RESUMO
Biologically active metabolites are a valuable resource for development of drug candidates and lead structures for drug design. This digest highlights a selection of biologically active metabolites that have been used as new chemical entities for development or as lead structures for drug design.
Assuntos
Descoberta de Drogas , Preparações Farmacêuticas/metabolismo , Bibliotecas de Moléculas Pequenas/metabolismo , Estrutura Molecular , Preparações Farmacêuticas/síntese química , Preparações Farmacêuticas/química , Bibliotecas de Moléculas Pequenas/síntese química , Bibliotecas de Moléculas Pequenas/químicaRESUMO
Allosteric modulation of metabotropic glutamate receptor 2 (mGlu2) has demonstrated efficacy in preclinical rodent models of several brain disorders, leading to industry and academic drug discovery efforts. Although the pharmacology and binding sites of some mGlu2 allosteric modulators have been characterized previously, questions remain about the nature of the allosteric mechanism of cooperativity with glutamate and whether structurally diverse allosteric modulators bind in an identical manner to specific allosteric sites. To further investigate the in vitro pharmacology of mGlu2 allosteric modulators, we developed and characterized a novel mGlu2 positive allosteric modulator (PAM) radioligand in parallel with functional studies of a structurally diverse set of mGlu2 PAMs and negative allosteric modulators (NAMs). Using an operational model of allosterism to analyze the functional data, we found that PAMs affect both the affinity and efficacy of glutamate at mGlu2, whereas NAMs predominantly affect the efficacy of glutamate in our assay system. More importantly, we found that binding of a novel mGlu2 PAM radioligand was inhibited by multiple structurally diverse PAMs and NAMs, indicating that they may bind to the mGlu2 allosteric site labeled with the novel mGlu2 PAM radioligand; however, further studies suggested that these allosteric modulators do not all interact with the radioligand in an identical manner. Together, these findings provide new insights into the binding sites and modes of efficacy of different structurally and functionally distinct mGlu2 allosteric modulators and suggest that different ligands either interact with distinct sites or adapt different binding poses to shared allosteric site(s).
Assuntos
Receptores de Glutamato Metabotrópico/efeitos dos fármacos , Regulação Alostérica , Sítio Alostérico , Animais , Linhagem Celular , Ácido Glutâmico/metabolismo , Células HEK293 , Humanos , Ligantes , Mutagênese , Ligação Proteica , Ensaio Radioligante , Ratos , Receptores de Glutamato Metabotrópico/genética , Receptores de Glutamato Metabotrópico/metabolismoRESUMO
Due to increased interest in As(III) S-adenosylmethionine methyltransferase (AS3MT), a search for chemical probes that can help elucidate function was initiated. A homology model was built based on related enzymes, and virtual screening produced 426 potential hits. Evaluation of these compounds in a functional enzymatic assay revealed several modest inhibitors including an O-substituted 2-amino-3-cyano indole scaffold. Two iterations of near neighbor searches revealed compound 5 as a potent inhibitor of AS3MT with good selectivity over representative methyltransferases DOT1L and NSD2 as well as a representative set of diverse receptors. Compound 5 should prove to be a useful tool to investigate the role of AS3MT and a potential starting point for further optimization.
Assuntos
Inibidores Enzimáticos/farmacologia , Metiltransferases/antagonistas & inibidores , HumanosRESUMO
The diiodobinorsnoutane, bi(5-iodopentacyclo[4.3.0.0(2,4).0(3,8).0(5,7)]non-4-yl) (5), exists in a sterically hindered gauche conformation rather than an anti or an averaged (freely rotating) C2v structure. Density functional theory (DFT) predictions place the gauche conformation 11 kcal/mol more stable than the anti conformation with a barrier of 17 kcal/mol connecting the minima. These are consistent with variable-temperature NMR (17.1 ± 0.8 kcal/mol) estimates and X-ray analysis. Predictions of the torsional profiles of the yet-unsynthesized bromo-, chloro-, and fluoro- analogues show a progressive lowering of the barriers.
RESUMO
BACKGROUND AND PURPOSE: Inhibitors of voltage-gated sodium channels (NaVs) are important anti-epileptic drugs, but the contribution of specific channel isoforms is unknown since available inhibitors are non-selective. We aimed to create novel, isoform selective inhibitors of Nav channels as a means of informing the development of improved antiseizure drugs. EXPERIMENTAL APPROACH: We created a series of compounds with diverse selectivity profiles enabling block of NaV1.6 alone or together with NaV1.2. These novel NaV inhibitors were evaluated for their ability to inhibit electrically evoked seizures in mice with a heterozygous gain-of-function mutation (N1768D/+) in Scn8a (encoding NaV1.6) and in wild-type mice. KEY RESULTS: Pharmacologic inhibition of NaV1.6 in Scn8aN1768D/+ mice prevented seizures evoked by a 6-Hz shock. Inhibitors were also effective in a direct current maximal electroshock seizure assay in wild-type mice. NaV1.6 inhibition correlated with efficacy in both models, even without inhibition of other CNS NaV isoforms. CONCLUSIONS AND IMPLICATIONS: Our data suggest NaV1.6 inhibition is a driver of efficacy for NaV inhibitor anti-seizure medicines. Sparing the NaV1.1 channels of inhibitory interneurons did not compromise efficacy. Selective NaV1.6 inhibitors may provide targeted therapies for human Scn8a developmental and epileptic encephalopathies and improved treatments for idiopathic epilepsies.
RESUMO
The absolute stereochemistry of chiral drugs is usually established via X-ray crystallography. However, vibrational circular dichroism (VCD) spectroscopy coupled with quantum mechanics simulations offers a rapid alternative to crystallography and is readily applied to both crystalline and non-crystalline samples. VCD is an effective complement to X-ray analysis of drug candidates, and it can be used as a high-throughput means of assessing absolute stereochemistry at all phases of the discovery process (hundreds of assignments per year). The practical implementation (or fee-for-service outsourcing) of VCD and selected case studies are illustrated with an emphasis on providing utility and impact to pharmaceutical discovery programs.
Assuntos
Preparações Farmacêuticas/química , Aminoquinolinas/química , Dicroísmo Circular/instrumentação , Cristalografia por Raios X , N-Metilaspartato/química , Receptores Histamínicos H3/química , Receptores Histamínicos H3/metabolismo , Estereoisomerismo , Relação Estrutura-Atividade , Sulfonamidas/químicaRESUMO
Dopamine (D(2)) partial agonists (D2PAs) have been regarded as a potential treatment for schizophrenia patients with expected better side effect profiles than currently marketed antipsychotics. Herein we report the synthesis and SAR of a series of aminothiazole fused benzazepines as selective D(2) partial agonists. These compounds have good selectivity, CNS drug-like properties and tunable D(2) partial agonism. One of the key compounds, 8h, has good in vitro/in vivo ADME characteristics, and is active in a rat amphetamine-induced locomotor activity model.
Assuntos
Benzazepinas/síntese química , Benzazepinas/farmacologia , Agonistas de Dopamina/síntese química , Agonistas de Dopamina/farmacologia , Receptores de Dopamina D2/agonistas , Animais , Antipsicóticos/síntese química , Antipsicóticos/química , Antipsicóticos/farmacologia , Benzazepinas/química , Bioensaio , Modelos Animais de Doenças , Agonistas de Dopamina/química , Agonismo Parcial de Drogas , Humanos , Concentração Inibidora 50 , Estrutura Molecular , Ligação Proteica/efeitos dos fármacos , Ratos , Relação Estrutura-AtividadeRESUMO
A series of 4-piperidin-4-ylidenemethyl-benzamide δ-opioid receptor agonists is described with an emphasis on balancing the potency, subtype selectivity and in vitro ADME and safety properties. The three sites impacting SAR are substitutions on the aryl group (R(1)), the piperidine nitrogen (R(2)), and the amide (R(3)). Each region contributes to the balance of properties for δ opioid activity and a desirable CNS profile, and two clinical candidates (20 and 24) were advanced.
Assuntos
Benzamidas/farmacologia , Sistema Nervoso Central/efeitos dos fármacos , Piperidinas/farmacologia , Receptores Opioides delta/agonistas , Benzamidas/química , Sistema Nervoso Central/metabolismo , Relação Dose-Resposta a Droga , Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Células HEK293 , Humanos , Estrutura Molecular , Piperidinas/química , Receptores Opioides delta/metabolismo , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
A novel series of piperazine derivatives exhibits sub-nanomolar binding and enhanced subtype selectivity as δ-opioid agonists. The synthesis and SAR are described as well as the application of computational models to improve in vitro ADME and safety properties suitable for CNS indications, specifically microsomal clearance, permeability, and hERG channel inhibition.
Assuntos
Sistema Nervoso Central/efeitos dos fármacos , Piperazinas/farmacologia , Receptores Opioides delta/agonistas , Animais , Sistema Nervoso Central/metabolismo , Simulação por Computador , Cães , Relação Dose-Resposta a Droga , Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Humanos , Estrutura Molecular , Piperazinas/síntese química , Piperazinas/química , Receptores Opioides delta/metabolismo , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
NBI-921352 (formerly XEN901) is a novel sodium channel inhibitor designed to specifically target NaV1.6 channels. Such a molecule provides a precision-medicine approach to target SCN8A-related epilepsy syndromes (SCN8A-RES), where gain-of-function (GoF) mutations lead to excess NaV1.6 sodium current, or other indications where NaV1.6 mediated hyper-excitability contributes to disease (Gardella and Møller, 2019; Johannesen et al., 2019; Veeramah et al., 2012). NBI-921352 is a potent inhibitor of NaV1.6 (IC500.051 µM), with exquisite selectivity over other sodium channel isoforms (selectivity ratios of 756 X for NaV1.1, 134 X for NaV1.2, 276 X for NaV1.7, and >583 Xfor NaV1.3, NaV1.4, and NaV1.5). NBI-921352is a state-dependent inhibitor, preferentially inhibiting inactivatedchannels. The state dependence leads to potent stabilization of inactivation, inhibiting NaV1.6 currents, including resurgent and persistent NaV1.6 currents, while sparing the closed/rested channels. The isoform-selective profile of NBI-921352 led to a robust inhibition of action-potential firing in glutamatergic excitatory pyramidal neurons, while sparing fast-spiking inhibitory interneurons, where NaV1.1 predominates. Oral administration of NBI-921352 prevented electrically induced seizures in a Scn8a GoF mouse,as well as in wild-type mouse and ratseizure models. NBI-921352 was effective in preventing seizures at lower brain and plasma concentrations than commonly prescribed sodium channel inhibitor anti-seizure medicines (ASMs) carbamazepine, phenytoin, and lacosamide. NBI-921352 waswell tolerated at higher multiples of the effective plasma and brain concentrations than those ASMs. NBI-921352 is entering phase II proof-of-concept trials for the treatment of SCN8A-developmental epileptic encephalopathy (SCN8A-DEE) and adult focal-onset seizures.
Assuntos
Epilepsia , Canal de Sódio Disparado por Voltagem NAV1.6 , Animais , Mutação com Ganho de Função , Camundongos , Mutação , Canal de Sódio Disparado por Voltagem NAV1.6/genética , Neurônios/fisiologia , Ratos , Sódio , Bloqueadores dos Canais de Sódio/farmacologiaRESUMO
Huwentoxin-IV (HwTx-IV), a peptide discovered in the venom of the Chinese bird spider Cyriopagopus schmidti, has been reported to be a potent antinociceptive compound due to its action on the genetically-validated NaV1.7 pain target. Using this peptide for antinociceptive applications in vivo suffers from one major drawback, namely its negative impact on the neuromuscular system. Although studied only recently, this effect appears to be due to an interaction between the peptide and the NaV1.6 channel subtype located at the presynaptic level. The aim of this work was to investigate how HwTx-IV could be modified in order to alter the original human (h) NaV1.7/NaV1.6 selectivity ratio of 23. Nineteen HwTx-IV analogues were chemically synthesized and tested for their blocking effects on the Na+ currents flowing through these two channel subtypes stably expressed in cell lines. Dose-response curves for these analogues were generated, thanks to the use of an automated patch-clamp system. Several key amino acid positions were targeted owing to the information provided by earlier structure-activity relationship (SAR) studies. Among the analogues tested, the potency of HwTx-IV E4K was significantly improved for hNaV1.6, leading to a decreased hNaV1.7/hNaV1.6 selectivity ratio (close to 1). Similar decreased selectivity ratios, but with increased potency for both subtypes, were observed for HwTx-IV analogues that combine a substitution at position 4 with a modification of amino acid 1 or 26 (HwTx-IV E1G/E4G and HwTx-IV E4K/R26Q). In contrast, increased selectivity ratios (>46) were obtained if the E4K mutation was combined to an additional double substitution (R 26A/Y33W) or simply by further substituting the C-terminal amidation of the peptide by a carboxylated motif, linked to a marked loss of potency on hNaV1.6 in this latter case. These results demonstrate that it is possible to significantly modulate the selectivity ratio for these two channel subtypes in order to improve the potency of a given analogue for hNaV1.6 and/or hNaV1.7 subtypes. In addition, selective analogues for hNaV1.7, possessing better safety profiles, were produced to limit neuromuscular impairments.
RESUMO
Positive modulators at benzodiazepine sites of α2- and α3-containing GABA(A) receptors are believed to be anxiolytic. Negative allosteric modulators of α5-containing GABA(A) receptors enhance cognition. By oocyte two-electrode voltage clamp and subsequent structure-activity relationship studies, we discovered cinnoline and quinoline derivatives that were both positive modulators at α2-/α3-containing GABA(A) receptors and negative modulators at α5-containing GABA(A) receptors. In addition, these compounds showed no functional activity at α1-containing GABA(A) receptors. Such dual functional modulators of GABA(A) receptors might be useful for treating comorbidity of anxiety and cognitive impairments in neurological and psychiatric illnesses.
Assuntos
Receptores de GABA-A/química , Regulação Alostérica , Benzodiazepinas/química , Compostos Heterocíclicos com 2 Anéis/síntese química , Compostos Heterocíclicos com 2 Anéis/química , Compostos Heterocíclicos com 2 Anéis/farmacologia , Técnicas de Patch-Clamp , Teoria Quântica , Quinolinas/síntese química , Quinolinas/química , Quinolinas/farmacologia , Receptores de GABA-A/metabolismo , Relação Estrutura-AtividadeRESUMO
Nonselective antagonists of voltage-gated sodium (NaV) channels have been long used for the treatment of epilepsies. The efficacy of these drugs is thought to be due to the block of sodium channels on excitatory neurons, primarily NaV1.6 and NaV1.2. However, these currently marketed drugs require high drug exposure and suffer from narrow therapeutic indices. Selective inhibition of NaV1.6, while sparing NaV1.1, is anticipated to provide a more effective and better tolerated treatment for epilepsies. In addition, block of NaV1.2 may complement the anticonvulsant activity of NaV1.6 inhibition. We discovered a novel series of aryl sulfonamides as CNS-penetrant, isoform-selective NaV1.6 inhibitors, which also displayed potent block of NaV1.2. Optimization focused on increasing selectivity over NaV1.1, improving metabolic stability, reducing active efflux, and addressing a pregnane X-receptor liability. We obtained compounds 30-32, which produced potent anticonvulsant activity in mouse seizure models, including a direct current maximal electroshock seizure assay.
Assuntos
Amidas/química , Sistema Nervoso Central/metabolismo , Epilepsia/tratamento farmacológico , Canal de Sódio Disparado por Voltagem NAV1.6/metabolismo , Bloqueadores dos Canais de Sódio/metabolismo , Bloqueadores dos Canais de Sódio/farmacologia , Animais , Cães , Células Hep G2 , Humanos , Células Madin Darby de Rim Canino , Camundongos , Modelos Moleculares , Canal de Sódio Disparado por Voltagem NAV1.6/química , Domínios Proteicos , Isoformas de Proteínas/antagonistas & inibidores , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Bloqueadores dos Canais de Sódio/química , Bloqueadores dos Canais de Sódio/uso terapêutico , Relação Estrutura-AtividadeRESUMO
Mutations in the gene TARDBP, which encodes TAR DNA-binding protein 43 (TDP-43), are a rare cause of familial forms of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). While the majority of mutations are found in the C-terminal glycine-rich domain, an alanine to valine amino acid change at position 90 (A90V) in the bipartite nuclear localization signal (NLS) of TDP-43 has been described. This sequence variant has previously been shown to cause cytoplasmic mislocalization of TDP-43 and decrease protein solubility, leading to the formation of insoluble aggregates. Since the A90V mutation has been described both in patients as well as healthy controls, its pathogenic potential in ALS and FTD remains unclear. Here we compare properties of overexpressed A90V to the highly pathogenic M337V mutation. Though both mutations drive mislocalization of the protein to the cytoplasm to the same extent, M337V produces more significant damage in terms of protein solubility, levels of pathogenic phosphorylation, and formation of C-terminal truncated protein species. Furthermore, the M337V, but not the A90V mutant, leads to a downregulation of histone deacetylase 6 and Ras GTPase-activating protein-binding protein. We conclude that in the absence of another genetic or environmental 'hit' the A90V variant is not sufficient to cause the deleterious phenotypes associated with ALS and FTD, despite prominent cytoplasmic protein relocalization of TDP-43.
RESUMO
UNLABELLED: The histamine type 3 receptor (H3) is a G protein-coupled receptor implicated in several disorders of the central nervous system. Herein, we describe the radiolabeling and preclinical evaluation of a candidate radioligand for the H3 receptor, 4-(1S,2S)-2-(4-cyclobutylpiperazine-1-carbonyl)cyclopropyl]-N-methyl-benzamide (5), and its comparison with one of the frontrunner radioligands for H3 imaging, namely, GSK189254 (1). Compounds 1 and 5 were radiolabeled with tritium and carbon-11 for in vitro and in vivo imaging experiments. The in vitro binding of [(3)H]1 and [(3)H]5 was examined by (i) saturation binding to rat and nonhuman primate brain tissue homogenate and (ii) in vitro autoradiography on tissue sections from rat, guinea pig, and human brain. The in vivo binding of [(11)C]1 and [(11)C]5 was examined by PET imaging in mice and nonhuman primates. Bmax values obtained from Scatchard analysis of [(3)H]1 and [(3)H]5 binding were in good agreement. Autoradiography with [(3)H]5 on rat, guinea pig, and human brain slices showed specific binding in regions known to be enhanced in H3 receptors, a high degree of colocalization with [(3)H]1, and virtually negligible nonspecific binding in tissue. PET measurements in mice and nonhuman primates demonstrated that [(11)C]5 binds specifically and reversibly to H3 receptors in vivo with low nonspecific binding in brain tissue. Whereas [(11)C]1 showed similar binding characteristics in vivo, the binding kinetics appeared faster for [(11)C]5 than for [(11)C]1. CONCLUSIONS: [(11)C]5 has suitable properties for quantification of H3 receptors in nonhuman primate brain and has the potential to offer improved binding kinetics in man compared to [(11)C]1.
Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/diagnóstico por imagem , Radioisótopos de Carbono/farmacocinética , Histamínicos/farmacologia , Receptores Histamínicos H3/metabolismo , Doença de Alzheimer/patologia , Animais , Autorradiografia , Benzamidas/química , Benzamidas/farmacologia , Benzazepinas/farmacologia , Relação Dose-Resposta a Droga , Feminino , Cobaias , Haplorrinos , Histamínicos/química , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Niacinamida/análogos & derivados , Niacinamida/farmacologia , Piperazinas/química , Piperazinas/farmacologia , Ligação Proteica/efeitos dos fármacos , Ratos , Reprodutibilidade dos Testes , Fatores de Tempo , Distribuição Tecidual/efeitos dos fármacos , Distribuição Tecidual/fisiologia , Trítio/farmacocinéticaRESUMO
Many neuropsychiatric drugs interact with more than one molecular target, and therapeutic indices might be improved by prospectively designing compounds with profiles optimized against a combination of targets. The dibenzo-epine scaffold is considered a privileged structure, and this scaffold has been explored rigorously in the search for potential novel neuropharmacologic treatments. Members of this chemical class are known to interact with many receptors and transporters, particularly those of the biogenic amine class. In this study, four points of diversity within a dibenzo-epine scaffold were varied systematically and the pharmacologic profiles of the compounds were assessed across 14 receptors and transporters thought to be important to clinical profiles of efficacy and safety. The resulting data were analyzed using a modified forward selection linear regression procedure, thus revealing potential pharmacophoric relationships of the assessed targets within this chemical class. The results highlight a strong covariance across numerous targets. Moreover, the outcome quantifies the innately problematic issue of prospectively designing compounds with defined affinities across multiple targets. Finally, an exploration of the correspondence of binding affinities to in vitro functional activity reveals an additional layer of complexity central to prospectively designing compounds to engage multiple targets. The apparent relatedness of the 5-HT(2a) and D2 activities suggests that the structural pharmacophores of these receptors overlap more closely with each other than with members of their respective families.
Assuntos
Antidepressivos/farmacologia , Antipsicóticos/farmacologia , Ensaio Radioligante , Receptores Dopaminérgicos/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Receptores de Serotonina/metabolismo , Linhagem Celular , Humanos , LigantesRESUMO
The synthesis of (-)-1, a potent antibacterial agent, was achieved stereoselectively in nine steps from readily available starting materials. Directed metalations were developed to assemble a pentasubstituted pyridine with appropriately positioned aldehyde and dimethylmorpholine substituents for a key tertiary amino effect reaction (T-reaction) that led to the spirocylic architecture. Ultimately, (-)-1 was isolated as the thermodynamically most favored stereoisomer.
Assuntos
Antibacterianos/síntese química , DNA Girase/química , Escherichia coli/química , Morfolinas/química , Naftiridinas/síntese química , Piridinas/química , Antibacterianos/química , Antibacterianos/farmacologia , Ciclização , Estrutura Molecular , Naftiridinas/química , EstereoisomerismoRESUMO
Atropisomers exist when axial chirality is present as a result of conformationally restricted rotation around a single bond. The interconversion rate of the individual atropisomers is critical to the assessment of chiral stability of a drug throughout scale-up, development, production, and storage as well as in vivo pharmacokinetics. We describe the application of vibrational circular dichroism spectroscopy coupled with quantum mechanics simulations to assign the absolute axial chirality and measure the racemization half-life of a series of potential anxiolytic drugs that act as γ-aminobutyric acid modulators.
Assuntos
Ansiolíticos/química , Dicroísmo Circular/métodos , Descoberta de Drogas/métodos , Modelos Químicos , Ácido gama-Aminobutírico/química , Simulação por Computador , Cinética , Teoria Quântica , EstereoisomerismoRESUMO
Herein, we describe the discovery of inhibitors of norepinephrine (NET) and dopamine (DAT) transporters with reduced activity relative to serotonin transporters (SERT). Two compounds, 8b and 21a, along with nomifensine were tested in a rodent receptor occupancy study and demonstrated dose-dependent displacement of radiolabeled NET and DAT ligands. These compounds were efficacious in a rat forced swim assay (model of depression) and also had activity in rat spontaneous locomotion assay.
RESUMO
Monte Carlo (MC)-extended linear response (ELR) calculations have been used for prediction of binding affinities of celecoxib analogues with the COX-2 enzyme. Three physically motivated descriptors from the MC simulations were used in a regression equation to fit 45 experimental activities with r(2)=0.71 and q(2)=0.68. The ELR approach provides a promising screen for optimization of enzyme inhibitors.