Discovery of the first non-peptide antagonist of the motilin receptor

A first-in-class non-peptide antagonist of the motilin receptor was identified through electronic screening of our corporate database against a 3D pharmacophore. The pharmacophore was developed from the motilin 22 residue endogenous peptide using NMR structural data, principles of peptide folding, and peptide structure activity relationships. The NMR data supported helical content within the peptide, and both the hydrophobic staple and N-capping box motifs were identified in the motilin sequence. The conformational features of these motifs were imposed on the peptide structure, providing a constrained conformer as a starting point for database searching. A trisubstituted cyclopentene lead was identified directly from the electronic search. Compounds in this series inhibit the binding of 125I-motilin to human antral smooth muscle membrane and antagonize motilin-induced intracellular calcium mobilization in cells expressing the human motilin receptor. A potent compound developed through optimization, RWJ 68023, is active in binding and cell-based functional assays and is also effective in inhibiting motilin-induced contractility in segments of rabbit duodenum. This orally active compound is currently undergoing clinical evaluation for the treatment of gastrointestinal disorders associated with altered motility.     

Effects of an orally active non-peptide bradykinin B2 receptor antagonist,FR173657, on plasma exudation in rat carrageenin-induced pleurisy

1. Effects of an orally active non-peptide (BK) B₂ receptor antagonist, {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 ((E)-3-(6-acetamido-3-pyridyl)- N-[N-[2,4-dichloro-3-[(2-methyl-8-quinolinyl)oxymethyl]phenyl]-N-methylaminocarbonylmethyl] acrylamide) on the plasma exudation in rat carrageenin-induced pleurisy were investigated.
2. Plasma exudation induced by intrapleural injection of bradykinin (BK, 3 nmol per rat) into male SD strain rats (SPF, 8 weeks old) were significantly inhibited by oral administration of novel B₂ receptor antagonist {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 (3–30 mg kg⁻¹, 1 h before BK injection) in a dose-dependent manner, whereas that induced by histamine was not.
3. The inhibitory effect of 30 mg kg⁻¹ {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 persisted for more than 4 h.
4. Intrapleural injection of λ-carrageenin (2% (w/v), 0.1 ml per rat) caused marked plasma exudation and accumulation of exudates from 1 h after carrageenin injection. The maximum plasma exudation response was observed 5 h after carrageenin. The oral administration of {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 to rats (30 mg kg⁻¹, 1 h before carrageenin) significantly (by 50–77%) blunted the plasma exudation 1, 3, 5, and 7 h after carrageenin, causing a significant parallel reduction (by 42–57%) in the volume of exudates.
5. The anti-inflammatory effect of {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 on rat carrageenin-induced pleurisy was almost equipotent with that of the peptide B₂ antagonist Hoe140 (1 mg kg⁻¹, i.v.), a plasma kallikrein inhibitor, soy bean trypsin inhibitor (0.3 mg per rat, intrapleural injection) and bromelain (10 mg kg⁻¹, i.v.).
6. In pleurisy induced by intrapleural injection of a histamine releaser, compound 48/80, the plasma exudation was observed only within 20 min after the injection. This plasma exudation was not affected by {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657, although it was completely inhibited by a mixture of pyrilamine (5 mg kg⁻¹, i.v.) and methysergide (3 mg kg⁻¹, i.v.).
7. These results indicate that {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 is an orally active, promising anti-inflammatory agent for kinin-dependent inflammation.

     

Effects of the orally active non-peptide bradykinin B2 receptor antagonist, FR173657, on plasma extravasation in guinea pig airways

We investigated the effect of the orally active non-peptide bradykinin B2 receptor antagonist, FR173657 (E)-3-(6-acetamido-3-pyridyl)-N-[N-[2.4-di-chloro-3-[(2-methyl-8-quinoli nyl)oxymethyl]phenyl]-N-methy-laminocarbonylmethyl] acrylamide), on plasma extravasation mediated by activation of sensory nerves in guinea pig airways. Plasma extravasation was assessed by the photometric measurement of the extravasated Evans blue after formamide extraction. We found that the increase in Evans blue dye extravasation evoked by an aerosol of bradykinin (0.1 mM, 2 min) in the presence of phosphoramidon (2.5 mg/kg, i.v.) was abolished completely by FR173657 (20 mg/kg, p.o.) in the trachea and main bronchi. In sensitized guinea pigs pretreated with phosphoramidon, FR173657 (20 mg/kg, p.o.) inhibited plasma extravasation evoked by ovalbumin aerosol (5%, 2 min) by 77+/-14.2% in the trachea and 65+/-11.2% in the main bronchi. FR173657 (20 mg/kg, p.o.) did not affect the plasma extravasation caused by aerosolised capsaicin. These findings suggest that FR173657 is an orally active, promising anti-inflammatory agent for kinin-dependent inflammation following antigen challenge.     

Discovery of a novel, orally active, small molecule gonadotropin-releasing hormone (GnRH) receptor antagonist

Gonadotropin releasing hormone (GnRH) plays an important role in the biology of reproduction. The use of GnRH receptor antagonists has been reported in the literature for the treatment of breast, ovarian, and prostate cancers. In this article, we report the synthesis, in vitro characterization, pharmacokinetics, and pharmacodynamics of an orally bioavailable, potent, small molecule GnRH receptor antagonist N-{4,6-dimethoxy-2-[(3-morpholin-4-ylpropyl)amino]pyrimidin-5-yl}-5-[3,3,6-trimthyl-2,3-dihydro-1H-inden-5-yl)oxy]-2-furamide (compound 1).     

Discovery of orally active nonpeptide bradykinin B2 receptor antagonists

Orally active nonpeptide bradykinin (BK) B2 receptor antagonists have been discovered by using directed random screening and chemical modification. These compounds displaced [3H]BK binding to B2 receptors in guinea-pig ileum membranes, rat uterus membranes and human lung fibroblasts with nanomolar IC50s. They did not inhibit different specific radio-ligand bindings to other receptor sites including B2 receptors. In isolated guinea-pig ileum preparations, these compounds had no agonistic effect on smooth muscle contraction at 10(-6) M, and caused parallel rightward shifts of the concentration-response curves to BK on contraction with higher p A2 values. They also blocked human B2 receptor-mediated phosphatidylinositol hydrolysis without agonistic effect. In vivo, the oral administrations of these antagonists potently inhibited BK-induced bronchoconstriction in guinea-pigs. They also reduced carrageenin-induced paw edema and caerulein-induced pancreatitis in rats. Moreover, these compounds alleviated kaolin-induced pain in mice by oral administration. These results show that our compounds are potent, selective, and orally active BK B2 receptor antagonists and that they may have therapeutic potential against inflammatory diseases and pain.     

Biological effect of orally active platelet-activating factor receptor antagonist SM-10661

SM-10661 [(+/-)-(cis)-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one HCl] displayed marked in vitro inhibition of rabbit platelet aggregation induced by 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (alkyl-PAF), 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (C16-PAF), and 1-O-octadecyl-2-acetyl-sn-glycero-3-phosphocholine, with IC50, values of 5.50, 5.94, and 3.68 microM, respectively. It also inhibited alkyl-PAF-induced aggregation of human platelets with an IC50 of 3.00 microM, but it did not inhibit platelet aggregation induced by ADP, collagen, arachidonic acid, the thromboxane A2 agonist U46619, or the Ca ionophore A23187, at concentrations up to 400 microM. Furthermore, SM-10661 antagonized [3H]-C16-PAF binding to rabbit platelets competitively, with an IC50 of 1.0 microM. SM-10661 protected against alkyl-PAF-induced lethality in mice with an ID50 of 6.0 mg/kg intravenously or 24 mg/kg orally. In guinea pig, SM-10661 inhibited the alkyl-PAF (0.1 micrograms/kg)-induced increase in bronchial pressure, with an ID50 of 0.7 mg/kg intravenously or 15 mg/kg orally. Bronchial hyperreactivity to bombesin after the infusion of alkyl-PAF was also inhibited dose-dependently by the infusion of SM-10661, with an ID50 of 25 mg/kg. In addition, SM-10661 inhibited alkyl-PAF (0.01 micrograms/kg)-induced hypotension in rats, with an ID50 of 0.36 mg/kg intravenously or 33 mg/kg orally. SM-10661, when given orally, showed rapid absorption and good duration of pharmacological activity in rats and rabbits.     

Discovery of a novel, orally active himbacine-based thrombin receptor antagonist (SCH 530348) with potent antiplatelet activity

The discovery of an exceptionally potent series of thrombin receptor (PAR-1) antagonists based on the natural product himbacine is described. Optimization of this series has led to the discovery of 4 (SCH 530348), a potent, oral antiplatelet agent that is currently undergoing Phase-III clinical trials for acute coronary syndrome (unstable angina/non-ST segment elevation myocardial infarction) and secondary prevention of cardiovascular events in high-risk patients.     

Discovery of novel non-peptide CCR1 receptor antagonists

Ligands for the CCR1 receptor (MIP-1alpha and RANTES) have been implicated in a number of chronic inflammatory diseases, most notably multiple sclerosis and rheumatoid arthritis. Because these ligands share a common receptor, CCR1, we sought to discover antagonists for this receptor as an approach to treating these disorders. A novel series of 4-hydroxypiperidines has been discovered by high throughput screening (HTS) which potently inhibits the binding of MIP-1alpha and RANTES to the recombinant human CCR1 chemokine receptor. The structure-activity relationships of various segments of this template are described as the initial HTS lead 1 was optimized synthetically to the highly potent receptor antagonist 6s. This compound has been shown to have at least 200-fold selectivity for inhibition of CCR1 over other human 7-TM receptors, including other chemokine receptors. In addition, data obtained from in vitro functional assays demonstrate the functional antagonism of compound 6s and structurally related analogues against the CCR1 receptor in a concentration dependent manner. The discovery and optimization of potent and selective CCR1 receptor antagonists represented by compound 6s potentially represent a novel approach to the treatment of chronic inflammatory diseases.     

The identification of an orally active,nonpeptide bradykinin B2 receptor antagonist,FR173657

1. An orally active, nonpeptide bradykinin (BK) B₂ receptor antagonist, {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 (E)-3-(6-acetamido-3 - pyridyl) - N - [N - [2 - 4 -dichloro-3-[(2-methyl-8-quinolinyl) oxymethyl]phenyl]-N-methylaminocarbonylmethyl]acrylamide) has been identified.
2. This compound displaced [³H]-BK binding to B₂ receptors present in guinea-pig ileum membranes with an IC₅₀ of 5.6×10⁻¹⁰ M and in rat uterus with an IC₅₀ of 1.5×10⁻⁹ M. It did not inhibit different specific radio-ligand binding to other receptor sites.
3. In human lung fibroblast IMR-90 cells, {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 displaced [³H]-BK binding to B₂ receptors with an IC₅₀ of 2.9×10⁻⁹ M and a K_i of 3.6×10⁻¹⁰ M, but did not reduce [³H]-des-Arg¹⁰-kallidin binding to B₁ receptors.
4. In guinea-pig isolated preparations, {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 antagonized BK-induced contractions with an IC₅₀ of 7.9×10⁻⁹ M, but did not antagonize acetylcholine or histamine-induced contractions even at a concentration of 10⁻⁶ M. {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 caused parallel rightward shifts of the concentration-response curves to BK at concentrations of 10⁻⁹ M and 3.2×10⁻⁹ M, and a little depression of the maximal response in addition to the parallel rightward shift of the concentration-response curve at a concentration of 10⁻⁸ M. Analysis of the data yield a pA₂ of 9.2±0.2 (n=5) and a slope of 1.5±0.2 (n=5).
5. In vivo, the oral administration of {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 inhibited BK-induced bronchoconstriction dose-dependently in guinea-pigs with an ED₅₀ of 0.075 mg kg⁻¹, but did not inhibit histamine-induced bronchoconstriction even at 1 mg kg⁻¹. {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 also inhibited carrageenin-induced paw oedema with an ED₅₀ of 6.8 mg kg⁻¹ 2 h after the carrageenin injection in rats.
6. These results show that {"type":"entrez-nucleotide","attrs":{"text":"FR173657","term_id":"257935500","term_text":"FR173657"}}FR173657 is a potent, selective, and orally active bradykinin B₂ receptor antagonist.

     

Discovery of potent, orally-active, and muscle-selective androgen receptor modulators based on an N-aryl-hydroxybicyclohydantoin scaffold

A novel, N-aryl-bicyclohydantoin selective androgen receptor modulator scaffold was discovered through structure-guided modifications of androgen receptor antagonists. A prototype compound (7R,7aS)-10b from this series is a potent and highly tissue-selective agonist of the androgen receptor. After oral dosing in a rat atrophied levator ani muscle model, (7R,7aS)-10b demonstrated efficacy at restoring levator ani muscle mass to that of intact controls and exhibited >50-fold selectivity for muscle over prostate.     

Discovery of novel A3 adenosine receptor ligands based on chromone scaffold

A project focused on the discovery of new chemical entities (NCEs) as AR ligands that incorporate a benzo-γ-pyrone [(4H)-1-benzopyran-4-one] substructure has been developed. Accordingly, two series of novel chromone carboxamides placed at positions C2 (compounds 2-13) and C3 (compounds 15-26) of the γ-pyrone ring were synthesized using chromone carboxylic acids (compounds 1 or 14) as starting materials. From this study and on the basis of the obtained structure-activity relationships it was concluded that the chromone carboxamide scaffold represent a novel class of AR ligands. The most remarkable chromones were compounds 21 and 26 that present a better affinity for A3AR (Ki = 3680 nM and Ki = 3750 nM, respectively). Receptor-driven molecular modeling studies provide information on the binding/selectivity data of the chromone. The data so far acquired are instrumental for future optimization of chromone carboxamide as a selective A3AR antagonist.     

Discovery of an orally available PAR-1 antagonist as a novel antiplatelet agent

Antiplatelet therapy is a key treatment in atherothrombotic disease and platelet is activated via multiple pathways. Current agents do not interfere with all pathways including the protease-activated receptor-1 (PAR-1) pathway stimulated by thrombin. New antiplatelet agents targeting PAR-1 are aimed to reduce thrombosis ideally without increasing bleeding risk. This article provides a review of the new class of agents, PAR-1 antagonists.     

ATC0175: an orally active melanin-concentrating hormone receptor 1 antagonist for the potential treatment of depression and anxiety

Melanin-concentrating hormone (MCH) has been implicated in a variety of physiological events. Recent studies clearly suggest that MCH plays an important role in the regulation of stress and emotion. To date, two receptor subtypes of MCH (MCH1R and MCH2R) have been identified. MCH1R has been suggested to mediate most of the physiological functions of MCH. Recently, we synthesized an orally active, nonpeptidic antagonist of MCH1R, N-(cis-4-{[4-(dimethylamino)quinazolin-2-yl]amino}cyclohexyl)-3,4-difluorobenzamide hydrochloride (ATC0175). This compound is a potent antagonist with a high affinity for MCH1R and additional affinities for 5-HT1A and 5-HT2B receptors. The receptor binding and the functional assay (MCH-induced increase in [Ca2+]i) indicated that ATC0175 is a noncompetitive antagonist at MCH1Rs. ATC0175 exhibited anxiolytic effects in numerous animal models of anxiety including the elevated plus-maze test, social interaction test, stress-induced hyperthermia and maternal separation-induced vocalization. Like with other stress-related peptide receptor antagonists, such as antagonists of corticotropin-releasing factor or vasopressin V1b receptor antagonists, anxiolytic effects of ATC0175 were more pronounced in models containing a stress component. ATC0175 also exhibited antidepressant effects in the forced swimming test. ATC0175 increased swimming performance without altering climbing behavior, as observed with selective serotonin reuptake inhibitors. ATC0175 has adequate ADME profile (reasonable oral bioavailability and brain penetration) and potent oral activity in animal models. In contrast, ATC0175 did not affect spontaneous locomotor activity, hexobarbital-induced sleeping time and did not impair rotarod performance. Thus, ATC0175 may be devoid of unwanted central nervous system side effects, which are sometimes observed with current medications. In addition, ATC0175 was well tolerated in rat repeated toxicity study, and had no genotoxic liability. Therefore, ATC0175 has the potential to be effective in the treatment of patients with depression and/or anxiety disorders.     

Pharmacological characteristics and clinical application of losartan, an orally active AT1 angiotensin II receptor antagonist]

Losartan is the first orally active angiotensin II receptor type 1 antagonist for a new class of cardiovascular therapeutic agent. Losartan is converted to an active metabolite (E3174) after oral administration in humans and rats. Both losartan and E3174 contribute to the net angiotensin II receptor blockade and produce anti-hypertensive effect. Losartan not only blocks the vasoconstrictive effect of angiotensin II but also inhibits its mitogenic effect; thus losartan is expected to protect against end-organ-damage-related hypertension and chronic heart failure. Unlike angiotensin-coverting-enzyme inhibitor, losartan does not elicit adverse effects of cough and angioneurotic edema by its blockade of angiotensin II receptor. It is also expected to reduce proteinuria in nephropathy. In addition to its blockade of angiotensin II receptor, losartan blocks thromboxane A2 receptor and facilitates excretion of uric acid, although therapeutic importance of these effects are under investigation. In summary, losartan, an angiotensin II type 1 receptor antagonist is a new class of antihypertensive agent and its therapeutic potentials are not merely reduction of blood pressure but total protection from end-organ damage resulting from activation of both the systemic and local renin-angiotensin system.     

T-226296: a novel, orally active and selective melanin-concentrating hormone receptor antagonist

Through the screening of our in-house chemical compound library, we found a novel melanin-concentrating hormone (MCH) receptor antagonist, T-226296, a (-) enantiomer of N-[6-(dimethylamino)-methyl]-5,6,7,8-tetrahydro-2-naphthalenyl]-4'-fluoro[1,1'-biphenyl]-4-carboxamide. T-226296 exhibited high affinity for cloned human and rat MCH receptors (SLC-1) in receptor binding assays (IC50=5.5+/-0.12 nM for human SLC-1; 8.6+/-0.32 nM for rat SLC-1). T-226296 had high selectivity over other receptors, including the second subtype of the MCH receptor, SLT (MCH2), transporters and ion channels. In Chinese hamster ovary (CHO) cells expressing human SLC-1, T-226296 reversed the MCH-mediated inhibition of forskolin-stimulated cAMP accumulation, inhibited MCH-induced intracellular Ca2+ increase, and also inhibited MCH-stimulated arachidonic acid release. In rats, oral administration of T-226296 (30 mg/kg) almost completely suppressed the food intake induced by intracerebroventricular injection of MCH. These results clearly indicate that T-226296 is a novel, orally active and selective MCH receptor antagonist that will be promising for further exploring the physiology and pathophysiology of MCH-SLC-1 signaling.     

In vitro and antinociceptive profile of HON0001, an orally active NMDA receptor NR2B subunit antagonist

The analgesic activity and side effect liabilities of a novel NR2B antagonist, 7-hydroxy-6-methoxy-2-methyl-1-(2-(4-(trifluoromethyl)phenyl)ethyl)-1,2,3,4-tetrahydroisoquinoline hydrochloride (HON0001) were investigated. HON0001 inhibited [3H]MK-801 binding to rat brain membranes in a biphasic manner, with IC50 values of 54.68+/-4.96 nM and 46.48+/-5.85 muM for high- and low-affinity sites, respectively. HON0001 inhibited [3H]ifenprodil binding to membranes of rat cerebral cortex with an IC50 value of 57.01+/-3.4 nM, consistent with the results obtained for high-affinity sites of [3H]MK-801 binding. HON0001 exhibited no or negligible affinity for other receptors, transporters and ion channels, while HON0001 had a moderate agonistic activity at mu-opioid receptors and affinity for dopamine D1 receptors. HON0001 exhibited an analgesic effect in carrageenan-induced mechanical hyperalgesia and in the Seltzer model of partial sciatic nerve ligation following oral administration. In contrast, unlike MK-801, HON0001 did not affect spontaneous locomotor activity, rotarod performance and step-through latency in a passive avoidance task even at doses much higher than antinociceptive doses. HON0001 exhibited excellent brain penetration with a brain-to-plasma ratio of 34.5. These findings show that HON0001 is an orally active NR2B antagonist and that it may be useful for treating patients with neuropathic and other conditions without causing the side effects often observed with currently available non-subtype selective NMDA receptor antagonists.     

Asymmetric synthesis of conformationally constrained fingolimod analogues--discovery of an orally active sphingosine 1-phosphate receptor type-1 agonist and receptor type-3 antagonist

Compound 1 (FTY720, Fingolimod) represents a new generation of immunosuppressant that modulates lymphocyte trafficking by interacting with the S1P(1) receptor. Compound 1 also provides a template molecule for studying the molecular biology of S1P receptors and related enzymes (kinases and phosphatases). In this study, two conformationally constrained analogues of 1 ( 3a and 3c) were asymmetrically synthesized in high optical purity. In vitro assessment documented that both analogues are Sphk2 substrates, their phosphorylated species are potent S1P(1) receptor agonists, and 3a-P is a potent S1P 3 antagonist. After oral administration in mice, both compounds evoked lymphopenia, but their duration of action differed markedly.