Design, synthesis and structure-activity relationship studies of novel and diverse cyclooxygenase-2 inhibitors as anti-inflammatory drugs.

Because of the pivotal role of cyclooxygenase (COX) in the inflammatory processes, non-steroidal anti-inflammatory drugs (NSAIDs) that suppress COX activities have been used clinically for the treatment of inflammatory diseases/syndromes; however, traditional NSAIDs exhibit serious side-effects such as gastrointestinal damage and hyper sensitivity owing to their COX-1 inhibition. Also, COX-2 inhibition-derived suppressive or preventive effects against initiation/proliferation/invasion/motility/recurrence/metastasis of various cancers/tumours such as colon, gastric, skin, lung, liver, pancreas, breast, prostate, cervical and ovarian cancers are significant. In this study, design, synthesis and structure-activity relationship (SAR) of various novel {2-[(2-, 3- and/or 4-substituted)-benzoyl, (bicyclic heterocycloalkanophenyl)carbonyl or cycloalkanecarbonyl]-(5- or 6-substituted)-1H-indol-3-yl}acetic acid analogues were investigated to seek and identify various chemotypes of potent and selective COX-2 inhibitors for the treatment of inflammatory diseases, resulting in the discovery of orally potent agents in the peripheral-inflammation model rats. The SARs and physicochemical properties for the analogues are described as significant findings. For graphical abstract: see Supplementary Material. ( www.informahealthcare.com/enz ).

Novel acid-type cyclooxygenase-2 inhibitors: Design, synthesis, and structure-activity relationship for anti-inflammatory drug.

Cyclooxygenase (COX) is a key rate-limiting enzyme for prostaglandin (PG) production cascades in the human body. The mechanisms of both the anti-inflammation effects and the side-effects of traditional COX inhibitors are associated with the existence of two COX isoforms. Thus while COX-1 is predominantly expressed ubiquitously and constitutively, and it serves a housekeeping role in processes such as gastrointestinal (GI) mucosa protection, COX-2 is absent or exhibits a low level of expression in most tissues, and is highly upregulated in response to endotoxin, virus, inflammatory or tissue-injury stimuli/signals, and tumour promoter in the various types of organs, tissues, and cells. Furthermore, COX-2 contribution to PGE(2) and PGI(2) production evokes and sustains systemic or peripheral inflammatory disease, but it is not involved in the COX-1-mediated GI tract events. Also, hypersensitivity of aspirin owing to its inhibitory action against COX-1 is a significant concern clinically. Consequently, highly selective COX-2 inhibitors have been needed for the treatment of inflammatory- and inflammation related-diseases that include pyrexia, inflammation, pain, rheumatoid arthritis, osteoarthritis, and cancers. In this study, a series of novel [2-{[(4-substituted or 4,5-disubstituted)-pyridin-2-yl]carbonyl}-(5- or 6-substituted or 5,6-disubstituted)-1H-indol-3-yl]acetic acid analogues was designed, synthesized, and evaluated to identify potent and selective COX-2 inhibitors as potential agents against inflammatory diseases. As significant findings, the present study clarified unique structure-activity relationship of the analogues toward potent and selective COX-2 inhibition in vitro, and identified 2-{6-fluoro-2-[4-methyl-2-pridinyl)carbonyl]-1H-indol-3-yl}acetic acid as a potent and selective COX-2 inhibitor in vitro that demonstrated orally potent anti-inflammation efficacy against carrageenan-induced oedema formation in the foot of SPF/VAF male SD rats as a peripheral inflammation model in vivo.

Discovery of a novel COX-2 inhibitor as an orally potent anti-pyretic and anti-inflammatory drug: design, synthesis, and structure-activity relationship.

Cyclooxygenase (COX) has been considered as a significant pharmacological target because of its pivotal roles in the prostaglandin biosynthesis and following cascades that lead to various (patho)physiological effects. Non-steroidal anti-inflammatory drugs (NSAIDs) that suppress COX activities have been used clinically for the treatment of fever, inflammation, and pain; however, nonselective COX inhibitors exhibit serious side-effects such as gastrointestinal damage because of their inhibitory activities against COX-1. Thus, COX-1 is constitutive and expressed ubiquitously and serves a housekeeping role, while COX-2 is inducible or upregulated by inflammatory/injury stimuli such as interleukin-1ß, tumor necrosis factor-α, and lipopolysaccharide in macrophage, monocyte, synovial, liver, and lung, and is associated with prostaglandin E2 and prostacyclin production that evokes or sustains systemic/peripheral inflammatory symptoms. Also, hypersensitivity of aspirin is a significant concern clinically. Hence, design, synthesis, and structure-activity relationship of [2-{[(4-substituted)-pyridin-2-yl]carbonyl}-(6- or 5-substituted)-1H-indol-3-yl]acetic acid analogues were investigated to discover novel acid-type COX-2 inhibitor as an orally potent new-class anti-pyretic and anti-inflammatory drug. As significant findings, compounds 1-3 demonstrated potent COX-2 inhibitory activities with high selectivities for COX-2 over COX-1 in human cells or whole-blood in vitro, and demonstrated orally potent anti-pyretic activity against lipopolysaccharide-induced systemic-inflammatory fever model in F344 rats. Also compound 1 demonstrated orally potent anti-inflammatory activity against edema formation and a suppressive effect against PGE2 production in carrageenan-induced peripheral-inflammation model on the paw of SD rats. These results suggest that compounds 1-3 are potential agents for the treatment of inflammatory disease and are useful for further pharmacological COX-2 inhibitor investigations.

Effects of the selective EP4 antagonist, CJ-023,423 on chronic inflammation and bone destruction in rat adjuvant-induced arthritis.

Prostaglandin E2 (PGE2) produced by cyclooxygenase (COX) is a potent pro-inflammatory mediator. We have recently discovered CJ-023,423, a highly selective antagonist of EP4 receptors, one of the PGE2 receptors. This agent is suitable for exploring the effects of blocking EP4 receptors following oral administration in rats. In this study, CJ-023,423 was used in rats with adjuvant-induced arthritis (AIA) to investigate the role of the EP4 receptor in chronic inflammation and bone destruction. These effects were compared with those of rofecoxib, a selective COX-2 inhibitor. CJ-023,423 had significant inhibitory effects on paw swelling, inflammatory biomarkers, synovial inflammation and bone destruction in AIA rats. In particular, the inhibitory effect on paw swelling in AIA rats was comparable to that of rofecoxib. These results suggest that PGE2 acting via the EP4 receptor is involved in the development of chronic inflammation and bone destruction, particularly with respect to oedema in AIA rats. This is the first study to confirm the in-vivo effects of EP4 receptor blockade on inflammation and bone destruction in AIA rats with a small-molecule compound.

Characterization of binding affinity of CJ-023,423 for human prostanoid EP4 receptor.

In order to characterize the receptor binding pharmacology of CJ-023,423, a potent and selective EP4 antagonist, we performed a radioligand receptor binding assay under various assay conditions. An acidic (pH 6) and hypotonic buffer is a conventional, well-known buffer for prostaglandin E2 receptor binding assays. CJ-023,423 showed moderate binding affinity for human EP4 receptor under conventional buffer conditions. However, its binding affinity was greatly increased under neutral (pH 7.4) and isotonic buffer conditions. In this report, the binding mechanism between CJ-023,423 and human EP4 receptor is discussed based on the binding affinities determined under various assay conditions.

In vitro pharmacological characterization of CJ-042794, a novel, potent, and selective prostaglandin EP(4) receptor antagonist.

Activation of the prostaglandin E(2) (PGE(2)) EP(4) receptor, a G-protein-coupled receptor (GPCR), results in increases in intracellular cyclic AMP (cAMP) levels via stimulation of adenylate cyclase. Here we describe the in vitro pharmacological characterization of a novel EP(4) receptor antagonist, CJ-042794 (4-{(1S)-1-[({5-chloro-2-[(4-fluorophenyl)oxy]phenyl}carbonyl)amino]ethyl}benzoic acid). CJ-042794 inhibited [(3)H]-PGE(2) binding to the human EP(4) receptor with a mean pK(i) of 8.5, a binding affinity that was at least 200-fold more selective for the human EP(4) receptor than other human EP receptor subtypes (EP(1), EP(2), and EP(3)). CJ-042794 did not exhibit any remarkable binding to 65 additional proteins, including GPCRs, enzymes, and ion channels, suggesting that CJ-042794 is highly selective for the EP(4) receptor. CJ-042794 competitively inhibited PGE(2)-evoked elevations of intracellular cAMP levels in HEK293 cells overexpressing human EP(4) receptor with a mean pA(2) value of 8.6. PGE(2) inhibited the lipopolysaccharide (LPS)-induced production of tumor necrosis factor alpha (TNFalpha) in human whole blood (HWB); CJ-042794 reversed the inhibitory effects of PGE(2) on LPS-induced TNFalpha production in a concentration-dependent manner. These results suggest that CJ-042794, a novel, potent, and selective EP(4) receptor antagonist, has excellent pharmacological properties that make it a useful tool for exploring the physiological role of EP(4) receptors.

Effect of prostanoid EP4 receptor antagonist, CJ-042,794, in rat models of pain and inflammation.

Recent study suggests that the proinflammatory and nociceptive effects of prostaglandin E(2) are mediated by prostanoid receptor subtype EP(4) and prostanoid EP(4) receptor may be a potential target for the treatment of inflammatory pain. Here we describe pharmacological characterization of a novel prostanoid EP(4) receptor antagonist, CJ-042,794 (4-{(1S)-1-[({5-chloro-2-[(4-fluorophenyl) oxy] phenyl} carbonyl) amino] ethyl} benzoic acid) in comparison with piroxicam (non-steroidal anti-inflammatory drug) or rofecoxib (cyclooxygenase-2 inhibitor). CJ-042,794 competitively antagonized cAMP accumulation with a pA(2) value of 8.7 in HEK293 cells overexpressing rat prostanoid EP(4) receptors. Orally administered CJ-042,794 dose-dependently inhibited carrageenan-induced mechanical hyperalgesia with an ED(50) value of 4.7 mg/kg (11 micromol/kg) and its maximal activity was somewhat less effective than that of 10 mg/kg piroxicam (30 micromol/kg p.o.). When CJ-042,794 and rofecoxib were administered to adjuvant-induced arthritis rats on Days 12-22 twice daily, both compounds reversed paw swelling to normal levels. These results suggest that a pharmacological blockade of the prostanoid EP(4) receptor may represent a new therapeutic strategy in signs and symptomatic relief of osteoarthritis and/or rheumatoid arthritis.

CJ-023,423, a novel, potent and selective prostaglandin EP4 receptor antagonist with antihyperalgesic properties.

The prostaglandin (PG) EP(4) receptor subtype is expressed by peripheral sensory neurons. Although a potential role of EP(4) receptor in pain has been suggested, a limited number of selective ligands have made it difficult to explore the physiological functions of EP(4) or its potential as a new analgesic target. Here, we describe the in vitro and in vivo pharmacology of a novel EP(4) receptor antagonist, N-[({2-[4-(2-ethyl-4,6-dimethyl-1H-imidazo [4,5-c] pyridin-1-yl) phenyl]ethyl}amino) carbonyl]-4-methylbenzenesulfonamide (CJ-023,423). In vitro, CJ-023,423 inhibits [(3)H]PGE(2) binding to both human and rat EP(4) receptors with K(i) of 13 +/- 4 and 20 +/- 1 nM, respectively. CJ-023,423 is highly selective for the human EP(4) receptor over other human prostanoid receptor subtypes. It also inhibits PGE(2)-evoked elevation in intracellular cAMP at the human and rat EP(4) receptors with pA(2) of 8.3 +/- 0.03 and 8.2 +/- 0.2 nM, respectively. In vivo, oral administration of CJ-023,423 significantly reduces thermal hyperalgesia induced by intraplantar injection of PGE(2) (ED(50) = 12.8 mg/kg). CJ-023,423 is also effective in models of acute and chronic inflammatory pain. CJ-023,423 significantly reduces mechanical hyperalgesia in the carrageenan model. Furthermore, CJ-023,423 significantly reverses complete Freund's adjuvant-induced chronic inflammatory pain response. Taken together, the present data indicate that CJ-023,423, a highly potent and selective antagonist of both human and rat EP(4) receptors, produces antihyperalgesic effects in animal models of inflammatory pain. Thus, specific blockade of the EP(4) receptor signaling may represent a novel therapeutic approach for the treatment of inflammatory pain.

Pharmacological separation between peripheral and central functions of cyclooxygenase-2 with CIAA, a novel cyclooxygenase-2 inhibitor.

There are many reports concerning the physiological and pathological involvement of cyclooxygenase (COX)-2 in the central nervous system and peripheral tissue cells. Selective COX-2 inhibitors that mainly distribute peripherally have not been reported thus far. Therefore central and peripheral roles of COX-2 remain classified pharmacologically. In this study, in vivo pharmacological profiles of CIAA ([6-chloro-2-(4-chlorobenzoyl)-1H-indol-3-yl]acetic acid), a novel selective COX-2 inhibitor which distributes at higher concentrations in plasma than in brain, were compared with those of well-known selective COX-2 inhibitors, celecoxib and rofecoxib. Additionally, the possibility of pharmacological separation between peripheral and central actions of COX-2 with the inhibitors was investigated. CIAA selectively inhibited COX-2 activity compared with COX-1 in in vitro assays with rat whole blood. The compound exhibited lower brain penetration and higher plasma concentration (the brain/plasma concentration ratio was approximately 0.02) than celecoxib and rofecoxib after oral administration. Therefore, CIAA is mainly expected to act peripherally. Edema and prostaglandin E2 (PGE2) production in Carrageenan-injected rat paws, and pyrexia and PGE2 production in the brain in lipopolysaccharide (LPS)-injected rats were measured in in vivo experiments. CIAA exhibited lower ratios of anti-pyretic/anti-edematous activities and of inhibitory activities of PGE2 production in brain/paw than those of celecoxib and rofecoxib, and these ratios well-reflected brain/plasma concentration ratios. In conclusion, we discovered a novel selective COX-2 inhibitor, CIAA, which distributes at higher concentrations in plasma than in brain, which would make possible the pharmacological separation of the peripheral and central functions of COX-2.