinin B1 receptor, the pharmacologies of the binding of [35S]compound A and [3H][Leu9]des-Arg10-kallidin were the same. The high signal-to-noise ratio obtained with [35S]compound A will allow this ligand to be a very useful tool for future investigations of the bradykinin B1 receptor.
Assuntos
Antagonistas de Receptor B1 da Bradicinina , Calidina/análogos & derivados , Receptor B1 da Bradicinina/metabolismo , Animais , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/fisiologia , Ligação Competitiva/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Células CHO , Cricetinae , Cricetulus , Cães , Relação Dose-Resposta a Droga , Humanos , Imidazóis/metabolismo , Imidazóis/farmacologia , Técnicas In Vitro , Calidina/metabolismo , Lipopolissacarídeos/farmacologia , Masculino , Quinoxalinas/metabolismo , Quinoxalinas/farmacologia , Coelhos , Ensaio Radioligante , Ratos , Receptor B1 da Bradicinina/genética , Transfecção , Trítio , Vasoconstrição/efeitos dos fármacosAssuntos
Agonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Glicina/análogos & derivados , Receptores de Glutamato Metabotrópico/efeitos dos fármacos , Animais , Benzamidas/farmacologia , Sítios de Ligação , Células CHO , Cricetinae , Agonistas de Aminoácidos Excitatórios/química , Antagonistas de Aminoácidos Excitatórios/química , Glicina/farmacologia , Humanos , Hidrazinas/farmacologia , Ftalimidas/farmacologia , Ratos , Receptor de Glutamato Metabotrópico 5 , Receptores de Glutamato Metabotrópico/química , Resorcinóis/farmacologia , Relação Estrutura-AtividadeRESUMO
Selective bradykinin (BK) B 1 receptor antagonists could be novel therapeutic agents for the treatment of pain and inflammation. Elucidation of the structure activity relationships of the structurally novel HTS lead compound 1 provided potent hBK B 1 receptor antagonists with excellent receptor occupancy in the CNS of hBK B 1 transgenic rats.
Assuntos
Aminas/química , Benzofenonas/química , Benzofenonas/farmacologia , Antagonistas de Receptor B1 da Bradicinina , Animais , Benzofenonas/síntese química , Linhagem Celular , Cães , Humanos , Estrutura Molecular , Ratos , Receptor B1 da Bradicinina/metabolismo , Relação Estrutura-AtividadeRESUMO
Selective bradykinin (BK) B(1) receptor antagonists have been shown to be antinociceptive in animal models and could be novel therapeutic agents for the treatment of pain and inflammation. Elucidation of the structure-activity relationships of the biphenyl moiety of the lead compound 1 provided a potent new structural class of BK B(1) receptor antagonists.
Assuntos
Analgésicos/química , Anti-Inflamatórios não Esteroides/química , Antagonistas de Receptor B1 da Bradicinina , Cicloexanos/química , Hidrocarbonetos Fluorados/química , Piridinas/química , Analgésicos/síntese química , Analgésicos/farmacologia , Animais , Animais Geneticamente Modificados , Anti-Inflamatórios não Esteroides/síntese química , Anti-Inflamatórios não Esteroides/farmacologia , Cicloexanos/síntese química , Cicloexanos/farmacologia , Humanos , Hidrocarbonetos Fluorados/síntese química , Hidrocarbonetos Fluorados/farmacologia , Piridinas/síntese química , Piridinas/farmacologia , Ratos , Receptor B1 da Bradicinina/genética , Relação Estrutura-AtividadeRESUMO
A novel class of 2,3-diaminopyridine bradykinin B1 receptor antagonists is disclosed. Structure-activity relationship studies (SARs) that led to compounds with significantly improved potency and pharmacokinetic properties relative to the lead compound are described.
Assuntos
Aminopiridinas/farmacologia , Antagonistas de Receptor B1 da Bradicinina , Piridinas/síntese química , Aminopiridinas/química , Desenho de Fármacos , Humanos , Cinética , Modelos Moleculares , Piridinas/farmacologia , Relação Estrutura-AtividadeRESUMO
We have identified a family of highly selective allosteric modulators of the group I metabotropic glutamate receptor subtype 5 (mGluR5). This family of closely related analogs exerts a spectrum of effects, ranging from positive to negative allosteric modulation, and includes compounds that do not themselves modulate mGluR5 agonist activity but rather prevent other family members from exerting their modulatory effects. 3,3'-Difluorobenzaldazine (DFB) has no agonist activity, but it acts as a selective positive allosteric modulator of human and rat mGluR5. DFB potentiates threshold responses to glutamate, quisqualate, and 3,5-dihydroxyphenylglycine in fluorometric Ca2+ assays 3- to 6-fold, with EC50 values in the 2 to 5 microM range, and at 10 to 100 microM, it shifts mGluR5 agonist concentration-response curves approximately 2-fold to the left. The analog 3,3'-dimethoxybenzaldazine (DMeOB) acts as a negative modulator of mGluR5 agonist activity, with an IC50 of 3 microM in fluorometric Ca2+ assays, whereas the analog 3,3'-dichlorobenzaldazine (DCB) does not exert any apparent modulatory effect on mGluR5 activity. However, DCB seems to act as an allosteric ligand with neutral cooperativity, preventing the positive allosteric modulation of mGluRs by DFB as well as the negative modulatory effect of DMeOB. None of these analogs affects binding of [3H]quisqualate to the orthosteric (glutamate) site, but they do inhibit [3H]3-methoxy-5-(2-pyridinylethynyl)pyridine binding to the site for 2-methyl-6-(phenylethynyl)-pyridine, a previously identified negative allosteric modulator. With the use of these compounds, we provide evidence that allosteric sites on GPCRs can respond to closely related ligands with a range of pharmacological activities from positive to negative modulation as well as to neutral competition of this modulation.
Assuntos
Agonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Receptores de Glutamato Metabotrópico/metabolismo , Regulação Alostérica/efeitos dos fármacos , Regulação Alostérica/fisiologia , Animais , Células CHO , Cricetinae , Relação Dose-Resposta a Droga , Agonistas de Aminoácidos Excitatórios/química , Antagonistas de Aminoácidos Excitatórios/química , Humanos , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , Receptor de Glutamato Metabotrópico 5 , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/antagonistas & inibidoresRESUMO
Antagonists of the B1 bradykinin receptor (B1R) offer the promise of novel therapeutic agents for the treatment of inflammatory and neuropathic pain. However, the in vivo characterization of the pharmacodynamics of B1R antagonists is hindered by the low level of B1R expression in healthy tissue and the profound species selectivity exhibited by many compounds for the human B1R. To circumvent these issues, we generated a transgenic rat expressing the human B1R under the control of the neuron-specific enolase promoter. Membranes prepared from whole brain homogenates of heterozygous transgenic rats indicate a B1R expression level of 30 to 40 fmol/mg; there is no detectable B1R expression in control nontransgenic rats. The pharmacological profile of the B1R expressed in the transgenic rat matches that expected of the human, but not the rat receptor. The mapping of the transgene insertion site to rat chromosome 1 permitted the development of a reliable assay for the identification of homozygous transgenic rats. Significantly, homozygous transgenic rats express 2-fold more B1R than heterozygous animals. Autoradiographic analyses of tissue sections from transgenic rats reveal that the B1R is broadly expressed in both the brain and spinal cord. The human B1R expressed in the transgenic rat functions in an in vitro contractile assay and thus has the potential to elicit a functional response in vivo. Using the humanized B1R transgenic rat, an assay was developed that is suitable for the routine evaluation of a test compound's ability to occupy the human B1R in the central nervous system.
Assuntos
Animais Geneticamente Modificados/genética , Modelos Animais , Ratos/genética , Receptor B1 da Bradicinina/biossíntese , Receptor B1 da Bradicinina/genética , Animais , Animais Geneticamente Modificados/metabolismo , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Células CHO , Cricetinae , Relação Dose-Resposta a Droga , Feminino , Humanos , Íleo/efeitos dos fármacos , Íleo/metabolismo , Masculino , Fragmentos de Peptídeos/farmacologia , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologiaRESUMO
Bradykinin (BK) plays an important role in the pathophysiological processes accompanying pain and inflammation. Selective bradykinin B1 receptor antagonists have been shown to be anti-nociceptive in animal models and could be novel therapeutic agents for the treatment of pain and inflammation. We have explored chemical modifications in a series of dihydroquinoxalinone sulfonamides to evaluate the effects of various structural changes on biological activity. The optimization of a screening lead compound, facilitated by a homology model of the BK B1 receptor, culminated in the discovery of a potent human BK B1 receptor antagonist. Results from site-directed mutagenesis studies and experiments in an animal pain model are presented.