Inhibitors of cyclooxygenase-2: November 1999 - April 2000

Copper(II) complexes as potential anticancer and Nonsteroidal anti-inflammatory agents: In vitro and in vivo studies

Copper-based compounds are promising entities for target-specific next-generation anticancer and NSAIDS therapeutics. In lieu of this, benzimidazole scaffold plays an important role, because of their wide variety of potential functionalizations and coordination modes. Herein, we report three copper complexes 1-3 with benzimidazole-derived scaffolds, a biocompatible molecule, and secondary ligands viz, 1-10-phenanthroline and 2,2'-bipyridyl. All the copper complexes have been designed, synthesized and adequately characterized using various spectroscopic techniques. In-vitro, human serum albumin (HSA) binding was also carried out using fluorescence technique and in-silico molecular modeling studies, which exhibited significant binding affinities of the complexes with HSA. Furthermore, copper complexes 1-3 were tested for biological studies, i.e., anticancer as well as NSAIDS. In vitro cytotoxicity results were carried out on cultured MCF-7 cell lines. To get the insight over the mechanism of action, GSH depletion and change in lipid peroxidation were tested and thus confirmed the role of ROS generation, responsible for the cytotoxicity of the complexes 1-3. Moreover, the copper complexes 1-3 were tested for potential to act as NSAIDS on albino rats and mice in animal studies in-vivo. Additionally, we also predicted the mechanism of action of the copper complexes 1-3 using molecular modeling studies with COX-2 inhibitor.

In vivo assessment of newly synthesized achiral copper(ii) and zinc(ii) complexes of a benzimidazole derived scaffold as a potential analgesic, antipyretic and anti-inflammatory

Two new complexes of copper(ii) and zinc(ii) were synthesized and characterized using various spectroscopic techniques. The newly synthesized compounds were screened for analgesic, antipyretic and anti-inflammatory activities.

Synthesis and structure-activity relationship studies of urea-containing pyrazoles as dual inhibitors of cyclooxygenase-2 and soluble epoxide hydrolase

A series of dual inhibitors containing a 1,5-diarylpyrazole and a urea were designed, synthesized, and evaluated as novel COX-2/sEH dual inhibitors in vitro using recombinant enzyme assays and in vivo using a lipopolysaccharide (LPS) induced model of pain in rats. The best inhibition potencies and selectivity for sEH and COX-2 over COX-1 were obtained with compounds (21b, 21i, and 21j) in which both the 1,5-diaryl-pyrazole group and the urea group are linked with a three-methylene group. Compound 21i showed the best pharmacokinetic profiles in both mice and rats (higher AUC and longer half-life). Following subcutaneous administration at 10 mg/kg, compound 21i exhibited antiallodynic activity that is more effective than the same dose of either a COX-2 inhibitor (celecoxib) or a sEH inhibitor (t-AUCB) alone, as well as coadministration of both inhibitors. Thus, these novel dual inhibitors exhibited enhanced in vivo antiallodynic activity in a nociceptive behavioral assay.

Novel anti-inflammatory agents based on pyrazole based dimeric compounds; design, synthesis, docking and in vivo activity

Series of pyrazole ester prodrugs analogues have been synthesized and found to contain highly potent inhibitors of the cyclooxygenase-2 (COX-2) enzyme. The paper describes synthesis of the target pyrazole analogues. The structure of the synthesized mutual ester prodrugs (6-8c) were confirmed by (1)H-, (13)C-NMR mass spectroscopy (MS) and their purity were ascertained by TLC and elemental analyses. The biological in vivo evaluation of these compounds in experimental models (carrageenan-induced oedema) proved the presence of anti-inflammatory activity. Docking studies into the catalytic site of COX-2 were used to identify potential anti-inflammatory lead compounds. One lead derivative was chosen endowed with good binding energies.

Synthesis and evaluation of novel 2-substituted-quinazolin-4(3H)-ones as potent analgesic and anti-inflammatory agents

A novel series of 2-substituted-quinazolin-4(3H)-ones were synthesized by reacting 3,5-disubstituted-anthranilic acid with acetic anhydride/benzoyl chloride, which were further reacted with different primary amines to obtain 2,6,8-substituted-quinazolin-4(3H)-ones 6a-f, 7, 8. All the synthesized compounds were characterized and screened for analgesic and anti-inflammatory activities. Compounds 6,8-dibromo-2-phenyl-3-(4'-carboxyl phenyl)quinazolin-4(3H)-one 7 and 6,8-dibromo-2-phenyl-3-(2'-phenylethanoic acid)quinazolin-4(3H)-one 8 displayed good analgesic and anti-inflammatory activity in comparison to the reference standards acetyl salicylic acid and indomethacin, respectively.

Novel 2-(4-methylsulfonylphenyl)pyrimidine derivatives as highly potent and specific COX-2 inhibitors

New series of 2-(4-methylsulfonylphenyl) and 2-(4-sulfamoylphenyl)pyrimidines were synthesized and evaluated for their ability to inhibit cyclooxygenase-2 (COX-2). COX-1 and COX-2 inhibitory activity of these compounds was determined using purified enzyme (PE) and human whole blood (HWB) assays. Extensive structure-activity relationship (SAR) work was carried out within these series, and a wide number of potent and specific COX-2 inhibitors were identified (HWB COX-2 IC(50)=2.4-0.3nM and 80- to 780-fold more selective than rofecoxib).

Synthesis and Pharmacological Evaluation of Some 3-(4-Methoxyphenyl)-2-substitutedamino-quinazolin-4(3H)-ones as Analgesic and Anti-inflammatory Agents

A variety of novel 3-(4-methoxyphenyl)-2-substitutedamino-quinazolin-4(3H)-ones were synthesized by reacting the amino group of 2-hydrazino-3-(4-methoxyphenyl)-quinazolin-4(3H)-one with a variety of alkyl and aryl ketones. The starting material 2-hydrazino-3-(4-methoxyphenyl)-quinazolin-4(3H)-one was synthesized from 4-methoxyaniline. The title compounds were investigated for analgesic, anti-inflammatory and ulcerogenic index activities. While the test compounds exhibited significant activity, compounds 2-(1-methylpropylidene)-hydrazino-3-(4-methoxyphenyl)-quinazolin-4(3H)-one (A1), 2-(1-ethylpropylidene)-hydrazino-3-(4-methoxyphenyl)-quinazolin-4(3H)-one (A2) and 2-(1-methylbutylidene)-hydrazino-3-(4-methoxyphenyl)-quinazolin-4(3H)-one (A3) showed moderately more potent analgesic activity and the compound 2-(1-methylbutylidene)-hydrazino-3-(4-methoxyphenyl)-quinazolin-4(3H)-one (A3) showed moderately more potent anti-inflammatory activity when compared to the reference standard diclofenac sodium. Interestingly the test compounds showed only mild ulcerogenic potential when compared to aspirin.

Synthesis and Pharmacological Evaluation of Some 3-(4-Methylphenyl)-2-substituted amino-3H-quinazolin-4-ones as Analgesic and Anti-inflammatory Agents

A variety of 3-(4-methyl phenyl)-2-substituted amino-3H-quinazolin-4-ones were synthesized by reacting the amino group of 2-hydrazino-3-(4-methyl phenyl)-3H-quinazolin-4-one with a variety of aldehydes and ketones. The starting material 2-hydrazino-3-(4-methyl phenyl)-3H-quinazolin-4-one was synthesized from 4-methyl aniline. The title compounds were investigated for analgesic, anti-inflammatory, and ulcerogenic index activities. While the test compounds exhibited significant activity, compounds Al, A2, and A3 showed more potent analgesic activity and the compound A3 showed more potent anti-inflammatory activity when compared to the reference standard diclofenac sodium. Interestingly, the test compounds showed only mild ulcerogenic potential when compared to aspirin.

Focused combinatorial library design based on structural diversity, druglikeness and binding affinity score

The advent of focused library and virtual screening has reduced the disadvantage of combinatorial chemistry and changed it to a realizable and cost-effective tool in drug discovery. Usually, genetic algorithms (GAs) are used to quickly finding high-scoring molecules by sampling a small subset of the total combinatorial space. Therefore, scoring functions play essential roles in focused library design. Reported here is our initial attempt to establish a new approach for generating a target-focused library using the combination of the scores of structural diversity and binding affinity with our newly improved drug-likeness scoring functions. Meanwhile, a software package, named LD1.0, was developed on the basis of the new approach. One test on a cyclooxygenase (COX)2-focused library successfully reproduced the structures that have been experimentally studied as COX2-selective inhibitors. Another test is on a peroxisome proliferator-activated receptors gamma-focused library design, which not only reproduces the key fragments in the approved (thiazolidinedione) TZD drugs, but also generates some new structures that are more active than the approved drugs or published ligands. Both of the two tests took approximately 15% of the running time of the ordinary molecular docking method. Thus, our new approach is an effective, reliable, and practical way for building up a properly sized focused library with a high hit rate, novel structure, and good ADME/T profile.

Design, synthesis, biological evaluation and molecular docking of curcumin analogues as antioxidant, cyclooxygenase inhibitory and anti-inflammatory agents

Curcuminoids were isolated from Curcuma longa and their pyrazole and isoxazole analogues were synthesized and evaluated for antioxidant, COX-1/COX-2 inhibitory and anti-inflammatory activities. The designed analogues significantly enhance COX-2/COX-1 selectivity and possess significant anti-inflammatory activity in carrageenan induced rat paw edema assay. Pyrazole, isoxazole analogues of curcumin (4 and 7) exhibited higher antioxidant activity than trolox. Molecular docking study revealed the binding orientations of curcumin analogues in the active sites of COX and thereby helps to design novel potent inhibitors.

Synthesis and Selective Cyclooxygenase-2 Inhibitory Activity of a Series of Novel, Nitric Oxide Donor-Containing Pyrazoles

The synthesis of a series of novel pyrazoles containing a nitrate (ONO(2)) moiety as a nitric oxide (NO)-donor functionality is reported. Their COX-1 and COX-2 inhibitory activities in human whole blood are profiled. Our data demonstrate that pyrazole ring substituents play an important role in COX-2 selective inhibition, such that a cycloalkyl pyrazole (6b) was found to be a potent and selective COX-2 inhibitor. Other modifications at the 3 position of the central pyrazole ring (17b, 23b, 26b-I) enhanced COX-2 inhibitory potency. Among the pyrazoles synthesized, the oxime (23b) was identified as the most potent COX-2 selective inhibitor. Accordingly, 23b was profiled pharmacologically in the rat after oral administration and shown to possess potent antiinflammatory activity in the carrageenan-induced air-pouch model and less gastric toxicity than a standard COX-2 inhibitor when administered with background aspirin treatment. We suggest that the enhanced gastric tolerance of an NO-donor COX-2 selective inhibitor has the potential to augment the clinical profile of this drug class.

Synthesis and selective cyclooxygenase-2 (COX-2) inhibitory activity of a series of novel bicyclic pyrazoles

Novel series of pyrazolo[5,1-b]1,3-oxazolidines, pyrazolo[5,1-b]1,3-oxazines and imidazolidino[1,2-d]pyrazoles were synthesized. These compounds were evaluated in vitro for their ability to inhibit cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in human whole blood (HWB). Several of the compounds were found to be novel and selective COX-2 inhibitors, the most potent and selective being 1-(5-cyclohexyl (2H,3H-pyrazolo[5,1-b]-1,3-oxazolidin-6-yl)-4-(methylsulfonyl)benzene, 7a (IC(5o) for COX-1>100 microM; for COX-2=1.3 microM).

Inhibitory mode of 1,5-diarylpyrazole derivatives against cyclooxygenase-2 and cyclooxygenase-1: molecular docking and 3D QSAR analyses

The Lamarckian genetic algorithm of AutoDock 3.0 has been employed to dock 40 1,5-diarylpyrazole class compounds into the active sites of cyclooxygenase-2 (COX-2) and cyclooxygenase-1 (COX-1). The binding models were demonstrated in the aspects of inhibitor's conformation, subsite interaction, and hydrogen bonding. The data of geometrical parameters and RMSD values compared with the known inhibitor, SC-558 (43), show that these inhibitors interact respectively with COX-2 and COX-1 in a very similar way. The r(2) values of 0.648 for COX-2 and 0.752 for COX-1 indicate that the calculated binding free energies correlate well with the inhibitory activities. The structural and energetic differences in inhibitory potencies of 1,5-diarylpyrazoles were reasonably explored, and the COX-2/COX-1 selectivity was demonstrated by the three-dimensional (3D) interaction models of inhibitors complexing with these two enzymes. Using the binding conformations of 1,5-diarylpyrazoles, consistent and highly predictive 3D quantitative structure-activity relationship (QSAR) models were developed by performing comparative molecular field analyses (CoMFA) and comparative molecular similarity analyses (CoMSIA). The q(2) values are 0.635 and 0.641 for CoMFA and CoMSIA models, respectively. The predictive ability of these models was validated by SC-558 (43) and a set of 10 other compounds that were not included in the training set. Mapping these models back to the topology of the active site of COX-2 leads to a better understanding of vital diarylpyrazole compounds and COX-2 interactions. Structure-based investigations and the final 3D QSAR results provided possible guidelines and accurate activity predictions for novel inhibitor design.

A facile one-pot synthesis of 4,5-diaryl-2,2-dimethyl-3(2H)-furanones

An efficient and practical one-pot synthesis of 4,5-diaryl-2,2-dimethyl-3(2H)-furanones has been achieved from 1,2-diarylethanones and 2-bromoisobutyryl cyanide in the presence of excess base, by employing the 'hard soft acid base' principle. The reaction scope of 2-bromoisobutyryl cyanide could be expanded to prepare a variety of 2,2-dimethyl-3(2H)-furanone derivatives other than 4,5-diaryl-2,2-dimethyl-3(2H)-furanones.