Design, synthesis, and biological evaluation of substituted hydrazone and pyrazole derivatives as selective COX-2 inhibitors: Molecular docking study

New arylhydrazone derivatives and a series of 1,5-diphenyl pyrazoles were designed and synthesized from 1-(4-chlorophenyl)-4,4,4-trifuorobutane-1,3-dione 1. The newly synthesized compounds were investigated in vivo for their anti-inflammatory activities using carrageenan-induced rat paw oedema model. Moreover, they were tested for their inhibitory activity against ovine COX-1 and COX-2 using an in vitro cyclooxygenase (COX) inhibition assay. Some of the new compounds (2f, 6a and 6d) showed a reasonable in vitro COX-2 inhibitory activity, with IC?? value of 0.45 μM and selectivity index of 111.1. A virtual screening was carried out through docking the designed compounds into the COX-2 binding site to predict if these compounds have analogous binding mode to the COX-2 inhibitors. Docking study of the synthesized compounds 2f, 6a and 6d into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.     

Synthesis,modeling and biological evaluation of some pyrazolo[3,4-d]pyrimidinones and pyrazolo[4,3-e][1,2,4]triazolo[4,3-a]pyrimidinones as anti-inflammatory agents

New pyrazolo[3,4-d]pyrimidinone and pyrazolo[4,3-e][1,2,4]triazolo[4,3-a]pyrimidinone derivatives were synthesized. They have been evaluated for their anti-inflammatory activity using in vitro (COX-1/COX-2) inhibitory assay. Moreover, compounds with promising in vitro activity and COX-1/COX-2 selectivity indices were subjected for in vivo anti-inflammatory testing using formalin induced paw edema and cotton-pellet induced granuloma assays for acute and chronic models, respectively. Compounds (2c, 3i, 6a, 8 and 12) showed promising COX-2 inhibitory activity and high selectivity compared to celecoxib. Most of the compounds exhibited potential anti-inflammatory activity for both in vivo acute and chronic models. Almost all compounds displayed safe gastrointestinal profile and low ulcerogenic potential guided by histopathological examination. Furthermore, molecular docking experiments rationalized the observed in vitro anti-inflammatory activity of selected candidates. In silico predictions of the pharmacokinetic and drug-likeness properties recommended accepted profiles of the majority of compounds. In conclusion, this work provides an extension of the chemical space of pyrazolopyrimidinone and pyrazolotriazolopyrimidinone chemotypes for the anti-inflammatory activity.     

Synthesis, biological evaluation and molecular modeling study of pyrazole and pyrazoline derivatives as selective COX-2 inhibitors and anti-inflammatory agents. Part 2

New pyrazole and pyrazoline derivatives have been synthesized and their ability to inhibit ovine COX-1/COX-2 isozymes was evaluated using in vitro cyclooxygenase (COX) inhibition assay. Among the tested compounds, N-((5-(4-chlorophenyl)-1-phenyl-3-(trifluoromethyl)-1H-pyrazol-4-yl)methylene)-3,5-bis(trifluoromethyl)aniline 8d exhibit optimal COX-2 inhibitory potency (IC(50)=0.26 lM) and selectivity (SI)=>192.3] comparable with reference drug celecoxib (IC(50) value of 0.28 lM and selectivity index of 178.57). Moreover, the anti-inflammatory activity of selected compounds, which are the most selective COX-2 inhibitors in the COX inhibition assay, was investigated in vivo using carrageenan-induced rat paw edema model. Molecular modeling was conducted to study the ability of the active compounds to bind into the active site of COX-2 which revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.     

Synthesis and cyclooxygenase inhibitory activities of linear 1-(methanesulfonylphenyl or benzenesulfonamido)-2-(pyridyl)acetylene regioisomers

A group of 1-(aminosulfonylphenyl and methylsulfonylphenyl)-2-(pyridyl)acetylene regioisomers were designed such that a COX-2 SO2NH2 pharmacophore was located at the para-position of the phenyl ring, or a SO2Me pharmacophore was placed at the ortho-, meta- or para-position of the phenyl ring, on an acetylene template (scaffold). The point of attachment of the pyridyl ring to the acetylene linker was simultaneously varied (2-pyridyl, 3-pyridyl, 4-pyridyl, 3-methyl-2-pyridyl) to determine the combined effects of positional, steric, and electronic substituent properties upon COX-1 and COX-2 inhibitory potency and COX isozyme selectivity. These target linear 1-(phenyl)-2-(pyridyl)acetylenes were synthesized via a palladium-catalyzed Sonogashira cross-coupling reaction. Structure-activity relationship (SAR) data (IC50 values) acquired by determination of the in vitro ability of the title compounds to inhibit the COX-1 and COX-2 isozymes showed that the position of the COX-2 SO2NH2 or SO2Me pharmacophore on the phenyl ring, and the point of attachment of the pyridyl ring to the acetylene linker, were either individual, or collective, determinants of COX-2 inhibitory potency and selectivity. A number of compounds discovered in this study, particularly 1-(4-aminosulfonylphenyl)-2-(3-methyl-2-pyridyl)acetylene (22), 1-(3-methanesulfonylphenyl)-2-(2-pyridyl)acetylene (27), 1-(3-methanesulfonylphenyl)-2-(4-pyridyl)acetylene (29), 1-(4-methanesulfonylphenyl)-2-(2-pyridyl)acetylene (30), and 1-(4-methanesulfonylphenyl)-2-(3-pyridyl)acetylene (31), exhibit potent (IC50 = 0.04-0.33 microM range) and selective (SI = 18 to >312 range) COX-2 inhibitory activities, that compare favorably with the reference drug celecoxib (COX-2 IC50 = 0.07 microM; COX-2 SI = 473). The sulfonamide (22), and methylsulfonyl (27 and 31), compounds exhibited anti-inflammatory activities (ID50 = 59.9-76.6 mg/kg range) that were intermediate in potency between the reference drugs aspirin (ID50 = 128.7 mg/kg) and celecoxib (ID50 = 10.8 mg/kg).     

Synthesis and biological evaluation of 2-trifluoromethyl/sulfonamido-5,6-diaryl substituted imidazo[2,1-b]-1,3,4-thiadiazoles: a novel class of cyclooxygenase-2 inhibitors

A series of 2-trifluoromethyl/sulfonamido-5,6-diarylsubstituted imidazo[2,1-b]-1,3,4-thiadiazole derivatives 15a-j have been synthesized by the reaction of 2-amino-5-trifluoromethyl/sulfonamido-1,3,4-thiadiazoles 14a-b and appropriately substituted alpha-bromo-1,2-(p-substituted)diaryl-1-ethanones 13a-h. Structures of these compounds were established by IR, (1)H NMR, (13)C NMR, Mass, and HRMS data. The selected compounds were evaluated for their preliminary in vitro cyclooxygenase inhibitory activity against COX-2 and COX-1enzymes using colorimetric method. The compounds tested showed selective inhibitory activity toward COX-2 (80.6-49.4%) over COX-1 (30.6-8.6), amongst them compounds 15f and 15j showed appreciable COX-2 selective inhibitory activity. These compounds also exhibited significant anti-inflammatory activity (70.09-42.32%), which is comparable to that of celecoxib in the carrageenan-induced rat paw edema method.     

Evaluation of glycolamide esters of indomethacin as potential cyclooxygenase-2 (COX-2) inhibitors

A number of novel indomethacin glycolamide esters were synthesized and tested for their cyclooxygenase (COX-1 and COX-2) inhibition properties in vitro. Many of these compounds proved to be selective COX-2 inhibitors, and subtle structural changes in the substituents on the glycolamide ester moiety altered the inhibitory properties as well as potencies significantly. Their in vitro data were rationalized through molecular modeling studies. Few of them displayed anti-inflammatory activity in vivo. Compound 32, [1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indol-3-yl]acetic acid 2-morpholin-4-yl-2-oxo ethyl ester, was identified as a promising compound in this class and its good anti-inflammatory activity was demonstrated in the in vivo model.     

Design, synthesis and biological evaluation of some pyrazole derivatives as anti-inflammatory-antimicrobial agents

The synthesis of novel series of structurally related 1H-pyrazolyl derivatives is described. All the newly synthesized compounds were tested for their in vivo anti-inflammatory activity by two different bioassays namely; cotton pellet-induced granuloma and sponge implantation model of inflammation in rats. In addition, COX-1 and COX-2 inhibitory activities, ulcerogenic effects and acute toxicity were determined. The same compounds were evaluated for their in vitro antimicrobial activity against Escherichia coli, as an example of Gram negative bacteria, Staphylococcus aureus as an example of Gram positive bacteria, and Candida albicans as a representative of fungi. The combined anti-inflammatory data from local and systemic in vivo animal models showed that compounds 4, 5, 8, 9, 11 and 12a exhibited anti-inflammatory activity comparable to that of indomethacin with no or minimal ulcerogenic effects and high safety margin (LD(50)>500 mg/Kg). In addition, compounds 4, 7, 10, 12a and 12b displayed appreciable antibacterial activities when compared with ampicillin, especially against S. aureus. Compounds 4 and 12a are the most distinctive derivatives identified in the present study because of their remarkable in vivo and in vitro anti-inflammatory potency and their pronounced antibacterial activities comparable to ampicillin against Gram positive. On the other hand, compound 12a exhibited good selective inhibitory activity against COX-2 enzyme. Therefore, such compound would represent a fruitful matrix for the development of anti-inflammatory-antimicrobial candidates.     

Design, synthesis, and biological evaluation of N-acetyl-2-carboxybenzenesulfonamides: a novel class of cyclooxygenase-2 (COX-2) inhibitors

N-Acetyl-2-carboxybenzenesulfonamide (11), and a group of analogues possessing an appropriately substituted-phenyl substituent (4-F, 2,4-F(2), 4-SO(2)Me, 4-OCHMe(2)) attached to its C-4, or C-5 position, were synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1/COX-2 inhibition studies showed that 11 is a more potent inhibitor (COX-1 IC(50)=0.06microM; COX-2 IC(50)=0.25microM) than aspirin (COX-1 IC(50)=0.35microM; COX-2 IC(50)=2.4microM), and like aspirin [COX-2 selectivity index (S.I.)=0.14], 11 is a nonselective COX-2 inhibitor (COX-2 S.I.=0.23). Regioisomers having a 2,4-difluorophenyl substituent attached to the C-4 (COX-2 IC(50)=0.087microM; COX-2 S.I. >1149), or C-5 (COX-2 IC(50)=0.77microM, SI>130), position of 11 exhibited the most potent and selective COX-2 inhibitory activity relative to the reference drug celecoxib (COX-1 IC(50)=33.1microM; COX-2 IC(50)=0.07microM; COX-2 S.I.=472). N-Acetyl-2-carboxybenzenesulfonamide (11, ED(50)=49 mg/kg), and its C-4 2,4-difluorophenyl derivative (ED(50)=91 mg/kg), exhibited superior antiinflammatory activity (oral dosing) in a carrageenan-induced rat paw edema assay compared to aspirin (ED(50)=129 mg/kg). These latter compounds exhibited comparable analgesic activity to the reference drug diflunisal, and superior analgesic activity compared to aspirin, in a 4% NaCl-induced abdominal constriction assay. A molecular modeling (docking) study indicated that the SO(2)NHCOCH(3) substituent present in N-acetyl-2-carboxy-4-(2,4-fluorophenyl)benzenesulfonamide, like the acetoxy substituent in aspirin, is suitably positioned to acetylate the Ser(530) hydroxyl group in the COX-2 primary binding site. The results of this study indicate that the SO(2)NHCOCH(3) pharmacophore present in N-acetyl-2-carboxybenzenesulfonamides is a suitable bioisostere for the acetoxy (OCOMe) group in aspirin.     

Synthesis of celecoxib analogs that possess a N-hydroxypyrid-2(1H)one 5-lipoxygenase pharmacophore: biological evaluation as dual inhibitors of cyclooxygenases and 5-lipoxygenase with anti-inflammatory activity

A hitherto unknown class of celecoxib analogs was designed for evaluation as dual inhibitors of the 5-lipoxygenase/cyclooxygenase-2 (5-LOX/COX-2) enzymes. These compounds possess a SO(2)Me (11a), or SO(2)NH(2) (11b) COX-2 pharmacophore at the para-position of the N(1)-phenyl ring in conjunction with a 5-LOX N-hydroxypyrid-2(1H)one iron-chelating moiety in place of the celecoxib C-5 tolyl group. The title compounds 11a-b are weak inhibitors of the COX-1 and COX-2 isozymes (IC(50)=7.5-13.2 microM range). In contrast, the SO(2)Me (11a, IC(50)=0.35 microM), and SO(2)NH(2) (11b, IC(50)=4.9 microM), compounds are potent inhibitors of the 5-LOX enzyme comparing favorably with the reference drug caffeic acid (5-LOX IC(50)=3.47 microM). The SO(2)Me (11a, ED(50)=66.9 mg/kg po), and SO(2)NH(2) (11b, ED(50)=99.8 mg/kg po) compounds exhibited excellent oral anti-inflammatory (AI) activities being more potent than the non-selective COX-1/COX-2 inhibitor drug aspirin (ED(50)=128.9 mg/kg po) and less potent than the selective COX-2 inhibitor celecoxib (ED(50)=10.8 mg/kg po). The N-hydroxypyridin-2(1H)one moiety constitutes a novel pharmacophore for the design of cyclic hydroxamic mimetics capable of chelating 5-LOX iron for exploitation in the design of 5-LOX inhibitory AI drugs.     

Synthesis,biological evaluation and molecular modeling of dihydro-pyrazolyl-thiazolinone derivatives as potential COX-2 inhibitors

A series of dihydro-pyrazolyl-thiazolinone derivatives (5a–5t) have been synthesized and their biological activities were also evaluated as potential cyclooxygenase-2 (COX-2) inhibitors. Among these compounds, compound 2-(3-(3,4-dimethylphenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-one (5a) displayed the most potent COX-2 inhibitory activity with IC₅₀ of 0.5 μM, but weak to COX-1. Docking simulation was performed to position compound 5a into the COX-2 active site to determine the probable binding model. Based on the preliminary results, compound 5a with potent inhibitory activity and low toxicity would be a potential and selective anti-cyclooxygenase-2 agent.     

Synthesis and biological evaluation of isoxazolo[4,5-d]pyridazin-4-(5H)-one analogues as potent anti-inflammatory agents

In this study, eighteen new isoxazolo[4,5-d]pyridazin-4(5H)-one derivatives possessing either a 1,3,4-thiadiazole or a 1,2,4-triazole-5-thione moiety were synthesized and tested for anti-inflammatory activity in vitro (COX-1/COX-2, 5-LOX) and in vivo (rat paw edema assay). Compounds 15, 16, 25, 26 and 28-30 showed dual COX-2 (IC(50)'s in the 2.1-10.9 μM range), and 5-LOX (IC(50)'s in the 6.3-63.5 μM range) inhibitory activity. When administered orally to rats, dual COX-2/5-LOX inhibitors showed higher anti-inflammatory activity in vivo (30-45% reduction of the inflammatory response) than the reference drug ibuprofen (18%). Among dual COX-2/5-LOX inhibitors, the most potent compound (28) exhibited the best anti-inflammatory profile by inhibiting both COX-2 (IC(50)=2.1 μM) and 5-LOX (IC(50)=6.3 μM) enzymes. We investigated the binding interactions of compound 28 by an enzyme-ligand molecular modeling (docking) studies, which showed favorable binding interactions in both COX-2 and 5-LOX active sites. Furthermore, the dual acting COX-2/5-LOX compound 28 exhibited a superior gastrointestinal safety profile (ulcer index=0.25) compared to the reference drug ibuprofen (UI=7.0) when administered orally at the same molar dose. These observations suggest that isoxazolo[4,5-d]pyridazin-4(5H)-one analogs represent a new scaffold to design potent, effective, and safe anti-inflammatory agents possessing dual COX-2/5-LOX inhibitory activity.     

Design, synthesis, and biological evaluation of 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines as cyclooxygenase-2 (COX-2) and lipoxygenase (LOX) inhibitors

A series of 20 novel 1-(4-sulfamylphenyl)-3-trifluoromethyl-5-indolyl pyrazolines were designed, synthesized, and screened in vitro for anti-inflammatory activity. These compounds were designed for evaluation as dual inhibitors of cyclooxygenases (COX-1 and COX-2) and lipoxygenases (LOX-5, LOX-12, and LOX-15) that are responsible for inflammation and pain. All pyrazoline molecules prepared are optically active and compounds that are more potent in COX-2 inhibitory activity (5a and 5f) were resolved by chiral column and each enantiomer was tested for cyclooxygenase inhibitory activity. Molecular modeling and comparison of molecular models of 5a enantiomers with that of celecoxib model shows that 5a (enantiomer-1) and 5a (enantiomer-2) have more hydrogen bonding interactions in the catalytic domain of COX-2 enzyme than celecoxib. Compounds 5a, 5e, and 5f showed moderate to good LOX-5 and LOX-15 inhibitory activity and this is comparable to that of celecoxib and more potent than rofecoxib.     

Synthesis and anti-inflammatory activity of some new 4,5-dihydro-1,5-diaryl-1H-pyrazole-3-substituted-heteroazole derivatives

A series of 4,5-dihydro-1,5-diaryl-1H-pyrazole-3-substituted-heteroazoles were designed and synthesized in order to obtain new compounds with potential anti-inflammatory activity. The title compounds were screened for in vivo anti-inflammatory activity by using Carrageenan induced rat paw edema method. Diclofenac sodium was used as a standard drug for comparison. Out of the 30 compounds tested, compound 19a, 19b, 25a, 25b exhibited significant anti-inflammatory activity. Selected compounds were also screened for in vitro COX-2 inhibition assay and analgesic activity in the acetic acid induced writhing model.     

Design, synthesis and biological evaluation of pyridine acyl sulfonamide derivatives as novel COX-2 inhibitors

A series of pyridine acyl sulfonamide derivatives (1-24) have been designed and synthesized and their biological activities were also evaluated as potential cyclooxygenase-2 (COX-2) inhibitors. Among all the compounds, compound 23 displayed the most potent COX-2 inhibitory activity with an IC(50) of 0.8 μM. Antitumor and anti-inflammatory assays indicated that compound 23 owned high antiproliferative activity against B16-F10, HepG2 and MCF-7 cancer cell lines as well as COX-2-derived prostaglandin E(2) (PGE(2)) inhibitory activity of murine macrophage RAW 264.7 cell line with IC(50) values of 2.8, 1.2, 1.8 and 0.15 μM, respectively. Docking simulation was performed to position compound 23 into the COX-2 active site to determine the probable binding model.     

Isomeric acetoxy analogs of celecoxib and their evaluation as cyclooxygenase inhibitors

A group of celecoxib analogs having a SO(2)NH(2) (9a-f), or SO(2)Me (12a-f), COX-2 pharmacophore at the para-position of the N-1 phenyl ring in conjunction with a C-5 phenyl ring having a variety of substituents (4-, 3-, 2-OAc; 4-Me,2-OAc, 4-Me,3-OAc, 4-F,2-OAc) was synthesized for evaluation as cyclooxygenase (COX) inhibitors of the COX-1/COX-2 isozymes. Within this group of compounds, 1-(4-aminosulfonylphenyl)-3-trifluoromethyl-5-(2-acetoxy-4-fluorophenyl)pyrazole (9f) emerged as the most potent (COX-1 IC(50)=0.7 μM; COX-2 IC(50)=0.015 μM) and selective (COX-2 selectivity index=47) inhibitor agent that exhibited good anti-inflammatory activity (ED(50)=42.3mg/kg) which was lower than the reference drug celecoxib (ED(50)=10.8 mg/kg), but greater than ibuprofen (ED(50)=67.4 mg/kg) and aspirin (ED(50)=128.7 mg/kg). Molecular modeling studies for 9f showed that the SO(2)NH(2) group assumes a position within the secondary pocket of the COX-2 active site wherein the SO(2)NH(2) oxygen atom is hydrogen bonded to the H90 residue (2.90?), the SO(2)NH(2) nitrogen atom forms a hydrogen bond with L352 (N?O=2.80?), and the acetyl group is positioned in the vicinity of the S530 residue where the acetyl oxygen atom undergoes hydrogen bonding to L531 (2.99?).     

Chalcone derivatives bearing chromen or benzo[f]chromen moieties: Design,synthesis, and evaluations of anti-inflammatory,analgesic, selective COX-2 inhibitory activities

Thirty-eight chalcone derivatives bearing a chromen or benzo[f]chromen moiety were synthesized and evaluated for their anti-inflammatory and analgesic activities. Using an ear edema model, anti-inflammatory activities were observed for compounds 3a-3s (ear inflammation: 1.75–3.71 mg) and 4a-4s (ear inflammation: 1.71–4.94 mg). All compounds also displayed analgesic effects with inhibition values of 66.7–100% (3a-3s) and 96.2–100% (4a-4s). The 12 compounds that displayed excellent anti-inflammatory and analgesic effects were tested for their inhibitory activity against ovine COX-1 and COX-2. Six compounds bearing a chromen moiety were weak inhibitors of the COX-1 isozyme but showed moderate COX-2 isozyme inhibitory effects (IC₅₀s from 0.37 μM to 0.83 μM) and COX-2 selectivity indexes (SI: 22.49–9.34). Those bearing a benzo[f]chromen moiety were more selective toward COX-2 than those bearing a chromen moiety with IC₅₀s from 0.25 μM to 0.43 μM and COX-2 selectivity indexes from SI: 31.08 to 20.67.     

Synthesis of some pyrazolyl benzenesulfonamide derivatives as dual anti-inflammatory antimicrobial agents

Four series of pyrazolylbenzenesulfonamide derivatives were synthesized and evaluated for their anti-inflammatory activity using cotton pellet induced granuloma and carrageenan-induced rat paw edema bioassays. Moreover, COX-1 and COX-2 inhibitory activity, ulcerogenic effect and acute toxicity were also determined. Furthermore, the target compounds were screened for their in-vitro antimicrobial activity against Eischerichia coli, Staphylococcus aureus and Candida albicans. Compounds 4-(3-Phenyl-4-cyano-1H-pyrazol-1-yl)benzenesulfonamide 9a and 4-(3-Tolyl-4-cyano-1H-pyrazol-1-yl)benzenesulfonamide 9b were not only found to be the most active dual anti-inflammatory antimicrobial agents in the present study with good safety margin and minimal ulcerogenic effect but also exhibited good selective inhibitory activity towards COX-2. A docking pose for 9a and 9b separately in the active site of the human COX-2 enzyme was also obtained. Therefore, these compounds would represent a fruitful matrix for the development of dual anti-inflammatory antimicrobial candidates with remarkable COX-2 selectivity.     

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).