Structural modification of indomethacin toward selective inhibition of COX-2 with a significant increase in van der Waals contributions

We have synthesized a fluorinated analogue of indomethacin bearing a 3,3,3-trifluoroprop-1-enyl group at its 2-position and evaluated its inhibitory activity towards the COX-1 and COX-2 enzymes in vitro. The results revealed that this fluorinated analogue exhibited much greater inhibitory activity and selectivity towards COX-2 than indomethacin. The increased affinity between the fluorinated analogue and COX-2 was attributed to a significant increase in van der Waals contacts (i.e. van der Waals contributions in ΔG were ?13.80?kcal/mol for COX-1 and ?18.46?kcal/mol for COX-2), explaining an effect of the fluorine substituent in enzyme selectivity. This newly synthesized fluorinated analogue therefore represents a potent and selective COX-2 inhibitor.     

Toward the understanding of the molecular basis for the inhibition of COX-1 and COX-2 by phenolic compounds present in Uruguayan propolis and grape pomace

Propolis and grape pomace have significant amounts of phenols which can take part in anti-inflammatory mechanisms. As the cyclooxygenases 1 and 2 (COX-1 and COX-2) are involved in said mechanisms, the possibility for a selective inhibition of COX-2 was analyzed in vitro and in silico. Propolis and grape pomace from Uruguayan species were collected, extracted in hydroalcoholic mixture and analyzed. Based on phenols previously identified, and taking as reference the crystallographic structures of COX-1 and COX-2 in complex with the commercial drug Celecoxib, a molecular docking procedure was devised to adjust 123 phenolic molecular models at the enzyme-binding sites. The most important results of this work are that the extracts have an overall inhibition activity very similar in COX-1 and COX-2, i.e. they do not possess selective inhibition activity for COX-2. Nevertheless, 10 compounds of the phenolic database turned out to be more selective and 94 phenols resulted with similar selectivity than Celecoxib, an outcome that accounts for the overall experimental inhibition measures. Binding site environment observations showed increased polarity in COX-2 as compared with COX-1, suggesting that polarity is the key for selectivity. Accordingly, the screening of molecular contacts pointed to the residues: Arg106, Gln178, Leu338, Ser339, Tyr341, Tyr371, Arg499, Ala502, Val509, and Ser516, which would explain, at the atomic level, the anti-inflammatory effect of the phenolic compounds. Among them, Gln178 and Arg499 appear to be essential for the selective inhibition of COX-2.     

Design and synthesis of novel quinazolinones conjugated ibuprofen,indole acetamide,or thioacetohydrazide as selective COX-2 inhibitors: anti-inflammatory,analgesic and anticancer activities

Novel quinazolinones conjugated with indole acetamide (4a–c), ibuprofen (7a–e), or thioacetohydrazide (13a,b, and 14a-d) were designed to increase COX-2 selectivity. The three synthesised series exhibited superior COX-2 selectivity compared with the previously reported quinazolinones and their NSAID analogue and had equipotent COX-2 selectivity as celecoxib. Compared with celecoxib, 4 b, 7c, and 13 b showed similar anti-inflammatory activity in vivo, while 13 b and 14a showed superior inhibition of the inflammatory mediator nitric oxide, and 7 showed greater antioxidant potential in macrophages cells. Moreover, all selected compounds showed improved analgesic activity and 13 b completely abolished the pain response. Additionally, compound 4a showed anticancer activity in tested cell lines HCT116, HT29, and HCA7. Docking results were consistent with COX-1/2 enzyme assay results. In silico studies suggest their high oral bioavailability. The overall findings for compounds (4a,b, 7c, 13 b, and 14c) support their potential role as anti-inflammatory agents.     

选择性co x 一2 抑制剂在胶质瘤放疗中的研究进展

环氧合酶（cyclooxygenase,COX）又名前列腺素内过氧化物合成酶,是前列腺素类似物合成的限速酶。COX-2是其诱导型酶。胶质瘤中COX-2的高表达被认为与肿瘤的侵袭性、预后相关。COX-2在胶质瘤的发生发展过程中发挥重要作用。选择性COX-2抑制剂通过直接和间接的作用机制而成为放射增敏剂。它们通过直接作用肿瘤细胞增强放射反应性,同时间接通过前列腺素影响肿瘤的血管形成抑制肿瘤生长。在体内和体外的研究表明选择性COX-2抑制剂可以增强胶质瘤对放射的反应性．降低恶性胶质瘤患者术后放射的必需照射剂量。而且在提高肿瘤放射敏感性的同时不增加对正常组织的放射损伤,甚至对正常组织有放射保护作用。因此,放疗联合选择性COX-2抑制剂可能成为胶质瘤治疗的新的有效途径。     

COX-1/COX-2 inhibition activities and molecular docking study of newly designed and synthesized pyrrolo[3,4-c]pyrrole Mannich bases

In the present paper we describe the biological activity of newly designed and synthesized series of pyrrolo[3,4-c]pyrrole Mannich bases (7a-n). The Mannich bases were obtained in good yields by one-pot, three-component condensation of pyrrolo[3,4–c]pyrrole scaffold (6a-c) with secondary amines and an excess of formaldehyde solution in C₂H₅OH. The chemical structures of the compounds were characterized by ¹H NMR, ¹³C NMR, FT-IR, and elemental analysis. Moreover, single crystal X-ray diffraction has been recorded for compound 7l. All synthesized derivatives were investigated for their potencies to inhibit COX-1 and COX-2 enzymes by colorimetric inhibitor screening assay. In order to analyse the intermolecular interactions between the ligands and cyclooxygenase, experimental data were supported with the results of molecular docking simulations. According to the results, all of the tested compounds inhibited the activity of COX-1 and COX-2.     

Design and biological evaluation of novel hybrids of 1, 5-diarylpyrazole and Chrysin for selective COX-2 inhibition

The overexpress of COX-2 was clearly associated with carcinogenesis and COX-2 as a possible target has long been exploited for cancer therapy. In this work, we described the design and synthesis of a series of diarylpyrazole derivatives integrating with chrysin. Among them, compound e9 exhibited the most potent inhibitory activity against COX-2 and antiproliferative activity against Hela cells with IC₅₀ value of 1.12?μM. Further investigation revealed that e9 could induce apoptosis of Hela cells by mitochondrial depolarization and block the G1 phase of cell cycle in a dose-dependent manner. Besides, molecular docking simulation results was further confirmed that e9 could bind well with COX-2. In summary, compound e9 may be promising candidates for cancer therapy.     

New phenolic cinnamic acid derivatives as selective COX-2 inhibitors. Design,synthesis, biological activity and structure-activity relationships

Selective inhibition of cyclooxygenase (COX)-2 enzyme is an important achievement when looking for potent anti-inflammatory agents, with fewer gastrointestinal side effects. In this work, a new series of cinnamic acid derivatives, namely hexylamides, have been designed, synthesized and evaluated in human blood for their inhibitory activity of COX-1 and COX-2 enzymes. From this, new structure-activity relationships were built, showing that phenolic hydroxyl groups are essential for both COX-1 and COX-2 inhibition. Furthermore, the presence of bulky hydrophobic di-tert-butyl groups in the phenyl ring strongly contributes for selective COX-2 inhibition. In addition, a correlation with the theoretical log P has been carried out, showing that lipophilicity is particularly important for COX-2 inhibition. Further, a plasma protein binding (PPB) prediction has been performed revealing that PPB seems to have no influence in the activity of the studied compounds. From the whole study, effective selective inhibitors of COX-2 were found, namely compound 9 (IC₅₀ = 3.0 ± 0.3 μM), 10 (IC₅₀ = 2.4 ± 0.6 μM) and 23 (IC₅₀ = 1.09 ± 0.09 μM). Those can be considered starting point hit compounds for further optimization as potential non-steroidal anti-inflammatory drugs.     

Design and synthesis of a biotinylated probe of COX-2 inhibitor nimesulide analog JCC76

JCC76 is a derivative of cyclooxygenase-2(COX-2) selective inhibitor nimesulide and exhibits potent anti-breast cancer activity. It selectively induces apoptosis of Her2 positive breast cancer cells. However, the specific molecular targets of JCC76 still remain unclear, which significantly withdraw the further drug development of JCC76. To identify the molecular targets of JCC76, a six carbon linker and biotin conjugated JCC76 probe was designed and synthesized. The anti-proliferation activity of the probe and its analogs was evaluated.     

Synthesis,antitumour activities and molecular docking of thiocarboxylic acid ester-based NSAID scaffolds: COX-2 inhibition and mechanistic studies

A new series of NSAID thioesters were synthesized and evaluated for their in vitro antitumor effects against a panel of four human tumor cell lines, namely: HepG2, MCF-7, HCT-116 and Caco-2, using the MTT assay. Compared to the reference drugs 5-FU, afatinib and celecoxib, compounds 2b, 3b, 6a, 7a, 7b and 8a showed potent broad-spectrum antitumor activity against the selected tumour cell lines. Accordingly, these compounds were selected for mechanistic studies about COX inhibition and kinase assays. In vitro COX-1/COX-2 enzyme inhibition assay results indicated that compounds 2b, 3b, 6a, 7a, 7b, 8a and 8?b selectively inhibited the COX-2 enzyme (IC₅₀?=?～0.20–0.69?μM), with SI values of (>72.5–250) compared with celecoxib (IC₅₀?=?0.16?μM, COX-2 SI:?>?312.5); however, all the tested compounds did not inhibit the COX-1 enzyme (IC₅₀?>?50?μM). On the other hand, EGFR, HER2, HER4 and cSrc kinase inhibition assays were evaluated at a 10?μM concentration. The selected candidates displayed limited activities against the various tested kinases; the compounds 2a, 3b, 6a, 7a, 7b and 8a showed no activity to weak activity (% inhibition?=?～0–10%). The molecular docking study revealed the importance of the thioester moiety for the interaction of the drugs with the amino acids in the active sites of COX-2. The aforementioned results indicated that thioester based on NSAID scaffolds derivatives may serve as new antitumor compounds.     

Synthesis,anti-inflammatory,analgesic, COX-1/2 inhibition activities and molecular docking study of pyrazoline derivatives

Design, synthesis and pharmacological activities of a group of 1,3,5-trisubstituted pyrazolines were reported. The chemical structures of the synthesized compounds have been assigned on the basis of IR, MS, ¹H NMR, and ¹³C NMR spectral analyses. The synthesized 1,3,5-trisubstituted pyrazoline derivatives were evaluated in vivo for anti-inflammatory, analgesic activities and in vitro for COX-1/2 inhibition assay. Among the tested compounds, derivatives 4h, 6e, 7a, 7e, and 9 showed more potent anti-inflammatory and analgesic activities than the reference drug celecoxib. On the basis of their higher activities in the in vivo studies compared with celecoxib, the five compounds 4h, 6e, 7a, 7e and 9 were selected to test their inhibitory activities against ovine COX-1/2 using an in vitro cyclooxygenase inhibition assay. Docking study of compounds 7a, 7e and 9 into the COX-2 binding site revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.     

Indolyl esters and amides related to indomethacin are selective COX-2 inhibitors

Previous studies from our laboratory have revealed that esterification/amidation of the carboxylic acid moiety in the nonsteroidal anti-inflammatory drug, indomethacin, generates potent and selective COX-2 inhibitors. In the present study, a series of reverse ester/amide derivatives were synthesized and evaluated as selective COX-2 inhibitors. Most of the reverse esters/amides displayed time-dependent COX-2 inhibition with IC₅₀ values in the low nanomolar range. Replacement of the 4-chlorobenzoyl group on the indole nitrogen with a 4-bromobenzyl moiety resulted in compounds that retained selective COX-2 inhibitory potency. In addition to inhibiting COX-2 activity in vitro, the reverse esters/amides also inhibited COX-2 activity in the mouse macrophage-like cell line, RAW264.7. Overall, this strategy broadens the scope of our previous methodology of neutralizing the carboxylic acid group in NSAIDs as a means of generating COX-2-selective inhibitors and is potentially applicable to other NSAIDs.     

COX-1/COX-2 inhibition assays and histopathological study of the new designed anti-inflammatory agent with a pyrazolopyrimidine core

Four pyrazolopyrimidine series were prepared with a substitution at position- 4 by Schiff base, triazole, oxadiazole and pyrazole moieties (7a-f, 8a,b, 9a-f, 10a,b and 13a,b), respectively. All the synthesized compounds were evaluated in vitro against COX-2 and in vivo against carrageenan-induced rat paw edema as anti-inflammatory agents. Regarding the anti-inflammatory activity (AI) compounds 7c, 7f, 8a, and 9a showed higher activity with respect to celecoxib. Compounds 9a, 7d, and 7f were closely selective to celecoxib. Also, 7c and 7d were safer than indomethacin and similar to celecoxib as resulted from the histopathological study. In addition, the docking study that showed the binding mode of prominent pyrazolopyrimidine compounds inside the COX-2 receptor. Formation of unexpected pyrazole 13a and 13b was briefly discussed using 2D NMR.     

Synthesis of new pyrazoles and pyrozolo [3,4-b] pyridines as anti-inflammatory agents by inhibition of COX-2 enzyme

New pyrazoles and pyrazolo[3,4-b] pyridines were synthesized and their structure was confirmed by elemental analyses as well as IR, ¹H NMR, ¹³C NMR, and mass spectral data. All the newly synthesized derivatives were evaluated in vitro for inhibitory activity against COX-1 and COX-2 enzymes and their IC₅₀ values were calculated, most of the derivatives showed good inhibitory activity with derivatives IVb, IVh and IVJ showing inhibitory activity better than celecoxib. Moreover, the eight most potent derivatives IVa, IVb, IVc, IVd, IVe, IVh, IVJ, and IVL were selected for in vivo assay to measure their effect on paw edema in rates and their ulcerogenic effect. Compounds IVa, IVb and IVc were found to be the most active and selective as COX-2 inhibitors and most effective in protection from edema, they were also found to have lowest ulcerogenic effect among all derivatives.     

Exploring the molecular determinants of substrate-selective inhibition of cyclooxygenase-2 by lumiracoxib

Lumiracoxib is a substrate-selective inhibitor of endocannabinoid oxygenation by cyclooxygenase-2 (COX-2). We assayed a series of lumiracoxib derivatives to identify the structural determinants of substrate-selective inhibition. The hydrogen-bonding potential of the substituents at the ortho positions of the aniline ring dictated the potency and substrate selectivity of the inhibitors. The presence of a 5′-methyl group on the phenylacetic acid ring increased the potency of molecules with a single ortho substituent. Des-fluorolumiracoxib (2) was the most potent and selective inhibitor of endocannabinoid oxygenation. The positioning of critical substituents in the binding site was identified from a 2.35 Å crystal structure of lumiracoxib bound to COX-2.     

Structural basis for proton conduction and inhibition by the influenza M2 protein

The influenza M2 protein forms an acid‐activated and drug‐sensitive proton channel in the virus envelope that is important for the virus lifecycle. The functional properties and high‐resolution structures of this proton channel have been extensively studied to understand the mechanisms of proton conduction and drug inhibition. We review biochemical and electrophysiological studies of M2 and discuss how high‐resolution structures have transformed our understanding of this proton channel. Comparison of structures obtained in different membrane‐mimetic solvents and under different pH using X‐ray crystallography, solution NMR, and solid‐state NMR spectroscopy revealed how the M2 structure depends on the environment and showed that the pharmacologically relevant drug‐binding site lies in the transmembrane (TM) pore. Competing models of proton conduction have been evaluated using biochemical experiments, high‐resolution structural methods, and computational modeling. These results are converging to a model in which a histidine residue in the TM domain mediates proton relay with water, aided by microsecond conformational dynamics of the imidazole ring. These mechanistic insights are guiding the design of new inhibitors that target drug‐resistant M2 variants and may be relevant for other proton channels.     

Synthesis and evaluation of 1,5-diaryl-substituted tetrazoles as novel selective cyclooxygenase-2 (COX-2) inhibitors

A series of 1,5-diaryl-substituted tetrazole derivatives was synthesized via conversion of readily available diaryl amides into corresponding imidoylchlorides followed by reaction with sodium azide. All compounds were evaluated by cyclooxygenase (COX) assays in vitro to determine COX-1 and COX-2 inhibitory potency and selectivity. Tetrazoles 3a-e showed IC₅₀ values ranging from 0.42 to 8.1 mM for COX-1 and 2.0 to 200 μM for COX-2. Most potent compound 3c (IC₅₀ (COX-2) = 2.0 μM) was further used in molecular modeling docking studies.     

Structural basis for glutamate racemase inhibition

d-Glutamic acid is a required biosynthetic building block for peptidoglycan, and the enzyme glutamate racemase (GluR) catalyzes the inter-conversion of D and L-glutamate enantiomers. Therefore, GluR is considered as an attractive target for the design of new antibacterial drugs. Here, we report the crystal structures of GluR from Streptococcus pyogenes in both inhibitor-free and inhibitor-bound forms. The inhibitor free GluR crystallized in two different forms, which diffracted to 2.25 Å and 2.5 Å resolution, while the inhibitor-bound crystal diffracted to 2.5 Å resolution. GluR is composed of two domains of α/β protein that are related by pseudo-2-fold symmetry and the active site is located at the domain interface. The inhibitor, γ-2-naphthylmethyl-d-glutamate, which was reported earlier as a novel potent competitive inhibitor, makes several hydrogen bonds with protein atoms, and the naphthyl moiety is located in the hydrophobic pocket. The inhibitor binding induces a disorder in one of the loops near the active site. In both crystal forms, GluR exists as a dimer and the interactions seen at the dimer interface are almost identical. This agrees well with the results from gel filtration and dynamic light-scattering studies.     

Rational design of biodegradable sulphonamide candidates treating septicaemia by synergistic dual inhibition of COX-2/PGE2 axis and DHPS enzyme

A new series of co-drugs was designed based on hybridising the dihydropteroate synthase (DHPS) inhibitor sulphonamide scaffold with the COX-2 inhibitor salicylamide pharmacophore through biodegradable linkage to achieve compounds with synergistic dual inhibition of COX-2/PGE2 axis and DHPS enzyme to enhance antibacterial activity for treatment of septicaemia. Compounds 5 b, 5j, 5n and 5o demonstrated potent in vitro COX-2 inhibitory activity comparable to celecoxib. 5j and 5o exhibited ED₅₀ lower than celecoxib in carrageenan-induced paw edoema test with % PGE2 inhibition higher than celecoxib. Furthermore, 5 b, 5j and 5n showed gastric safety profile like celecoxib. Moreover, in vivo antibacterial screening revealed that, 5j showed activity against S.aureus and E.coli higher than sulfasalazine. While, 5o revealed activity against E.coli higher than sulfasalazine and against S.aureus comparable to sulfasalazine. Compound 5j achieved the target goal as potent inhibitor of COX-2/PGE2 axis and in vivo broad-spectrum antibacterial activity against induced septicaemia in mice.     

3-(2-Methoxytetrahydrofuran-2-yl)pyrazoles: a novel class of potent, selective cyclooxygenase-2 (COX-2) inhibitors

A series of 3-(2-methoxytetrahydrofuran-2-yl)pyrazoles (4–10) was synthesized. The compounds were evaluated for their ability to inhibit cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) activity in human whole blood (HWB). The compound, 5-(4-methanesulfonylphenyl)-3-(2-methoxytetrahydrofuran-2-yl)-1-p-tolyl-1H-pyrazole 5 showed potent and selective COX-2 inhibition (IC₅₀ for COX-1: >100 μM and COX-2: 1.2 μM).     

Design,synthesis of celecoxib-tolmetin drug hybrids as selective and potent COX-2 inhibitors

Three novel series of diarylpyrazole 10b-d and triarylpyrazole derivatives 11a-d &12a-d were synthesized through Vilsmier-Haack condition. The structures of prepared compounds were determined through IR, ¹H NMR, ¹³C NMR, Mass spectral and elemental analysis. Docking of the synthesized compounds over COX-2 active site ensure their selectivity. Moreover, the target compounds were evaluated for both in vitro and in vivo inhibitory activity. All compounds were more selective for COX-2 isozyme than COX-1 isozyme and with excellent anti-inflammatory activity. Compounds 11b, 11d and 12b showed the highest anti-inflammatory activity (67.4%, 62.7%, 61.4% respectively), lower ulcerogenic liability (UI = 2.00, 2.75, 3.25 respectively) than indomethacin (UI = 14) and comparable to celecoxib (UI = 1.75) which were confirmed from the histopatholgical study.