N-(3-Arylaminopyridin-4-yl)alkanesulfonamides as pyridine analogs of nimesulide: cyclooxygenases inhibition, anti-inflammatory studies and insight on metabolism.

Nimesulide, a COX-2 preferential inhibitor with a favorable gastric and cardiovascular safety profile, was responsible for some cases of acute liver failure attributed to the nitrobenzene ring. A series of analogs of nimesulide resulting from isosteric replacement of the nitrobenzene ring by the pyridine nucleus, was synthesized and their ability to inhibit both cyclooxygenases (COXs) isoforms was evaluated in vitro using a human whole blood model. Compounds 19c, 23b and 23c displayed an important inhibitory activity associated to a COX-2/COX-1 selectivity ratio similar to or higher than that of celecoxib. The anti-inflammatory activity and the ability of several compounds to decrease leukocyte infiltration were further evaluated in vivo in a model of a λ carrageenan-induced pleurisy. Plasma assays were performed on blood samples collected from rats and allowed us to identify the 4-position of the phenyl ring as a major metabolism site explaining the occasionally observed lack of correlation between in vitro and in vivo results.

Pyridine analogues of nimesulide: design, synthesis, and in vitro and in vivo pharmacological evaluation as promising cyclooxygenase 1 and 2 inhibitors.

Nonsteroidal anti-inflammatory drugs (NSAIDs) represent one of the most prescribed medications, although the chronic use of such pharmacological agents is commonly associated with numerous side effects. The demonstration that the use of COX-2 selective or preferential inhibitors is associated with a better tolerability opened new horizons in the search of safer drugs for the management of inflammation. In the present study, we report the synthesis and the pharmacological evaluation of pyridine analogues of nimesulide, a COX-2 preferential inhibitor. The cyclooxygenases (COXs) inhibitory activities were evaluated in vitro using a human whole blood model. According to the in vitro results, a selection of compounds exhibiting moderate to high COX-2/COX-1 selectivity ratio (from weak COX-2 preferential inhibitors to compounds displaying a celecoxib-like selectivity profile) were further evaluated in vivo in a model of lambda carrageenan-induced pleurisy in rats. Some of the selected compounds displayed similar or improved anti-inflammatory properties when compared to nimesulide and celecoxib.

Structure-based pharmacophore of COX-2 selective inhibitors and identification of original lead compounds from 3D database searching method.

A four-point pharmacophore of COX-2 selective inhibitors was derived from a training set of 16 compounds, using the Catalyst program. It consists of a H bond acceptor, two hydrophobic groups and an aromatic ring, in accordance with SAR data of the compounds and with topology of the COX-2 active site. This hypothesis, combined with exclusion volume spheres representing important residues of the COX-2 binding site, was used to virtually screen the Maybridge database. Eight compounds were selected for an in vitro enzymatic assay. Five of them show COX-2 inhibition close to that of nimesulide and rofecoxib, two reference COX-2 selective inhibitors. As a result, structure-based pharmacophore generation was able to identify original lead compounds, inhibiting the COX-2 isoform.

Evaluation of original dual thromboxane A2 modulators as antiangiogenic agents.

Angiogenesis is a promising target for the therapy of several diseases including cancer. This study was undertaken to characterize the antiangiogenic properties of a series of original dual thromboxane A(2) (TXA(2)) inhibitors derived from torasemide, a marketed loop diuretic with TXA(2) antagonistic properties, by evaluating their effects on human endothelial cell migration, adhesion, and viability in vitro, as well as in the ex vivo rat aortic ring assay. All drugs tested exhibited a marked affinity toward human platelet TXA(2) receptor, significantly prevented platelet aggregation induced by U-46,619, a stable TXA(2) receptor agonist, and inhibited platelet TXA(2) synthase without affecting cyclooxygenase (COX)-1 or COX-2 enzymatic activities. These dual TXA(2) inhibitors dose dependently inhibited endothelial cell migration in chemotaxis assays using vascular endothelial growth factor (VEGF) as a chemoattractant but failed to affect cell adhesion and viability. The highest rates of cell migration inhibition were obtained with original compounds BM-567 and BM-573 (50.3 and 59.4% inhibition, respectively) when used at the final concentration of 10 microM. In addition, pretreatment of endothelial cells with these two drugs significantly prevented U-46,619-induced intracellular Ca(2+) pool mobilization, thus suggesting a mechanistic link between inhibition of the TXA(2) pathway and reduced endothelial cell migration. Treatment of rat aortic explants with U-46,619 (9,11-dideoxy-9,11-methanoepoxy-prostaglandin F(2)) significantly enhanced vessel sprouting whereas aortic rings treated with some of the compounds, including BM-567 (N-n-pentyl-N'-[2-(cyclohexylamino)-5-nitrobenzenesulfonyl]urea) and BM-573 (N-tert-butyl-N'-[5-nitro-2-p-toluylaminobenzenesulfonyl]urea), showed a significant decrease in vessel sprouting, which was not reversed by the addition of VEGF. These data suggest that our original dual TXA(2) inhibitors bear antiangiogenic properties, mainly by inhibiting endothelial cell migration.

The use of nimesulide and its analogues in cancer chemoprevention.

Non-steroidal anti-inflammatory drugs (NSAIDs), which are known to be cyclooxygenase (COX) inhibitors, have been reported to exert anti-proliferative and pro-apoptotic effects on a variety of cancer cells. Since the COX-2 isoform was found to be overexpressed in a many human cancers, a particular attention was paid on the possible use of selective COX-2 inhibitors in cancer chemoprevention. The present review focuses on the state of the art in cancer research developed with COX-2 preferential/selective inhibitors belonging to the family of N-arylmethanesulfonamides, in particular nimesulide and NS-398.

From the design to the clinical application of thromboxane modulators.

Arachidonic acid (AA) metabolites are key mediators involved in the pathogenesis of numerous cardiovascular, pulmonary, inflammatory, and thromboembolic diseases. One of these bioactive metabolites of particular importance is thromboxane A(2) (TXA(2)). It is produced by the action of thromboxane synthase on the prostaglandin endoperoxide H(2) (PGH(2)) which results from the enzymatic transformation of AA by the cyclooxygenases. It is a potent inducer of platelet aggregation, vasoconstriction and bronchoconstriction, and has been involved in a series of major pathophysiological conditions. Therefore, TXA(2) receptor antagonists, thromboxane synthase inhibitors and drugs combining both properties have been developed by different laboratories since the early 1980s. Several compounds have been launched on the market and others are under clinical evaluation. In the first part of this review, we will describe the physiological properties of TXA(2), thromboxane synthase and thromboxane receptors. The second part is dedicated to a description of each class of thromboxane modulators with the advantages and disadvantages they offer. In the third part, we aim to describe recent studies performed with the most interesting thromboxane modulators in major pathologies: myocardial infarction and thrombosis, atherosclerosis, diabetes, pulmonary embolism, septic shock, preeclampsia, and asthma. Each pathology will be systematically reviewed. Finally, in the last part we will highlight the latest perspectives in drug design of thromboxane modulators and in their future therapeutic applications such as cancer, metastasis and angiogenesis.

Activation of the thromboxane A2 pathway in human prostate cancer correlates with tumor Gleason score and pathologic stage.

OBJECTIVE: We investigated the potential involvement of the thromboxane A(2) (TXA(2)) pathway in human prostate cancer (PCa). METHODS: Expression of cyclooxygenase-2 (COX-2), TXA(2) synthase (TXS), and TXA(2) receptors (TPRs), the main actors of the TXA(2) pathway, was analyzed on serial tissue sections from 46 human PCa specimens. RESULTS: The expression levels of COX-2, TXS, and TPRs were significantly higher in malignant than in corresponding nontumoral prostatic epithelial cells. Increased immunoreactivity for these antigens was also observed in high-grade prostate intraepithelial neoplasia (HGPIN) glands. COX-2, TXS, and TPR proteins usually displayed a coordinated overexpression pattern in PCa lesions, as assessed in serial tissue sections. Increased levels of these proteins in the tumors were all significantly associated with higher Gleason scores and pathologic stages. CONCLUSIONS: Proteins specifically involved in the TXA(2) pathway are up-regulated in human PCa and their level of expression is associated with tumor extraprostatic extension and loss of differentiation. Our study is the first to examine simultaneously all key proteins involved in this pathway including TXA(2) receptors and results suggest that the TXA(2) pathway may be a potential target for PCa prevention/therapy.

Synthesis, molecular modelling and enzymatic evaluation of (+/-)3,5-diphenyl-2-thioxoimidazolidin-4-ones as new potential cyclooxygenase inhibitors.

A series of substituted (+/-)3,5-diphenyl-2-thioxoimidazolin-4-ones was synthesized in order to design new type-2 cyclooxygenase (COX-2) inhibitors. This study has led to molecules which completely inhibit human recombinant COX-2 at 50 microM. Molecular modelling highlighted drug interactions with the active site of both cyclooxygenases and suggested modifications to enhance the selectivity of the compounds. In human blood, COX-2 expression was then induced by LPS, and the inhibitory potency of these drugs was disappointing. This weak activity was attributed to a poor aqueous stability of these imidazolidinones substituted by two aryl in position 3 and 5 (15 min < t(1/2) < 130 min). The improvement of the stability of this heterocycle could generate a novel template to treat COX-associated diseases such as arthritis, rheumatoid polyarthritis and cancer.

A new potential cyclooxygenase-2 inhibitor, pyridinic analogue of nimesulide.

In this paper, the binding mode of original pyridinic compounds structurally related to nimesulide, a preferential cyclooxygenase (COX)-2 inhibitor, is analyzed by docking simulations in order to understand structure-activity relationships of this family. Structural modifications are proposed to reverse the selectivity of the more active inhibitor of the series characterized by a preferential activity on COX-1. On the basis of these modifications, a new compound with a bromo substituent was designed and showed a COX-2 selective inhibition.

Carbonic anhydrase inhibitors: synthesis and inhibition of cytosolic/membrane-associated carbonic anhydrase isozymes I, II, and IX with sulfonamides incorporating hydrazino moieties.

Targeting proteins overexpressed in hypoxic tumors is as an important means of controlling cancer disease. One such protein is the carbonic anhydrase (CA) isoenzyme IX, which in some types of tumors is overexpressed 150-200-fold. We report here a series of sulfonamide derivatives, prepared from 2-carbohydrazido- and 4-carbohydrazido-benzenesulfonamides, which were further derivatized by reaction with aryl isocyanates or arylsulfonyl isocyanates. Several low nanomolar CA IX inhibitors were detected in this way. SAR is discussed for the diverse types of inhibitors and their affinity for different isozymes, with the aim of obtaining isozyme-specific CA IX inhibitors, with putative applications as antitumor drugs.

Design, synthesis, and pharmacological evaluation of pyridinic analogues of nimesulide as cyclooxygenase-2 selective inhibitors.

In this study, we report the synthesis and pharmacological evaluation of original pyridinic sulfonamides related to nimesulide, a cyclooxygenase-2 (COX-2) preferential inhibitor widely used as an anti-inflammatory agent. These original pyridinic derivatives were synthesized in three steps starting from the condensation of 3-bromo-4-nitropyridine N-oxide with appropriately substituted phenols, thiophenols, or anilines followed by a reduction of the nitro moiety into the corresponding aminopyridine, which was finally condensed with alkane- or trifluoromethanesulfonyl chloride to obtain the corresponding sulfonamides. The pK(a) determinations demonstrated that the major ionic form present in solution at physiological pH depends on the nature of the sulfonamide moiety subsituent. Indeed, alkanesulfonamides were mainly present as zwitterionic molecules while trifluoromethanesulfonamides, more acidic derivatives, were mainly present as anionic molecules. The in vitro pharmacological evaluation of the synthesized compounds against COX-1 and COX-2 was performed in a human whole blood model. Results obtained demonstrated that most of alkanesulfonamide derivatives displayed a COX-2 preferential inhibition with selectivity ratio values (IC(50)(COX-1)/IC(50)(COX-2)) up to 7.92 (celecoxib displaying a ratio value of 7.46 in the same test). On the other hand, trifluoromethanesulfonamide derivatives displayed weaker selectivity ratios although they exhibited IC(50) values against COX-2 up to 0.09 microM (celecoxib IC(50) against COX-2: 0.35 microM). Finally, in vivo evaluation of selected compounds showed that they exhibited anti-inflammatory properties similar to that of nimesulide when tested in a carrageenan-induced rat paw oedema model.

Effects of COX-2 inhibitors on ROS produced by Chlamydia pneumoniae-primed human promonocytic cells (THP-1).

Chronic inflammation through foam cells and macrophages is important in atherosclerosis development, and can be considered as therapeutic targets. Cyclooxygenase and NADPH-oxidase were expressed within atherosclerotic lesions. Reactive oxygen species produced by NADPH oxidase were found to trigger the cyclooxygenase-2 expression. The effects of preferential COX-2 inhibitors on ROS produced by Chlamydia-primed human monocytes (THP-1 cells) were evaluated by fluorescence, chemiluminescence, oxymetry, and EPR spin trapping. Fluorescence assays showed an increased production of ROS with Chlamydia versus cells primed by 10(-8)M PMA. COX-2 inhibitors inhibited in a dose-dependent manner the luminol-enhanced CL while ibuprofen and diclofenac increased the chemiluminescence response. By EPR spin trapping, COX-2 inhibitors, ibuprofen, and diclofenac, exhibited a dose-dependent inhibiting effect (10 and 100muM) on the EPR signal appearance. Our cell model combining EPR, chemiluminescence, and oxymetry appeared relevant to study the modulating effects of preferential COX-2 inhibitors on the cell oxidant activity and chronic inflammatory diseases.

Progress in the field of GPIIb/IIIa antagonists.

Platelet aggregation plays an important role in pathological situations such as myocardial infarction, unstable angina, peripheral artery disease, and stroke. Thus, pharmacological agents that specifically inhibit platelet aggregation are of great interest in the treatment and prevention of these cardiovascular diseases. Since binding of activated glycoprotein IIb/IIIa complex, a platelet surface integrin, to fibrinogen is the final step leading to platelet aggregation regardless of the initial stimulus, many researches have focused on the development of drugs that could antagonize this integrin. Three intravenous glycoprotein IIb/IIIa antagonists are currently marketed for the prevention of myocardial infarction in patients undergoing percutaneous intervention: Abciximab, Eptifibatide and Tirofiban. To further test the clinical efficacy of these agents, oral glycoprotein IIb/IIIa antagonists have been developed but only led to disappointing clinical results. Nevertheless, due to recognized usefulness of oral agents for the prevention and treatment of cardiovascular diseases, a great number of new orally active compounds are under clinical or preclinical evaluation. The aim of this review is to describe the chemical, pharmacological and clinical properties of existing and forthcoming glycoprotein IIb/IIIa antagonists.

First and second generations of COX-2 selective inhibitors.

The identification and characterization of the inducible form of cyclooxygenases (COX-2) stimulated the investigations to develop efficient, non-steroidal anti-inflammatory drugs (NSAIDs) with reduced side effects (essentially gastro-intestinal toxicity) compared to classical NSAIDs. This review focuses on the chemical and pharmacological properties (pre-clinical data) of marketed COX-2 inhibitors.

Recent development in the field of dual COX / 5-LOX inhibitors.

Cyclooxygenases and lipoxygenase are key enzymes in the arachidonic acid metabolism. Dual inhibitors are drugs able to block both the COX and the 5-LOX metabolic pathways. Compared to COX or LOX pathways single inhibitors, dual inhibitors present at least two major advantages. First, dual inhibitors, by acting on the two major arachidonic acid metabolic pathways, possess a wide range of anti-inflammatory activities. Secondly, dual inhibitors appear to be almost exempt from gastric toxicity, which is the most troublesome side effect of non-selective COX inhibitors.

New developments on thromboxane modulators.

Thromboxane A(2) (TXA(2)) is a labile product formed from arachidonic acid by cyclooxygenase. The pathogenesis of numerous cardiovascular, pulmonary, and thromboembolic diseases can be related to this metabolite. Therefore, TXA(2) modulators have been developed for 20 years. This review will highlight the evolution in the field of TXA(2) modulators.

Modulation of the arachidonic cascade with omega3 fatty acids or analogues: potential therapeutic benefits.

Increasing interest in the role of omega3 fatty acids has arisen in these latest years since evidence of their implication in the cardioprotective fish based diet of the Inuit has been demonstrated. Furthermore, several in vitro, in vivo and epidemiological studies support the benefit of this fatty acids intake in various pathological states such as in the cardiovascular, cancer, inflammation, psychiatric, paediatric, pulmonary, dermatological and ophthalmologic fields. This review will focus on metabolism and pharmacological implication of omega3 fatty acids intake as well as its interest in the prevention or treatment of the above-mentioned pathologies.

Carbonic anhydrase inhibitors: synthesis and topical intraocular pressure lowering effects of fluorine-containing inhibitors devoid of enhanced reactivity.

Polyfluorinated carbonic anhydrase inhibitors (CAIs) show very good inhibitory properties against carbonic anhydrase (CA) and excellent in vivo antiglaucoma properties after topical administration in rabbits. Still, the pentafluorinated compounds reported previously by this group (Scozzafava et al. J. Med. Chem. 2000, 43, 4542-4551) showed high reactivity with thiol groups of cysteine, glutathione, and presumably other proteins containing such moieties, which may lead to severe ocular side effects. Here, we report an approach for obtaining fluorinated CA inhibitors without the undesired enhanced reactivity. Thus, new compounds have been obtained by attaching moieties with reduced reactivity toward aromatic substitution reactions to the molecules of aromatic/heterocyclic sulfonamides possessing derivatizable amino moieties. The employed tails of the 2,3,5,6-tetrafluorobenzoyl, 2,3,5,6-tetrafluophenylsulfonyl, and pentafluorophenylureido types induced excellent CA inhibitory properties in the new reported sulfonamides, mainly against the isozymes involved in aqueous humor secretion, CA II and CA IV, whereas affinity for CA I was lower. Several low-nanomolar CA II inhibitors were detected, which did not react with cysteine or glutathione, in contrast to the corresponding perfluorinated compounds previously reported. These derivatives also showed a potent reduction of the intraocular pressure (IOP) in hypertensive rabbits, amounting to 13-21 mmHg at 1 h postadministration (compared to 5 mmHg obtained with dorzolamide, a clinically used drug), and the decreased IOP was maintained for 4-5 h after the administration. These compounds constitute valuable candidates for obtaining topically acting antiglaucoma CA inhibitors of a new generation, with enhanced efficacy, prolonged duration of action, and reduced side effects.

New developments on thromboxane and prostacyclin modulators part I: thromboxane modulators.

The pathogenesis of numerous cardiovascular, pulmonary, inflammatory, and thromboembolic diseases can be related to arachidonic acid (AA) metabolites. One of these bioactive metabolites of particular importance is thromboxane A(2) (TXA(2)). It is produced by the action of thromboxane synthase on the prostaglandin endoperoxide H(2)(PGH(2)), which results from the enzymatic degradation of AA by the cyclooxygenases. TXA(2) is a potent inducer of platelet aggregation, vasoconstriction and bronchoconstriction. It is involved in a series of major pathophysiological states such as asthma, myocardial ischemia, pulmonary hypertension, and thromboembolic disorders. Therefore, TXA(2) receptor antagonists, thromboxane synthase inhibitors and drugs combining both properties have been developed by several pharmaceutical companies since the early 1980s. Several compounds have been launched on the market and others are under clinical evaluation. Moreover, the recent literature reported the interest of thromboxane modulators, which combine another pharmacological activity such as, platelet activating factor antagonism, angiotensin II antagonism, or 5-lipoxygenase inhibition. In this review, we will propose a description of the recently described thromboxane modulators of major interest from both a pharmacological and a chemical point of view.

New developments on thromboxane and prostacyclin modulators part II: prostacyclin modulators.

Prostacyclin (PGI(2)) is a potent endogenous inhibitor of platelet function and possesses a strong vasodilator effect. Furthermore, prostacyclin is currently presented as the physiologic antagonist of thromboxane A(2)(TXA(2)), which exhibits pro-aggregatory and vasoconstrictor properties. So, the balance between PGI(2) and TXA(2) production is crucial for the cardiovascular system. Indeed, an imbalance in the production or effect of these products is deleterious for the circulatory system and can lead to characterized vascular diseases such as hypertension, stroke, atherosclerosis or myocardial infarction. Although the biological effects of PGI(2) are considered to be clinically useful, its use as therapeutic agent is largely limited by both its chemical and metabolic instability. Actually, several prostacyclin agonists have been synthesized and pharmacologically evaluated. Among these, some have been clinically evaluated as therapeutic agents in several vascular diseases. This review focuses on the latest chemical and pharmacological developments in the field of the prostacyclin agonists.