Design,synthesis and biological screening of some novel celecoxib and etoricoxib analogs with promising COX-2 selectivity,anti-inflammatory activity and gastric safety profile

Two new series of 4,6-diaryl-3-cyanopyridine 4a-r and 1,3,5-triaryl-2-pyrazolines 6a-f and were prepared. The new compounds were evaluated for their in vitro COX-2 selectivity and in vivo anti-inflammatory activity. Compounds 4o,r and 6d,f had moderate to high selectivity index (S.I.) compared to celecoxib (selectivity indexes of 4.5, 3.14, 4.79 and 3.21, respectively) and also, showed in vivo anti-inflammatory activity approximately equal to or higher than celecoxib (edema inhibition % = 60.5, 64.5, 59.3 and 59.3, after 3 h, respectively) and the effective anti-inflammatory doses were (ED₅₀ = 10.1, 7.8, 8.46 and 10.7 mg/kg respectively, celecoxib ED₅₀ = 10.8 mg/kg) and ulcerogenic liability were determined for these compounds which showed promising activity by being more potent than celecoxib with nearly negligible ulcerogenic liability compared to celecoxib (reduction in ulcerogenic liability versus celecoxib = 85, 82, 74 and 67%, respectively).     

Design,synthesis, cyclooxygenase inhibition and biological evaluation of new 1,3,5-triaryl-4,5-dihydro-1H-pyrazole derivatives possessing amino/methanesulfonyl pharmacophore

A new series of 1,3,5-triaryl-4,5-dihydro-1H-pyrazole 10a–l was designed and synthesized via cyclization of chalcones 8a–f with 4-amino/methanesulfonylphenylhydrazine hydrochloride 9a–b. All the synthesized compounds were evaluated for their cyclooxygenase (COX) inhibition, anti-inflammatory activity, ulcerogenic liability and analgesic activity. All compounds were more COX-2 inhibitors than COX-1. While most compounds showed good anti-inflammatory activity, the trimethoxy derivatives (10a, 10b, 10g and 10h) were the most potent derivatives (ED₅₀ = 55.78, 53.99, 67.65 and 69.20 μmol/kg respectively) in comparison with celecoxib (ED₅₀ = 82.15 μmol/kg). Compounds 10a, 10b, 10g and 10h (ulcer index = 2.68, 1.20, 2.63 and 2.66 respectively) showed less ulceration effect than celecoxib (ulcer index = 2.90). Also, Compounds 10a, 10b, 10g and 10h showed analgesic activity higher than celecoxib and comparable to that of ibuprofen. In addition, molecular docking studies were performed for compounds 10a, 10b, 10g and 10h and the results were in agreement with that obtained from the in vitro COX inhibition assays.     

Design,synthesis of 2,3-disubstitued 4(3H)-quinazolinone derivatives as anti-inflammatory and analgesic agents: COX-1/2 inhibitory activities and molecular docking studies

A new series, 2-substituted mercapto-3-[2-(pyridin-2-yl)ethyl]-4(3H)-quinazolinone 1–21, was synthesized and evaluated for in vivo anti-inflammatory and analgesic activities and in vitro COX-1/COX-2 inhibition. Compounds 1, 4, 5, 6, 8, 10, 13, 14, 15, 16, and 17 exhibited potent anti-inflammatory and analgesic properties, with ED₅₀ values of 50.3–112.1 mg/kg and 12.3–111.3 mg/kg, respectively. These values may be compared with those of diclofenac sodium (ED₅₀ = 112.2 and 100.4 mg/kg) and celecoxib (ED₅₀ = 84.3 and 71.6 mg/kg). Compounds 4 and 6 possessed strong COX-2 inhibitory activity with IC₅₀ (0.33 μM and 0.40 μM, respectively) and selectivity index (SI > 303.0 and >250.0, respectively) values that are similar to those of the reference drug celecoxib (IC₅₀ 0.30 μM and COX-2 SI > 333). Compounds 5, 8, and 13 demonstrated effective COX-2 inhibitory activity with IC₅₀ values of 0.70–0.80 μM and COX-2 SI > 125–142. Potent COX-2 inhibitors, such as compounds 4, 6, and 13, were docked into the active site pockets of COX-1 and COX-2, with the greatest recognition occurring at the COX-2 binding site and insignificant interactions at the binding site of the COX-1 pocket.     

New hybrid molecules combining benzothiophene or benzofuran with rhodanine as dual COX-1/2 and 5-LOX inhibitors: Synthesis,biological evaluation and docking study

New molecular hybrids combining benzothiophene or its bioisostere benzofuran with rhodanine were synthesized as potential dual COX-2/5-LOX inhibitors. The benzothiophene or benzofuran scaffold was linked at position -2 with rhodanine which was further linked to various anti-inflammatory pharmacophores so as to investigate the effect of such molecular variation on the anti-inflammatory activity. The target compounds were evaluated for their in vitro COX/LOX inhibitory activity. The results revealed that, compound 5h exhibited significant COX-2 inhibition higher than celecoxib. Furthermore, compounds 5a, 5f and 5i showed COX-2 inhibitory activity comparable to celecoxib. Compound 5h showed selectivity index SI = 5.1 which was near to that of celecoxib (SI = 6.7). Compound 5h displayed LOX inhibitory activity twice than that of meclofenamate sodium. Moreover, compounds 5a, 5e and 5f showed significant LOX inhibitory activity higher than that of meclofenamate sodium. Compound 5h was screened for its in vivo anti-inflammatory activity using formalin-induced paw edema and gastric ulcerogenic activity tests. The results revealed that, it showed in vivo decrease in formalin-induced paw edema volume higher than celecoxib. It also displayed gastrointestinal safety profile as celecoxib. The biological results were also consistent with the docking studies at the active sites of the target enzymes COX-2 and 5-LOX. Also, compound 5h showed physicochemical, ADMET, and drug-like properties within those considered adequate for a drug candidate.     

1-(4-Methane(amino)sulfonylphenyl)-3-(4-substituted-phenyl)-5-(4-trifluoromethylphenyl)-1H-2-pyrazolines/pyrazoles as potential anti-inflammatory agents

2-Pyrazolins 14a–l and pyrazoles 15a–l were designed as celecoxib analogs for the evaluation of their in vitro COX-1/COX-2 inhibitory activity and the in vivo anti-inflammatory activity. Compounds 14i, 15a, 15d and 15f were the most COX-2 selective derivatives (S.I. = 5.93, 6.08, 5.03 and 5.27 respectively) while the pyrazoline derivatives 14g and 14i exhibited the highest AI activity (ED₅₀ = 190.5 and 160.1 μmol/kg po, respectively).     

New 1,2-diaryl-4-substituted-benzylidene-5-4H-imidazolone derivatives: Design,synthesis and biological evaluation as potential anti-inflammatory and analgesic agents

A new series of 1,2-diaryl-4-substituted-benzylidene-5-4H-imidazolone derivatives 10a-h was designed and synthesized for evaluation as selective COX-2 inhibitors, anti-inflammatory agents and as analgesic agents. All compounds were more selective for COX-2 isozyme and showed good in vivo anti-inflammatory activity. Compounds 10a, 10b, 10e and 10f were the most COX-2 selective compounds (S.I. = 10.76, 10.87, 8.69 and 9.14 respectively), the most potent anti-inflammatory derivatives (ED₅₀ = 65.7, 60.2, 76.3 and 107.4 μmol/kg respectively) in comparison with Celecoxib (COX-2 S.I. = 8.61, ED₅₀ = 82.2 μmol/kg) and were less ulcerogenic (ulcer indexes = 1.22–3.02) than Ibuprofen (ulcer index = 20.25) and comparable to Celecoxib (ulcer index = 2.93). The four derivatives (10a, 10b, 10e and 10f) showed considerable analgesic activities which are clearly parallel to their anti-inflammatory activities.     

Celecoxib analogs possessing a N-(4-nitrooxybutyl)piperidin-4-yl or N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridin-4-yl nitric oxide donor moiety: Synthesis,biological evaluation and nitric oxide release studies

A new group of hybrid nitric oxide (NO) releasing anti-inflammatory (AI) coxib prodrugs (NO-coxibs) wherein the para-tolyl moiety present in celecoxib was replaced by a N-(4-nitrooxybutyl)piperidyl 15a–b, or N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridyl 17a–b, NO-donor moiety was synthesized. All compounds released a low amount of NO upon incubation with phosphate buffered saline (PBS) at pH 7.4 (2.4–5.8% range). In comparison, the percentage NO released was higher (3.1–8.4% range) when these nitrate prodrugs were incubated in the presence of l-cysteine. In vitro COX-1/COX-2 isozyme inhibition studies showed this group of compounds are moderately more potent, and hence selective, inhibitors of the COX-2 relative to the COX-1 enzyme. AI structure–activity relationship data acquired showed that compounds having a MeSO₂ COX-2 pharmacophore exhibited superior AI activity compared to analogs having a H₂NSO₂ substituent. Compounds having a MeSO₂ COX-2 pharmacophore in conjunction with a N-(4-nitrooxybutyl)piperidyl (ED₅₀ = 132.4 mg/kg po), or a N-(4-nitrooxybutyl)-1,2,3,6-tetrahydropyridyl (ED₅₀ = 118.4 mg/kg po), moiety exhibited an AI potency profile that is similar to aspirin (ED₅₀ = 128.7 mg/kg po) but lower than ibuprofen (ED₅₀ = 67.4 mg/kg po).     

Synthesis,biological evaluation and docking analysis of 3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones as potential cyclooxygenase-2 (COX-2) inhibitors

As a part of our continued efforts to discover new COX inhibitors, a series of 3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones were synthesized and evaluated for in vitro COX inhibitory potential. Within this series, seven compounds (3a–d, 3h, 3k and 3q) were identified as potential and selective COX-2 inhibitors (COX-2 IC₅₀’s in 1.79–4.35 μM range; COX-2 selectivity index (SI) = 6.8–16.7 range). Compound 3b emerged as most potent (COX-2 IC₅₀ = 1.79 μM; COX-1 IC₅₀ >30 μM) and selective COX-2 inhibitor (SI >16.7). Further, compound 3b displayed superior anti-inflammatory activity (59.86% inhibition of edema at 5 h) in comparison to celecoxib (51.44% inhibition of edema at 5 h) in carrageenan-induced rat paw edema assay. Structure–activity relationship studies suggested that N-phenyl ring substituted with p-CF₃ substituent (3b, 3k and 3q) leads to more selective inhibition of COX-2. To corroborate obtained experimental biological data, molecular docking study was carried out which revealed that compound 3b showed stronger binding interaction with COX-2 as compared to COX-1.     

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-5H-furan, 2-oxo-3H-1,3-oxazole, and 1H-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-5H-furan derivative 6b was identified as potent COX inhibitor with selectivity toward COX-1 (COX-1 IC₅₀ = 0.061 μM and COX-2 IC₅₀ = 0.325 μM; selectivity index (SI) = 0.19). Among the 1H-pyrazole derivatives, 11b was found to be a potent COX-2 inhibitor, about 38 times more potent than Rofecoxib (COX-2 IC₅₀ = 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 IC₅₀ = 1 μM, COX-2 IC₅₀ = 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.     

Molecular design,synthesis and biological evaluation of cyclic imides bearing benzenesulfonamide fragment as potential COX-2 inhibitors. Part 2

A group of cyclic imides (1–10) was designed for evaluation as a selective COX-2 inhibitors and investigated in vivo for their anti-inflammatory activity. Compounds 6a, 6b, 8a, 8b, 9a, 9b, 10a and 10b were proved to be potent COX-2 inhibitors with IC₅₀ range of 0.1–4.0 μM. In vitro COX-1/COX-2 inhibition structure–activity studies identified compound 8a as a highly potent (IC₅₀ = 0.1 μM), and an extremely selective [COX-2 (SI) > 1000] comparable to celecoxib [COX-2 (SI) > 384], COX-2 inhibitor that showed superior anti-inflammatory activity (ED₅₀ = 72.4 mg/kg) relative to diclofenac (ED₅₀ = 114 mg/kg). Molecular modeling 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. The study showed that the homosulfonamide fragment of 8a inserted deep inside the 2°-pocket of the COX-2 active site, where the SO₂NH₂ group underwent H-bonding interaction with Gln¹⁹²(2.95 Å), Phe⁵¹⁸(2.82 Å) and Arg⁵¹³(2.63 and 2.73 Å). Docking study of the synthesized compound 8a into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.     

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 IC₅₀ = 0.07 μM; selectivity index = 687.1) that was more selective than the reference drug celecoxib (COX-2 IC₅₀ = 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-MeSO₂ COX-2 pharmacophore group on the C-2 phenyl ring is oriented in the vicinity of the COX-2 secondary pocket (Arg⁵¹³, Phe⁵¹⁸ and Val⁵²³) and the carboxylic acid substituent can interact with Ser⁵³⁰. The structure activity data acquired indicate that the size and nature of the C-4 quinoline substituent are important for COX-2 inhibitory activity.     

Pyrazole-hydrazone derivatives as anti-inflammatory agents: Design,synthesis, biological evaluation,COX-1,2/5-LOX inhibition and docking study

A new series of pyrazole-hydrazone derivatives 4a-i were designed and synthesized, their chemical structures were confirmed by IR, ¹H NMR, ¹³C NMR, MS spectral data and elemental analysis. IC₅₀ values for all prepared compounds to inhibit COX-1, COX-2 and 5-LOX enzymes were determined in vitro. Compounds 4a (IC₅₀ = 0.67 μM) and 4b (IC₅₀ = 0.58 μM) showed better COX-2 inhibitory activity than celecoxib (IC₅₀ = 0.87 μM) with selectivity index (SI = 8.41, 10.55 in sequent) relative to celecoxib (SI = 8.85). Also, compound 4a and 4b exhibited superior inhibitory activity against 5-LOX (IC₅₀ = 1.92, 2.31 μM) higher than zileuton (IC₅₀ = 2.43 μM). All target pyrazoles were screened for their ability to reduce nitric oxide production in LPS stimulated peritoneal macrophages. Compounds 4a, 4b, 4f and 4i displayed concentration dependent reduction and were screened for in vivo anti-inflammatory activity using carrageenan-induced rat paw edema assay. Compound 4f showed the highest anti-inflammatory activity (% edema inhibition = 15–20%) at all doses when compared to reference drug celecoxib (% edema inhibition = 15.7–17.5%). Docking studies were carried out to investigate the interaction of target compounds with COX-2 enzyme active site.     

Synthesis,potential anti-inflammatory and analgesic activities study of (S)-N-substituted-1-phenyl-3,4-dihydroisoquinoline-2(1H)-carboxamides

A series of (S)-N-substitued-1-phenyl-3,4-dihydroisoquinoline-2(1H)-carboxamide derivatives were designed, synthesized and evaluated for their anti-inflammatory and analgesic effects in vivo. Among the synthesized compounds 2a and 2n showed the best anti-inflammatory activity (inhibition rate: 95% and 92.7%, respectively) and analgesic effect (inhibition rate: 100% and 100%, respectively), which was greater than that or nearly equivalent to that of indomethacin. Compounds 2a and 2n were selected to test their inhibitory effects against ovine COX-1 and COX-2 using the cyclooxygenase inhibition assay in vitro. Compounds 2a and 2n are weak inhibitors of COX-1 isozyme but displayed moderate COX-2 isozyme inhibitory effects (IC₅₀ = 0.47 μM and 1.63 μM, respectively) and COX-2 selectivity indexes (SI = 11.5 and 4.8). Furthermore, compound 2a was more inhibitors of COX-2 isozyme active than the reference drug celecoxib.     

Synthesis and biological evaluation of N-difluoromethyl-1,2-dihydropyrid-2-one acetic acid regioisomers: Dual Inhibitors of cyclooxygenases and 5-lipoxygenase

A new group of acetic acid (7a–c, R¹ = H), and propionic acid (7d–f, R¹ = Me), regioisomers wherein a N-difluoromethyl-1,2-dihydropyrid-2-one moiety is attached via its C-3, C-4, and C-5 position was synthesized. This group of compounds exhibited a more potent inhibition, and hence selectivity, for the cyclooxygenase-2 (COX-2) relative to the COX-1 isozyme. Attachment of the N-difluoromethyl-1,2-dihydropyrid-2-one ring system to an acetic acid, or propionic acid, moiety confers potent 5-LOX inhibitory activity, that is, absent in traditional arylacetic acid NSAIDs. 2-(1-Difluoromethyl-2-oxo-1,2-dihydropyridin-5-yl)acetic acid (7c) exhibited the best combination of dual COX-2 and 5-LOX inhibitory activities. Molecular modeling (docking) studies showed that the highly electronegative CHF₂ substituent present in 7c, that showed a modest selectivity for the COX-2 isozyme, is oriented within the secondary pocket (Val523) present in COX-2 similar to the sulfonamide (SO₂NH₂) COX-2 pharmacophore present in celecoxib, and that the N-difluoromethyl-1,2-dihydropyrid-2-one pharmacophore is oriented close to the region containing the LOX enzyme catalytic iron (His361, His366, and His545). Accordingly, the N-difluoromethyl-1,2-dihyrdopyrid-2-one moiety possesses properties suitable for the design of dual COX-2/5-LOX inhibitory drugs.     

Hybrid fluorescent conjugates of COX-2 inhibitors: Search for a COX-2 isozyme imaging cancer biomarker

The observation that the cyclooxygenase-2 (COX-2) isozyme is over-expressed in multiple types of cancer, relative to that in adjacent non-cancerous tissue, prompted this investigation to prepare a group of hybrid fluorescent conjugates wherein the COX inhibitors ibuprofen, (S)-naproxen, acetyl salicylic acid, a chlororofecoxib analog and celecoxib were coupled via a linker group to an acridone, dansyl or rhodamine B fluorophore. Within this group of compounds, the ibuprofen-acridone conjugate (10) showed potent and selective COX-2 inhibition (COX-2 IC₅₀ = 0.67 μM; SI = 110.6), but its fluorescence emission (λ_em = 417, 440 nm) was not suitable for fluorescent imaging of cancer cells that over-express the COX-2 isozyme. In comparison, the celecoxib-dansyl conjugate (25) showed a slightly lower COX-2 potency and selectivity (COX-2 IC₅₀ = 1.1 μM; SI > 90) than the conjugate 10, and it possesses a better fluorescence emission (λ_em = 500 nm). Ultimately, a celecoxib-rhodamine B conjugate (28) that exhibited moderate COX-2 potency and selectivity (COX-2 IC₅₀ = 3.9 μM; SI > 25) having the best fluorescence emission (λ_em = 580 nm) emerged as the most promising biomarker for fluorescence imaging using a colon cancer cell line that over-expresses the COX-2 isozyme.     

Synthesis,biological evaluation,and docking analysis of a novel family of 1-methyl-1H-pyrrole-2,5-diones as highly potent and selective cyclooxygenase-2 (COX-2) inhibitors

As a continuous research for discovery of new COX-2 inhibitors, we present the simple chemical synthesis, in vitro biological screening, and molecular docking study of 1H-pyrrole-2,5-dione derivatives. New synthetic compounds were evaluated for the inhibitory activities on LPS-induced PGE₂ production in RAW 264.7 macrophage cells as well as the COX-1 and COX-2 inhibitory potency. Among them, compound 9d (MPO-0029) was identified as more potent and selective COX-2 inhibitor [PGE₂ IC₅₀ = 8.7 nM, COX-2 IC₅₀ = 6.0 nM; COX-2 selectivity index (SI) = >168] than celecoxib. Molecular docking experiments were further performed against COX-2 and COX-1 isozymes to determine their probable binding models. Results of molecular docking studies revealed that compound 9d (MPO-0029) has stronger binding interaction with COX-2 than with COX-1 isozyme, and provided successfully complementary theoretical support for the obtained experimental biological data.     

Novel 3-substituted-1-aryl-5-phenyl-6-anilinopyrazolo[3,4-d]pyrimidin-4-ones: Docking,synthesis and pharmacological evaluation as a potential anti-inflammatory agents

Novel 3-substituted-1-aryl-5-phenyl-6-anilino-pyrazolo[3,4-d]pyrimidin-4-ones of pharmacological significance were synthesized by the reaction of ethyl-(5-amino-3-methylthio-1-aryl-5-phenyl-2H-pyrazole)-4-carboxylates 3a–c with S-methyl diphenyl thiourea independently to produce 1-aryl-3-thiomethyl-5-phenyl-pyrazolo[3,4-d]pyrimidines 4a–c in DMF with catalytic amount of K₂CO₃, which on further treatment with different aromatic amines independently under same reaction conditions generated for compounds 5a–l. The compounds were screened for the anti-inflammatory activity and evaluated for ulcerogenic potential. The compounds 5i exhibited superior anti-inflammatory activity in comparison with diclofenac sodium and comparable activity with celecoxib at a dose of 25 mg/kg. The other compounds 4c, 5c, 5f and 5l were found as active with inhibition of edema in the range of 35–39 after 3 h of administration of test compounds. The ulcerogenic potential of active compounds was observed to be quite lesser as compared to standard. COX-2 docking score of the active compound 5i was found to be better than standard celecoxib.     

Novel quinoline incorporating 1,2,4-triazole/oxime hybrids: Synthesis,molecular docking,anti-inflammatory,COX inhibition,ulceroginicity and histopathological investigations

A series of novel quinolines incorporating 1,2,4-triazole/oxime hybrids were prepared. They showed remarkable anti-inflammatory activity and exhibited very low incidence of gastric ulceration, compared to indomethacin. Most of the compounds tested showed remarkable inhibition of the COX-1 isozyme, with IC₅₀’s ranging from 0.48 to 28 µM. Compounds 7c and 9g showed high safety profiles with normal stomach tissue integrity. Docking studies supported the observed in vitro inhibitory activity towards the COX enzymes that may explain their promising anti-inflammatory activity relative to indomethacin. Moreover, differences between the COX-1 and COX-2 isozymes in observed energy scores, as well as in the number of interactions with some of the compounds tested, might predict their higher selectivity towards COX-1 rather than COX-2. Compound 9e was found to inhibit both COXs non-competitively with K_i values of 81 µM and 94.6 µM.     

Synthesis,docking simulation,biological evaluations and 3D-QSAR study of 5-Aryl-6-(4-methylsulfonyl)-3-(metylthio)-1,2,4-triazine as selective cyclooxygenase-2 inhibitors

A series of 5-Aryl-6-(4-methylsulfonyl)-3-(metylthio)-1,2,4-triazine derivatives were synthesized and their COX-1/COX-2 inhibitory activity as well as in vivo anti-inflammatory and analgesic effects were evaluated. All of compounds showed strong inhibition of COX-2 with IC₅₀ values in the range of 0.1–0.2 μM and in most cases had stronger anti-inflammatory and analgesic effects than indomethacin at doses 3 and 6 mg/kg. Among them, 5-(4-chlorophenyl)-6-(4-(methylsulfonyl) phenyl)-3-(methylthio)-1,2,4-triazine (9c) was the most potent and selective COX-2 compound; its selectivity index of 395 was comparable to celecoxib (SI = 405). Evaluation of anti-inflammatory and analgesic effects of 9c showed its higher potency than indomethacin and hence could be considered as a promising lead candidate for further drug development. Furthermore, the affinity data of these compounds were rationalized through enzyme docking simulation and 3D-QSAR study by k-Nearest Neighbour Molecular Field Analysis.     

Discovery of novel analgesic and anti-inflammatory 3-arylamine-imidazo[1,2-a]pyridine symbiotic prototypes

We describe herein the design, synthesis and pharmacological evaluation of novel 3-arylamine-imidazo[1,2-a]pyridine derivatives structurally designed as novel symbiotic prototypes presenting analgesic and anti-inflammatory properties. The derivatives obtained were submitted to in vivo assays of nociception, hyperalgesia and inflammation, and to in vitro assays of human PGHS-2 inhibition. These assays allowed the identification of compound LASSBio-1135 (3a) as an anti-inflammatory and analgesic symbiotic prototype. This compound inhibited moderately the human PGHS-2 enzyme activity (IC₅₀ = 18.5 μM) and reverted the capsaicin-induced thermal hyperalgesia (100 μmol/kg, po) similarly to p38 MAPK inhibitor SB-203580 (2). Additionally, LASSBio-1135 (3a) presented activity similar to celecoxib (1) regarding the reduction of the carrageenan-induced rat paw edema (33% of inhibition at 100 μmol/kg, po). We also discovered derivatives LASSBio-1140 (3c) and LASSBio-1141 (3e) as analgesic and anti-inflammatory prototypes, which were able to attenuate the capsaicin-induced thermal hyperalgesia (100 μmol/kg, po) and reduce the carrageenan-induced paw edema (ED₅₀ = 11.5 μmol/kg (3.3 mg/kg) and 14.5 μmol/kg (4.1 mg/kg), respectively), being both more active than celecoxib (1), despite the fact that their effects involve a different mechanism of action. Additionally, derivative LASSBio-1145 (3j) showed remarkable analgesic (ED₅₀ = 22.7 μmol/kg (8.9 mg/kg)) and anti-inflammatory (ED₅₀ = 8.7 μmol/kg (3.4 mg/kg)) profile in vivo (100 μmol/kg; po), in AcOH-induced abdominal constrictions in mice and carrageenan-induced rat paw edema models, respectively, being a novel orally-active anti-inflammatory drug candidate that acts as a selective PGHS-2 inhibitor (IC₅₀ = 2.8 μM).