Anti-diabetic efficacy and impact on amino acid metabolism of GRA1, a novel small-molecule glucagon receptor antagonist.

Hyperglucagonemia is implicated in the pathophysiology of hyperglycemia. Antagonism of the glucagon receptor (GCGR) thus represents a potential approach to diabetes treatment. Herein we report the characterization of GRA1, a novel small-molecule GCGR antagonist that blocks glucagon binding to the human GCGR (hGCGR) and antagonizes glucagon-induced intracellular accumulation of cAMP with nanomolar potency.

Discovery of a novel glucagon receptor antagonist N-[(4-{(1S)-1-[3-(3, 5-dichlorophenyl)-5-(6-methoxynaphthalen-2-yl)-1H-pyrazol-1-yl]ethyl}phenyl)carbonyl]-β-alanine (MK-0893) for the treatment of type II diabetes.

A potent, selective glucagon receptor antagonist 9m, N-[(4-{(1S)-1-[3-(3,5-dichlorophenyl)-5-(6-methoxynaphthalen-2-yl)-1H-pyrazol-1-yl]ethyl}phenyl)carbonyl]-β-alanine, was discovered by optimization of a previously identified lead. Compound 9m is a reversible and competitive antagonist with high binding affinity (IC(50) of 6.6 nM) and functional cAMP activity (IC(50) of 15.

Discovery of N-aryl-2-acylindole human glucagon receptor antagonists.

A novel class of N-aryl-2-acylindole human glucagon receptor (hGCGR) antagonists is reported. These compounds demonstrate good pharmacokinetic profiles in multiple preclinical species. One compound from this series, indole 33, is orally active in a transgenic murine pharmacodynamic model.

Discovery of cyclic guanidines as potent, orally active, human glucagon receptor antagonists.

In the course of the development of an aminobenzimidazole class of human glucagon receptor (hGCGR) antagonists, a novel class of cyclic guanidine hGCGR antagonists was discovered. Rapid N-dealkylation resulted in poor pharmacokinetic profiles for the benchmark compound in this series. A strategy aimed at blocking oxidative dealkylation led to a series of compounds with improved rodent pharmacokinetic profiles.

Chronic treatment with a glucagon receptor antagonist lowers glucose and moderately raises circulating glucagon and glucagon-like peptide 1 without severe alpha cell hypertrophy in diet-induced obese mice.

Aims/hypothesis: Antagonism of the glucagon receptor (GCGR) represents a potential approach for treating diabetes. Cpd-A, a potent and selective GCGR antagonist (GRA) was studied in preclinical models to assess its effects on alpha cells.

Methods: Studies were conducted with Cpd-A to examine the effects on glucose-lowering efficacy, its effects in combination with a dipeptidyl peptidase-4 (DPP-4) inhibitor, and the extent and reversibility of alpha cell hypertrophy associated with GCGR antagonism in mouse models.

Discovery of novel, potent, selective, and orally active human glucagon receptor antagonists containing a pyrazole core.

A novel class of 1,3,5-pyrazoles has been discovered as potent human glucagon receptor antagonists. Notably, compound 26 is orally bioavailable in several preclinical species and shows selectivity towards cardiac ion channels, other family B receptors such hGIP and hGLP1, and a large panel of enzymes and additional receptors. When dosed orally, compound 26 is efficacious in suppressing glucagon induced plasma glucose excursion in rhesus monkey and transgenic murine pharmacodynamic models at 1 and 10 mpk, respectively.

Discovery of potent, orally active benzimidazole glucagon receptor antagonists.

The discovery and optimization of potent and selective aminobenzimidazole glucagon receptor antagonists are described. One compound possessing moderate pharmacokinetic properties in multiple preclinical species was orally efficacious at inhibiting glucagon-mediated glucose excursion in transgenic mice expressing the human glucagon receptor, and in rhesus monkeys. The compound also significantly lowered glucose levels in a murine model of diabetes.

Cloning and expression of canine glucagon receptor and its use to evaluate glucagon receptor antagonists in vitro and in vivo.

Glucose homeostasis is maintained by the combined actions of insulin and glucagon. Hyperglucagonemia and/or elevation of glucagon/insulin ratio have been reported in diabetic patients and in animal models of diabetes. Therefore, antagonizing glucagon receptor function has long been considered a useful approach to lower hyperglycemia.

Design and synthesis of conformationally constrained tri-substituted ureas as potent antagonists of the human glucagon receptor.

A series of conformationally constrained tri-substituted ureas were synthesized, and their potential as glucagon receptor antagonists was evaluated. This effort resulted in the identification of compound 4a, which had a binding IC50 of 4.0 nM and was shown to reduce blood glucose levels at 3 mg/kg in glucagon-challenged mice containing a humanized glucagon receptor.

Direct observation (NMR) of the efficacy of glucagon receptor antagonists in murine liver expressing the human glucagon receptor.

The demonstration of pharmacodynamic efficacy of novel chemical entities represents a formidable challenge in the early exploration of synthetic lead classes. Here, we demonstrate a technique to validate the biological efficacy of novel antagonists of the human glucagon receptor (hGCGR) in the surgically removed perfused liver prior to the optimization of the pharmacokinetic properties of the compounds. The technique involves the direct observation by (13)C NMR of the biosynthesis of [(13)C]glycogen from [(13)C]pyruvate via the gluconeogenic pathway.

Discovery of novel, potent, and orally active spiro-urea human glucagon receptor antagonists.

A novel class of spiro-ureas has been discovered as potent human glucagon receptor antagonists in both binding and functional assays. Preliminary studies have revealed that compound 15 is an orally active human glucagon receptor antagonist in a transgenic murine pharmacodynamic model at 10 and 30 mpk. Compound 15 is orally bioavailable in several preclinical species and shows selectivity toward cardiac ion channels and other family B receptors, such as hGIP1 and hGLP.

Discovery and investigation of a novel class of thiophene-derived antagonists of the human glucagon receptor.

A novel class of antagonists of the human glucagon receptor (hGCGR) has been discovered. Systematic modification of the lead compound identified substituents that were essential for activity and those that were amenable to further optimization. This SAR exploration resulted in the synthesis of 13, which exhibited good potency as an hGCGR functional antagonist (IC50 = 34 nM) and moderate bioavailability (36% in mice).

Hepatic glucagon receptor binding and glucose-lowering in vivo by peptidyl and non-peptidyl glucagon receptor antagonists.

Glucagon receptor antagonists have been actively pursued as potential therapeutics for the treatment of type 2 diabetes. Peptidyl and non-peptidyl glucagon receptor antagonists have been shown to block glucagon-induced blood glucose elevation in both animals and humans. How the antagonists and the glucagon receptor interact in vivo has not been reported and is the subject of the current study.

Phytosphingosine 1-phosphate: a high affinity ligand for the S1P(4)/Edg-6 receptor.

It has been reported recently that the phosphorylated form of the immunomodulator FTY720 activates sphingosine 1-phosphate G protein-coupled receptors. Therefore, understanding the biology of this new class of receptors will be important in clarifying the immunological function of bioactive lysosphingolipid ligands. The S1P(4) receptor has generated interest due to its lymphoid tissue distribution.

Beta(3)-adrenoceptor agonist-induced increases in lipolysis, metabolic rate, facial flushing, and reflex tachycardia in anesthetized rhesus monkeys.

The effects of two beta(3)-adrenergic receptor agonists, (R)-4-[4-(3-cyclopentylpropyl)-4,5-dihydro-5-oxo-1H-tetrazol-1-yl]-N-[4-[2-[[2-hydroxy-2-(3-pyridinyl)ethyl]amino]ethyl]phenyl]benzenesulfonamide and (R)-N-[4-[2-[[2-hydroxy-2-(3-pyridinyl)- ethyl]amino]ethyl]phenyl]-1-(4-octylthiazol-2-yl)-5-indolinesulfonamide, on indices of metabolic and cardiovascular function were studied in anesthetized rhesus monkeys. Both compounds are potent and specific agonists at human and rhesus beta(3)-adrenergic receptors. Intravenous administration of either compound produced dose-dependent lipolysis, increase in metabolic rate, peripheral vasodilatation, and tachycardia with no effects on mean arterial pressure.

Human beta3 adrenergic receptor agonists containing cyanoguanidine and nitroethylenediamine moieties.

Pyridineethanolamine derivatives containing cyanoguanidine or nitroethylenediamine moieties were examined as human beta3 adrenergic receptor (AR) agonists. Notably, indoline derivatives 6a and 11 were potent beta3 AR agonists (beta3 EC50 = 13 and 19 nM, respectively), which showed good selectivity over binding to and minimal activation of the beta1 and beta2 ARs.

Tetrahydroisoquinoline derivatives containing a benzenesulfonamide moiety as potent, selective human beta3 adrenergic receptor agonists.

Tetrahydroisoquinoline derivatives containing a 4-(hexylureido)benzenesulfonamide were examined as human beta3 adrenergic receptor (AR) agonists. Notably, 4,4-biphenyl derivative 9 was a 6 nM full agonist of the beta3 AR. Naphthyloxy compound 18 (beta3 EC50 = 78 nM) did not activate the beta1 and beta2 ARs at 10 microM, and showed >1000-fold selectivity over binding to the beta1 and beta2 ARs.

Discovery of a potent, orally bioavailable beta(3) adrenergic receptor agonist, (R)-N-[4-[2-[[2-hydroxy-2-(3-pyridinyl)ethyl]amino]ethyl]phenyl]-4-[4 -[4-(trifluoromethyl)phenyl]thiazol-2-yl]benzenesulfonamide.

As part of our investigation into the development of orally bioavailable beta(3) adrenergic receptor agonists, we have identified a series of pyridylethanolamine analogues possessing a substituted thiazole benzenesulfonamide pharmacophore that are potent human beta(3) agonists with excellent selectivity against other human beta receptor subtypes. Several of these compounds also exhibited an improved pharmacokinetic profile in dogs. For example, thiazole sulfonamide 2e (R = 4-F(3)C-C(6)H(4)) is a potent full beta(3) agonist (EC(50) = 3.

L-750355, a human beta3-adrenoceptor agonist; in vitro pharmacology and profile of activity in vivo in the rhesus monkey.

The profile of in vitro and in vivo biology of a human beta3-adrenoceptor agonist, (S)-N-[4-[2-[[3[(2-amino-5-pyridinyl)oxy]-2-hydroxy-propyl]amino]-eth yl]-phenyl]-4-isopropylbenzenesulfonamide, L-750355, is described. Using cloned human and rhesus beta1-, beta2- and beta3-adrenoceptors, expressed in Chinese hamster ovary (CHO) cells, L-750355 was shown to be a potent, albeit partial, agonist for the human (EC(50)=10 nM; % maximal receptor activation=49%) and rhesus (EC(50)=28 nM; % maximal receptor activation=34%) beta3-adrenoceptors. Furthermore, L-750355 stimulates lipolysis in rhesus adipocytes in vitro.

Human beta3-adrenergic receptor agonists containing 1,2,3-triazole-substituted benzenesulfonamides.

Compounds containing a 1,2,3-triazole-substituted benzenesulfonamide were prepared and found to be potent and selective human beta3-adrenergic receptor agonists. The most interesting compound, trifluoromethylbenzyl analogue 12e (beta3 EC50 = 3.1 nM with >1500-fold selectivity over binding to both beta1- and beta2 receptors), stimulates lipolysis in the rhesus monkey (ED50 = 0.

Potent, selective 3-pyridylethanolamine beta3 adrenergic receptor agonists possessing a thiazole benzenesulfonamide pharmacophore.

A series of thiazole benzenesulfonamide-substituted 3-pyridylethanolamines was prepared and evaluated for their human beta3 adrenergic receptor agonist activity. Incorporation of aryl and heteroaryl substitution in the 4-position of the thiazole ring resulted in a number of highly potent and selective beta3 agonists. Results of preliminary in vivo evaluation of several of these compounds is described.

Substituted oxazole benzenesulfonamides as potent human beta3 adrenergic receptor agonists.

As a part of our investigation into the development of orally bioavailable beta3 adrenergic receptor agonists, we have identified a series of substituted oxazole derivatives that are potent beta3 agonists with excellent selectivity against other beta receptors. Several of these compounds showed excellent oral bioavailability in dogs. One example, cyclopentylethyloxazole 5f is a potent beta3 agonist (EC50 = 14 nM, 84% activation) with 340-fold and 160-fold selectivity over beta1 and beta2 receptors, respectively, and has 38% oral bioavailability in dogs.

Synthesis and SAR of benzyl and phenoxymethylene oxadiazole benzenesulfonamides as selective beta3 adrenergic receptor agonist antiobesity agents.

Benzyl and phenoxymethylene substituted oxadiazoles are potent and orally bioavailable beta3 adrenergic receptor (AR) agonists. The 4-trifluormethoxy substituted 5-benzyl oxadiazole 5f has an EC50 of 8 nM in the beta3 AR agonist assay with 100-fold selectivity over beta1 and beta2 AR binding inhibition activity. Its oral bioavailability in dogs is 30 +/- 4%, with a half-life of 3.

Discovery of an orally bioavailable alkyl oxadiazole beta3 adrenergic receptor agonist.

5-n-Pentyl oxadiazole substituted benzenesulfonamide 8 is a potent and selective beta3 adrenergic receptor agonist (beta3 EC50 = 23 nM, beta1 IC50 = 3000 nM, beta2 IC50 = 3000 nM). The compound has high oral bioavailability in dogs (62%) and rats (36%) and is among the most orally bioavailable beta3 adrenergic receptor agonists reported to date.

Potent and selective human beta(3)-adrenergic receptor antagonists.

Although the functional presence of beta(3)-adrenergic receptors (beta(3)-AR) in rodents is well established, its significance in human adipose tissue has been controversial. One of the issues confounding the experimental data has been the lack of potent and selective human beta(3)-AR ligands analogous to the rodent-specific agonist BRL37344. Recently, we described a new class of aryloxypropanolamine beta(3)-AR agonists that potently and selectively activate lipolysis in rhesus isolated adipocytes and stimulate the metabolic rate in rhesus monkeys in vivo.