Herein, we report the identification of the HIV protease inhibitor amprenavir as a selective cannabinoid receptor 2 (CB2) agonist and describe structure-activity relationship (SAR) studies toward repurposing this peripherally restricted scaffold for high CB2 potency and CNS exposure. This exercise yielded compounds with exceptional CB2 potency (EC(50)s <10 nM), no appreciable activity at the CB1 receptor, and high predicted permeability/low P-gp efflux activity. Selected compounds were profiled in rat i.v. dosing cassettes; several novel amprenavir analogues displayed good t(1/2) (>2 h), moderate plasma clearance, and appreciable brain exposure. Additionally, fully flexible protein-ligand docking studies with molecular dynamics (MD) simulations were used to predict the most likely mode of interaction of highly potent analogue VU6077967 with CB2 and to provide a rationale for the observed selectivity of this series relative to CB1.

For many inborn errors of metabolism (IEM) the understanding of disease mechanisms remains limited, in part explaining their unmet medical needs. The expressivity of IEM disease phenotypes is affected by disease-modifying factors, including rare and common polygenic variation. We hypothesize that we can identify these modulating pathways using molecular signatures of IEM in combination with multiomic data and gene regulatory networks generated from non-IEM animal and human populations. We tested this approach by identifying and subsequently validating glucocorticoid signaling as a candidate modifier of mitochondrial fatty acid oxidation disorders, and recapitulating complement signaling as a modifier of inflammation in Gaucher disease. Our work describes a novel approach that can overcome the rare disease-rare data dilemma and reveal new IEM pathophysiology and potential drug targets using multiomics data in seemingly healthy populations.

CB1 and CB2 cannabinoid receptors are members of the GPCR superfamily that modulate the effects of endocannabinoids. CB1 is the most abundant CB receptor in the central nervous system, while CB2 is present both peripherally and in the brain. CB2 plays a role in inflammation, as well as neurodegenerative and psychiatric disorders. To identify new ligands for CB2, we screened a library of FDA-approved drugs for activity at the receptor using a thallium flux assay, resulting in the discovery of the immunosuppressant mycophenolate mofetil as a potent, selective activator of CB2. Further characterization of the compound confirmed agonist activity in a variety of complementary assays, including PI hydrolysis, cAMP inhibition, and β-arrestin recruitment. Radioligand binding assays established a non-competitive interaction with the site occupied by [3H]CP55,940. CB2 agonists GW-842,166X and MDA7 were also profiled, revealing that GW-842,166X exhibits a similar activity profile to mycophenolate mofetil, whereas MDA7 presents a distinct profile. These differences provide insight into the complex CB2 pharmacology impacting preclinical and clinical studies, and ultimately, new treatment strategies for brain disorders.

This Letter describes the discovery of novel mGlu5 NAMs VU6031545 and VU6024945. Starting from previously reported picolinamide compounds, a structure-activity relationship study of various core isosteres was conducted, leading to the identification of thieno[3,2-b]pyridine-5-carboxamide and 2,3-difluorobenzamide as competent core replacements. These compounds are highly potent as well as brain penetrant with an IVIVC agreement and improved oral bioavailability in rats.

ML133 is a selective inhibitor of the inward-rectifier potassium channel Kir2.1 and has found extensive use as a tool with which to probe Kir biology. Despite its utility as a tool compound, ML133 has only modest on-target potency (manual patch clamp (MPC) Kir2.1 IC50 = 1.5 μM, pH 7.4), and its in vivo pharmacokinetics (PK) were previously uncharacterized. In the present study, we report a next-generation series of Kir2.1 inhibitors based on the ML133 scaffold, along with the rat PK of ML133 and selected analogs. Compound 5s (VU6080824) was ultimately identified as having superior potency to ML133 in both the thallium flux and MPC functional assays and has excellent PK properties suitable for use as an improved Kir2.1 tool compound in rodents.

The M 5 muscarinic acetylcholine receptor (M 5 mAChR) represents a promising therapeutic target for neurological disorders. However, the high conservation of its orthosteric binding site poses significant challenges for drug development. While selective positive allosteric modulators (PAMs) offer a potential solution, a structural understanding of the M 5 mAChR and its allosteric binding sites remains limited. Here, we present a 2.8 Å cryo-electron microscopy structure of the M 5 mAChR complexed with heterotrimeric G q protein and the agonist iperoxo, completing the active-state structural characterization of the mAChR family. To identify the binding site of M 5 -selective PAMs, we implement an integrated approach combining mutagenesis, pharmacological assays, structural biology, and molecular dynamics simulations. Our mutagenesis studies reveal that selective M 5 PAMs bind outside previously characterized M 5 mAChR allosteric sites. Subsequently, we obtain a 2.1 Å structure of M 5 mAChR co-bound with acetylcholine and the selective PAM VU6007678, revealing an allosteric pocket at the extrahelical interface between transmembrane domains 3 and 4 that is confirmed through mutagenesis and simulations. These findings demonstrate the diverse mechanisms of allosteric regulation in mAChRs and highlight the value of integrating pharmacological and structural approaches to identify allosteric binding sites.

The first syntheses of the Phomopsis-isolated natural products phochrodines A-C are reported. Functional group manipulations on a key 5H-chromeno[4,3-b]pyridine intermediate, itself synthesized from intramolecular Suzuki-Miyaura coupling, enabled facile and high-yielding syntheses of all three natural products. Additionally, sufficient material was generated to enable detailed pharmacological profiling of each compound. Preliminary drug metabolism and pharmacokinetic (DMPK) experiments and ancillary pharmacology screening revealed phochrodine C (3) as an attractive scaffold for further modification, particularly for medicinal chemists working in the antidepressant space.

The M5 muscarinic acetylcholine receptor (M5 mAChR) represents a promising therapeutic target for neurological disorders. However, the high conservation of its orthosteric binding site has posed significant challenges for drug development. While selective positive allosteric modulators (PAMs) offer a potential solution, a structural understanding of the M5 mAChR and its allosteric binding sites has remained limited. Here, we present a 2.8 Å cryo-electron microscopy structure of the M5 mAChR complexed with heterotrimeric Gq protein and the agonist iperoxo, completing the active-state structural characterization of the mAChR family. To identify the binding site of M5-selective PAMs, we implemented an integrated approach combining mutagenesis, pharmacological assays, structural biology, and molecular dynamics simulations. Our mutagenesis studies revealed that selective M5 PAMs bind outside previously characterized M5 mAChR allosteric sites. Subsequently, we obtained a 2.1 Å structure of M5 mAChR co-bound with acetylcholine and the selective PAM VU6007678, revealing a novel allosteric pocket at the extrahelical interface between transmembrane domains 3 and 4 that was confirmed through mutagenesis and simulations. These findings demonstrate the diverse mechanisms of allosteric regulation in mAChRs and highlight the value of integrating pharmacological and structural approaches to identify novel allosteric binding sites.

Herein, we report the synthesis and characterization of a novel set of substituted indazole-ethanamines and indazole-tetrahydropyridines as potent serotonin receptor subtype 2 (5-HT2) agonists. Specifically, we examine the 5-HT2 pharmacology of the direct indazole analogs of 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and related serotonergic tryptamines, and highlight the need for rigorous characterization of 5-HT2 subtype selectivity for these analogs, particularly for the 5-HT2B receptor subtype. Within this series, the potent analog VU6067416 (19d) was optimized to have suitable preclinical pharmacokinetic properties for in vivo dosing, although potent 5-HT2B agonist activity precluded further characterization for this series. Additionally, in silico docking studies suggest that the high potency of 19d may be a consequence of a halogen-bonding interaction with Phe2345.38 in the 5-HT2A orthosteric pocket.

The first syntheses of the Alpinia officinarum natural products alpinidinoid C and officinine B are reported. These unusual dimeric diarylheptanoids were accessed from a 3-substituted pyridine intermediate via a blue-light-mediated, triple-Minisci-type alkylation. Very few reports utilize N-(acyloxy)phthalimides (NAPs) in the construction of natural products, and the syntheses reported herein highlight the power of this methodology toward the orthogonal construction of highly substituted arenes.

ADVERTISEMENT RETURN TO ARTICLES ASAPPREVEditorialNEXTBrain-Penetrant Macrocycles: Design Considerations, Future Prospects, and Call for PapersCori A. MalinkyCori A. MalinkyUniversity of Oklahoma, 101 Stephenson Parkway, Norman, Oklahoma 73019, United StatesMore by Cori A. Malinky and Aaron M. Bender*Aaron M. BenderVanderbilt Center for Neuroscience Drug Discovery, Department of Pharmacology, Vanderbilt University, 393 Nichol Mill Ln., Franklin, Tennessee 37067, United States*[email protected]More by Aaron M. Benderhttps://orcid.org/0000-0003-0432-1648Cite this: J. Med. Chem. 2024, XXXX, XXX, XXX-XXXPublication Date (Web):May 7, 2024Publication History Received24 April 2024Published online7 May 2024https://doi.org/10.1021/acs.jmedchem.4c00968Published 2024 by American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views-Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (1 MB) Get e-AlertscloseSUBJECTS:Cancer,Central nervous system,Ligands,Macrocycles,Receptors Get e-Alerts

Herein we report progress toward a backup clinical candidate to the M1 positive allosteric modulator (PAM) VU319/ACP-319. Scaffold-hopping from the pyrrolo[2,3-b]pyridine-based M1 PAM VU6007477 to isomeric pyrrolo[3,2-b]pyridine and thieno[3,2-b]pyridine congeners identified several backup contenders. Ultimately, VU6007496, a pyrrolo[3,2-b]pyridine, advanced into late stage profiling, only to be plagued with unanticipated, species-specific metabolism and active/toxic metabolites which were identified in our phenotypic seizure liability in vivo screen, preventing further development. However, VU6007496 proved to be a highly selective and CNS penetrant M1 PAM, with minimal agonism, that displayed excellent multispecies IV/PO pharmacokinetics (PK), CNS penetration, no induction of long-term depression (or cholinergic toxicity) and robust efficacy in novel object recognition (minimum effective dose = 3 mg/kg p.o.). Thus, VU6007496 can serve as another valuable in vivo tool compound in rats and nonhuman primates, but not mouse, to study selective M1 activation.

This Letter details our efforts to develop novel, non-acetylene-containing metabotropic glutamate receptor subtype 5 (mGlu5) negative allosteric modulators (NAMs) with improved pharmacological properties. This endeavor involved replacing the ether-linked pyrimidine moiety, a metabolic liability, with various 5-membered heterocycles. From this exercise, we identified VU6043653, a highly brain penetrant and selective mGlu5 NAM which displayed moderate potency against both human and rat mGlu5. Moreover, VU6043653 has overall improved pharmacological and drug metabolism and pharmacokinetic profiles when compared to its predecessor compounds. Most notably, VU6043653 exhibits low predicted human hepatic clearance, a clean cytochrome P450 profile, and minimal inhibition of the dopamine transporter.

Antagonists of the serotonin receptor 2B (5-HT2B) have shown great promise as therapeutics for the treatment of pulmonary arterial hypertension, valvular heart disease, and related cardiopathies. Herein, we describe a high-throughput screen campaign that led to the identification of highly potent and selective 5-HT2B antagonists. Furthermore, selected compounds were profiled for their predicted ability to cross the blood-brain barrier. Two exemplary compounds, VU0530244 and VU0631019, were predicted to have very limited potential for brain penetration in human subjects, a critical profile for the development of 5-HT2B antagonists devoid of centrally-mediated adverse effects.

The cardiotoxicity associated with des-ethyl-dexfen-fluramine(norDF) and related agonists of the serotonin receptor 2B (5-HT2B) has solidified the receptor's place as an "antitarget"in drug discovery. Conversely, a growing body of evidence has highlightedthe utility of 5-HT2B antagonists for the treatment ofpulmonary arterial hypertension (PAH), valvular heart disease (VHD),and related cardiopathies. In this Perspective, we summarize the linkbetween the clinical failure of fenfluramine-phentermine (fen-phen)and the subsequent research on the role of 5-HT2B in diseaseprogression, as well as the development of drug-like and receptorsubtype-selective 5-HT2B antagonists. Such agents representa promising class for the treatment of PAH and VHD, but their utilityhas been historically understudied due to the clinical disasters associatedwith 5-HT2B. Herein, it is our aim to examine the currentstate of 5-HT2B drug discovery, with an emphasis on thereceptor's role in the central nervous system (CNS) versusthe periphery.

Previously described approaches for the alkylation of NH-sulfoximines typically rely either on transition metal catalysis, or the use of traditional alkylation reagents and strong bases. Herein, we report a straightforward alkylation of diverse NH-sulfoximines under simple Mitsunobu-type conditions, despite the unusually high pKa of the NH center.

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.

Ligands for the serotonin 2B receptor (5-HT2B) have shown potential to treat pulmonary arterial hypertension in preclinical models but cannot be used in humans because of predicted off-target neurological effects. The aim of this study was to develop novel systemically restricted compounds targeting 5-HT2B. Here, we show that mice treated with VU6047534 had decreased RVSP compared with control treatment in both the prevention and intervention studies using Sugen-hypoxia. VU6047534 is a novel 5-HT2B partial agonist that is peripherally restricted and able to both prevent and treat Sugen-hypoxia-induced pulmonary arterial hypertension. We have synthesized and characterized a structurally novel series of 5-HT2B ligands with high potency and selectivity for the 5-HT2B receptor subtype. Next-generation 5-HT2B ligands with similar characteristics, and predicted to be systemically restricted in humans, are currently advancing to investigational new drug-enabling studies.

Commonly known as "Quaaludes," methaqualone (1) is a sedative-hypnotic medication, with effects resembling barbiturates and other downers, that exerts its effects through modulation of γ-aminobutyric acid type A receptors (GABAAR). Following the discovery of the sedative and euphoric effects of methaqualone (1), it was quickly adopted by pharmaceutical companies and promoted by clinicians around the world as a "safe" sleeping pill option, and for a period it was available over the counter. The popularity of methaqualone (1) soared worldwide, and many people began to use it recreationally for its sedative-hypnotic-like psychoactive effects. Not long after its introduction, many individuals began to misuse the drug leading to overdoses and drug dependence which brought to light methaqualone's (1) addictive nature. In this review, the background, synthesis, pharmacology, metabolism, and pharmacokinetics of methaqualone (1) will be covered along with its discovery, history, and the derivatives that are currently available around the world through manufacture in clandestine laboratories.

Non‐selective antagonists of muscarinic acetylcholine receptors (mAChRs) that broadly inhibit all five mAChR subtypes provide an efficacious treatment for some movement disorders, including Parkinson’s disease and dystonia. Despite their efficacy in these and other central nervous system disorders, anti‐muscarinic therapy has limited utility due to severe adverse effects that often limit their tolerability by patients. Recent advances in understanding the roles that each mAChR subtype plays in disease pathology suggest that highly selective ligands for individual subtypes may underlie the anti‐parkinsonian and anti‐dystonic efficacy observed with the use of non‐selective anti‐muscarinic therapeutics. Our recent work has indicated that the M4 muscarinic acetylcholine receptor has several important roles in opposing aberrant neurotransmitter release, intracellular signaling pathways, and brain circuits associated with movement disorders. This raises the possibility that selective antagonists of M4 may recapitulate the efficacy of non‐selective anti‐muscarinic therapeutics and may decrease or eliminate the adverse effects associated with these non‐selective drugs. However, this hypothesis has not been directly tested due to lack of selective antagonists of M4. Here we utilize genetic mAChR knockout animals in combination with non‐selective mAChR antagonists to confirm that the M4 receptor underlies the locomotor‐stimulating and anti‐parkinsonian efficacy in rodent models. We also report the synthesis, discovery, and characterization of a series of first‐in‐class selective M4 antagonists. These novel compounds have ideal pharmacokinetic properties for in vivo evaluations, and we have confirmed that these optimized compounds have anti‐parkinsonian and anti‐dystonic efficacy in pharmacological and genetic models of movement disorders. These data provide critical pre‐clinical rationale for the development of M4 antagonists and represent a potential novel treatment mechanism to meet the unmet clinical need across several movement disorders.