Selective inhibitors of cyclooxygenase-2

Metal complexes as potential modulators of inflammatory and autoimmune responses

In this perspective, we highlight recent examples in the development of transition metal complexes as modulators of inflammatory and autoimmune responses.

Over the past few decades, the realm of inorganic medicinal chemistry has been dominated by the study of the anti-cancer properties of transition metal complexes, particularly those based on platinum or ruthenium. However, comparatively less attention has been focused on the development of metal complexes for the treatment of inflammatory or autoimmune diseases. Metal complexes possess a number of advantages that render them as attractive alternatives to organic small molecules for the development of therapeutic agents. In this perspective, we highlight recent examples in the development of transition metal complexes as modulators of inflammatory and autoimmune responses. The studies presented here serve to highlight the potential of transition metal complexes in modulating inflammatory or immune pathways in cells.

Amide derivatives of benzene-sulfonanilide, pharmaceutical composition thereof and method for cancer treatment using the same (US20120095092)

A series of sulfonamide derivatives incorporating an aromatic scaffold based on 1,4-phenylene diamine was prepared by a succession of five reactions. The lead molecule of these compounds was nimesulide (4-nitro-2-phenoxymethane-sulfoanilide), a cyclooxygenase (COX) inhibitor acting on both COX-1 and 2 isoforms, with some selectivity for COX-2. The new compounds from the patent are claimed to act as efficient antitumor agents, against a multitude of tumor types, such as leukemia, non-small cell lung cancer, colon cancer, brain cancer, melanoma, ovarian cancer, etc., although no COX inhibition data or other rationale to explain their biological effects are provided. As these compounds incorporate a methanesulfonamide moiety it is not unexpected that they may also appreciably inhibit tumor-associated carbonic anhydrases (CAs), such as isoforms CA IX and XII.

Inflammation and cancer: chemical approaches to mechanisms, imaging, and treatment

The inflammatory response represents a first line of defense against invading pathogens and is important to human health. Chronic inflammation contributes to the etiology of multiple diseases, especially those associated with aging, such as cancer and cardiovascular disease. The chemistry of the inflammatory response is complex and involves the generation of highly reactive oxidants and electrophiles designed to kill the pathogen as well as the release of small molecule and protein mediators of intercellular signaling, chemotaxis, vasoconstriction, and wound-healing. Oxidation of unsaturated fatty acids--either nonenzymatic or enzymatic--contributes to the inflammatory response and associated cellular pathologies. The current perspective summarizes our research on unsaturated fatty acid oxidation in the context of inflammation and cancer. In addition to understanding the consequences of DNA and protein modification by lipid electrophiles, our research has focused on the development of molecularly targeted agents to image and treat cancer.

Development and validation of a reversed-phase liquid chromatographic method for separation and simultaneous determination of COX-2 inhibitors in pharmaceuticals and its application to biological fluids

An isocratic reversed-phase high-performance liquid chromatographic method has been developed for separation and simultaneous determination of COX-2 inhibitors, viz., celecoxib, rofecoxib, valdecoxib, nimesulide and nabumetone, using 4-chloro-2-nitroaniline as internal standard. Good chromatographic separation was achieved using a reversed-phase Inertsil C(18) column with mobile phase consisting of methanol and 0.05% aqueous glacial acetic acid (68:32 v/v) using photodiode array (PDA) detector at 230 nm. It was validated with respect to accuracy, precision, linearity, limit of detection and quantification. The linearity range was found to be 1.0--20 microg/mL and the percentage recoveries were between 97.55 and 100.14. The method is suitable not only for the estimation of active ingredients in pharmaceutical dosage forms but also in vitro estimations in human plasma. It is simple, rapid, selective and capable of detecting and determining COX-2 inhibitors with a detection limit of 0.127--1.040 microg/mL simultaneously.

Carbonic anhydrase inhibitors: X-ray crystallographic structure of the adduct of human isozyme II with the antipsychotic drug sulpiride

The X-ray crystal structure for the adduct of human carbonic anhydrase (hCA) II with sulpiride, a sulfonamide derivative clinically used as antipsychotic drug, has been resolved at a resolution of 1.6 A. This compound is an effective inhibitor of the physiologically most relevant isozyme hCA II (K(i) of 40 nM), being only a moderate or moderate-weak inhibitor of the cytosolic isozyme hCA I (K(i) of 1200 nM) and the membrane-bound isozyme hCA IV (K(i) of 620 nM). Sulpiride shows CA inhibitory properties of the same magnitude as dichlorophenamide, a clinically used antiglaucoma sulfonamide, or valdecoxib, a COX-2 selective inhibitor recently shown to inhibit CA. The binding of sulpiride to the hCA II active site is similar to that of other sulfonamide inhibitors, considering the interactions of the sulfonamide zinc anchoring group, but differs considerably when the organic scaffold of the molecule is analyzed. Indeed, one unprecedented hydrogen bond involving the imino moiety of the carboxamido group of sulpiride and a water molecule was observed, together with a unique stacking interaction of the N-methyl-pyrrolidine ring of the inhibitor and the aromatic ring of Phe 131 of the enzyme active site, which has been observed only recently in another CA-sulfonamide complex.

Differential binding mode of diverse cyclooxygenase inhibitors

Non-steroidal anti-inflammatory drugs (NSAIDs) are competitive inhibitors of cyclooxygenase (COX), the enzyme that mediates biosynthesis of prostaglandins and thromboxanes from arachidonic acid. There are at least two different isoforms of the enzyme known as COX-1 and -2. Site directed mutagenesis studies suggest that non-selective COX inhibitors of diverse chemical families exhibit differential binding modes to the two isozymes. These results cannot clearly be explained from the sole analysis of the crystal structures of COX available from X-ray diffraction studies. With the aim to elucidate the structural features governing the differential inhibitory binding behavior of these inhibitors, molecular modeling studies were undertaken to generate atomic models compatible with the experimental data available. Accordingly, docking of different COX inhibitors, including selective and non-selective ligands: rofecoxib, ketoprofen, suprofen, carprofen, zomepirac, indomethacin, diclofenac and meclofenamic acid were undertaken using the AMBER program. The results of the present study provide new insights into a better understanding of the differential binding mode of diverse families of COX inhibitors, and are expected to contribute to the design of new selective compounds.

Ester and amide derivatives of the nonsteroidal antiinflammatory drug, indomethacin, as selective cyclooxygenase-2 inhibitors

Recent studies from our laboratory have shown that derivatization of the carboxylate moiety in substrate analogue inhibitors, such as 5,8,11,14-eicosatetraynoic acid, and in nonsteroidal antiinflammatory drugs (NSAIDs), such as indomethacin and meclofenamic acid, results in the generation of potent and selective cyclooxygenase-2 (COX-2) inhibitors (Kalgutkar et al. Proc. Natl. Acad. Sci. U.S.A. 2000, 97, 925-930). This paper summarizes details of the structure-activity studies involved in the transformation of the arylacetic acid NSAID, indomethacin, into a COX-2-selective inhibitor. Many of the structurally diverse indomethacin esters and amides inhibited purified human COX-2 with ICo5 values in the low-nanomolar range but did not inhibit ovine COX-1 activity at concentrations as high as 66 microM. Primary and secondary amide analogues of indomethacin were more potent as COX-2 inhibitors than the corresponding tertiary amides. Replacement of the 4-chlorobenzoyl group in indomethacin esters or amides with the 4-bromobenzyl functionality or hydrogen afforded inactive compounds. Likewise, exchanging the 2-methyl group on the indole ring in the ester and amide series with a hydrogen also generated inactive compounds. Inhibition kinetics revealed that indomethacin amides behave as slow, tight-binding inhibitors of COX-2 and that selectivity is a function of the time-dependent step. Conversion of indomethacin into ester and amide derivatives provides a facile strategy for generating highly selective COX-2 inhibitors and eliminating the gastrointestinal side effects of the parent compound.

Synthesis and activity of sulfonamide-substituted 4,5-diaryl thiazoles as selective cyclooxygenase-2 inhibitors

A series of sulfonamide-substituted 4,5-diarylthiazoles was prepared via three synthetic routes as selective COX-2 inhibitors. Recently in the synthesis of selective COX-2 inhibitors we have discovered that the sulfonamide moiety is a suitable replacement for the methylsulfonyl moiety yielding compounds with activity both in vitro and in vivo.

Design and synthesis of sulfonyl-substituted 4,5-diarylthiazoles as selective cyclooxygenase-2 inhibitors

A series of novel sulfone substituted 4,5-diarylthiazoles have been synthesized and evaluated for their inhibition of the two isoforms of human cyclooxygenase (COX-1 and COX-2). This series displays exceptionally selective COX-2 inhibition.

Terphenyl cyclooxygenase-2 (COX-2) inhibitors: optimization of the central ring and o-biphenyl analogs

The discovery of terphenyl derivatives as highly selective COX-2 inhibitors resulted from our efforts to overcome poor pharmacokinetics demonstrated by the COX-2 selective diarylthiophene DuP 697 [2-bromo-4-(4'-sulfonylmethyl)phenyl-5-(4'-fluoro)phenylthiophe ne]. Detailed SAR related to the ortho-biphenyls and variants of the central ring are described herein.