RESUMO
Metabotropic glutamate receptor 7 (mGlu7) is a G protein coupled receptor that has demonstrated promise as a therapeutic target across a number of neurologic and psychiatric diseases. Compounds that modulate the activity of mGlu7, such as positive and negative allosteric modulators, may represent new therapeutic strategies to modulate receptor activity. The endogenous neurotransmitter associated with the mGlu receptor family, glutamate, exhibits low efficacy and potency in activating mGlu7, and surrogate agonists, such as the compound L-(+)-2-Amino-4-phosphonobutyric acid (L-AP4), are often used for receptor activation and compound profiling. To understand the implications of the use of such agonists in the development of positive allosteric modulators (PAMs), we performed a systematic evaluation of receptor activation using a system in which mutations can be made in either protomer of the mGlu7 dimer; we employed mutations that prevent interaction with the orthosteric site as well as the G-protein coupling site of the receptor. We then measured increases in calcium levels downstream of a promiscuous G protein to assess the effects of mutations in one of the two protomers in the presence of two different agonists and three positive allosteric modulators. Our results reveal that distinct PAMs, for example N-[3-Chloro-4-[(5-chloro-2-pyridinyl)oxy]phenyl]-2-pyridinecarboxamide (VU0422288) and 3-(2,3-Difluoro-4-methoxyphenyl)-2,5-dimethyl-7-(trifluoromethyl)pyrazolo[1,5-a]pyrimidine (VU6005649), do exhibit different maximal levels of potentiation with L-AP4 versus glutamate, but there appear to be common stable receptor conformations that are shared among all of the compounds examined here. SIGNIFICANCE STATEMENT: This manuscript describes the systematic evaluation of the mGlu7 agonists glutamate and L-(+)-2-Amino-4-phosphonobutyric acid (L-AP4) in the presence and absence of three distinct potentiators examining possible mechanistic differences. These findings demonstrate that mGlu7 potentiators display subtle variances in response to glutamate versus L-AP4.
Assuntos
Ácido Glutâmico , Regulação Alostérica/fisiologia , Ácido Glutâmico/farmacologia , Ácido Glutâmico/metabolismoRESUMO
M4 muscarinic receptors are highly expressed in the striatum and cortex, brain regions that are involved in diseases such as Parkinson's disease, schizophrenia, and dystonia. Despite potential therapeutic advantages of specifically targeting the M4 receptor, it has been historically challenging to develop highly selective ligands, resulting in undesired off-target activity at other members of the muscarinic receptor family. Recently, we have reported first-in-class, potent, and selective M4 receptor antagonists. As an extension of that work, we now report the development and characterization of a radiolabeled M4 receptor antagonist, [3H]VU6013720, with high affinity (pKd of 9.5 ± 0.2 at rat M4, 9.7 at mouse M4, and 10 ± 0.1 at human M4 with atropine to define nonspecific binding) and no significant binding at the other muscarinic subtypes. Binding assays using this radioligand in rodent brain tissues demonstrate loss of specific binding in Chrm4 knockout animals. Dissociation kinetics experiments with various muscarinic ligands show differential effects on the dissociation of [3H]VU6013720 from M4 receptors, suggesting a binding site that is overlapping but may be distinct from the orthosteric site. Overall, these results demonstrate that [3H]VU6013720 is the first highly selective antagonist radioligand for the M4 receptor, representing a useful tool for studying the basic biology of M4 as well for the support of M4 receptor-based drug discovery. SIGNIFICANCE STATEMENT: This manuscript describes the development and characterization of a novel muscarinic (M) acetylcholine subtype 4 receptor antagonist radioligand, [3H]VU6013720. This ligand binds to or overlaps with the acetylcholine binding site, providing a highly selective radioligand for the M4 receptor that can be used to quantify M4 protein expression in vivo and probe the selective interactions of acetylcholine with M4 versus the other members of the muscarinic receptor family.
Assuntos
Acetilcolina , Receptores Muscarínicos , Ratos , Humanos , Camundongos , Animais , Acetilcolina/metabolismo , Receptores Muscarínicos/metabolismo , Receptor Muscarínico M4/metabolismo , Atropina , Ligantes , Colinérgicos , Antagonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/metabolismo , Receptor Muscarínico M2/metabolismo , Ensaio Radioligante , Receptor Muscarínico M1/metabolismoRESUMO
Herein, we report on the further chemical optimization of the first reported mGlu7 positive allosteric modulator (PAM), VU6027459. Replacement of the quinoline core by a cinnoline scaffold increased mGlu7 PAM potency by â¼ 10-fold, and concomitant introduction of a chiral tricyclic motif led to potent mGlu7 PAMs with enantioselective mGlu receptor selectivity profiles. Of these, VU6046980 emerged as a putative in vivo tool compound with excellent CNS penetration (Kp = 4.1; Kp,uu = 0.7) and efficacy in preclinical models. However, either off-target activity at the sigma-1 receptor or activity at a target not elucidated by large ancillary pharmacology panels led to sedation not driven by activation of mGlu7 (validated in Grm7 knockout mice). Thus, despite a significant advance, a viable mGlu7 PAM in vivo tool remains elusive.
Assuntos
Regulação Alostérica , Camundongos , AnimaisRESUMO
We describe here a series of metabotropic glutamate receptor 7 (mGlu7) negative allosteric modulators (NAMs) with a saturable range of activity in inhibiting responses to an orthosteric agonist in two distinct in vitro pharmacological assays. The range of inhibition among compounds in this scaffold provides highly structurally related ligands with differential degrees of receptor blockade that can be used to understand inhibitory efficacy profiles in native tissue or in vivo.
Assuntos
Regulação Alostérica , LigantesRESUMO
In this manuscript, we report a series of chiral 6-azaspiro[2.5]octanes and related spirocycles as highly potent and selective antagonists of the muscarinic acetylcholine receptor subtype 4 (mAChR4). Chiral separation and subsequent X-ray crystallographic analysis of early generation analogs revealed the R enantiomer to possess excellent human and rat M4 potency, and further structure-activity relationship (SAR) studies on this chiral scaffold led to the discovery of VU6015241 (compound 19). Compound 19 is characterized by high M4 potency and selectivity across multiple species, excellent aqueous solubility, and moderate brain exposure in rodents after intraperitoneal administration.
Assuntos
Antagonistas Muscarínicos/farmacologia , Receptor Muscarínico M4/antagonistas & inibidores , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Antagonistas Muscarínicos/síntese química , Antagonistas Muscarínicos/química , Receptor Muscarínico M4/metabolismo , Relação Estrutura-AtividadeRESUMO
This Letter describes our ongoing effort to improve the clearance of selective M5 antagonists. Herein, we report the replacement of the previously disclosed piperidine amide (4, disclosed in Part 1) with a pyrrolidine amide core. Several compounds within this series provided good potency, subtype selectivity, and low to moderate clearance profiles. Interestingly, the left-hand side SAR for this series diverged from our earlier efforts.
Assuntos
Amidas , Pirrolidinas , Amidas/farmacologia , Pirrolidinas/farmacologia , Cinética , Antagonistas MuscarínicosRESUMO
The lack of potent and selective tool compounds with pharmaceutically favorable properties limits the in vivo understanding of muscarinic acetylcholine receptor subtype 5 (M5) biology. Previously, we presented a highly potent and selective M5 antagonist VU6019650 with a suboptimal clearance profile as our second-generation tool compound. Herein, we disclose our ongoing efforts to generate next-generation M5 antagonists with improved clearance profiles. A mix and match approach between VU6019650 (lead) and VU0500325 (HTS hit) generated a piperidine amide-based novel M5 antagonist series. Several analogs within this series, including 29f, provided good on-target potency with improved clearance profiles, though room for improvement remains.
Assuntos
Amidas , Receptores Muscarínicos , Amidas/farmacologia , Cinética , Piperidinas/farmacologiaRESUMO
This letter describes synthesis and evaluation of two series of dual mGlu2/mGlu3 positive allosteric modulators with moderate mGlu3 potency and robust mGlu2 potency in thallium flux assays. These compounds were profiled their ability to modulate mGlu3-mediated signaling in central neurons by co-application of a selective mGlu2 NAM to isolate mGlu3-selective effects. Using acute mouse brain slices from the prefrontal cortex, potentiation of group II mGlu receptor agonist Ca2+ signaling in PFC pyramidal cells with either the dual mGlu2/mGlu3 PAM 16e or 23d demonstrated effects mediated selectively via mGlu3.
Assuntos
Sinalização do Cálcio/efeitos dos fármacos , Neurônios/metabolismo , Receptores de Glutamato Metabotrópico/administração & dosagem , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/metabolismo , Animais , Linhagem Celular , Desenho de Fármacos , Humanos , Camundongos , Estrutura Molecular , Neurônios/efeitos dos fármacos , Córtex Pré-Frontal/citologia , Células Piramidais , Receptores de Glutamato Metabotrópico/genética , Relação Estrutura-AtividadeRESUMO
This Letter describes the synthesis and optimization of a series of heteroaryl-pyrrolidinone positive allosteric modulators (PAMs) of the muscarinic acetylcholine receptor M1 (mAChR M1). Through the continued optimization of M1 PAM tool compound VU0453595, with a focus on replacement of the 6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-one with a wide variety of alternative 4,5-dihydropyrrolo-fused heteroaromatics, the generation of M1 PAMs with structurally novel chemotypes is disclosed. Two compounds from these subseries, 8b (VU6005610) and 20a (VU6005852), show robust selectivity for the M1 mAChR, and no M1 agonism. Both compounds have favorable preliminary PK profiles in vitro;8b additionally demonstrates high brain exposure in a rodent IV cassette model.
Assuntos
Descoberta de Drogas , Pirrolidinonas/farmacologia , Receptor Muscarínico M1/agonistas , Regulação Alostérica/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Pirrolidinonas/síntese química , Pirrolidinonas/química , Ratos , Relação Estrutura-AtividadeRESUMO
Further optimization of the VU0486321 series of highly selective and CNS-penetrant mGlu1 PAMs identified unique 'molecular switches' on the central aromatic ring that engendered positive cooperativity with multiple mGlu subtypes across the receptor family, resulting in compounds with comparable activity at Group I (mGlu1/5) and Group III (mGlu4/6/7/8) mGlu receptors, receptors. These exciting data suggests this PAM chemotype appears to bind to multiple mGlu receptors, and that subtype selectivity is dictated by the degree of cooperativity, not a subtype selective, unique allosteric binding site. Moreover, there is interesting therapeutic potential for mGlu1/4/7/8 PAMs, as well as the first report of a GPCR allosteric 'privileged structure'.
Assuntos
Cumarínicos/química , Furanos/química , Receptor de Glutamato Metabotrópico 5/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Regulação Alostérica , Cumarínicos/metabolismo , Furanos/metabolismo , Humanos , Receptor de Glutamato Metabotrópico 5/química , Receptores de Glutamato Metabotrópico/química , Relação Estrutura-AtividadeRESUMO
This Letter details our efforts to develop novel tricyclic M4 PAM scaffolds with improved pharmacological properties. This endeavor involved a "tie-back" strategy to replace the 3-amino-4,6-dimethylthieno[2,3-b]pyridine-2-carboxamide core which lead to the discovery of two novel tricyclic cores: a 7,9-dimethylpyrido[3',2':4,5]thieno[3,2-d]pyrimidine core and 2,4-dimethylthieno[2,3-b:5,4-c']dipyridine core. Both tricyclic cores displayed low nanomolar potency against the human M4 receptor.
Assuntos
Descoberta de Drogas , Pirimidinas/farmacologia , Receptor Muscarínico M4/antagonistas & inibidores , Relação Dose-Resposta a Droga , Humanos , Estrutura Molecular , Pirimidinas/síntese química , Pirimidinas/química , Receptor Muscarínico M4/metabolismo , Relação Estrutura-AtividadeRESUMO
A high throughput screen (HTS) identified a novel, but weak (EC50 = 6.2 µM, 97% Glu Max) mGlu4 PAM chemotype based on a 1,4-thiazepane core, VU0544412. Reaction development and chemical optimization delivered a potent mGlu4 PAM VU6022296 (EC50 = 32.8 nM, 108% Glu Max) with good CNS penetration (Kp = 0.45, Kp,uu = 0.70) and enantiopreference. Finally, VU6022296 displayed robust, dose-dependent efficacy in reversing Haloperidol-Induced Catalepsy (HIC), a rodent preclinical Parkinson's disease model.
Assuntos
Catalepsia/tratamento farmacológico , Modelos Animais de Doenças , Descoberta de Drogas , Fármacos Neuroprotetores/farmacologia , Doença de Parkinson/tratamento farmacológico , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Regulação Alostérica/efeitos dos fármacos , Animais , Catalepsia/induzido quimicamente , Relação Dose-Resposta a Droga , Haloperidol , Camundongos , Estrutura Molecular , Fármacos Neuroprotetores/síntese química , Fármacos Neuroprotetores/química , Receptores de Glutamato Metabotrópico/metabolismo , Relação Estrutura-AtividadeRESUMO
This Letter details our ongoing efforts to develop selective positive allosteric modulators (PAMs) of the mGlu2/4 heterodimeric receptor that exists in the CNS and may represent a novel drug target to modulate the glutamatergic system. As multiple hit-to-lead campaigns from HTS hits failed to produce selective small molecule mGlu2/4 heterodimer PAMs, we were inspired by the work of Portoghese to synthesize and evaluate a set of nine bivalent tethered ligands (possessing an mGlu2 PAM at one terminus and an mGlu4 PAM at the other). Utilizing G protein-Inwardly Rectifying Potassium (GIRK) channel functional assays, we found that the tethered ligands displayed PAM activity in a cell line co-expressing both mGlu2 and mGlu4 but also in cells expressing mGlu2 or mGlu4 alone. In a CODA-RET assay, one of the tethered ligands potentiated mGlu2/4 heterodimers; however, another compound displayed 75-fold preference for the mGlu2/2 homodimer over heterodimeric mGlu2/4 or homomeric mGlu4/4. This work highlights the development of mGlu receptor PAMs with homodimer/heterodimer preference and expands the potential for PAMs as tethered ligands beyond the more classical antagonists and NAMs.
Assuntos
Benzamidas/farmacologia , Indanos/farmacologia , Receptores de Glutamato Metabotrópico/agonistas , Regulação Alostérica/efeitos dos fármacos , Animais , Benzamidas/síntese química , Células HEK293 , Humanos , Indanos/síntese química , Ligantes , Estrutura Molecular , Estrutura Quaternária de Proteína , Ratos , Receptores de Glutamato Metabotrópico/química , Relação Estrutura-AtividadeRESUMO
This Letter details our efforts to discover structurally unique M4 PAMs containing 5,6-heteroaryl ring systems. In an attempt to improve the DMPK profiles of the 2,3-dimethyl-2H-indazole-5-carboxamide and 1-methyl-1H-benzo[d][1,2,3]triazole-6-carboxamide cores, we investigated a plethora of core replacements. This exercise identified a novel 2,3-dimethylimidazo[1,2-a]pyrazine-6-carboxamide core that provided improved M4 PAM activity and CNS penetration.
Assuntos
Imidazóis/química , Pirazinas/química , Receptor Muscarínico M4/química , Regulação Alostérica , Desenho de Fármacos , Avaliação Pré-Clínica de Medicamentos , Humanos , Imidazóis/metabolismo , Cinética , Ligação Proteica , Pirazinas/metabolismo , Receptor Muscarínico M4/metabolismo , Relação Estrutura-AtividadeRESUMO
This Letter details our efforts to develop new M4 PAM scaffolds with improved pharmacological properties. This endeavor involved replacing the 3,4-dimethylpyridazine core with two novel cores: a 2,3-dimethyl-2H-indazole-5-carboxamide core or a 1-methyl-1H-benzo[d][1,2,3]triazole-6-carboxamide core. Due to shallow SAR, these cores were further evolved into two unique tricyclic cores: an 8,9-dimethyl-8H-pyrazolo[3,4-h]quinazoline core and an 1-methyl-1H-[1,2,3]triazolo[4,5-h]quinazoline core. Both tricyclic cores displayed low nanomolar potency against both human and rat M4.
Assuntos
Piridazinas/química , Quinazolinas/química , Receptor Muscarínico M4/química , Triazóis/química , Regulação Alostérica , Animais , Desenho de Fármacos , Meia-Vida , Humanos , Concentração Inibidora 50 , Piridazinas/metabolismo , Piridazinas/farmacocinética , Quinazolinas/metabolismo , Quinazolinas/farmacocinética , Ratos , Receptor Muscarínico M4/metabolismo , Relação Estrutura-Atividade , Triazóis/metabolismo , Triazóis/farmacocinéticaRESUMO
A High-Throughput Screening (HTS) campaign identified a fundamentally new mGlu7 NAM chemotype, based on an ethyl-8-methoxy-4-(4-phenylpiperazin-1-yl)quinolone carboxylate core. The initial hit, VU0226390, was a potent mGlu7 NAM (IC50 = 647 nM, 6% L-AP4 min) with selectivity versus the other group III mGlu receptors (>30 µM vs. mGlu4 and mGlu8). A multi-dimensional optimization effort surveyed all regions of this new chemotype, and found very steep SAR, reminiscent of allosteric modulators, and unexpected piperazine mimetics (whereas classical bioisosteres failed). While mGlu7 NAM potency could be improved (IC50s ~ 350 nM), the necessity of the ethyl ester moiety and poor physiochemical and DMPK properties precluded optimization towards in vivo tool compounds or clinical candidates. Still, this hit-to-lead campaign afforded key medicinal chemistry insights and new opportunities.
Assuntos
Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Regulação Alostérica/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Triagem em Larga Escala , Humanos , Estrutura Molecular , Receptores de Glutamato Metabotrópico/metabolismo , Relação Estrutura-AtividadeRESUMO
This letter describes the further optimization of a series of mGlu3 NAMs based on an N-aryl phenoxyethoxy pyridinone core. A multidimensional optimization campaign, with focused matrix libraries, quickly established challenging SAR, enantiospecific activity, differences in assay read-outs (Ca2+ flux via a promiscuous G protein (Gα15) versus native coupling to GIRK channels), identified both full and partial mGlu3 NAMs and a new in vivo tool compound, VU6017587. This mGlu3 NAM showed efficacy in tail suspension, elevated zero maze and marble burying, suggesting selective inhibition of mGlu3 affords anxiolytic-like and antidepressant-like phenotypes in mice.
Assuntos
Ansiolíticos/farmacologia , Antidepressivos/farmacologia , Piridonas/farmacologia , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Animais , Ansiolíticos/síntese química , Ansiolíticos/química , Antidepressivos/síntese química , Antidepressivos/química , Relação Dose-Resposta a Droga , Camundongos , Estrutura Molecular , Piridonas/síntese química , Piridonas/química , Ratos , Receptores de Glutamato Metabotrópico/metabolismo , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
This letter describes a diversity-oriented library approach to rapidly assess diverse heterocycles as bioisosteric replacements for a metabolically labile amide moiety within a series of mGlu7 negative allosteric modulators (NAMs). SAR rapidly honed in on either a 1,2,4- or 1,3,4-oxadizaole ring system as an effective bioisostere for the amide. Further optimization of the southern region of the mGlu7 NAM chemotype led to the discovery of VU6019278, a potent mGlu7 NAM (IC50â¯=â¯501â¯nM, 6.3% L-AP4 Min) with favorable plasma protein binding (rat fuâ¯=â¯0.10), low predicted hepatic clearance (rat CLhepâ¯=â¯27.7â¯mL/min/kg) and high CNS penetration (rat Kpâ¯=â¯4.9, Kp,uuâ¯=â¯0.65).
Assuntos
Amidas/química , Compostos Heterocíclicos/química , Receptores de Glutamato Metabotrópico/química , Regulação Alostérica , Animais , Sistema Nervoso Central/metabolismo , Hepatócitos/citologia , Hepatócitos/metabolismo , Compostos Heterocíclicos/metabolismo , Concentração Inibidora 50 , Pirazóis/química , Pirazóis/metabolismo , Ratos , Receptores de Glutamato Metabotrópico/metabolismo , Relação Estrutura-AtividadeRESUMO
This Letter details our efforts to replace the 2,4-dimethylquinoline carboxamide core of our previous M4 PAM series, which suffered from high predicted hepatic clearance and protein binding. A scaffold hopping exercise identified a novel 3,4-dimethylcinnoline carboxamide core that provided good M4 PAM activity and improved clearance and protein binding profiles.
Assuntos
Receptor Muscarínico M4/química , Regulação Alostérica , Amidas/química , Azetidinas/química , Benzeno/química , Estrutura Molecular , Ligação Proteica , Pirazinas/química , Piridinas/química , Pirimidinas/química , Relação Estrutura-AtividadeRESUMO
This letter describes a focused exercise to explore the role of the ß-amino carboxamide moiety found in all of the first generation M4 PAMs and question if the NH2 group served solely to stabilize an intramolecular hydrogen bond (IMHB) and enforce planarity. To address this issue (and to potentially find a substitute for the ß-amino carboxamide that engendered P-gp and contributed to solubility liabilities), we removed the NH2, generating des-amino congeners and surveyed other functional groups in the ß-position. These modifications led to weak M4 PAMs with poor DMPK properties. Cyclization of the ß-amino carboxamide moiety by virtue of a pyrazole ring re-enforced the IMHB, led to potent (and patented) M4 PAMs, many as potent as the classical bicyclic ß-amino carboxamide analogs, but with significant CYP1A2 inhibition. Overall, this exercise indicated that the ß-amino carboxamide moiety most likely facilitates an IMHB, and is essential for M4 PAM activity within classical bicyclic M4 PAM scaffolds.