RESUMO
Herein we describe the discovery and optimization of a new series of 2,3-disubstituted and 2,3,6-trisubstituted muscarinic acetylcholine receptorâ 4 (M4 ) positive allosteric modulators (PAMs). Iterative libraries enabled rapid exploration of one-dimensional structure-activity relationships (SAR) and identification of potency-enhancing heterocycle and N-alkyl pyrazole substituents. Further optimization led to identification of the potent, receptor-subtype-selective, brain-penetrant tool compound 24 (7-[3-[1-[(1-fluorocyclopentyl)methyl]pyrazol-4-yl]-6-methyl-2-pyridyl]-3-methoxycinnoline). It is efficacious in preclinical assays that are predictive of antipsychotic effects, producing dose-dependent reversal of amphetamine-induced hyperlocomotion in rats and mice, but not in M4 knockout mice. Cholinergic-related adverse effects observed in rats treated with 24 at unbound plasma concentrations more than 3-fold higher than an efficacious dose in the hyperlocomotion assay were fewer and less severe than those observed in rats treated with the nonselective M4 agonist xanomeline, suggesting a receptor-subtype-selective PAM has the potential for an improved safety profile.
Assuntos
Descoberta de Drogas , Piridinas/química , Piridinas/farmacologia , Receptor Muscarínico M4/efeitos dos fármacos , Regulação Alostérica , Animais , Humanos , Ratos , Receptor Muscarínico M4/metabolismo , Relação Estrutura-AtividadeRESUMO
Previous work has suggested that activation of mGlu5 receptor augments NMDA receptor function and thereby may constitute a rational approach addressing glutamate hypofunction in schizophrenia and a target for novel antipsychotic drug development. Here, we report the in vitro activity, in vivo efficacy and safety profile of 5PAM523 (4-Fluorophenyl){(2R,5S)-5-[5-(5-fluoropyridin-2-yl)-1,2,4-oxadiazol-3-yl]-2-methylpiperidin-1-yl}methanone), a structurally novel positive allosteric modulator selective of mGlu5. In cells expressing human mGlu5 receptor, 5PAM523 potentiated threshold responses to glutamate in fluorometric calcium assays, but does not have any intrinsic agonist activity. 5PAM523 acts as an allosteric modulator as suggested by the binding studies showing that 5PAM523 did not displace the binding of the orthosteric ligand quisqualic acid, but did partially compete with the negative allosteric modulator, MPyEP. In vivo, 5PAM523 reversed amphetamine-induced locomotor activity in rats. Therefore, both the in vitro and in vivo data demonstrate that 5PAM523 acts as a selective mGlu5 PAM and exhibits anti-psychotic like activity. To study the potential for adverse effects and particularly neurotoxicity, brain histopathological exams were performed in rats treated for 4 days with 5PAM523 or vehicle. The brain exam revealed moderate to severe neuronal necrosis in the rats treated with the doses of 30 and 50 mg/kg, particularly in the auditory cortex and hippocampus. To investigate whether this neurotoxicity is mechanism specific to 5PAM523, similar safety studies were carried out with three other structurally distinct selective mGlu5 PAMs. Results revealed a comparable pattern of neuronal cell death. Finally, 5PAM523 was tested in mGlu5 knock-out (KO) and wild type (WT) mice. mGlu5 WT mice treated with 5PAM523 for 4 days at 100 mg/kg presented significant neuronal death in the auditory cortex and hippocampus. Conversely, mGlu5 KO mice did not show any neuronal loss by histopathology, suggesting that enhancement of mGlu5 function is responsible for the toxicity of 5PAM523. This study reveals for the first time that augmentation of mGlu5 function with selective allosteric modulators results in neurotoxicity.
Assuntos
Antipsicóticos/toxicidade , Benzamidas/toxicidade , Encéfalo/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Fármacos Atuantes sobre Aminoácidos Excitatórios/toxicidade , Oxidiazóis/toxicidade , Receptor de Glutamato Metabotrópico 5/metabolismo , Regulação Alostérica , Animais , Antipsicóticos/química , Antipsicóticos/farmacocinética , Benzamidas/química , Benzamidas/farmacocinética , Encéfalo/patologia , Encéfalo/fisiopatologia , Células CHO , Morte Celular/fisiologia , Células Cultivadas , Cricetulus , Fármacos Atuantes sobre Aminoácidos Excitatórios/química , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacocinética , Feminino , Humanos , Masculino , Camundongos da Linhagem 129 , Camundongos Knockout , Necrose/patologia , Necrose/fisiopatologia , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurônios/fisiologia , Síndromes Neurotóxicas/patologia , Síndromes Neurotóxicas/fisiopatologia , Oxidiazóis/química , Oxidiazóis/farmacocinética , Ratos Sprague-Dawley , Ratos Wistar , Receptor de Glutamato Metabotrópico 5/genéticaRESUMO
This manuscript concludes the Structure Activity Relationship (SAR) on the pyridazinone scaffold and identifies a compound with subnanomolar p38α activity and 24h coverage in the rat arthritis efficacy model.
Assuntos
Proteína Quinase 14 Ativada por Mitógeno/antagonistas & inibidores , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/farmacologia , Piridazinas/síntese química , Piridazinas/farmacologia , Piridinas/síntese química , Piridinas/farmacologia , Animais , Cães , Relação Dose-Resposta a Droga , Haplorrinos , Humanos , Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Estrutura Molecular , Inibidores de Proteínas Quinases/administração & dosagem , Piridazinas/administração & dosagem , Piridinas/administração & dosagem , Ratos , Relação Estrutura-AtividadeRESUMO
Next generation NNRTIs are sought which possess both broad spectrum antiviral activity against key mutant strains and a high genetic barrier to the selection of new mutant viral strains. Pyridones were evaluated as an acyclic conformational constraint to replace the aryl ether core of MK-4965 (1) and the more rigid indazole constraint of MK-6186 (2). The resulting pyridone compounds are potent inhibitors of HIV RT and have antiviral activity in cell culture that is superior to other next generation NNRTI's.
Assuntos
Transcriptase Reversa do HIV/antagonistas & inibidores , Piridonas/química , Inibidores da Transcriptase Reversa/síntese química , Sítios de Ligação , Linhagem Celular , Simulação por Computador , Desenho de Fármacos , Ativação Enzimática/efeitos dos fármacos , HIV/enzimologia , Transcriptase Reversa do HIV/metabolismo , Humanos , Estrutura Terciária de Proteína , Pirazóis/química , Piridinas/química , Piridonas/síntese química , Piridonas/farmacologia , Inibidores da Transcriptase Reversa/química , Inibidores da Transcriptase Reversa/farmacologiaRESUMO
The development and synthesis of potent p38α MAP kinase inhibitors containing a pyridazinone platform is described. Evolution of the p38α selective pyridopyridazin-6-one series from the p38α/ß dual inhibitor 2H-quinolizin-2-one series will be discussed in full detail.
Assuntos
Proteína Quinase 14 Ativada por Mitógeno/antagonistas & inibidores , Inibidores de Proteínas Quinases/síntese química , Piridazinas/química , Animais , Sítios de Ligação , Domínio Catalítico , Simulação por Computador , Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacocinética , Estrutura Terciária de Proteína , Piridazinas/síntese química , Piridazinas/farmacocinética , Ratos , Relação Estrutura-AtividadeRESUMO
Studies were conducted to investigate mutation pathways among subtypes A, B, and C of human immunodeficiency virus type 1 (HIV-1) during resistance selection with nonnucleoside reverse transcriptase inhibitors (NNRTIs) in cell culture under low-multiplicity of infection (MOI) conditions. The results showed that distinct pathways were selected by different virus subtypes under increasing selective pressure of NNRTIs. F227C and Y181C were the major mutations selected by MK-4965 in subtype A and C viruses during resistance selection. With efavirenz (EFV), F227C and V106M were the major mutations responsible for viral breakthrough in subtype A viruses, whereas a single pathway (G190A/V106M) accounted for mutation development in subtype C viruses. Y181C was the dominant mutation in the resistance selection with etravirine (ETV) in subtype A, and E138K/H221Y were the mutations detected in the breakthrough viruses from subtype C viruses with ETV. In subtype B viruses, on the other hand, known NNRTI-associated mutations (e.g., Y181C, P236L, L100I, V179D, and K103N) were selected by the NNRTIs. The susceptibility of the subtype A and B mutant viruses to NNRTIs was determined in order to gain insight into the potential mechanisms of mutation development. Collectively, these results suggest that minor differences may exist in conformation of the residues within the NNRTI binding pocket (NNRTIBP) of reverse transcriptase (RT) among the three subtypes of viruses. Thus, the interactions between NNRTIs and the residues in the NNRTIBPs of different subtypes may not be identical, leading to distinct mutation pathways during resistance selection in cell culture.
Assuntos
Farmacorresistência Viral/genética , Transcriptase Reversa do HIV/antagonistas & inibidores , HIV-1/efeitos dos fármacos , Inibidores da Transcriptase Reversa/farmacologia , Alcinos , Benzoxazinas/química , Benzoxazinas/farmacologia , Linhagem Celular , Ciclopropanos , HIV-1/genética , Humanos , Estrutura Molecular , Mutação , Nitrilas , Pirazóis/química , Pirazóis/farmacologia , Piridazinas/química , Piridazinas/farmacologia , Piridinas/química , Piridinas/farmacologia , Pirimidinas , Replicação Viral/efeitos dos fármacosRESUMO
The development and synthesis of potent p38alpha MAP kinase inhibitors containing a 2H-quinolizin-2-one platform is described. Evolution of the 2H-quinolizin-2-one series from an early lead to solving off target activity and pharmacokinetic issues is also discussed.
Assuntos
Anti-Inflamatórios/síntese química , Inibidores de Proteínas Quinases/síntese química , Quinolizinas/química , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/farmacocinética , Linhagem Celular , Cães , Haplorrinos , Humanos , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacocinética , Quinolizinas/síntese química , Quinolizinas/farmacocinética , Ratos , Relação Estrutura-Atividade , Fator de Necrose Tumoral alfa/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Nonnucleoside reverse transcriptase inhibitors (NNRTIs) are the mainstays of therapy for the treatment of human immunodeficiency virus type 1 (HIV-1) infections. However, the effectiveness of NNRTIs can be hampered by the development of resistance mutations which confer cross-resistance to drugs in the same class. Extensive efforts have been made to identify new NNRTIs that can suppress the replication of the prevalent NNRTI-resistant viruses. MK-4965 is a novel NNRTI that possesses both diaryl ether and indazole moieties. The compound displays potency at subnanomolar concentrations against wild-type (WT), K103N, and Y181C reverse transcriptase (RT) in biochemical assays. MK-4965 is also highly potent against the WT virus and two most prevalent NNRTI-resistant viruses (viruses that harbor the K103N or the Y181C mutation), against which it had 95% effective concentrations (EC(95)s) of <30 nM in the presence of 10% fetal bovine serum. The antiviral EC(95) of MK-4965 was reduced approximately four- to sixfold when it was tested in 50% human serum. Moreover, MK-4965 was evaluated with a panel of 15 viruses with NNRTI resistance-associated mutations and showed a superior mutant profile to that of efavirenz but not to that of etravirine. MK-4965 was similarly effective against various HIV-1 subtypes and viruses containing nucleoside reverse transcriptase inhibitor or protease inhibitor resistance-conferring mutations. A two-drug combination study showed that the antiviral activity of MK-4965 was nonantagonistic with each of the 18 FDA-licensed drugs tested vice versa in the present study. Taken together, these in vitro data show that MK-4965 possesses the desired properties for further development as a new NNRTI for the treatment of HIV-1 infection.
Assuntos
Fármacos Anti-HIV/farmacologia , Transcriptase Reversa do HIV/antagonistas & inibidores , HIV-1/efeitos dos fármacos , Pirazóis/farmacologia , Piridinas/farmacologia , Inibidores da Transcriptase Reversa/farmacologia , Alcinos , Benzoxazinas/farmacologia , Linhagem Celular , Ciclopropanos , Farmacorresistência Viral , Humanos , Nevirapina/farmacologia , Nitrilas , Piridazinas/farmacologia , PirimidinasRESUMO
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) have been shown to be a key component of highly active antiretroviral therapy (HAART). The use of NNRTIs has become part of standard combination antiviral therapies producing clinical outcomes with efficacy comparable to other antiviral regimens. There is, however, a critical issue with the emergence of clinical resistance, and a need has arisen for novel NNRTIs with a broad spectrum of activity against key HIV-1 RT mutations. Using a combination of traditional medicinal chemistry/SAR analyses, crystallography, and molecular modeling, we have designed and synthesized a series of novel, highly potent NNRTIs that possess broad spectrum antiviral activity and good pharmacokinetic profiles. Further refinement of key compounds in this series to optimize physical properties and pharmacokinetics has resulted in the identification of 8e (MK-4965), which has high levels of potency against wild-type and key mutant viruses, excellent oral bioavailability and overall pharmacokinetics, and a clean ancillary profile.
Assuntos
Transcriptase Reversa do HIV/antagonistas & inibidores , HIV-1/efeitos dos fármacos , HIV-1/enzimologia , Pirazóis/síntese química , Pirazóis/farmacologia , Piridinas/síntese química , Piridinas/farmacologia , Inibidores da Transcriptase Reversa/síntese química , Inibidores da Transcriptase Reversa/farmacologia , Administração Oral , Animais , Compostos de Bromo/síntese química , Compostos de Bromo/química , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Transcriptase Reversa do HIV/química , Transcriptase Reversa do HIV/genética , Transcriptase Reversa do HIV/metabolismo , HIV-1/genética , Modelos Moleculares , Estrutura Molecular , Mutação/genética , Nucleosídeos/química , Nucleosídeos/farmacologia , Pirazóis/química , Piridinas/química , Ratos , Ratos Sprague-Dawley , Inibidores da Transcriptase Reversa/química , Relação Estrutura-AtividadeRESUMO
Using a combination of traditional Medicinal Chemistry/SAR analysis, crystallography, and molecular modeling, we have designed and synthesized a series of novel, highly potent NNRTIs that possess broad antiviral activity against a number of key clinical mutations.