Optimization of imidazole amide derivatives as cannabinoid-1 receptor antagonists for the treatment of obesity

Several imidazole-based cyclohexyl amides were identified as potent CB-1 antagonists, but they exhibited poor oral exposure in rodents. Incorporation of a hydroxyl moiety on the cyclohexyl ring provided a dramatic improvement in oral exposure, together with a ca. 10-fold decrease in potency. Further optimization provided the imidazole 2-hydroxy-cyclohexyl amide 45, which exhibited hCB-1 K(i)=3.7nM, and caused significant appetite suppression and robust, dose-dependent reduction of body weight gain in industry-standard rat models.     

Potent oxadiazole CGRP receptor antagonists for the potential treatment of migraine

A pharmacophore model was built, based on known CGRP receptor antagonists, and this was used to aid the identification of novel leads. Analogues were designed, modelled and synthesised which incorporated alternative ‘LHS’ fragments linked via either an amide or urea to a privileged ‘RHS’ fragment commonly found in CGRP receptor antagonists. As a result a novel series of oxadiazole CGRP receptor antagonists has been identified and the subsequent optimisation to enhance both potency and bioavailability is presented.     

Discovery of cannabinoid-1 receptor antagonists by virtual screening

In this work, we tried to find a new scaffold for a CB1 receptor antagonist using virtual screening. We first analyzed structural features for the known cannabinoid-1 receptor antagonists and, then, we built pharmacophore models using the HipHop concept and carried out a docking study based on our homology CB1 receptor 3D structure. The most active compound, including thiazole-4-one moiety, showed an activity value of 125 nM IC₅₀, with a good PK profile.     

Hologram QSAR model for the prediction of human oral bioavailability

A drug intended for use in humans should have an ideal balance of pharmacokinetics and safety, as well as potency and selectivity. Unfavorable pharmacokinetics can negatively affect the clinical development of many otherwise promising drug candidates. A variety of in silico ADME (absorption, distribution, metabolism, and excretion) models are receiving increased attention due to a better appreciation that pharmacokinetic properties should be considered in early phases of the drug discovery process. Human oral bioavailability is an important pharmacokinetic property, which is directly related to the amount of drug available in the systemic circulation to exert pharmacological and therapeutic effects. In the present work, hologram quantitative structure–activity relationships (HQSAR) were performed on a training set of 250 structurally diverse molecules with known human oral bioavailability. The most significant HQSAR model (q² = 0.70, r² = 0.93) was obtained using atoms, bond, connection, and chirality as fragment distinction. The predictive ability of the model was evaluated by an external test set containing 52 molecules not included in the training set, and the predicted values were in good agreement with the experimental values. The HQSAR model should be useful for the design of new drug candidates having increased bioavailability as well as in the process of chemical library design, virtual screening, and high-throughput screening.     

Optimization of triaryl bis-sulfones as cannabinoid-2 receptor ligands

Structure-activity relationship on our recently reported triaryl bis-sulfone class of cannabinoid-2 (CB2) receptor selective inverse agonists was explored. Modifications to the methane sulfonamide, substitutions to B and C phenyl rings, and replacements of the C-ring were investigated. A compound with excellent CB2 activity, selectivity for CB2 over CB1, and in vivo plasma levels was identified.     

Triaryl bis-sulfones as cannabinoid-2 receptor ligands: SAR studies

We recently reported that compound 1 is a potent inhibitor of the CB2 receptor with high selectivity over CB1. This paper describes the SAR development for this class of compounds. Variation of the substitution pattern on the aromatic rings, as well as the groups linking them together, led to sub-nanomolar inhibitors of the CB2 receptor, with high selectivity over CB1.     

Peripheral cannabinoid-1 receptor inverse agonism reduces obesity by reversing leptin resistance

Obesity-related leptin resistance manifests in loss of?leptin's ability to reduce appetite and increase energy expenditure. Obesity is also associated with increased activity of the endocannabinoid system, and CB(1) receptor (CB(1)R) inverse agonists reduce body weight and the associated metabolic complications, although adverse neuropsychiatric effects halted their therapeutic development. Here we show that in mice with diet-induced obesity (DIO), the peripherally restricted CB(1)R inverse agonist JD5037 is equieffective with its brain-penetrant parent compound in reducing appetite, body weight, hepatic steatosis, and insulin resistance, even though it does not occupy central CB(1)R or induce related behaviors. Appetite and weight reduction by JD5037 are mediated by resensitizing DIO mice to endogenous leptin through reversing the hyperleptinemia by decreasing leptin expression and secretion by adipocytes and increasing leptin clearance via the?kidney. Thus, inverse agonism at peripheral CB(1)R not only improves cardiometabolic risk in obesity but has antiobesity effects by reversing leptin resistance.     

Diarylimidazolyl oxadiazole and thiadiazole derivatives as cannabinoid CB1 receptor antagonists

Since the CB1 receptor antagonist SR141716 (rimonabant) was reported to modulate food intake, CB1 antagonism has been considered as a new therapeutic target in the treatment of obesity. Several series of derivatives based on diarylimidazolyl oxadiazole and thiadiazole scaffolds were synthesized and tested for CB1 receptor binding affinity. SAR studies directed toward the optimization of imidazole scaffolds resulted in the discovery of 10s which showed highest potency for CB1 receptor binding affinity (IC₅₀ = 1.91 nM) prepared to date.     

Discovery of a novel series of melanin-concentrating hormone receptor 1 antagonists for the treatment of obesity

A new class of MCHR1 antagonists was discovered via a high-throughput screen. Optimization of the lead structure resulted in the identification of indole 10e. This compound possesses good pharmacokinetic properties across preclinical species and is efficacious in reducing food consumption in an MCH cannulated rat model and a cynomolgus monkey food consumption model.     

Synthesis and evaluation of urea-based indazoles as melanin-concentrating hormone receptor 1 antagonists for the treatment of obesity

A series of urea-based N-1-(2-aminoethyl)-indazoles was synthesized and evaluated for melanin-concentrating hormone receptor 1 (MCHr1) antagonism in both binding and functional assays. Several compounds that acted as MCHr1 antagonists were identified, and optimization afforded a compound with excellent binding affinity, good functional potency, and oral efficacy in a chronic model for weight loss in diet-induced obese mice.     

Convergent QSAR studies on a series of NK3 receptor antagonists for schizophrenia treatment

The dopamine hypothesis states that decreased dopaminergic neurotransmission reduces schizophrenia symptoms. Neurokinin-3 receptor (NK₃) antagonists reduce dopamine release and have shown positive effects in pre-clinical and clinical trials. We employed 2D and 3D-QSAR analysis on a series of 40 non-peptide NK₃ antagonists. Multivariate statistical analysis, PCA and HCA, were performed to rational training/test set splitting and PLS regression was employed to construct all QSAR models. We constructed one highly predictive CoMFA model (q^2?=?0.810 and r^2?=?0.929) and acceptable HQSAR and CoMSIA models (HQSAR q^2?=?0.644 and r^2?=?0.910; CoMSIA q^2?=?0.691, r^2?=?0.911). The three different techniques provided convergent physicochemical results. All models indicate cyclopropane, piperidine and di-chloro-phenyl ring attached to cyclopropane ring and also the amide group attached to the piperidine ring could play an important role in ligand–receptor interactions. These findings may contribute to develop potential NK₃ receptor antagonists for schizophrenia.     

Divalent cannabinoid-1 receptor ligands: A linker attachment point survey of SR141716A for development of high-affinity CB1R molecular probes

The cannabinoid-1 receptor (CB1R) inverse agonist SR141716A has proven useful for study of the endocannabinoid system, including development of divalent CB1R ligands possessing a second functional motif attached via a linker unit. These have predominantly employed the C3 position of the central pyrazole ring for linker attachment. Despite this precedent, a novel series of C3-linked CB1R-D2R divalent ligands exhibited extremely high affinity at the D2R, but only poor affinity for the CB1R. A systematic linker attachment point survey of the SR141716A pharmacophore was therefore undertaken, establishing the C5 position as the optimal site for linker conjugation. This linker attachment survey enabled the identification of a novel divalent ligand as a lead compound to inform ongoing development of high-affinity CB1R molecular probes.     

Bicyclic and tricyclic heterocycle derivatives as histamine H3 receptor antagonists for the treatment of obesity

A novel series of non-imidazole bicyclic and tricyclic histamine H₃ receptor antagonists has been discovered. Compound 17 was identified as a centrally penetrant molecule with high receptor occupancy which demonstrates robust oral activity in rodent models of obesity. In addition compound 17 possesses clean CYP and hERG profiles and shows no behavioral changes in the Irwin test.     

Identification, optimisation and in vivo evaluation of oxadiazole DGAT-1 inhibitors for the treatment of obesity and diabetes

A novel series of DGAT-1 inhibitors was discovered from an oxadiazole amide high throughput screening (HTS) hit. Optimisation of potency and ligand lipophilicity efficiency (LLE) resulted in a carboxylic acid containing clinical candidate 53 (AZD3988), which demonstrated excellent DGAT-1 potency (0.6 nM), good pharmacokinetics and pre-clinical in vivo efficacy that could be rationalised through a PK/PD relationship.     

Identification of piperazine-bisamide GHSR antagonists for the treatment of obesity

Piperazine-bisamide analogs were discovered as partial agonists of human growth hormone secretagogue receptor (GHSR) in a high throughput screen. The partial agonists were optimized for potency and converted into antagonists through structure–activity relationship (SAR) studies. The efforts also led to the identification of potent antagonist with favorable PK profile suitable as a tool compound for in vivo studies.     

3-D QSAR studies of triazolinone based balanced AT1/AT2 receptor antagonists

Essential structural and physicochemical requirements in terms of common biophoric sites (pharmacophore) and secondary sites for binding and interacting with AT1 and AT2 receptors have been identified using APEX-3-D expert system on 16 N2- aryl triazolinone biphenyl sulphonamides. Among several biophoric 3-D QSAR models two models (Nos. 1 and 2) having R2 > 0.7, chance <0.05 and match >0.5 and two models (Nos. 3 and 4) having R2 > 0.89, chance <0.03 and match >0.5 with three biophoric sites and two secondary sites (except model No. 4 with three secondary sites) describe the variation in AT1 and AT2 antagonistic activities, respectively.     

Pyridopyrimidine based cannabinoid-1 receptor inverse agonists: Synthesis and biological evaluation

The synthesis, SAR and binding affinities are described for cannabinoid-1 receptor (CB1R) specific inverse agonists based on pyridopyrimidine and heterotricyclic scaffolds. Food intake and pharmacokinetic evaluation of several of these compounds indicate that they are effective orally active modulators of CB1R.