Oxicams Bind in a Novel Mode to the Cyclooxygenase Active Site via a Two-water-mediated H-bonding Network*

Windsor M.A., Hermanson D.J., Kingsley P.J., Xu S., Crews B.C., Ho W., Keenan C.M., Banerjee S., Sharkey K.A., Marnett L.J.

Cyclooxygenase-2 (COX-2) oxygenates arachidonic acid and the endocannabinoids 2-arachidonoylglycerol (2-AG) and arachidonoylethanolamide (AEA). We recently reported that (R)-profens selectively inhibit endocannabinoid oxygenation but not arachidonic acid oxygenation. In this work, we synthesized achiral derivatives of five profen scaffolds and evaluated them for substrate-selective inhibition using in vitro and cellular assays. The size of the substituents dictated the inhibitory strength of the analogs, with smaller substituents enabling greater potency but less selectivity. Inhibitors based on the flurbiprofen scaffold possessed the greatest potency and selectivity, with desmethylflurbiprofen (3a) exhibiting an IC(50) of 0.11 μM for inhibition of 2-AG oxygenation. The crystal structure of desmethylflurbiprofen complexed to mCOX-2 demonstrated a similar binding mode to other profens. Desmethylflurbiprofen exhibited a half-life in mice comparable to that of ibuprofen. The data presented suggest that achiral profens can act as lead molecules toward in vivo probes of substrate-selective COX-2 inhibition.

Vecchio A.J., Orlando B.J., Nandagiri R., Malkowski M.G.

Forli S., Olson A.J.

In modeling ligand-protein interactions, the representation and role of water are of great importance. We introduce a force field and hydration docking method that enables the automated prediction of waters mediating the binding of ligands with target proteins. The method presumes no prior knowledge of the apo or holo protein hydration state and is potentially useful in the process of structure-based drug discovery. The hydration force field accounts for the entropic and enthalpic contributions of discrete waters to ligand binding, improving energy estimation accuracy and docking performance. The force field has been calibrated and validated on a total of 417 complexes (197 training set; 220 test set), then tested in cross-docking experiments, for a total of 1649 ligand-protein complexes evaluated. The method is computationally efficient and was used to model up to 35 waters during docking. The method was implemented and tested using unaltered AutoDock4 with new force field tables.

Vecchio A.J., Malkowski M.G.

The cyclooxygenases (COX-1 and COX-2) oxygenate arachidonic acid (AA) in the committed step of prostaglandin biogenesis. Substitutions of I434V, H513R, and I523V constitute the only differences in residues lining the cyclooxygenase channel between COX-1 and COX-2. These changes create a hydrophobic pocket in COX-2, with Arg-513 located at the base of the pocket, which has been exploited in the design of COX-2-selective inhibitors. Previous studies have shown that COX-2, but not COX-1, can oxygenate endocannabinoid substrates, including 2-arachidonoyl glycerol (2-AG). To investigate the isoform-specific structural basis of endocannabinoid binding to COX-2, we determined the crystal structure of the 2-AG isomer 1-arachidonoyl glycerol (1-AG) in complex with wild type and R513H murine (mu) COX-2 to 2.2 and 2.35 Å, respectively, and R513H muCOX-2 in complex with AA to 2.45 Å resolution. The 2,3-dihydroxypropyl moiety of 1-AG binds near the opening of the cyclooxygenase channel in the space vacated by the movement of the Leu-531 side chain, validating our previous hypothesis implicating the flexibility of the Leu-531 side chain as a determinant for the ability of COX-2 to oxygenate endocannabinoid substrates. Functional analyses carried out to compliment our structural findings indicated that Y355F and R513H muCOX-2 constructs had no effect on the oxygenation of 1-AG and 2-AG, whereas substitutions that resulted in a shortened side chain for Leu-531 had only modest effects. Both AA and 1-AG bind to R513H muCOX-2 in conformations similar to those observed in the co-crystal structures of these substrates with wild type enzyme.

Dong L., Vecchio A.J., Sharma N.P., Jurban B.J., Malkowski M.G., Smith W.L.

Prostaglandin endoperoxide H synthases 1 and 2, also known as cyclooxygenases (COXs) 1 and 2, convert arachidonic acid (AA) to prostaglandin endoperoxide H(2). Prostaglandin endoperoxide H synthases are targets of nonspecific nonsteroidal anti-inflammatory drugs and COX-2-specific inhibitors called coxibs. PGHS-2 is a sequence homodimer. Each monomer has a peroxidase and a COX active site. We find that human PGHS-2 functions as a conformational heterodimer having a catalytic monomer (E(cat)) and an allosteric monomer (E(allo)). Heme binds tightly only to the peroxidase site of E(cat), whereas substrates, as well as certain inhibitors (e.g. celecoxib), bind the COX site of E(cat). E(cat) is regulated by E(allo) in a manner dependent on what ligand is bound to E(allo). Substrate and nonsubstrate fatty acids (FAs) and some COX inhibitors (e.g. naproxen) preferentially bind to the COX site of E(allo). AA can bind to E(cat) and E(allo), but the affinity of AA for E(allo) is 25 times that for E(cat). Palmitic acid, an efficacious stimulator of human PGHS-2, binds only E(allo) in palmitic acid/murine PGHS-2 co-crystals. Nonsubstrate FAs can potentiate or attenuate actions of COX inhibitors depending on the FA and whether the inhibitor binds E(cat) or E(allo). Our studies suggest that the concentration and composition of the free FA pool in the environment in which PGHS-2 functions in cells, the FA tone, is a key factor regulating PGHS-2 activity and its responses to COX inhibitors. We suggest that differences in FA tone occurring with different diets will likely affect both base-line prostanoid synthesis and responses to COX inhibitors.

Wang J.L., Limburg D., Graneto M.J., Springer J., Hamper J.R., Liao S., Pawlitz J.L., Kurumbail R.G., Maziasz T., Talley J.J., Kiefer J.R., Carter J.

In this Letter, we provide the structure-activity relationships, optimization of design, testing criteria, and human half-life data for a series of selective COX-2 inhibitors. During the course of our structure-based drug design efforts, we discovered two distinct binding modes within the COX-2 active site for differently substituted members of this class. The challenge of a undesirably long human half-life for the first clinical candidate 1t(1/2)=360 h was addressed by multiple strategies, leading to the discovery of 29b-(S) (SC-75416) with t(1/2)=34 h.

Duggan K.C., Walters M.J., Musee J., Harp J.M., Kiefer J.R., Oates J.A., Marnett L.J.

Ho J., Coote M.L., Franco-Pérez M., Gómez-Balderas R.

The gas- and aqueous-phase acidities of a series of oxicams have been computed by combining M05-2X/6-311+G(3df,2p) gas-phase free energies with solvation free energies from the CPCM-UAKS, COSMO-RS, and SMD solvent models. To facilitate accurate gas-phase calculations, a benchmarking study was further carried out to assess the performance of various density functional theory methods against the high-level composite method G3MP2(+). Oxicams are typically diprotic acids, and several tautomers are possible in each protonation state. The direct thermodynamic cycle and the proton exchange scheme have been employed to compute the microscopic pK(a)s on both solution- and gas-phase equilibrium conformers, and these were combined to yield the macroscopic pK(a) values. Using the direct cycle of pK(a) calculation, the CPCM-UAKS model delivered reasonably accurate results with MAD ~ 1, whereas the SMD and COSMO-RS models' performance was less satisfactory with MAD ~ 3. Comparison with experiment also indicates that direct cycle calculations based on solution conformers generally deliver better accuracy. The proton exchange cycle affords further improvement for all solvent models through systematic error cancellation and therefore provides better reliability for the pK(a) prediction of compounds of these types. The latter approach has been applied to predict the pK(a)s of several recently synthesized oxicam derivatives.

Vecchio A.J., Simmons D.M., Malkowski M.G.

The cyclooxygenases (COX-1 and COX-2) are membrane-associated heme-containing homodimers that generate prostaglandin H(2) from arachidonic acid (AA). Although AA is the preferred substrate, other fatty acids are oxygenated by these enzymes with varying efficiencies. We determined the crystal structures of AA, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) bound to Co(3+)-protoporphyrin IX-reconstituted murine COX-2 to 2.1, 2.4, and 2.65 A, respectively. AA, EPA, and docosahexaenoic acid bind in different conformations in each monomer constituting the homodimer in their respective structures such that one monomer exhibits nonproductive binding and the other productive binding of the substrate in the cyclooxygenase channel. The interactions identified between protein and substrate when bound to COX-1 are conserved in our COX-2 structures, with the only notable difference being the lack of interaction of the carboxylate of AA and EPA with the side chain of Arg-120. Leu-531 exhibits a different side chain conformation when the nonproductive and productive binding modes of AA are compared. Unlike COX-1, mutating this residue to Ala, Phe, Pro, or Thr did not result in a significant loss of activity or substrate binding affinity. Determination of the L531F:AA crystal structure resulted in AA binding in the same global conformation in each monomer. We speculate that the mobility of the Leu-531 side chain increases the volume available at the opening of the cyclooxygenase channel and contributes to the observed ability of COX-2 to oxygenate a broad spectrum of fatty acid and fatty ester substrates.

Emsley P., Lohkamp B., Scott W.G., Cowtan K.

Coot is a molecular-graphics application for model building and validation of biological macromolecules. The program displays electron-density maps and atomic models and allows model manipulations such as idealization, real-space refinement, manual rotation/translation, rigid-body fitting, ligand search, solvation, mutations, rotamers and Ramachandran idealization. Furthermore, tools are provided for model validation as well as interfaces to external programs for refinement, validation and graphics. The software is designed to be easy to learn for novice users, which is achieved by ensuring that tools for common tasks are `discoverable' through familiar user-interface elements (menus and toolbars) or by intuitive behaviour (mouse controls). Recent developments have focused on providing tools for expert users, with customisable key bindings, extensions and an extensive scripting interface. The software is under rapid development, but has already achieved very widespread use within the crystallographic community. The current state of the software is presented, with a description of the facilities available and of some of the underlying methods employed.

Kabsch W.

The usage and control of recent modifications of the program packageXDSfor the processing of rotation images are described in the context of previous versions. New features include automatic determination of spot size and reflecting range and recognition and assignment of crystal symmetry. Moreover, the limitations of earlier package versions on the number of correction/scaling factors and the representation of pixel contents have been removed. Large program parts have been restructured for parallel processing so that the quality and completeness of collected data can be assessed soon after measurement.

Adams P.D., Afonine P.V., Bunkóczi G., Chen V.B., Davis I.W., Echols N., Headd J.J., Hung L., Kapral G.J., Grosse-Kunstleve R.W., McCoy A.J., Moriarty N.W., Oeffner R., Read R.J., Richardson D.C., et. al.

Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. However, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics.PHENIXhas been developed to provide a comprehensive system for macromolecular crystallographic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a tight integration between the algorithms.

Prusakiewicz J.J., Duggan K.C., Rouzer C.A., Marnett L.J.

Ibuprofen and mefenamic acid are weak, competitive inhibitors of cyclooxygenase-2 (COX-2) oxygenation of arachidonic acid (AA) but potent, noncompetitive inhibitors of 2-arachidonoylglycerol (2-AG) oxygenation. The slow, tight-binding inhibitor, indomethacin, is a potent inhibitor of 2-AG and AA oxygenation whereas the rapidly reversible inhibitor, 2'-des-methylindomethacin, is a potent inhibitor of 2-AG oxygenation but a poor inhibitor of AA oxygenation. These observations are consistent with a model in which inhibitors bind in one subunit of COX-2 and inhibit 2-AG binding in the other subunit of the homodimeric protein. In contrast, ibuprofen and mefenamate must bind in both subunits to inhibit AA binding.

Terwilliger T.C., Grosse-Kunstleve R.W., Afonine P.V., Moriarty N.W., Zwart P.H., Hung L., Read R.J., Adams P.D.

The highly automated PHENIX AutoBuild wizard is described. The procedure can be applied equally well to phases derived from isomorphous/anomalous and molecular-replacement methods.

Harman C.A., Turman M.V., Kozak K.R., Marnett L.J., Smith W.L., Garavito R.M.

The modification of the nonselective nonsteroidal anti-inflammatory drug, indomethacin, by amidation presents a promising strategy for designing novel cyclooxygenase (COX)-2-selective inhibitors. A series of α-substituted indomethacin ethanolamides, which exist as R/S-enantiomeric pairs, provides a means to study the impact of stereochemistry on COX inhibition. Comparative studies revealed that the R- and S-enantiomers of the α-substituted analogs inhibit COX-2 with almost equal efficacy, whereas COX-1 is selectively inhibited by the S-enantiomers. Mutagenesis studies have not been able to identify residues that manifest the enantioselectivity in COX-1. In an effort to understand the structural impact of chirality on COX-1 selectivity, the crystal structures of ovine COX-1 in complexes with an enantiomeric pair of these indomethacin ethanolamides were determined at resolutions between 2.75 and 2.85Å. These structures reveal unique, enantiomer-selective interactions within the COX-1 side pocket region that stabilize drug binding and account for the chiral selectivity observed with the (S)-α-substituted indomethacin ethanolamides. Kinetic analysis of binding demonstrates that both inhibitors bind quickly utilizing a two-step mechanism. However, the second binding step is readily reversible for the R-enantiomer, whereas for the S-enantiomer, it is not. These studies establish for the first time the structural and kinetic basis of high affinity binding of a neutral inhibitor to COX-1 and demonstrate that the side pocket of COX-1, previously thought to be sterically inaccessible, can serve as a binding pocket for inhibitor association.

Prohens R., Barbas R., Abrego G., Frontera A.

We report a joined crystallographic and computational work on the anhydrous form of the anti-inflammatory drug pranoprofen, which provides deeper insight into the complex interplay of π-stacking and H-bonding interactions in its molecular arrangement.

Redzicka A., Wojtkowiak K., Kochel A., Wiatrak B., Jęśkowiak-Kossakowska I., Jezierska A.

Glomb T., Świątek P., Środa-Pomianek K., Palko-Łabuz A., Wesołowska O., Wikiera A., Wojtkowiak K., Jezierska A., Kochel A., Lesyk R.

AbstractIn this research, a series of novel hydrazone derivatives based on pyrazolopyridothiazinylacetohydrazide were designed, synthesized, and evaluated for their in vitro cytotoxic potency on several human colon cancer cells (HTC116, HT‐29, and LoVo). After MTT and SRB assays four of the most active derivatives: hydrazide GH and hydrazones GH7, GH8, and GH11, were chosen for further investigation. Hydrazone GH11 had the highest cytotoxic activity (IC50 values of c.a. 0.5 μM). Additionally, the impact of novel derivatives on the oxidative stress level, apoptosis induction, and modulation of inflammation in colon cancer cells was examined. In all studies, the activity of the derivatives increased in order GH < GH7 < GH8 < GH11. At the same time, most of the research was conducted on compounds combined with apple pectin (PC). The most interesting observation was that all the studied derivatives applied together with PC showed significantly higher activity than observed in the case of using PC, hydrazide, or hydrazones separately. Finally, computational chemistry methods (molecular modeling and Density Functional Theory – DFT) were used to complement the experimental studies.

Qin M., Xing T., Zhang M., Han J., Yu S., Chen J., Ma Y.

Cyclooxygenase and inducible nitric oxide synthase are key proteins in two different pathways that produce inflammation. In this study, we based on the principle of pharmacophore combination to obtain small molecules that can block the dual targets of COXs and iNOS. We screened two pharmacophores with anti-inflammatory activity, chromone ring and sulfonamide from clinical drugs, natural products and other compounds with outstanding biological activity, and synthesized 9 novel chromone-sulfonamide derivatives, among which compounds 4a, 4b, 4c, 4d and 4i exhibited different degrees of COXs and iNOS inhibition. In particular, compound 4i exhibited the most significant dual inhibitory effect, with an IC50 of 28.83 ± 0.06 μM for PGE2 and an IC50 of 36.95 ± 3.9 μM for NO content, which was superior to the positive drugs ibuprofen (IBU, IC50 = 246.5 ± 3.8 μM) and L-canavanine (L-Can., IC50 = 440.0 ± 7.9 μM). In addition, the research group used Discovery Studio to dock the target compounds with COX-1, COX-2 and iNOS, respectively, and the results showed that compound 4i had the best docking method (its -CDOCK INTERACTION ENERGY scores were 48.2967, 45.3519 and 43.4412, respectively, which were better than those of other compounds), which was consistent with the results of activity experiments, and the chromone ring and sulfonamide group could form hydrogen bonds between the two target proteins, conjugation and van der Waals interactions, indicating that the chromone ring and sulfonamide group are key pharmacophores. In addition, a preliminary study of the structure-activity relationship of the compound was carried out to identify the key factors affecting the anti-inflammatory activity, and 4i matched the structure-activity relationship, which indicated that 4i was a lead compound for the development of dual COXs/iNOS inhibition for the treatment of inflammatory diseases.

Szczęśniak-Sięga B.M., Maniewska J., Wiatrak B., Janek T., Nowotarska P., Czyżnikowska Ż.

The design of novel anti-inflammatory drugs remains a critical area of research in the development of effective treatments for inflammatory diseases. In this study, a series of 1,2-benzothiazine was evaluated through a multifaceted approach. In particular, we investigated the potential interactions of the potential drugs with lipid bilayers, an important consideration for membrane permeability and overall pharmacokinetics. In addition, we evaluated their ability to inhibit cyclooxygenase 1 and cyclooxygenase 2 activity and selectivity using both a cyclooxygenase inhibition assay and molecular docking simulations. To evaluate their therapeutic potential, we performed in vitro assays to measure cytokine mRNA expression in inflamed cells. The antioxidant activity was evaluated using both in vitro assays, such as 2,2-diphenyl-1-picrylhydrazyl and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid scavenging, to determine the compounds’ capacity to neutralize free radicals and reduce oxidative stress. Theoretical calculations, including density functional theory, were used to predict the reactivity profiles of the compounds.

Sirlam M., Leutcha P.B., Nouemsi G.R., Zafar H., Tegha H.F., Sema D.K., Tankeu V.F., Ditchou Y.O., Poka M., Demana P., Atia-tul-Wahab, Choudhry M.I., Noundou X.S., Lannang A.M.

Tylińska B., Janicka-Kłos A., Gębarowski T., Nowotarska P., Plińska S., Wiatrak B.

Pyrimidine derivatives exhibit a wide range of biological activities, including anti-inflammatory properties. The aim of this study was to investigate the effects of tested pyrimidine derivatives on the activity of cyclooxygenase isoenzymes (COX-1 and COX-2), antioxidant properties, and their ability to inhibit the growth of inflammatory cells. In vitro tests were conducted to assess the ability of pyrimidine derivatives L1–L4 to inhibit COX-1 and COX-2 activity using the TMPD oxidation assay (N,N,N',N'-tetramethyl-p-phenylenediamine). The compounds’ ability to inhibit the growth of lipopolysaccharide (LPS)-stimulated THP-1 (human leukemia monocytic) monocyte cells and their impact on reactive oxygen species (ROS) levels in an inflammatory model were also evaluated. The binding properties of human serum albumin (HSA) were assessed using UV–Vis spectroscopy, circular dichroism (CD), and isothermal titration calorimetry (ITC). Among the tested pyrimidine derivatives, L1 and L2 showed high selectivity towards COX-2, outperforming piroxicam and achieving results comparable to meloxicam. In the sulforhodamine B (SRB) assay, L1 and L2 demonstrated dose-dependent inhibition of LPS-stimulated THP-1 cell growth. Additionally, ROS assays indicated that these compounds reduced free radical levels, confirming their antioxidant properties. Binding studies with albumin revealed that L1 and L2 formed stable complexes with HSA. These results suggest that these compounds could serve as a basis for further research into anti-inflammatory and anticancer drugs with reduced toxicity.

El-Ayouty M.M., Eltahawy N.A., Abd EL-sameaa A.M., Badawy A.M., Darwish K.M., Elhady S.S., Shokr M.M., Ahmed S.A.

Cleome amblyocarpa Barr. and Murb. from the family Cleomaceae is used in folk medicine as it has analgesic, anti-inflammatory, antibacterial and antioxidant activities.

Burman J., Manchanda K., Bhakhar K.A., Boharupi A.N., Gohlke H., Bharatam P.V.

Oxicams are important drugs that act as anti-inflammatory agents. Of them, piroxicam and its prodrugs are in daily use. The metabolic profiles of oxicams were explored using mass spectrometry methods and, in some cases, NMR. However, there is a noticeable gap in research regarding the in-depth exploration of the electronic structure of their reactive metabolites. The relative energies of the various metabolites of oxicams and the associated possible isomers have not been compared. In this work, the electronic characteristics of the reactive metabolites associated with important oxicams have been evaluated. This comparative analysis helped in identifying additional potential reactive metabolites of several oxicams. For example, the quinonimine metabolite of piroxicam has been suggested as an important possibility. This work highlights that in addition to mass spectrometry analysis, energy comparison of possible isomers needs to be carried out in drug metabolism studies.

Yıldız M.T., Osmaniye D., Saglik B.N., Levent S., Kurnaz R., Ozkay Y., Kaplancıklı Z.A.

AbstractThe frequent use of anti‐inflammatory drugs and the side effects of existing drugs keep the need for new compounds constant. For this purpose, flurbiprofen and ibuprofen‐like compounds, which are frequently used anti‐inflammatory compounds in this study, were synthesized and their structures were elucidated. Like ibuprofen and flurbiprofen, the compounds contain a residue of phenylacetic acid. On the other hand, it contains a secondary amine residue. Thus, it is planned to reduce the acidity, which is the biggest side effect of NSAI drugs, even a little bit. The estimated ADME parameters of the compounds were evaluated. Apart from internal use, local use of anti‐inflammatory compounds is also very important. For this reason, the skin permeability values of the compounds were also calculated. And it has been found to be compatible with reference drugs. The COX enzyme inhibitory effects of the obtained compounds were tested by in vitro experiments. Compound 2a showed significant activity against COX‐1 enzyme with an IC50 = 0.123 + 0.005 μM. The interaction of the compound with the enzyme active site was clarified by molecular dynamics studies.

C S S., Natarajan K.

Nonsteroidal anti-inflammatory drugs are FDA-approved for their anti-inflammatory, antipyretic (fever-reducing), and analgesic (pain-relieving) properties. These treat various diseases like rheumatoid arthritis, migraine, muscle pain, menstrual pain, fever, and gout. They can also reduce the need for opioids in acute trauma cases. These drugs are categorized into distinct groups based on their chemical structure and selectivity including COX-2 selective inhibitors (celecoxib and etoricoxib), acetylated salicylates (aspirin), non-acetylated salicylates (diflunisal and salsalate), propionic acids (naproxen and ibuprofen), enolic acid (meloxicam and piroxicam), acetic acids (diclofenac and indomethacin), naphthyl alanine (nabumetone), and anthranilic acids (meclofenamate and mefenamic acid). They can be used orally or topically like diclofenac gel and can be used for soft tissue injuries, acute tenosynovitis, and ankle sprains. However, due to high toxicity, the use of classical NSAIDs has been restricted. Therefore, new drugs with lower side effects and increased half-life should be developed. Multi-targeted inhibition can enhance efficacy or reduce side effects in treating inflammation and pain. This chapter focuses on existing NSAIDs, their mechanism of action, and drug leads from plant sources that may serve as anti-inflammatory compounds to combat classical NSAIDs.

Said M.F., George R.F., Fayed W., F Soliman A.A., Refaey R.H.

Background: The search is ongoing for ideal anti-inflammatory and analgesic agents with promising potency and reasonable selectivity. Methods: New N1-substituted pyrazoles with or without an acetamide linkage were synthesized and evaluated for their anti-inflammatory and analgesic activities. COX inhibitory testing, molecular docking, molecular dynamics simulation and antiproliferative activity assessments were performed. Results: All compounds exhibited anti-inflammatory activity up to 90.40% inhibition. They also exhibited good analgesic activity with up to 100% protection. N1-benzensulfonamides 3d, 6c and 6h were preferentially selective agents toward COX-2. Compound 3d showed good cytotoxicity against MCF-7 and HTC116 cancer cell lines. Molecular modeling studies predicted the binding pattern of the most active compounds. Molecular dynamics confirmed the docking results. All compounds showed remarkable pharmacokinetic properties.

Bello-Vargas E., Leyva-Peralta M.A., Gómez-Sandoval Z., Ordóñez M., Razo-Hernández R.S.

Among the biological targets extensively investigated to improve inflammation and chronic inflammatory conditions, cyclooxygenase enzymes (COXs) occupy a prominent position. The inhibition of these enzymes, essential for mitigating inflammatory processes, is chiefly achieved through Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). In this work, we introduce a novel method—based on computational molecular docking—that could aid in the structure-based design of new compounds or the description of the anti-inflammatory activity of already-tested compounds. For this, we used eight crystal complexes (four COX-1 and COX-2 each), and each pair had a specific NSAID: Celecoxib, Meloxicam, Ibuprofen, and Indomethacin. This selection was based on the ligand selectivity towards COX-1 or COX-2 and their binding mode. An interaction profile of each NSAID was compiled to detect the residues that are key for their binding mode, highlighting the interaction made by the Me group. Furthermore, we rigorously validated our models based on structural accuracy (RMSD < 1) and (R2 > 70) using eight NSAIDs and thirteen compounds with IC50 values for each enzyme. Therefore, this model can be used for the binding mode prediction of small and structurally rigid compounds that work as COX inhibitors or the prediction of new compounds that are designed by means of a structure-based approach.

Olubodun-Obadun T.G., Ishola I.O., Osumuo C.A., Adeyemi O.O.

Peripheral tissue damage and diseases could lead to persistent pain beyond possible resolution suggestive of disease-promoting condition which gives rise to chronic pain. The inability of current medications to manage some chronic inflammatory and painful conditions necessitate the need for better treatment options. Natural products have been a veritable source for the discovery of more efficacious and safer therapeutics. Cajanus cajan (L) Millsp, (Fabaceae) is used in traditional African medicines for the treatment of painful, gut disturbance and inflammatory conditions. Hence, the current study aims to investigate the anti-inflammatory and antinociceptive actions of the ethanol seed extract of Cajanus cajan (CC) in rodents and possible mechanisms of action. High performance liquid chromatography coupled with diode-array detection (HPLC-DAD) was used to identify 8 major flavonoids in CC. Antinociceptive activity was investigated using the acetic acid-induced writhing reflex, biphasic formalin-induced flinching behaviour and supraspinal hot plate-evoked nociception in mice. Carrageenan-induced rat paw oedema test was used to evaluate the anti-inflammatory action of CC in rats. Possible mechanism of antinociception and anti-inflammatory actions were examined using both in vivo model and molecular docking procedures against µ-opioid receptor (MOR), cyclooxygenase-2 (COX-2) and phospholipase A2 (PLA2) proteins, respectively. The chromatographic procedure qualitatively and quantitatively confirmed the presence of rutin, quercetin, gallic acid, luteolin, pinostrobin, BiochaninA, formononetin and apigenin in CC. The in vivo nociceptive assay, showed that CC (50, 100, or 200mg/kg, p.o.) significantly decreased mean number of writhing reflex with peak effect at 50mg/kg (72% inhibition) when compared with vehicle control in mouse writhing test. Similarly, the biphasic formalin-induced nociception was significantly reduced by CC (50mg/kg) with 24.61 and 66.73% inhibition of nociceptive reactions in both the early and late phases of formalin-induced inflammatory pain, respectively. In addition, CC significantly increased supraspinal thermally mediated pain threshold with maximum possible effects of 42.25 and 52.16% at CC 50 and 100mg/kg, respectively, in hot-plate test. Similarly, CC100mg/kg caused time course inhibition of carrageenan-induced paw oedema in rat with peak effect (65.78%, CC 100mg/kg; 6h). Interestingly, the antinociceptive action of CC was blocked by the pre-treatment of mice with L-NG-nitro arginine methyl ester (L-NAME) or naloxone. The molecular docking analysis revealed prominent interactions of pinostrobin, physcion and lupeol with MOR, COX-2, and PLA2, respectively. Findings from this study showed that Cajanus cajan seeds extract possesses anti-nociceptive and anti-inflammatory through inhibition of inflammatory mediators (PLA2/COX-2) and activation of opioidergic signaling.

Mikus J., Świątek P., Przybyła P., Krzyżak E., Marciniak A., Kotynia A., Redzicka A., Wiatrak B., Jawień P., Gębarowski T., Szczukowski Ł.

Secure and efficient treatment of diverse pain and inflammatory disorders is continually challenging. Although NSAIDs and other painkillers are well-known and commonly available, they are sometimes insufficient and can cause dangerous adverse effects. As yet reported, derivatives of pyrrolo[3,4-d]pyridazinone are potent COX-2 inhibitors with a COX-2/COX-1 selectivity index better than meloxicam. Considering that N-acylhydrazone (NAH) moiety is a privileged structure occurring in many promising drug candidates, we decided to introduce this pharmacophore into new series of pyrrolo[3,4-d]pyridazinone derivatives. The current paper presents the synthesis and in vitro, spectroscopic, and in silico studies evaluating the biological and physicochemical properties of NAH derivatives of pyrrolo[3,4-d]pyridazinone. Novel compounds 5a-c–7a-c were received with high purity and good yields and did not show cytotoxicity in the MTT assay. Their COX-1, COX-2, and 15-LOX inhibitory activities were estimated using enzymatic tests and molecular docking studies. The title N-acylhydrazones appeared to be promising dual COX/LOX inhibitors. Moreover, spectroscopic and computational methods revealed that new compounds form stable complexes with the most abundant plasma proteins–AAG and HSA, but do not destabilize their secondary structure. Additionally, predicted pharmacokinetic and drug-likeness properties of investigated molecules suggest their potentially good membrane permeability and satisfactory bioavailability.