COX-2 IC50 Research Articles

In vitro anti-inflammatory effects of naturally-occurring compounds from two Lauraceae plants

The in vitro anti-inflammatory effects of seven known lignans and one dihydrochalcone isolated from the leaves of two Lauraceae species (Pleurothyrium cinereum and Ocotea macrophylla), were evaluated through the inhibition of COX-1, COX-2, 5-LOX and the aggregation of rabbit platelets induced by PAF, AA and ADP. (+)-de-4"-O-methylmagnolin 4 was found to be a potent COX-2/5-LOX dual inhibitor and PAF-antagonist (COX-2 IC(50) 2.27 µM; 5-LOX IC(50) 5.05 µM; PAF IC(50) 2.51 µM). However, all compounds exhibited an activity at different levels, indicating good anti-inflammatory properties to be considered in further structural optimization studies.

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 (2.90Å), the SO(2)NH(2) nitrogen atom forms a hydrogen bond with L352 (N⋯O=2.80Å), and the acetyl group is positioned in the vicinity of the S530 residue where the acetyl oxygen atom undergoes hydrogen bonding to L531 (2.99Å).

Ocular Penetration and Anti-inflammatory Activity of Ketorolac 0.45% and Bromfenac 0.09% Against Lipopolysaccharide-Induced Inflammation

Anti-inflammatory activity of topical nonsteroidal anti-inflammatory drugs is mediated by suppression of cyclooxygenase (COX) isoenzymes. This study compared ocular penetration and inflammation suppression of topical ketorolac 0.45% and bromfenac 0.09% ophthalmic solutions in a rabbit model. At hour 0, 36 rabbits received ketorolac 0.45%, bromfenac 0.09%, or an artificial tear 3 times once every 20 min. Half of the rabbits in each group then received intravenous injections of lipopolysaccharide (LPS) and fluorescein isothiocyanate (FITC)-dextran at hour 1, and the other half at hour 10. Aqueous and iris-ciliary body (ICB) samples were collected in the former group at hour 2 (peak) and in the latter group at hour 11 (trough) An additional group of 6 animals received only FITC-dextran, and samples were collected 1 h later. Peak and trough nonsteroidal anti-inflammatory drug concentrations were compared with previously determined half-maximal inhibitory concentrations (IC(50)) for COX isoenzymes. Peak and trough aqueous and ICB concentrations of ketorolac were at least 7-fold or greater than those of bromfenac. At peak levels, both ketorolac 0.45% and bromfenac 0.09% significantly inhibited LPS-induced aqueous prostaglandin E(2) and FITC-dextran elevation (P < 0.01). At trough, both study drugs significantly inhibited LPS-induced aqueous prostaglandin E(2) elevation (P < 0.05), but only ketorolac 0.45% significantly reduced LPS-induced aqueous FITC-dextran elevation (P < 0.01). Aqueous and ICB ketorolac concentrations exceeded its IC(50) for COX-1 and COX-2 at peak and trough. Aqueous and ICB bromfenac levels exceeded its IC(50) for COX-2 at peak and trough, but not for COX-1 at trough aqueous levels and peak and trough ICB levels. Both ketorolac 0.45% and bromfenac 0.09% effectively suppressed inflammation at peak. At trough, only ketorolac 0.45% effectively suppressed inflammation as measured by FITC-dextran leakage. The difference in inflammation suppression may be due to differences in tissue concentrations and/or greater COX-1 suppression by ketorolac 0.45%.

Design, synthesis and biological evaluation of new 5,5-diarylhydantoin derivatives as selective cyclooxygenase-2 inhibitors.

A new group of 5,5-diarylhydantoin derivatives bearing a methylsulfonyl COX-2 pharmacophore at the para position of the C-5 phenyl ring were designed and synthesized as selective COX-2 inhibitors. In vitro COX-1/COX-2 inhibition structure-activity relationships identified 5-[4-(methylsulfonyl)phenyl]-5-phenyl-hydantoin (4) as a highly potent and selective COX-2 inhibitor (COX-2 IC50 = 0.077 μM; selectivity index > 1298). It was more selective than the reference drug celecoxib (COX-2 IC50 = 0.060 μM; selectivity index = 405). A molecular modeling study where 4 was docked in the binding site of COX-2 indicated that the p-MeSO2 COX-2 pharmacophore group on the C-5 phenyl ring is oriented in the vicinity of the COX-2 secondary pocket. The results of this study showed that the type of substituent on the N-3 hydantoin ring substituent is important for COX-2 inhibitory activity.

Design of novel N-phenylnicotinamides as selective cyclooxygenase-1 inhibitors

A series of N-phenylnicotinamides (1–40) were designed and evaluated in vitro for their COX inhibitory activities. Most of the synthesized compounds were proved to be potent and selective inhibitors of COX-1. Compound 28 showed the most potent COX-1 inhibitory activity (COX-1 IC50=0.68±0.07μM) and good selectivity (COX-2 IC50>100μM). This compound may be useful as a lead compound for superior COX-1 inhibitors. On the basis of the biological results, structure–activity relationships for the COX-1-inhibitory activities of the synthesized N-phenylnicotinamides were discussed concisely.

Synthesis, Anti-Inflammatory Activity, and in Vitro Antitumor Effect of a Novel Class of Cyclooxygenase Inhibitors: 4-(Aryloyl)phenyl Methyl Sulfones

Following our previous research on anti-inflammatory drugs (NSAIDs), we report on the design and synthesis of 4-(aryloyl)phenyl methyl sulfones. These substances were characterized for their capacity to inhibit cyclooxygenase (COX-1 and COX-2) isoenzymes. Molecular modeling studies showed that the methylsulfone group of these compounds was inserted deep in the pocket of the human COX-2 binding site, in an orientation that precludes hydrogen bonding with Arg120, Ser353, and Tyr355 through their oxygen atoms. The N-arylindole 33 was the most potent inhibitor of COX-2 and also the most selective (COX-1/COX-2 IC(50) ratio was 262). The indole derivative 33 was further tested in vivo for its anti-inflammatory activity in rats. This compound showed greater inhibitory activity than ibuprofen. Other compounds (20, 26, 9, and 30) showed strong activity against carrageenan-induced inflammation. The latter compounds showed a weak capacity to inhibit the proliferation of human cell lines K562, NCI-H460, and HT-29 in vitro.

Synthesis and biological evaluation of indomethacin analogs possessing a N-difluoromethyl-1,2-dihydropyrid-2-one ring system: A search for novel cyclooxygenase and lipoxygenase inhibitors

A novel class of indomethacin analogs were synthesized wherein a N-difluoromethyl-1,2-dihydropyrid-2-one moiety (5-LOX pharmacophore) was attached at its C-4 or C-5 position via either a C O ( 14a– b) or CH 2 ( 19a– b) linker to the indole N 1-position. In this regard, replacement of the 4-chlorobenzoyl group present in indomethacin by N-difluoromethyl-1,2-dihydropyrid-2-one-4-(or 5-)carbonyl and N-difluoromethyl-1,2-dihydropyrid-2-one-4-yl(or 5-yl)methylene moieties furnished compounds showing no inhibitory activities against the COX-2/5-LOX enzymes (except for the weak but selective COX-2 inhibitor 19a, COX-2 IC 50 = 31 μM), and moderate in vivo anti-inflammatory activities (except for the methylene compound 19a that was inactive). These structure–activity data indicate replacement of the 4-chlorobenzoyl group present in indomethacin by a N-difluoromethyl-1,2-dihydropyrid-2-one ring system connected by a C O or CH 2 linker is not a suitable approach for the design of dual COX-2/5-LOX inhibitory analogs of indomethacin.

Synthesis, biological evaluation, and docking studies of novel heterocyclic diaryl compounds as selective COX-2 inhibitors

Three novel series of diaryl heterocyclic derivatives bearing the 2-oxo-5 H-furan, 2-oxo-3 H-1,3-oxazole, and 1 H-pyrazole moieties as the central heterocyclic ring were synthesized and their in vitro inhibitory activities on COX-1 and COX-2 isoforms were evaluated using a purified enzyme assay. The 2-oxo-5 H-furan derivative 6b was identified as potent COX inhibitor with selectivity toward COX-1 (COX-1 IC 50 = 0.061 μM and COX-2 IC 50 = 0.325 μM; selectivity index (SI) = 0.19). Among the 1 H-pyrazole derivatives, 11b was found to be a potent COX-2 inhibitor, about 38 times more potent than Rofecoxib (COX-2 IC 50 = 0.011 μM and 0.398 μM, respectively), but showed no selectivity for COX-2 isoform. Compound 11c demonstrated strong and selective COX-2 inhibitory activity (COX-1 IC 50 = 1 μM, COX-2 IC 50 = 0.011 μM; SI = ∼92). Molecular docking studies of compounds 6b and 11b– d into the binding sites of COX-1 and COX-2 allowed to shed light on the binding mode of these novel COX inhibitors.

Design, synthesis and biological evaluation of new ( E)- and ( Z)-1,2,3-triaryl-2-propen-1-ones as selective COX-2 inhibitors

A group of ( E)-and ( Z)-1,2,3-triaryl-2-propen-1-one derivatives possessing a methylsulfonyl COX-2 pharmacophore at the para position of the C-1 phenyl ring were synthesized and evaluated as selective COX-2 inhibitors. In vitro COX-1/COX-2 structure–activity relationships were determined by varying the substituents on the C-3 propenone moiety. Among the 1,2,3-triaryl-2-propen-1-ones, ( Z)-1-(4-(methylsulfonyl)phenyl)-2,3-diphenylprop-2-en-1-one ( 3b) showed the most potency and selectivity on COX-2 inhibition (COX-2 IC 50 = 0.07 μM; selectivity index = 201). The Z-propenones were also found to be more potent and selective than their E-isomers for COX-2 inhibitory activity. The structure–activity data acquired indicate that the geometry of propenone and also the type of substituents on the C-3 propenone are important for COX-2 inhibitory activity.

Design, synthesis and biological evaluation of new 2,3-diarylquinoline derivatives as selective cyclooxygenase-2 inhibitors

A new group of 2,3-diarylquinoline derivatives possessing a methylsulfonyl COX-2 pharmacophore at the para-position of the C-2 phenyl ring were synthesized and evaluated as selective COX-2 inhibitors. In vitro COX-1/COX-2 structure–activity relationships were determined by varying the substituents on the C-4 quinoline ring. Among the 2,3-diarylquinolines, 2-(4-(methylsulfonyl) phenyl)-3-phenylquinoline-4-carboxylic acid ( 8) exhibited the highest potency and selectivity for COX-2 inhibitory activity (COX-2 IC 50 = 0.07 μM; selectivity index = 687.1) that was more selective than the reference drug celecoxib (COX-2 IC 50 = 0.06 μM; selectivity index = 405). A molecular modeling study where 8 was docked in the binding site of COX-2 indicated that the p-MeSO 2 COX-2 pharmacophore group on the C-2 phenyl ring is oriented in the vicinity of the COX-2 secondary pocket (Arg 513, Phe 518 and Val 523) and the carboxylic acid substituent can interact with Ser 530. The structure activity data acquired indicate that the size and nature of the C-4 quinoline substituent are important for COX-2 inhibitory activity.

Biological Evaluation of 2‐(4‐Amino‐Phenyl)‐3‐(3,5‐Dihydroxylphenyl) Propenoic Acid

2-(4-Aminophenyl)-3-(3,5-dihydroxylphenyl) propenoic acid (CSN-07001) is a new compound based on the combination of resveratrol and propenoic acid derivatives. In vitro cyclooxygenase (COX)/5-lipoxygenase (5-LOX) inhibition assays showed that the test compound exhibited a dual inhibitory activity against the COX (COX-1 IC(50) = 2.20 microM, COX-2 IC(50) = 1.76 microM) and 5-LOX (IC(50) = 0.28 microM) enzymes. Further, the enhanced COX-1/COX-2/5-LOX expression in lipopolysaccaride-induced lung inflammation in mice was also suppressed by CSN-07001 in a concentration-dependent manner. In vivo studies showed that CSN-07001 exhibited potent anti-inflammatory and antinociceptive effects in different experimental models. We further examined the risk of gastric damage induced by CSN-07001. The test compound was gastric-sparing in that it elicited markedly fewer stomach lesions than indomethacin in rats. Taken together, our data indicate that CSN-07001 exhibits a novel class of dual inhibitors of COX and 5-LOX having therapeutic potential as non-steroidal anti-inflammatory agents with an enhanced gastric safety profile.

Synthesis and biological evaluation of new 4-carboxyl quinoline derivatives as cyclooxygenase-2 inhibitors

A group of 4-carboxyl quinoline derivatives possessing a methylsulfonyl COX-2 pharmacophore at the para position of the C-2 phenyl ring were designed and synthesized as selective COX-2 inhibitors. In vitro COX-1/COX-2 structure–activity relationships were determined by varying the substituents on the C-7 and C-8 quinoline ring. Among the 4-carboxyl quinolines, 7,8,9,10-tetrahydro-2-(4-(methyl sulfonyl)phenyl)benzo[ h]quinoline-4-carboxylic acid ( 9e) was identified as potent and high selective COX-2 inhibitor (COX-2 IC 50 = 0.043 μM; selectivity index > 513) that was more potent than the reference drug celecoxib (COX-2 IC 50 = 0.060 μM; SI = 405). A molecular modeling study where 9e was docked in the binding site of COX-2 showed that the p-MeSO 2 substituent on the C-2 phenyl ring is oriented in the vicinity of the COX-2 secondary pocket (Arg513, Phe518 and Val523) and the carboxyl group can interact with Arg120. The structure activity data acquired indicate that the presence of lipophilic substituents on the C-7 and C-8 quinoline ring is important for COX-2 inhibitory activity.

Fenbufen based 3-[5-(substituted aryl)-1,3,4-oxadiazol-2-yl]-1-(biphenyl-4-yl)propan-1-ones as safer antiinflammatory and analgesic agents

The synthesis of a series of 3-[5-(substituted aryl)-1,3,4-oxadiazol-2-yl]-1-(biphenyl-4-yl)propan-1-ones derived from 4-oxo-4-(biphenyl-4-yl)butanoic acid (fenbufen) is described. The structures of these compounds were supported by IR, 1H NMR, mass spectrometric data and elemental analysis. These compounds were tested for their antiinflammatory, analgesic, ulcerogenic and lipid peroxidation actions. A few compounds were found to have very good antiinflammatory activity in carrageenan induced rat paw edema test, while a fair number of compounds showed significant analgesic activity in acetic acid induced writhing test. The newly synthesized compounds showed very low ulcerogenic action with reduced malondialdehyde (MDA) content, which is one of the byproducts of lipid peroxidation. In vitro COX-1 and COX-2 isozyme inhibition studies were also performed on some of the selected compounds. Compound 4i and 4h were found to be more selective towards COX-2 as indicated by COX-2 selectivity index of 36.06 and 29.05 (COX-2 IC 50 = 1.5 μM and 1.8 μM) respectively.

Preclinical pharmacology of robenacoxib: a novel selective inhibitor of cyclooxygenase‐2

This manuscript reports the results of preclinical studies in the rat with robenacoxib, a novel selective cyclooxygenase (COX)-2 inhibitor. Robenacoxib selectively inhibited COX-2 in vitro as evidenced from COX-1:COX-2 IC50 ratios of 27:1 in purified enzyme preparations and >967:1 in isolated cell assays. Binding to COX-1 was rapid and readily reversible (dissociation t(1/2) << 1 min), whilst COX-2 binding was slowly reversible (t(1/2) = 25 min). In vivo, robenacoxib inhibited PGE2 production (an index of COX-2 inhibition) in lipopolysaccharide (LPS)-stimulated air pouches (ID50 0.3 mg/kg) and for at least 24 h in zymosan-induced inflammatory exudate (at 2 mg/kg). Robenacoxib was COX-1 sparing, as it inhibited serum TxB2 synthesis ex vivo (an index of COX-1 inhibition) only at very high doses (100 mg/kg but not at 2-30 mg/kg). Robenacoxib inhibited carrageenan-induced paw oedema (ID50 0.40-0.48 mg/kg), LPS-induced fever (ID50 1.1 mg/kg) and Randall-Selitto pain (10 mg/kg). Robenacoxib was highly bound to plasma protein (99.9% at 50 ng/mL in vitro). After intravenous dosing, clearance was 2.4 mL/min/kg and volume of distribution at steady-state was 306 mL/kg. Robenacoxib was preferentially distributed into inflammatory exudate; the AUC for exudate was 2.9 times higher than for blood and the MRT in exudate (15.9 h) was three times longer than in blood (5.3 h). Robenacoxib produced significantly less gastric ulceration and intestinal permeability as compared with the reference nonsteroidal anti-inflammatory drug (NSAID), diclofenac, and did not inhibit PGE2 or 6-keto PGF(1alpha) concentrations in the stomach and ileum at 30 mg/kg. Robenacoxib also had no relevant effects on kidney function at 30 mg/kg. In summary, results of preclinical studies in rats studies suggest that robenacoxib has an attractive pharmacological profile for potential use in the intended target species, cats and dogs.

Effect of the oral absorption of benzenesulfonanilide-type cyclooxygenase-1 inhibitors on analgesic action and gastric ulcer formation

A benzensulfonanilide-type cyclooxygenase-1 (COX-1)-selective inhibitor, ZXX2-77: 4-amino-4′-chloro-N-methylbenzenesulfonanilide (4a), has been reported as a novel analgesic that does not cause gastric damage. This compound has a weak analgesic effect but has potent in vitro COX-1 inhibitory activity. Since the reason for the weak analgesic effect in vivo was thought to be the low rate of oral absorption, the blood concentration of ZXX2-77 (4a) was measured in rats. It was found that the Cmax value (1.2 µM) of ZXX2-77 (4a) at a dose of 30 mg/kg did not reach the COX-1 IC50 value (3.2 µM). On the other hand, ZXX2-79 (4b) (SO2NH derivative of ZXX2-77 (4a); 4-amino-4′-chlorobenzenesulfonanilide), which shows less potent COX inhibitory activities (COX-1 IC50 = 12 µM, COX-2 IC50 = 150 µM) than those of ZXX2-77 (4a) in vitro, was found to be more absorbable (Cmax = 16 µM at a dose of 30 mg/kg in rats) than ZXX2-77 (4a). Furthermore, ZXX2-79 (4b) not only showed a potent analgesic effect in a formalin test but also caused little gastric damage. These findings indicate that demethylated sulfonamide compounds are more easily absorbed than are N-methylated sulfonamide compounds and suggest that COX-1-selective inhibitors will be useful as analgesics that do not cause gastric damage. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci

Cyclooxygenase-1-Selective Inhibitors Are Attractive Candidates for Analgesics That Do Not Cause Gastric Damage. Design and in Vitro/in Vivo Evaluation of a Benzamide-Type Cyclooxygenase-1 Selective Inhibitor

Although cyclooxygenase-1 (COX-1) inhibition is thought to be a major mechanism of gastric damage by nonsteroidal anti-inflammatory drugs (NSAIDs), some COX-1-selective inhibitors exhibit strong analgesic effects without causing gastric damage. However, it is not clear whether their analgesic effects are attributable to COX-1-inhibitory activity or other bioactivities. Here, we report that N-(5-amino-2-pyridinyl)-4-(trifluoromethyl)benzamide ( 18f, TFAP), which has a structure clearly different from those of currently available COX-1-selective inhibitors, is a potent COX-1-selective inhibitor (COX-1 IC 50 = 0.80 +/- 0.05 microM, COX-2 IC 50 = 210 +/- 10 microM). This compound causes little gastric damage in rats even at an oral dose of 300 mg/kg, though it has an analgesic effect at as low a dose as 10 mg/kg. Our results show that COX-1-selective inhibitors can be analgesic agents without causing gastric damage.

Effect of acetaminophen, a cyclooxygenase inhibitor, on Morris water maze task performance in mice

Although the mechanism of action of acetaminophen (AAP) is not fully understood, some studies suggest that AAP and phenacetin (PHE) are selective cyclooxygenase (COX)-3 inhibitors. To examine the participation of COX-3 in memory formation, water maze performance was studied in mice treated with AAP, PHE or other COX inhibitors. Mice received intraperitoneal injections of drugs immediately after each training session. Administration of high-dose AAP [302.3 mg/kg (IC50 for COX-2)] or PHE [179.2 mg/kg (IC50 for COX-2)] and of non-specific (indomethacin: 20 mg/kg) or specific COX-2 (NS-398: 10 mg/kg) inhibitor impaired the performance in hidden platform (HP) not visible platform (VP) tasks, whereas low-dose (15.1 mg/kg) AAP facilitated performance in HP and VP tasks. The facilitation of performance by low-dose AAP was reversed by co-administration with a 5-HT(1/2) receptor antagonist (methysergide: 0.47 mg/kg). The middle-dose [69.5 mg/kg (IC50 for COX-3)] of AAP, the PHE [17.9 mg/kg (IC50 for COX-3)] and a specific COX-1 inhibitor (piroxicam: 10-20 mg/kg) did not influence performance in either task. These results suggest that the memory impairment by high-dose AAP and PHE and facilitation of performance by low-dose AAP could involve endogenous COX-2 and serotonergic neuronal activity, but not COX-3, respectively.

Synthesis and biological evaluation of methanesulfonamide analogues of rofecoxib: Replacement of methanesulfonyl by methanesulfonamido decreases cyclooxygenase-2 selectivity

A new group of 3-(4-substituted-phenyl)-4-(4-methylsulfonamidophenyl)-2(5 H)furanones in which the methylsulfonyl (MeSO 2) COX-2 pharmacophore present in rofecoxib was replaced by a methanesulfonamido (MeSO 2NH) moiety, and where the substituent at the para-position of the C-3 phenyl ring was simultaneously varied (H, F, Cl, Br, Me, OMe), were evaluated to determine the combined effects of steric and electronic substituent properties upon COX-1 and COX-2 inhibitory potency and COX isozyme selectivity. Structure–activity relationship (SAR) studies showed that compounds having a neutral (H), or electronegative halogen (F, Cl, Br), substituent at the para-position of the C-3 phenyl ring inhibited both COX-1 and COX-2 with COX-2 selectivity indexes in the 3.1–39.4 range. In contrast, compounds having an electron-donating Me or OMe substituent were selective inhibitors of COX-2 (COX-1 IC 50 > 100 μM). These SAR data indicate the 3-aryl-4-(4-methylsulfonamidophenyl)-2(5 H)furanone scaffold provides a suitable template to design COX inhibitors with variable COX-2 selectivity indexes.

Synthesis and biological evaluation of a novel class of rofecoxib analogues as dual inhibitors of cyclooxygenases (COXs) and lipoxygenases (LOXs)

A group of 4-(4-methanesulfonylphenyl)-3-phenyl-2(5H)furanones possessing an acetyl, 3-oxobut-1-ynyl, [hydroxyl(or alkoxy)imino]alkyl, [hydroxyl(or alkoxy)imino]alkynyl, and N-alkoxy(or N-phenoxy)carbonyl-N-hydroxy-N-ethylamino substituents at the para-position of the C-3 phenyl ring of rofecoxib were synthesized. This group of compounds was designed for evaluation as dual inhibitors of cyclooxygenases (COXs) and lipoxygenases (LOXs) that exhibit in vivo anti-inflammatory and analgesic activities. In vitro COX-1/COX-2, and 5-LOX/15-LOX, isozyme inhibition structure–activity relationships identified 3-[4-(1-hydroxyimino)ethylphenyl]-4-(4-methanesulfonylphenyl)-2(5H)furanone (17a) having an optimal combination of COX-2 (COX-2 IC50=1.4μM; COX-2 SI>71), and 5-LOX and 15 LOX (5-LOX IC50=0.28μM; 15-LOX IC50=0.32μM), inhibitory effects. It was also discovered that 3-[4-(3-hydroxyiminobut-1-ynyl)phenyl]-4-(4-methanesulfonylphenyl)-2(5H)furanone (18a) possesses dual COX-2 (IC50=2.7μM) and 5-LOX (IC50=0.30μM) inhibitor actions. Further in vivo studies employing a rat carrageenan-induced paw edema model showed that the oxime compounds (17a, 18a) were more potent anti-inflammatory agents than the 5-LOX inhibitor caffeic acid, and 15-LOX inhibitor nordihydroguaiaretic acid (NDGA), but less potent than the selective COX-2 inhibitor celecoxib. The results of this investigation showed that incorporation of a para-oxime moiety on the C-3 phenyl ring of rofecoxib provides a suitable template for the design of dual inhibitors of the COX and LOX enzymes.

Design and synthesis of new water-soluble tetrazolide derivatives of celecoxib and rofecoxib as selective cyclooxygenase-2 (COX-2) inhibitors

In an attempt to prepare a new water-soluble, parenteral COX-2 inhibitor, rofecoxib ( 9) and celecoxib ( 13) analogues were designed and synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors with in vivo anti-inflammatory activity. In this experiment, respective SO 2Me and SO 2NH 2 hydrogen-bonding pharmacophores were replaced by a tetrazole ring. Molecular modeling (docking) studies showed that the tetrazole ring of these two analogues ( 9 and 13) was inserted deep into the secondary pocket of the human COX-2 binding site where it undergoes electrostatic interaction with Arg 513. The rofecoxib ( 9) and celecoxib ( 13) analogues exhibited a high in vitro selectivity ( 9, COX-1 IC 50 = 3.8 nM; COX-2 IC 50 = 1.8 nM; SI = 2.11; 13, COX-1 IC 50 = 4.1 nM; COX-2 IC 50 = 1.9 nM; SI = 2.16) relative to the reference drug celecoxib (COX-1 IC 50 = 3.7 nM; COX-2 IC 50 = 2.2 nM; SI = 1.68) and also showed high aqueous solubility at pH higher than 7 and good anti-inflammatory activity in a carrageenan-induced rat paw edema assay. However, 9 and 13 had no significant damage on gastric mucosa.