Carrageenan-induced Rat Paw Edema Assay Research Articles

Synthesis of 1-(4-aminosulfonylphenyl)-3,5-diarylpyrazoline derivatives as potent antiinflammatory and antimicrobial agents

A new series of 1-(4-aminosulfonylphenyl)-3,5-diaryl pyrazolines (5) was synthesized by the reaction of appropriate chalcones 3 with 4-hydrazinobenzenesulfonamide hydrochloride (4) in ethanol in the presence of catalytic amount of acetic acid. All newly synthesized compounds were in vivo evaluated for their antiinflammatory activity using carrageenan-induced rat paw edema assay. Five of the newly synthesized compounds, 5d, 5g, 5h, 5i, and 5m displayed significant antiinflammatory activity, greater than 55% inhibition 3 h after the carrageenan injection. All the newly synthesized compounds were evaluated for their in vitro antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis); two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and two yeast (Candida albicans and Saccharomyces cerevisiae). Some of the newly synthesized compounds 5a, 5f, 5g, 5h, 5j, and 5k showed excellent antifungal activity, greater than the reference drug amphotericin B, against Saccharomyces cerevisiae.

Analogue-based design, synthesis and molecular docking analysis of 2,3-diaryl quinazolinones as non-ulcerogenic anti-inflammatory agents

In our effort to identify potent gastric sparing anti-inflammatory agents, a series of methyl sulfanyl/methyl sulfonyl substituted 2,3-diaryl quinazolinones were designed by analogue-based design strategy and synthesized for biological evaluation. Subsequently, the compounds were evaluated for both cyclooxygenase inhibitions by ovine COX assay and carrageenan-induced rat paw edema assay. All the methyl sulfonyl substituted quinazolinones were exhibited promising anti-inflammatory activity. In particular, 6-bromo-3-(4-methanesulfonyl-phenyl)-2-phenyl-3 H-quinazolin-4-one ( 18), 7-chloro-3-(4-methanesulfonyl-phenyl)-2-phenyl-3 H-quinazolin-4-one ( 19), 3-(4-methanesulfonyl-phenyl)-2-(4-methoxy-phenyl)-3 H-quinazolin-4-one ( 21) and 6-bromo-3-(4-methanesulfonyl-phenyl)-2-(4-methoxy-phenyl)-3 H-quinazolin-4-one ( 22) emerged as the most active compounds in the series. The results of ulcerogenic activity assay suggest that these compounds are gastric safe compared to indomethacin. The molecular docking analysis was performed to understand the binding interactions of these compounds to COX-2 enzyme. The results from the present investigation suggests that 2,3-diaryl quinazolinones as a promising template for the design of new gastric safe anti-inflammatory agents, which can be further explored for potential anti-inflammatory activity.

Synthesis of N-arylidene-2-(2-Phenoxyphenyl) Acetohydrazides as Anti-Inflammatory Agents.

Diclofenac sodium has been used for its anti-inflammatory actions for about 28 years, but since all the non-steroidal anti-inflammatory drugs (NSAIDs) suffer from the lethal gastro intestinal (GI) toxicities, diclofenac sodium is not an exception. The free -COOH group is thought to be responsible for the GI toxicity associated with all traditional NSAIDs. In the present research, the main motto was to develop new chemical entities as potential anti-inflammatory agents with no GI toxicities. A new type of 2-(2-phenoxyphenyl) acetohydrazide possessing N-arylidene substituents, was synthesized for evaluation as anti-inflammatory agents. The starting material 2-(2-Phenoxyphenyl) acetohydrazide was synthesized from 2-phenoxybenzoic acid in several steps according to the previous published method. Various substituted arylidene-2-phenoxynicotinic acid hydrazide derivatives were synthesized by the reaction of hydrazide 17 with selected aldehydes and screened for their potential anti-inflammatory activity. The structure of synthesized compounds was confirmed by different nuclear magnetic resonance technique, Fourier transform infrared spectroscopy (FTIR) and Mass-spectrometry data format. Qualitative structure-activity relationship data, acquired using the carrageenan-induced rat paw edema assay, showed that this group of arylidene-2-phenoxybenzoic acid hydrazides exhibit anti-inflammatory activity with significant reduction of rat paw edema (17-58% reduction in inflammation at different time intervals) in comparison with control group and a moderate to good activity range in comparison with diclofenac as the reference drug. Compounds 9a, 9d and 9e exhibited the most prominent and consistent anti-inflammatory activity. The compound, N-(4-Chlorobenzylidene)-2-(2-phenoxyphenyl) acetohydrazide (9d), exhibited the most in-vivo activity (32-58% reduction in inflammation) compared to the reference drug diclofenac (35-74% reduction in inflammation) in a carrageenan induced rat paw-edema assay.

Analgesic, anti-inflammatory and anti-platelet activities of the methanolic extract of Acacia modesta leaves

The current study was aimed to evaluate Acacia modesta for analgesic, anti-inflammatory, and anti-platelet activities. The analgesic and anti-inflammatory effects were assessed in rodents using acetic acid and formalin-induced nociception, hot plate and carrageenan-induced rat paw oedema tests. The intraperitoneal (i.p.) administration of the methanolic extract (50 and 100 mg/kg) produced significant inhibition (P\0.01) of the acetic acid-induced writhing in mice and suppressed formalin-induced licking response of animals in both phases of the test. In the hot plate assay the plant extract (100 mg/kg) increased pain threshold of mice. Naloxone (5 mg/kg i.p.) partially reversed the analgesic effect of the extract in formalin and hot plate tests.A. modesta (100 and 200 mg/kg i.p.) exhibited sedative effect in barbiturate-induced hypnosis test similar to that produced by diazepam (10 mg/kg i.p.). The plant extract(50-200 mg/kg i.p.) produced marked anti-inflammatory effect in carrageenan-induced rat paw oedema assay comparable to diclofenac and produced a dose-dependent(0.5-2.5 mg/mL) inhibitory effect against arachidonic acid induced platelet aggregation. These data suggest that A. modesta possesses peripheral analgesic and antiinflammatory properties, with analgesic effects partially associated with the opioid system.

Synthesis and anti-inflammatory evaluation of some pyrazolo[3,4-b]pyridines

Novel series of pyrazolo[3,4-b]pyridines with basic skeleton different from the known COX inhibitors were synthesized from 5-amino-1-[4-(aminosulfonyl)phenyl]-3-phenyl-1H-pyrazole, which in turn was prepared by the condensation of (4-sulfamoylphenyl)hydrazine with α-cyanoacetophenone. All the newly synthesized compounds were tested for their in vivo anti-inflammatory activity by carrageenan-induced rat paw edema assay. Some of the most potent compounds were evaluated in different COX and LOX assays. Some of the new compounds were found to possess moderate anti-inflammatory activity.

Synthesis and biological evaluation of some pyrazolylpyrazolines as anti-inflammatory–antimicrobial agents

A new series of pyrazolylpyrazolines ( 5a– k) was synthesized by the reaction of appropriate chalcones ( 3a– k) with 4-hydrazinobenzenesulfonamide hydrochloride ( 4) in ethanol. All the newly synthesized target compounds ( 5a– k) were screened for their anti-inflammatory activity using carrageenan-induced rat paw edema assay. Compounds 5g and 5j showed pronounced anti-inflammatory activity comparable to the reference standard nimesulide, whereas, compounds 5b, 5d and 5h displayed good anti-inflammatory activity. Additionally, the synthesized compounds were evaluated for their in vitro antimicrobial activity against two Gram-positive bacteria and two Gram-negative bacteria. Four compounds 5c, 5h– 5j showed good broad spectrum activity against all the tested Gram-positive and Gram-negative bacterial strains. Compound 5j could be identified as the most biologically active member within this study with an interesting dual anti-inflammatory and antibacterial profile.

Ring opening of phthalimide derivatives with benzylamine: Formation of carboxamides and their pharmacological evaluation

The ring opening of phthalimide derivatives viz N-cyclopentylphthalimide (1a), N-benzylphthalimide (1b), N-prop-2-ynylphthalimide (1c), 1-phthloylamino-3-[4-(2-methoxyphenyl)-piperizin-1-yl]-propane(1d) and 1-phthloylamino-4-[4-(2-methoxyphenyl)-piperizin-1-yl]-butane (1e) was accomplished using benzylamine in dimethylformamide (DMF) at room temperature to afford the corresponding carboxamides: benzamido-cyclopentane-2-(N-benzyl)-carboxamide (3a) benzamido-1-phenylmethylene-2-(N-benzyl)-carboxamide (3b) and 3-benzamido-prop-2-yne-2-(N-benzyl)- carboxamide (3c) and were unequivocally characterized by infrared, nuclear magnetic resonance, mass spectrometer and elemental analyses. The products obtained were screened for antiinflammatory and analgesic properties using carrageenan-induced rat paw oedema assay and acetic acid-induced writhing test, respectively. The most active compound was 3b for the antiinflammatory activity assay and for the analgesic activity test the most active compound was 3a. The activities were dose-dependent. All the compounds tested showed better analgesic activity than acetylsalicylic acid.

Design, synthesis, and biological evaluation of substituted 2-alkylthio-1,5-diarylimidazoles as selective COX-2 inhibitors

A new type of 1-aryl-5-(4-methylsulfonylphenyl)imidazoles, possessing C-2 alkylthio (SMe or SEt) substituents, were designed and synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors with in vivo anti-inflammatory activity. The compound, 1-(4-bromophenyl)-5-(4-methylsulfonylphenyl)-2-methylthioimidazole ( 11g), was the most potent and selective COX-2 inhibitor (COX-2 IC 50 = 0.43 μM with no inhibition of COX-1 up to 25 μM) relative to the reference drug celecoxib (COX-2 IC 50 = 0.21 μM with no inhibition of COX-1 up to 25 μM) and also showed very good anti-inflammatory activity compared to celecoxib in carrageenan-induced rat paw edema assay.

Synthesis and anti-inflammatory activity of 2,3-diaryl-4(3H)-quinazolinones

2,3-Diaryl-4(3H)-quinazolinones containing various substituents on diaryl rings have been synthesized and evaluated for their cyclooxygenase-2 inhibitory activity by the colorimetric COX (ovine) inhibitor screening assay and anti-inflammatory activity by the carrageenan-induced rat paw edema assay. 2-(4-Nitrophenyl)-3-(4-tolyl)-4(3H)-quinazolinone showed a maximum COX-2 inhibition of 27.72% at 22 µM concentration in the present series and exhibited a mild anti-inflammatory activity at a dose of 50 mg/kg in carrageenan-induced rat paw edema assay.

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.

Design, synthesis, and biological evaluation of substituted 3-alkylthio-4,5-diaryl-4 H-1,2,4-triazoles as selective COX-2 inhibitors

A new type of 4,5-diaryl-4 H-1,2,4-triazole, possessing C-3 thio and alkylthio (SH, SMe or SEt) substituents, was designed and synthesized for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors with in vivo anti-inflammatory activity. The compound, 3-ethylthio-5-(4-fluorophenyl)-4-(4-methylsulfonylphenyl)-4 H-1,2,4-triazole ( 10d), exhibited a high in vitro selectivity (COX-1 IC 50 = 20.5 nM; COX-2 IC 50 = 1.8 nM; SI = 11.39) 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 good anti-inflammatory activity compared to celecoxib in a carrageenan-induced rat paw edema assay.

Design, synthesis, and biological evaluation of linear 1-(4-, 3- or 2-methylsulfonylphenyl)-2-phenylacetylenes: A novel class of cyclooxygenase-2 inhibitors

A group of regioisomeric 1-(methylsulfonylphenyl)-2-phenylacetylenes possessing a COX-2 SO 2Me pharmacophore at the para-, meta- or ortho-position of the C-1 phenyl ring, in conjunction with a C-2 phenyl or substituted-phenyl ring substituent (3-F, 3-OMe, 3-OH, 3-OAc, 4-Me), were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. These target linear 1,2-diarylacetylenes were synthesized via a palladium-catalyzed Sonogashira cross-coupling reaction followed by oxidation of the respective 1-(methylthiophenyl)-2-phenylacetylene intermediate. In vitro COX-1/COX-2 isozyme inhibition structure–activity studies identified 1-(3-methylsulfonylphenyl)-2-(4-methylphenyl)acetylene ( 12d) as a potent COX-2 inhibitor (IC 50 = 0.32 μM) with a high COX-2 selectivity index (SI > 320) comparable to the reference compound rofecoxib (COX-2 IC 50 = 0.50 μM; COX-2 SI > 200). A molecular modeling study where ( 12d) was docked in the binding site of COX-2 showed that the MeSO 2 COX-2 pharmacophore was positioned in the vicinity of the secondary COX-2 binding site near Val 523. The 1-(4-methylsulfonylphenyl)-2-(3-acetoxyphenyl)acetylene ( 11f, COX-1 IC 50 = 1.00 μM; COX-2 IC 50 = 0.06 μM; COX-2 SI = 16.7) and 1-(3-methylsulfonylphenyl)-2-(3-acetoxyphenyl)acetylene ( 12f, COX-1 IC 50 = 6.5 μM; COX-2 IC 50 = 0.05 μM; COX-2 SI = 130) regioisomers exhibited comparable COX-2 inhibition, and moderately lower selective COX-2 selectivity, relative to the reference drug celecoxib (COX-1 IC 50 = 33.1 μM; COX-2 IC 50 = 0.07 μM; COX-2 SI = 472). The most potent anti-inflammatory agent 1-(3-methylsulfonylphenyl)-2-(4-methylphenyl)acetylene ( 12d) exhibited moderate oral anti-inflammatory activity (ED 50 = 129 mg/kg) at 3 h postdrug administration relative to the reference drug celecoxib (ED 50 = 10.8 mg/kg) in a carrageenan-induced rat paw edema assay. The structure–activity data acquired indicate that the acetylene moiety constitutes a suitable scaffold (template) to design novel acyclic 1,2-diarylacetylenes with selective COX-2, or dual COX-1/COX-2, inhibitory activities.

Design, synthesis, and biological evaluation of N-acetyl-2-(or 3-)carboxymethylbenzenesulfonamides as cyclooxygenase isozyme inhibitors

A group of N-acetyl-2-(or 3-)carboxymethylbenzenesulfonamides, possessing either a F or a substituted-phenyl ring substituent (4-F, 2,4-F 2, 4-SO 2Me, 4-OCHMe 2) attached to its C-4 or C-6 position, was prepared using a palladium-catalyzed Suzuki cross-coupling reaction for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. Although N-acetyl-3-carboxymethyl-6-fluorobenzenesulfonamide [ 14, COX-1 IC 50 = 2.26 μM; COX-2 IC 50 = 0.012 μM; COX-2 selectivity index (SI) = 188] and N-acetyl-3-carboxymethyl-6-(4-isopropoxyphenyl)benzenesulfonamide ( 20c, COX-1 IC 50 >100 μM; COX-2 IC 50 = 0.15 μM; COX-2 SI >667) exhibited potent in vitro COX-2 inhibitory activity and high COX-2 selectivity, both compounds were inactive anti-inflammatory agents in a carrageenan-induced rat paw edema assay. In contrast, the less potent and less selective COX-2 inhibitors N-acetyl-2-carboxymethyl-4-fluorobenzenesulfonamide ( 12, COX-1 IC 50 = 4.25 μM; COX-2 IC 50 = 0.978 μM; COX-2 SI = 4.3), N-acetyl-2-carboxymethyl-4-(2,4-difluorophenyl)benzenesulfonamide ( 17c, COX-1 IC 50 = 1.02 μM; COX-2 IC 50 = 1.00 μM; COX-2 SI = 1.02), and N-acetyl-3-carboxymethyl-6-(4-methanesulfonylphenyl)benzenesulfonamide ( 20e, COX-1 IC 50 = 0.109 μM; COX-2 IC 50 = 1.14 μM; COX-2 SI = 0.095) exhibited moderate anti-inflammatory activity where a 75 mg/kg oral dose reduced inflammation 26%, 14%, and 20%, respectively, at 3 h postdrug administration relative to the reference drug aspirin where a 50 mg/kg oral dose reduced inflammation by 25% at 3 h postdrug administration.

Anti-inflammatory and analgesic properties of water–ethanolic extract from Pothomorphe umbellata (Piperaceae) aerial parts

Anti-inflammatory and analgesic activities as well as the median lethal dose (LD 50) of water–ethanolic extract (PHE) of the aerial parts of Pothomorphe umbellata were evaluated in animal models. The ED 50 (oral) for the inhibition of carrageenan-induced rat paw edema assay was determined to be 550 mg/kg, while the LD 50 was higher than 2.0 g/kg. At a dose of 550 mg/kg, PHE inhibited the inflammatory process by 48.7% ( P < 0.05) on the third hour of the assay (edema peak) when compared to the untreated control. Indomethacin, the positive control used in this test, inhibited the edema by 58.6% at a dose of 10 mg/kg, when compared to the untreated control ( P < 0.05). All three fractions – hexane, methylene chloride and ethyl acetate – obtained by partition of PHE with respective solvents also showed inhibition of the edema induced by carrageenan over a period of 4 h but the methylene chloride fraction showed the best activity. The activity shown by the methylene chloride fraction at 200 mg/kg was comparable to that exhibited by indomethacin at a dose of 10 mg/kg. The number of writhings induced by a 0.6% acetic acid solution intraperitoneal injection was decreased by 22% ( P < 0.05) in the group treated orally with Pothomorphe umbellata crude extract. PHE also inhibited the granulomatous tissue formation in rats by 6.2% ( P < 0.05). In the same assay, topically applied dexamethasone decreased the granuloma formation by 14.2%. The above results suggest that Pothomorphe umbellata crude extract has analgesic and anti-inflammatory properties supporting its folkloric use for the treatment of these conditions.

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 2Me, 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 = 0.06 μM; COX-2 IC 50 = 0.25 μM) than aspirin (COX-1 IC 50 = 0.35 μM; COX-2 IC 50 = 2.4 μM), 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 = 0.087 μM; COX-2 S.I. >1149), or C-5 (COX-2 IC 50 = 0.77 μM, 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 = 33.1 μM; COX-2 IC 50 = 0.07 μM; 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 2NHCOCH 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 2NHCOCH 3 pharmacophore present in N-acetyl-2-carboxybenzenesulfonamides is a suitable bioisostere for the acetoxy (OCOMe) group in aspirin.

A New Class of Acyclic 2-Alkyl-1,1,2-Triaryl (Z)-Olefins as Selective Cyclooxygenase-2 Inhibitors

A new class of acyclic (Z)-2-alkyl-1,2-diphenyl-1-(4-methanesulfonylphenyl)ethenes (7) was designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1 and COX-2 isozyme inhibition structure-activity studies identified (Z)-1,2-diphenyl-1-(4-methanesulfonylphenyl)oct-1-ene (7d) as a potent COX-2 inhibitor (IC(50) = 0.42 microM) with a high COX-2 selectivity index (SI > 234). In a carrageenan-induced rat paw edema assay, (Z)-7d exhibited excellent antiinflammatory activity (ID(50) = 1.1 mg/kg). The molecular modeling and structure-activity data acquired indicate that (Z)-olefins having cis C-1 4-methanesulfonylphenyl and C-2 unsubstituted phenyl (or 4-acetoxyphenyl) substituents in conjunction with a C-1 phenyl ring and a C-2 alkyl substituent of appropriate length constitute a suitable template for the design of a novel class of acyclic (Z)-2-alkyl-1,1,2-triaryleth-1-ene COX-2 inhibitors.

Design, synthesis, and structure-activity relationship studies of 3,4,6-triphenylpyran-2-ones as selective cyclooxygenase-2 inhibitors.

A group of regioisomeric 3,4,6-triphenylpyran-2-ones with a MeSO(2) pharmacophore at the para-position of either a C-3 phenyl or a C-4 phenyl substituent on the central six-membered pyran-2-one ring were prepared and evaluated in vitro for their abilities to inhibit the isozymes COX-1 and COX-2. Structure-activity relationship (SAR) data, acquired by substituent modification at the para-position of the C-6 phenyl ring attached to the central pyranone, showed that 6-(4-methoxyphenyl)-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-one (12e) was the most potent and selective COX-2 inhibitor (COX-2 IC(50) = 0.02 microM; COX-1 IC(50) > 100 microM) with a high COX-2 selectivity index (SI > 5000) relative to the reference drugs celecoxib (COX-2 IC(50) = 0.07 microM; SI = 474) and rofecoxib (COX-2 IC(50) = 0.50 microM; SI > 200). 6-(4-Methoxyphenyl)-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-one (12e) was a more potent oral antiinflammatory agent (ID(50) = 5.6 mg/kg) than celecoxib (ID(50) = 10.8 mg/kg) in a carrageenan-induced rat paw edema assay. In a 4% NaCl-induced abdominal constriction assay, a 5 mg/kg oral dose of 12e exhibited good analgesic activity at different time intervals producing 37.5 and 69% inhibition of writhing at 30 and 60 min, respectively. In contrast, the corresponding 6-(4-methoxyphenyl)-4-(4-methanesulfonylphenyl)-3-phenylpyran-2-one regiosiomer (12o) was a less potent and selective COX-2 inhibitor (COX-2 IC(50) = 0.45 microM; SI = 70). A molecular modeling study for 12e indicated that the p-OMe substituent on the C-6 phenyl ring interacts with the COX-2 binding site amino acids Ile(345), Val(349), Leu(359), Leu(531), and Met(535) and that the OMe substituent may be responsible for proper orientation of the C-3 p-SO(2)Me-phenyl ring within the COX-2 secondary pocket (Gln(192), Arg(513), and Phe(518)). These results show that the COX-2 selectivity and potency of 3,4,6-triphenylpyranone regioisomers can be modulated by appropriate placement of the p-SO(2)Me pharmacophore on either the C-3 or C-4 phenyl moiety. In addition, electronic properties at the para-position of a C-6 phenyl substituent on the central pyranone ring govern COX-2 inhibitory potency and selectivity by controlling the orientation of the p-SO(2)Me pharmacophore within the COX-2 secondary pocket.

Design, synthesis, and biological evaluation of 6-substituted-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-ones: a novel class of diarylheterocyclic selective cyclooxygenase-2 inhibitors.

A group of 6-alkyl (alkoxy or alkylthio)-4-aryl-3-(4-methanesulfonylphenyl)pyran-2-ones (14a-v), possessing either a H or F substituent at the para-position of the C-4 phenyl ring, were designed for evaluation as selective cyclooxygenase-2 (COX-2) inhibitors with in vivo antiinflammatory-analgesic activities. Although 6-ethylthio-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-one (14s) exhibited a very high in vitro COX-2 inhibitory potency (IC(50) = 0.0032 muM) and COX-2 selectivity (SI > 120 000), 14s exhibited moderate antiinflammatory activity compared to celecoxib in a carrageenan-induced rat paw edema assay. In contrast, the less potent (IC(50) = 0.10 muM), and less selective (SI = 2880) COX-2 inhibitor 6-ethoxy-3-(4-methanesulfonylphenyl)-4-phenylpyran-2-one (14i) exhibited good antiinflammatory activity where a 1 mg/kg oral dose reduced inflammation 32 and 67% at 3 and 5 h postdrug administration relative to the reference drug celecoxib where a 50 mg/kg oral dose reduced inflammation by 79 and 58% at the respective 3 and 5 h time periods. Molecular modeling studies, where 14i was docked in the active site of both COX-1 and COX-2, reveals that the C-6 ethoxy substituent orients the pyran-2-one ring to position the SO(2)Me pharmacophore in the vicinity of the secondary pocket in COX-2. The absence of this COX-2 secondary pocket in the COX-1 binding site is due to the presence of the bulky Ile(523) in COX-1 such that access to the amino acid residues (Ile(517), Phe(518), Gln(192), and His(90)), which line the COX-2 secondary pocket with which the SO(2)Me pharmacophore could interact, is hindered. The six-membered pyran-2-one ring system is a suitable central template to design selective COX-2 inhibitors.

3‐O‐Substituted Benzyl Pyridazinone Derivatives as COX Inhibitors.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Design, syntheses, and evaluation of 2,3‐diphenylcycloprop‐2‐en‐1‐ones and oxime derivatives as potential cyclooxygenase‐2 (COX‐2) inhibitors with analgesic‐antiinflammatory activity

AbstractA group of 2,3‐diphenylcycloprop‐2‐enes having a variety of substituents at the para‐position of the C‐2 phenyl ring (H, F), and C‐3 phenyl ring (H, F, SMe, SOMe, SO2Me), in conjunction with either a C‐1 carbonyl, oxime, oxime acetate, benzoyl hydrazone, or hydrogen substituent were synthesized for in vivo evaluation as analgesic and antiinflammatory (AI) agents, and as potential selective cyclooxygenase‐2 (COX‐2) inhibitors. This group of cycloprop‐2‐ene compounds exhibited significant analgesic activity, since 4% NaCl‐induced abdominal constriction was reduced by 43–90% at 30 min, and 41–100% at 60 min, after drug administration relative to the reference drugs aspirin and celecoxib (58% and 32% inhibition at 30 min after drug administration) for a 50 mg/kg intraperitoneal dose. AI activities, determined using the carrageenan‐induced rat paw edema assay, showed that this class of cycloprop‐2‐ene compounds exhibited AI activities in the inactive‐to‐modest activity range (0–26% inhibition) for a 50 mg/kg oral dose. The AI potency order for a group of 2,3‐diphenylcycloprop‐2‐enes with respect to the C‐1 substituent was oxime&gt;hydrogen&gt;carbonyl&gt;benzoyl hydrazone. 2,3‐Diphenylcycloprop‐2‐en‐1‐one oxime (20) was the most active AI agent, inducing a 26% reduction in inflammation, relative to the reference drugs ibuprofen and celecoxib, which showed 52% and 58% reductions in inflammation, at 5 h after drug administration. In vitro COX‐1 and COX‐2 inhibition studies showed that 2,3‐diphenylcycloprop‐2‐en‐1‐one oxime (20) is a selective COX‐2 inhibitor (COX‐1 IC50&gt;100 μM; COX‐2 IC50=2.94 μM; COX‐2 selectivity index&gt;34). A molecular modeling study that docked the oxime (20) in the active site of the human COX‐2 isozyme showed that it binds in the vicinity of the mouth of the COX‐2 binding site with the O‐atom of the oxime (=N–OH) moiety separated from the NH2 group of Arg120 by about 3.65 Å. This orientation of the oxime compound (20) in the COX‐2 binding site could be due to a potentially strong ionic interaction between the =NOH oxime moiety and the guanidinium moiety of Arg120. Drug Dev. Res. 57:6–17, 2002. © 2002 Wiley‐Liss, Inc.