Effects of selective inhibitors of cyclo-oxygenase-1 (COX-1) and cyclo-oxygenase-2 (COX-2) on the spontaneous myogenic contractions in the upper urinary tract of the guinea-pig and rat

The role of cyclo-oxygenase-1 (COX-1) and cyclo-oxygenase-2 (COX-2) in the upper urinary tract of the guinea-pig and rat was examined using simultaneous tension recordings of the proximal and distal regions of the renal pelvis and the ureter. The guinea-pig upper urinary tract contracted at a frequency (7.52+/-0.3 min(-1) at 35 degrees C) significantly lower than the frequency in the proximal renal pelvis (21.6+/-1.3 min(-1)) and in the distal renal pelvis and ureter (20.2+/-1.4 min(-1)) of the rat (at 30 degrees C). Indomethacin (>/=1 microM for 60 min), decreased the motility index (amplitudexfrequency) (MI) in all three regions of the guinea-pig upper urinary tract, an effect which mainly arose from a decrease in the frequency of contractions. In the rat, indomethacin (1 - 30 microM for 60 min) significantly decreased the MI calculated in the proximal renal pelvis (>/=30 microM indomethacin), and in the distal renal pelvis (>/=10 microM indomethacin), arising from a significant decrease in the amplitude of contractions. The COX-1 inhibitor, valeryl salicylate (VSA) (5 - 100 microM for 60 min), had no effect on either the amplitude or frequency of contractions in the guinea-pig upper urinary tract. In contrast, VSA increased the force of contractions in the proximal and distal renal pelvis of the rat, whilst having little effect on the frequency of contractions. The COX-2 inhibitor, NS-398 (10 - 100 nM for 60 min) reduced the MI in the guinea-pig upper urinary tract in a concentration-dependent manner. The MIs calculated for the proximal renal pelvis, distal renal pelvis and ureter, were decreased by 72, 64 and 72% respectively, in 100 nM NS-398. NS-398 (10 - 100 nM) had no effect on any of the three parameters measured in either the proximal or distal renal pelvis of the rat. These data suggest that endogenously-released prostaglandins (PGs) maintain the myogenic contractility of the upper urinary tract in both the guinea-pig and rat. Moreover COX-2 is the primary enzyme involved in synthesizing PGs in the guinea-pig upper urinary tract, while COX-1 appears to be the predominantly active enzyme in the rat.     

Three-dimensional quantitative structure-activity relationships of cyclo-oxygenase-2 (COX-2) inhibitors: a comparative molecular field analysis

The three-dimensional quantitative structure-activity relationship (3D-QSAR) approach using comparative molecular field analysis (CoMFA) was applied to an extensive series of 305 varied diarylheterocyclic derivatives known as COX-2 selective inhibitors. X-ray crystal structure of COX-2 bound with SC-558, a selective COX-2 inhibitor, was used to derive the putative bioactive conformation of these inhibitors. Five statistically significant models were obtained from the randomly constituted training sets (229 compounds) and subsequently validated with the corresponding test sets (76 compounds). The best predictive model (n = 229, q(2) = 0.714, N = 8, r(2) = 0.905, s = 0.291, F = 261.545) was selected for further comparison of the CoMFA contour maps obtained for steric, electrostatic, and lipophilic fields with the enzyme structure. The high level of compatibility with the COX-2 enzyme topology shows the great accuracy of this model that can predict inhibitory activities for a wide range of compounds and offers important structural insight into designing novel antiinflammatory drugs prior to their synthesis.     

Synthesis and biological evaluation of N-substituted indole esters as inhibitors of cyclo-oxygenase-2 (COX-2)

A series of novel N-substituted indole carboxylic, acetic and propionic acid esters have been prepared as possible cyclo-oxygenase-2 (COX-2) enzyme inhibitors. Compounds 20, 23 were found slightly active against COX-2. The synthesis of indole carboxylic, acetic and propionic acid esters were furnished by using dicyclohexyl carbodiimide (DCC), dimethylamino pyridine (DMAP) as carboxylate activators. N-substitution of indole esters was verified with several benzyl and benzoyl group in presence of NaH in DMF, respectively.     

Selective cyclooxygenase-2 (COX-2) inhibitors and potential risk of cardiovascular events

Selective cyclooxygenase-2 (COX-2) inhibitors were developed as a response to the gastrointestinal toxicity of conventional nonsteroidal anti-inflammatory agents (NSAIDs). However, COX-2 inhibitors decrease vascular prostacyclin (PGI(2)) production and may disrupt the homeostatic mechanisms that limit the effects of platelet activation. Basic and clinical data raise concerns about a potential prothrombotic effect of this class of drugs. The widespread popularity of these agents mandates their prospective evaluation in patients with cardiovascular diseases or who are at risk for cardiovascular events.     

Selective cyclooxygenase-2 (COX-2) inhibitors reduce anti-Mycobacterium antibodies in adjuvant arthritic rats

Adjuvant arthritis, induced by Mycobacterium butyricum, is an experimental immunopathy that shares many features of human rheumatoid arthritis and, as such, is one of the most widely used models for studying the anti-inflammatory activity of compounds. In rats with adjuvant induced arthritis, IgG antibodies to M. butyricum have been detected and autoantigens that cross react with mycobacteria may be involved in the pathogenesis of adjuvant arthritis. In this study, the anti-inflammatory and immunosuppressive activities of two cyclooxygenase-2 selective inhibitors, flosulide and L-745,337, at doses of 0.1, 1 and 5 mg/kg/day, were examined in adjuvant arthritic rats. After 14 days of treatment, a clear dose-dependent inhibition of plantar edema was seen for both flosulide (ID50 lower than 0.1 mg/kg) and L-745,337 (ID50 = 0.4 mg/kg). Plasma levels of IgG anti-M. butyricum antibodies were also decreased by both drugs. In each case the maximal immunosuppressive effect was observed at doses lower than 5 mg/kg. The non-selective COX-2 inhibitor, indomethacin (1 mg/kg) decreased paw edema by 65% and the levels of IgG anti-M. butyricum by 45%. Neither cyclooxygenase selective inhibitors nor indomethacin decreased the delayed hypersensitivity reaction induced by M. butyricum. Thus, in vivo inhibition of COX-2 inhibited articular swelling and also the humoral immune response to Mycobacterium.     

Selective COX-2 inhibitors as anticancer agents: a patent review (2014-2018)

Introduction: COX-2 is a key enzyme in the process of prostaglandins (PGs) synthesis. The products of this enzyme could play a major role as the mediators of the inflammatory response and some other medical states such as cancer. The design and synthesis of novel selective COX-2 inhibitors have always been attractive to researchers. This review discusses the structures of novel COX-2 inhibitors synthesized during the last five years and describes their efficacy as anticancer agents.

Areas covered: It is well established that COX-2 is overexpressed in many different cancers and treatment with selective COX-2 inhibitors could relieve their symptoms and limit their adverse sequences.

Expert opinion: The diversity of selective COX-2 inhibitors is mainly related to the types of scaffolds. Monocyclic, bicyclic, tricyclic, and acyclic scaffolds with different pharmacological effects and toxicological profiles could be found in the family of selective COX-2 inhibitors. The great interest of the researchers in this field is due to the importance of selective COX-2 inhibitors as a relatively safe and effective set of compounds which could present different properties such as antirheumatic, anti-inflammatory, antiplatelet, anti-Alzheimer’s disease, anti-Parkinson’s disease, and anticancer.     

Selective COX-2 inhibitors as chemopreventive and therapeutic agents

Selective cyclooxygenase-2 (COX-2) inhibitors have received increasing attention for their role in the prevention and treatment of cancer. Considerable preclinical data support this use. Furthermore, clinical studies have shown that this enzyme is upregulated in a variety of premalignant and malignant states and that its inhibition can decrease colon polyp formation in patients with familial adenomatous polyposis. A number of studies are now investigating the use of COX-2 inhibitors to prevent or treat a number of different cancers. These ongoing trials will determine whether these agents are useful in the treatment of cancer.     

Selective COX-2 inhibitors and human inflammatory bowel disease

BACKGROUND: Much recent effort has been made to produce selective inhibitors of cyclo-oxygenase-2 (COX-2) in the belief that these will lack the gastrointestinal damaging effects of traditional non-steroidal anti-inflammatory drugs (NSAIDs). Inflammatory bowel disease is associated with increased local production of prostanoids. These prostanoids, particularly PGE2 and PGI2, may well be protective as inflammatory bowel disease is aggravated by NSAID use. AIM: To examine the effects of a traditional NSAID and a highly selective COX-2 inhibitor on the production of these prostanoids in human inflammatory bowel disease. METHODS: Colonic mucosal biopsies were obtained from patients undergoing routine colonoscopy and biopsy for diagnostic or surveillance purposes. Biopsies were incubated in culture medium containing 10% foetal calf serum and antibiotics, plus test drugs or vehicle for 24 h, after which time the medium was removed and the content of PGE2, PGI2 (measured as 6 keto-PGF1alpha) and thromboxane (Tx) A2 (measured as TxB2) determined. RESULTS: Biopsies obtained from diseased colonic mucosa produced significantly more PGE2, PGI2 and thromboxane A2 than did controls (for example, PGE2: ulcerative colitis, 4.17+/-1.06; Crohn's disease, 3.97+/-1.66; control, 0.12 +/-0.13 ng/mL, n = 8-12). These increases were inhibited to a similar extent by either a highly selective COX-2 inhibitor (L-745,337) or a traditional non-selective NSAID (indomethacin). CONCLUSIONS: Until selective COX-2 inhibitors have been assessed adequately in human inflammatory bowel disease, these compounds should not be assumed to be safe for the gastrointestinal tract in inflammatory bowel disease.     

Cyclooxygenase (COX)-2 selective inhibitors: aspirin, a dual COX-1/COX-2 inhibitor, to COX-2 selective inhibitors

Aspirin was developed as a non-steroidal anti-inflammatory drug (NSAID) in 1899. During the century after that, aspirin has been found to show its anti-inflammatory, analgesic and anti-pyretic activities by reducing prostaglandins biosynthesis through inhibition of cyclooxygenase (COX); and then COX was found to be constituted of two isoforms, constitutive COX-1 and inducible COX-2. Currently, novel NSAIDs, acting through selective inhibition of COX-2, that have efficacy as excellent as aspirin with significantly lower incidence of gastrointestinal adverse effects are available in America and some other countries, but not in Japan. Physiological and pathophysiological roles of COX-1 and COX-2 have been explained from studies in experimental animals, but there are many differences in species and diseases between animals and humans. Thus, physiological and pathophysiological roles of COX-2 were considered from the standpoint of clinical effects of the two latest COX-2 selective inhibitors, celecoxib and rofecoxib, on inflammation, pain, fever and colorectal cancer together with their adverse effects on gastrointestinal, renal and platelet functions; and the usefulness and limits of COX-2-selective inhibitors were discussed with the trends of new NSAIDs development.     

The mRNA expression of cyclo-oxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) in human breast cancer

AIMS: There is a growing body of evidence that cyclo-oxygenase 2 (COX-2) plays an important role in carcinogenesis and angiogenesis of human tumours. The present study aims to compare COX-2 expression in human breast cancer and adjacent non-cancerous tissue (ANCT), and to identify any correlation between COX-2 and VEGF expression. METHODS: Total cellular RNA was extracted from frozen breast tissue samples according to standard methodology. The mRNA copy numbers for COX-2 and vascular endothelial growth factor 189 (VEGF-189) were determined 40 infiltrating carcinomas and 40 matched ANCT specimens using quantitative RT-PCR and TaqMan methodology. RESULTS: The COX-2 mRNA copy number per microg of RNA was two-fold higher in ANCT compared with the cancerous tissue (p = 0.01). Median mRNA copy number was 5.44 x 10(6) for ANCT and 2.30 x 10(6) for tumour, (ANCT range: 1 x 10(6) to 4.12x 10(7)) (tumour range: 1.29 x 10(5) to 1.07 x 10(7)). There was a significant correlation between COX-2 and VEGF-189 mRNA copy numbers in the cancer specimens (correlation coefficient = 0.5528, p = 0.0076). CONCLUSIONS: COX-2 mRNA is overexpressed in both human breast cancer and ANCT. We found higher levels in the matched ANCT which suggests that paracrine effects may be important in the role of COX-2 in mammary carcinogenesis. Furthermore, our results indicate that in human breast cancers COX-2 overexpression is linked to VEGF-189 overexpression and therefore tumour angiogenesis.     

选择性环氧合酶-2抑制剂体外筛选模型的建立

目的:建立选择性环氧合酶-2(COX-2)抑制剂筛选模型。方法:以脂多糖(LPS)为刺激剂刺激大鼠腹腔巨噬细胞产生前列腺素E2(PGE2),采用放免法确定最佳刺激浓度和时间,以选择性COX-2抑制剂戊地昔布和达布非隆(darbufelone)为阳性对照药验证实验模型。结果:达布非隆和戊地昔布对COX-2和COX-1的半数抑制浓度(IC50)的比值分别为3．175×10-4和3．576×10-3。结论:本实验建立的COX-2抑制剂筛选模型比较灵敏,可靠,可用于选择性COX-2抑制剂的筛选。     

Anti-exudative effects of opioid receptor agonists in a rat model of carrageenan-induced acute inflammation of the paw

We evaluated the anti-exudative effects (Evan's blue) of mu-, delta- and kappa-opioid receptor agonists in a rat model of carrageenan-induced acute inflammation. The contribution of different components was assessed after the administration of: cyclosporine A, capsaicin, 6-hydroxydopamine, compound 48/80, and specific histamine-receptor antagonists. The results show that the mu-opioid receptor agonists morphine and fentanyl and the delta-opioid receptor agonists DPDPE (enkephalin, [D-Pen(2,5)]) and SNC 80 ((+)-4-[(alpha R)-alpha((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N diethylbenzamide) decrease plasma extravasation in a dose-dependent manner, with a biphasic response. The effects were reversed by specific antagonists, and are predominantly mediated by peripheral opioid receptors. The integrity of sensory and sympathetic fibres is essential for the anti-exudative effects of fentanyl and DPDPE. Histamine and functional histamine H(2) and H(3) receptors are required for morphine and fentanyl (but not DPDPE) inhibition of plasma extravasation, suggesting different mechanism for mu- and delta-opioid receptor agonists. The present findings implicate multiple sites and mechanisms in the anti-exudative effects of exogenous opioids.     

选择性环氧化酶2抑制剂的不良反应

选择性环氧化酶2(COX-2)抑制剂是治疗类风湿关节炎和骨关节炎的一类新型非甾体抗炎药(NSAIDs)。选择性COX-2抑制剂分为倾向性COX-2抑制剂(美洛昔康、尼美舒利和双氯芬酸等)和特异性COX-2抑制剂(塞来昔布、罗非昔布、伐地考昔、依托考昔等),前者对COX-2的抑制作用明显大于对COX-1的抑制作用,但在抑制COX-2的同时也会部分抑制COX-1,后者仅对COX-2有强烈抑制作用。选择性COX-2抑制剂的主要不良反应为消化道溃疡、穿孔或出血,肾功能损伤,凝血功能障碍,以及血栓形成等。其机制与选择性COX-2抑制剂能同时抑制COX-1和COX-2,减弱其对消化道黏膜的保护作用、使肾小球滤过率下降而加重钠钾潴留、抑制细胞色素P4502C9酶活性而降低华法林代谢率以及影响血栓素A2和前列腺素I2的平衡等有关。同时服用选择性COX-2抑制剂与质子泵抑制剂可降低消化道不良反应的发生率;高血压病患者或有水钠潴留倾向者服用选择性COX-2抑制剂时,应定期监测血药浓度及肾功能,调整降压药剂量,避免多种NSAIDs同时应用;选择性COX-2抑制剂与小剂量阿司匹林联合应用可防治心血管不良反应。一旦出现不良反应,应立即停药并对症治疗。     

Do selective cyclo-oxygenase-2 inhibitors have a future?

The dramatic withdrawal of rofecoxib on 30 September 2004, along with safety concerns about other cyclo-oxygenase (COX)-2 inhibitors (especially valdecoxib), raises important issues for clinicians, pharmaceutical companies and regulatory authorities. Some of these are examined in this article, including: (i) was the cardiotoxicity of rofecoxib evident long before its withdrawal?; (ii) is the thrombotic hazard a class effect that is applicable to all COX-2 inhibitors?; (iii) may conventional NSAIDs also confer a risk of cardiovascular thrombosis?; and (iv) is there any future for selective COX-2 inhibitors?     

Glycosylation of human cyclooxygenase-2 (COX-2) decreases the efficacy of certain COX-2 inhibitors

Prostanoids play an important role in a variety of physiological and pathophysiological processes including inflammation and cancer. The rate-limiting step in the prostanoid biosynthesis pathway is catalyzed by cyclooxygenase-2 (COX-2). COX-2 exists as two glycoforms, 72 and 74 kDa, the latter resulting from an additional glycosylation at Asn(580). In this study, Asn(580) was mutated, and the mutant and wild-type COX-2 genes were expressed in COS-1 cells to determine how glycosylation affects the inhibition of COX-2 activity by aspirin, flurbiprofen, ibuprofen, celecoxib, and etoricoxib. Results indicate that certain inhibitors were 2-5 times more effective at inhibiting COX-2 activity when the glycosylation site was eliminated, indicating that glycosylation of COX-2 at Asn(580) decreases the efficacy of some inhibitors.     

Selective cyclo-oxygenase-2 inhibitors and myocardial infarction: how strong is the link?

There are concerns that selective cyclo-oxygenase (COX)-2 inhibitors may be prothrombotic and increase the risk of myocardial infarction. This has largely arisen because of an unexpected finding of a higher rate of myocardial infarction in patients receiving rofecoxib compared with patients receiving naproxen in a study of gastrointestinal toxicity. The results of this study, a similar study of celecoxib versus ibuprofen or diclofenac, and data obtained from a meta-analysis of aspirin (acetylsalicylic acid) primary prevention trials suggest that differences in the rates of myocardial infarction between rofecoxib and naproxen may have been due to an unexpectedly low rate of myocardial infarction in patients receiving naproxen. However, population surveillance data also suggest that rofecoxib may be associated with a greater risk of myocardial infarction than celecoxib and certain nonselective nonsteroidal anti-inflammatory drugs. The magnitude of this increase in risk, if real, is uncertain but it is likely to be relatively small in patients for whom cardiovascular prophylaxis with aspirin is not indicated. Patients who require nonsteroidal anti-inflammatory therapy for arthritis and who are at high risk of cardiovascular disease should receive aspirin, probably in conjunction with selective COX-2 inhibitor therapy, as the risk of gastrointestinal ulceration may be lower than for aspirin plus a nonselective nonsteroidal anti-inflammatory drug. In patients who do not require aspirin for the prevention of cardiovascular events, the lower risk of gastrointestinal ulceration associated with COX-2 inhibitor compared with non-selective nonsteroidal anti-inflammatory drugs would be expected to outweigh any increase in the risk of myocardial infarction, if one exists.     

Selective inhibition of human cyclo-oxygenase-2 by meloxicam

Human cyclo-oxygenase-1 (hCOX-1) and-2 were expressed in stable transfected COS A.2 cells and in insect cells using a Sf9 baculovirus expression system. Inhibition of COX activity was examined using both whole cell and microsomal assays. Ibuprofen, naproxen, 6-MNA, diclofenac and indomethacin were selective for hCOX-1 or were equipotent inhibitors for COX-1 and COX-2. Piroxicam was equally inhibitory for both enzymes in the whole cell assay while it preferentially inhibited hCOX-2 in the microsomal assay. However, maximal inhibition of hCOX-2 by piroxica plateaued at 60%. Nimesulide was equipotent in the whole-cell assay but was five-fold selective for hCOX-2 in the microsomal assay. Meloxicam preferentially inhibited hCOX-2 in the whole cell assay at concentrations of 0.01 to 1 μmol/L but was an equipotent inhibitor of both enzymes at higher concentrations. In the microsomal assay, meloxicam exhibited high selectivity for hCOX-2 (75-fold). The preferential inhibition of hCOX-2 by meloxicam may explain the favourable gastrointestinal profile observed for meloxicam compared with other NSAIDs.     

A sensitive and relevant model for evaluating anti-inflammatory activity-papaya latex-induced rat paw inflammation.

A new model employing latex of papaya as an inflammagen has been developed for testing anti-inflammatory activity. The latex (exudate) was harvested from the unripe papaya fruit, which had been dried under vacuum. The latex was then suspended in 0.05 M sodium acetate buffer. This suspension when injected in rat hind paw produced concentration-dependent inflammation. Of the 0.25% of this suspension, 0.1 ml was found ideal for evaluating anti-inflammatory activity of test drugs. This concentration produced 70%-100% inflammation lasting for about 5 hr with a maximum effect at h 3. The test drugs employed were prednisolone, aspirin, indomethacin, phenylbutazone, ibuprofen, piroxicam, chloroquine, levamisole, and a mixture of boswellic acids. For comparison, these drugs were also tested against carrageenan-induced inflammation. All the test drugs--steroidal, aspirin, and non-aspirin-like--showed anti-inflammatory activity against latex-induced inflammation. The activity of chloroquine, levamisole, and boswellic acids was significantly more against latex as compared with that of the carrageenan model. The inflammation caused by latex may be attributed to both its hydrolytic enzymes--papain and chymopapain--and glutathione, the activator of these enzymes. These enzymes seem to act like lysosomal enzymes that are released in inflammatory disease processes which mediate inflammation by stimulating the synthesis of prostaglandins. The papaya latex-induced inflammation model appears to be a sensitive, broad-based, and relevant one likely to prove useful for discovering new and effective drugs against inflammation and rheumatoid arthritis.     

(Methylsulfonyl)phenyl-2-(5H)-furanones as COX-2 inhibitors

This patent describes synthesis and biological evaluation of a large number of cyclooxygenase-2 (COX-2) selective diarylfuranone inhibitors useful for the treatment of inflammatory diseases. A number of the specific analogues possess considerable anti-inflammatory activity in vivo.