Search

A series of pyrimidine analogues derived from ATC0175 were potent antagonists of human MCH-R1 in vitro. Significantly improved receptor selectivity was achieved with several analogues from this series, but no improvement in brain partitioning was noted. One example from this series was shown to inhibit food intake and decrease body weight in a chronic study. However no clear correlation between the pharmacodynamic effect and the pharmacokinetic data with respect to brain concentration was discernible leading us to conclude that the observed effect was most likely not due to interaction with the MCH-R1.

A new series of H 3 antagonists derived from the natural product Conessine are presented. Several compounds from these new series retain the potency and selectivity of earlier diamine based analogs while exhibiting improved PK characteristics. One compound ( 3u ) demonstrated functional antagonism of the H 3 receptor in an in vivo pharmacological model.

We have evaluated the anti-platelet and vascular pharmacology of AR246686, a novel 5-hydroxytryptamine2A (5-HT2A) receptor antagonist. AR246686 displayed high affinity binding to membranes of HEK cells stably expressing recombinant human and rat 5-HT2A receptors (Ki=0.2 nM and 0.4 nM, respectively). Functional antagonism (IC50=1.9 nM) with AR246686 was determined by inhibition of ligand-independent inositol phosphate accumulation in the 5-HT2A stable cell line. We observed 8.7-fold and 1360-fold higher affinity of AR246686 for the 5-HT2A receptor vs. 5-HT2C and 5-HT2B receptors, respectively. AR246686 inhibited 5-HT-induced amplification of ADP-stimulated human platelet aggregation (IC50=21 nM). Similar potency was observed for inhibition of 5-HT stimulated DNA synthesis in rat aortic smooth muscle cells (IC(50)=10 nM) and 5-HT-mediated contraction in rat aortic rings. Effects of AR246686 on arterial thrombosis and bleeding time were studied in a rat model of femoral artery occlusion. Oral dosing of AR246686 to rats resulted in prolongation of time to occlusion at 1 mg/kg, whereas increased bleeding time was observed at a dose of 20 mg/kg. In contrast, both bleeding time and time to occlusion were increased at the same dose (10 mg/kg) of clopidogrel. These results demonstrate that AR246686 is a high affinity 5-HT2A receptor antagonist with potent activity on platelets and vascular smooth muscle. Further, oral administration results in anti-thrombotic effects at doses that are free of significant effects on traumatic bleeding time.

5-Hydroxytryptamine (5-HT)(2C) receptor agonists hold promise for the treatment of obesity. In this study, we describe the in vitro and in vivo characteristics of lorcaserin [(1R)-8-chloro-2,3,4,5-tetrahydro-1-methyl-1H-3 benzazepine], a selective, high affinity 5-HT(2C) full agonist. Lorcaserin bound to human and rat 5-HT(2C) receptors with high affinity (K(i) = 15 +/- 1 nM, 29 +/- 7 nM, respectively), and it was a full agonist for the human 5-HT(2C) receptor in a functional inositol phosphate accumulation assay, with 18- and 104-fold selectivity over 5-HT(2A) and 5-HT(2B) receptors, respectively. Lorcaserin was also highly selective for human 5-HT(2C) over other human 5-HT receptors (5-HT(1A), 5-HT(3), 5-HT(4C), 5-HT5(5A), 5-HT(6), and 5-HT(7)), in addition to a panel of 67 other G protein-coupled receptors and ion channels. Lorcaserin did not compete for binding of ligands to serotonin, dopamine, and norepinephrine transporters, and it did not alter their function in vitro. Behavioral observations indicated that unlike the 5-HT(2A) agonist (+/-)-1-(2,5-dimethoxy-4-phenyl)-2-aminopropane, lorcaserin did not induce behavioral changes indicative of functional 5-HT(2A) agonist activity. Acutely, lorcaserin reduced food intake in rats, an effect that was reversed by pretreatment with the 5-HT(2C)-selective antagonist 6-chloro-5-methyl-1-[6-(2-methylpyridin-3-yloxy)pyridin-3-yl-carbamoyl]indoline (SB242,084) but not the 5-HT(2A) antagonist (R)-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-piperidine-methanol (MDL 100,907), demonstrating mediation by the 5-HT(2C) receptor. Chronic daily treatment with lorcaserin to rats maintained on a high fat diet produced dose-dependent reductions in food intake and body weight gain that were maintained during the 4-week study. Upon discontinuation, body weight returned to control levels. These data demonstrate lorcaserin to be a potent, selective, and efficacious agonist of the 5-HT(2C) receptor, with potential for the treatment of obesity.

We report on the synthesis, biological evaluation and structure–activity relationships for a series of 3-benzazepine derivatives as 5-HT2C receptor agonists. The compounds were evaluated in functional assays measuring [3H] phosphoinositol turnover in HEK-293 cells transiently transfected with h5-HT2C, h5-HT2A or h5-HT2B receptors. Several compounds are shown to be potent and selective 5-HT2C receptor agonists, which decrease food intake in a rat feeding model.

Insomnia affects a growing portion of the adult population in the U.S. Most current therapeutic approaches to insomnia primarily address sleep onset latency. Through the 5-hydroxytryptamine(2A) (5-HT(2A)) receptor, serotonin (5-HT) plays a role in the regulation of sleep architecture, and antagonists/inverse-agonists of 5-HT(2A) have been shown to enhance slow wave sleep (SWS). We describe here a series of 5-HT(2A) inverse-agonists that when dosed in rats, both consolidate the stages of NREM sleep, resulting in fewer awakenings, and increase a physiological measure of sleep intensity. These studies resulted in the discovery of 1-[3-(4-bromo-2-methyl-2H-pyrazol-3-yl)-4-methoxyphenyl]-3-(2,4-difluorophenyl)urea (Nelotanserin), a potent inverse-agonist of 5-HT(2A) that was advanced into clinical trials for the treatment of insomnia.

5-Hydroxytryptamine (5-HT)(2A) receptor inverse agonists are promising therapeutic agents for the treatment of sleep maintenance insomnias. Among these agents is nelotanserin, a potent, selective 5-HT(2A) inverse agonist. Both radioligand binding and functional inositol phosphate accumulation assays suggest that nelotanserin has low nanomolar potency on the 5-HT(2A) receptor with at least 30- and 5000-fold selectivity compared with 5-HT(2C) and 5-HT(2B) receptors, respectively. Nelotanserin dosed orally prevented (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI; 5-HT(2A) agonist)-induced hypolocomotion, increased sleep consolidation, and increased total nonrapid eye movement sleep time and deep sleep, the latter marked by increases in electroencephalogram (EEG) delta power. These effects on rat sleep were maintained after repeated subchronic dosing. In healthy human volunteers, nelotanserin was rapidly absorbed after oral administration and achieved maximum concentrations 1 h later. EEG effects occurred within 2 to 4 h after dosing, and were consistent with vigilance-lowering. A dose response of nelotanserin was assessed in a postnap insomnia model in healthy subjects. All doses (up to 40 mg) of nelotanserin significantly improved measures of sleep consolidation, including decreases in the number of stage shifts, number of awakenings after sleep onset, microarousal index, and number of sleep bouts, concomitant with increases in sleep bout duration. Nelotanserin did not affect total sleep time, or sleep onset latency. Furthermore, subjective pharmacodynamic effects observed the morning after dosing were minimal and had no functional consequences on psychomotor skills or memory. These studies point to an efficacy and safety profile for nelotanserin that might be ideally suited for the treatment of sleep maintenance insomnias.

We have evaluated the receptor pharmacology, antiplatelet activity, and vascular pharmacology of APD791 [3-methoxy-N-(3-(1-methyl-1H-pyrazol-5-yl)-4-(2-morpholinoethoxy)phenyl)benzamide] a novel 5-hydroxytryptamine 2A (5-HT(2A)) receptor antagonist. APD791 displayed high-affinity binding to membranes (K(i) = 4.9 nM) and functional inverse agonism of inositol phosphate accumulation (IC(50) = 5.2 nM) in human embryonic kidney cells stably expressing the human 5-HT(2A) receptor. In competition binding assays, APD791 was greater than 2000-fold selective for the 5-HT(2A) receptor versus 5-HT(2C) and 5-HT(2B) receptors, and was inactive when tested against a wide panel of other G-protein-coupled receptors. APD791 inhibited 5-HT-mediated amplification of ADP-stimulated human and dog platelet aggregation (IC(50) = 8.7 and 23.1 nM, respectively). Similar potency was observed for inhibition of 5-HT-stimulated DNA synthesis in rabbit aortic smooth muscle cells (IC(50) = 13 nM) and 5-HT-mediated vasoconstriction in rabbit aortic rings. Oral administration of APD791 to dogs resulted in acute (1-h) and subchronic (10-day) inhibition of 5-HT-mediated amplification of collagen-stimulated platelet aggregation in whole blood. Two active metabolites, APD791-M1 and APD791-M2, were generated upon incubation of APD791 with human liver microsomes and were also indentified in dogs after oral administration of APD791. The affinity and selectivity profiles of both metabolites were similar to APD791. These results demonstrate that APD791 is an orally available, high-affinity 5-HT(2A) receptor antagonist with potent activity on platelets and vascular smooth muscle.

GPR119 is a rhodopsin-like GPCR expressed in pancreatic beta-cells and incretin releasing cells in the GI tract. As with incretins, GPR119 increases cAMP levels in these cell types, thus making it a highly attractive potential target for the treatment of diabetes. The discovery of the first reported potent agonist of GPR119, 2-fluoro-4-methanesulfonyl-phenyl)-{6-[4-(3-isopropyl-[1,2,4]oxadiazol-5-yl)-piperidin-1-yl]-5-nitro-pyrimidin-4-yl}-amine (8g, AR231453), is described starting from an initial inverse agonist screening hit. Compound 8g showed in vivo activity in rodents and was active in an oral glucose tolerance test in mice following oral administration.

The synthesis and SAR of a novel 3-benzazepine series of 5-HT2C agonists is described. Compound 7d (lorcaserin, APD356) was identified as one of the more potent and selective compounds in vitro (pEC50 values in functional assays measuring [(3)H]phosphoinositol turnover: 5-HT2C = 8.1; 5-HT2A = 6.8; 5-HT2B = 6.1) and was potent in an acute in vivo rat food intake model upon oral administration (ED50 at 6 h = 18 mg/kg). Lorcaserin was further characterized in a single-dose pharmacokinetic study in rat (t1/2 = 3.7 h; F = 86%) and a 28-day model of weight gain in growing Sprague-Dawley rat (8.5% decrease in weight gain observed at 36 mg/kg b.i.d.). Lorcaserin was selected for further evaluation in clinical trials for the treatment of obesity.

A new family of Histamine H3 receptor antagonists (5a–t) has been prepared based on the structure of the natural product Conessine, a known H3 antagonist. Several members of the new series are highly potent and selective binders of rat and human H3 receptors and display inverse agonism at the human H3 receptor. Compound 5n exhibited promising rat pharmacokinetic properties and demonstrated functional antagonism of the H3 receptor in an in-vivo pharmacological model.

Melanin-concentrating hormone (MCH) is a cyclic peptide produced in the lateral hypothalamus. It has been implicated in a number of physiological processes including feeding behavior, energy balance, and the regulation of emotional states. Here, we report in vitro and in vivo profiles of ATC0065 [N(2)-[cis-4-({2-[4-bromo-2-(trifluoromethoxy)phenyl]ethyl}amino)cyclohexyl]-N(4), N(4)-dimethylquinazoline-2,4-diamine dihydrochloride] and ATC0175 [N-(cis-4-{[4-(dimethylamino)quinazolin-2-yl]amino}cyclohexyl)-3,4-difluorobenzamide hydrochloride], newly synthesized MCH receptor 1 (MCHR1) antagonists. Both ATC0065 and ATC0175 had high affinities for human MCHR1 with IC(50) values of 15.7 +/- 1.95 and 7.23 +/- 0.59 nM, respectively. Both ATC0065 (IC(50) = 21.4 +/- 1.57 nM) and ATC0175 (IC(50) = 13.5 +/- 0.78 nM) showed potent antagonist activities at MCHR1, as assessed by MCH-increased guanosine 5'-O-(3-[(35)S]thio)phosphate ([(35)S]GTPgammaS) binding to human MCHR1. Oral administration of ATC0065 (3-30 mg/kg) or ATC0175 (1-10 mg/kg) significantly reduced immobility time in the forced swimming test in rats, indicating antidepressant-like effects. Both ATC0065 and ATC0175 significantly reversed swim stress-induced anxiety in the elevated plus-maze test in rats and stress-induced hyperthermia in mice. ATC0175 significantly increased social interaction between unfamiliar rats and reduced separation-induced vocalizations in guinea pig pups, indicating anxiolytic potential. In contrast, ATC0065 and ATC0175 did not affect spontaneous locomotor activity or rotarod performance in rats. These findings indicate that ATC0065 and ATC0175 are potent and orally active MCHR1 antagonists with anxiolytic and antidepressant activity in rodents.

Reconstitution of purified sodium channels into phospholipid vesicles restores many aspects of sodium channel function including high-affinity neurotoxin binding and action at neurotoxin receptor sites 1-3 and 5, but neurotoxin binding and action at receptor site 4 has not previously been demonstrated in purified and reconstituted preparations. Toxin IV from the venom of the American scorpion Centruroides suffusus suffusus (Css IV), a β-scorpion toxin, shifts the voltage dependence of sodium channel activation by binding with high affinity to neurotoxin receptor site 4. Sodium channels were purified from rat brain and reconstituted into phospholipid vesicles composed of phosphatidylcholine and phosphatidylethanolamine (65 :35). 125 I-Css IV, purified by reversed-phase HPLC, bound rapidly and specifically to reconstituted sodium channels. Dissociation of the bound toxin was biphasic with half-times of 0.22 min -1 and 0.015 min -1 . At equilibrium, the toxin bound to two classes of specific high-affinity sites, a variable minor class with K D of ∼0.1 nM and a major class with a K D of ∼5 nM. Approximately 0.8 mol 125 I-Css IV was bound per mole of reconstituted, right-side-out sodium channels, as assessed from comparison of binding of saxitoxin and Css IV. Binding of Css IV was unaffected by membrane potential or by neurotoxins that bind at sites 1-3 or 5, consistent with the characteristics of binding of β-scorpion toxins to sodium channels in cells and membrane preparations. Our results show that specific, high-affinity binding at neurotoxin receptor site 4 on purified sodium channels can be restored by reconstitution into phospholipid vesicles and provide an experimental approach to analysis of the peptide components of the toxin receptor site.

Site-directed and monoclonal antibodies recognizing different extracellular regions of the RII sodium channel alpha subunit have been used to determine the sequences that comprise the receptor for alpha-scorpion toxins by evaluating the effect of antibody on voltage-dependent binding of radio-labeled toxin isolated from Leiurus quinquestriatus to both reconstituted rat brain sodium channel and rat brain synaptosomes. Of six antibodies tested, two recognizing amino acid residues 355-371 and 382-400 located on an extracellular loop between transmembrane segments S5 and S6 of domain I and one recognizing residues 1686-1703 of a similar loop of domain IV inhibit binding by 30-55%. Inhibition is concentration-(EC50 = 0.4-2 microM) and time- (t1/2 = 40-80 min) dependent. Five different monoclonal antibodies recognizing the same extracellular loop in domain I inhibit binding completely with similar EC50 values as observed for site-directed antibodies. Kinetic studies of the antibody effect are consistent with a slowly reversible competition for the toxin receptor site. Our results suggest that the extracellular loops between segments S5 and S6 of domains I and IV comprise at least part of the alpha-scorpion toxin receptor site and support the membrane topology models in which domains I and IV are adjacent in the tertiary structure of the channel protein and six transmembrane sequences are contained in each of the four homologous domains.