Structural and functional basis of cyclooxygenase inhibition

Inhibition of cyclooxygenase by blocking the reducing cosubstrate at the peroxidase site: Discovery of galangin as a novel cyclooxygenase inhibitor

Earlier we have shown that certain flavonoids (e.g., quercetin) are high-affinity reducing cosubstrates for cyclooxygenase (COX) 1 and 2. These compounds can bind inside the peroxidase active sites of COXs and donate an electron from one of their B-ring hydroxyl groups to hematin. Based on these earlier findings, it is postulated that some of the natural flavonoids such as galangin that are structural analogs of quercetin but lack the proper B-ring hydroxyl groups might function as novel inhibitors of COXs by blocking the effect of the reducing cosubstrates. This idea is tested in the present study. Computational docking analysis together with quantum chemistry calculation shows that galangin can bind inside the peroxidase active sites of COX-1 and COX-2 in a similar manner as quercetin, but it has little ability to effectively donate its electrons, thereby blocking the effect of the reducing cosubstrates like quercetin. Further experimental studies confirm that galangin can inhibit, both in vitro and in vivo, quercetin-mediated activation of the peroxidase activity of the COX-1/2 enzymes. The results of the present study demonstrate that galangin is a novel naturally-occurring inhibitor of COX-1 and COX-2, acting by blocking the function of the reducing cosubstrates at the peroxidase sites.

Development of Fluorescence Imaging Probes for Labeling COX-1 in Live Ovarian Cancer Cells

Recent experimental evidence demonstrated an aberrant overexpression of cyclooxygenase-1 (COX-1) in various cancers, which has stimulated the development of COX-1-selective inhibitors as promising anticancer drugs and cancer imaging agents. Herein we describe the synthesis and validation of 3-(furan-2-yl)-N-aryl 5-amino-pyrazoles as a novel class of COX-1 inhibitors, including molecular docking studies. Among all tested compounds, 4-(5-azido-3-(furan-2-yl)-1H-pyrazol-1-yl)benzoic 17 displayed a favorable COX-1 inhibition and selectivity profile (COX-1 IC₅₀ = 0.1 μM, SI >1000 over COX-2). Compound 17 was selected as a lead structure for developing the novel COX-1-selective fluorescent probe 22. Fluorescent probe 22 was prepared via click chemistry by installing a nitro-benzoxadiazole motif as a fluorophore into the 3-(furan-2-yl)-N-aryl 5-amino-pyrazole scaffold. Fluorescence probe 22 was tested in ovarian cancer cell line OVCAR-3, confirming its usefulness for targeting and visualizing COX-1 in living cells with confocal microscopy.

Tailoring the substitution pattern of Pyrrolidine-2,5-dione for discovery of new structural template for dual COX/LOX inhibition

Dual inhibition of the enzymatic pathways of cyclooxygenases (COX-1/COX-2) and lipoxygenase (LOX) is a rational approach for developing more efficient and safe anti-inflammatory agents. Herein, dual inhibitors of COX and LOX for the management of inflammation are reported. The structural modifications of starting pyrrolidine-2,5-dione aldehyde derivatives resulted in two structurally diverse families (Family A & B). Synthesized derivatives from both Families displayed preferential COX-2 affinity in submicromolar to nanomolar ranges. Disubstitution pattern of the most active series of compounds having N-(benzyl(4-methoxyphenyl)amino moiety presents a new template that is mimic to the diaryl pattern of traditional COX-2 inhibitors. Compound 78 with IC₅₀ value of 0.051 ± 0.001 μM emerged as the most active compound. Highly potent COX-2/5-LOX inhibitors have also demonstrated appreciable in-vivo anti-inflammatory activity through carrageenan induced paw edema test. Moreover, the involvement of histamine, bradykinin, prostaglandin, and leukotriene mediators to adjust the inflammatory response were also studied. Apart from COX inhibition, sulfonamide is considered an important template for carbonic anhydrase inhibition. Hence, we also evaluated six sulfonamide derivatives for off-target in-vitro bovine carbonic anhydrase-II inhibition. Biological results were finally rationalized by docking simulations. Typically, most active COX-2 inhibitors interact with the amino acid residues responsible for the COX-2 selectivity.

New nitric oxide-releasing indomethacin derivatives with 1,3-thiazolidine-4-one scaffold: Design, synthesis, in silico and in vitro studies

In this study we present design and synthesis of nineteen new nitric oxide-releasing indomethacin derivatives with 1,3-thiazolidine-4-one scaffold (NO-IND-TZDs) (6a-s), as a new safer and efficient multi-targets strategy for inflammatory diseases. The chemical structure of all synthesized derivatives (intermediaries and finals) was proved by NMR and mass spectroscopic analysis. In order to study the selectivity of NO-IND-TZDs for COX isoenzymes (COX-1 and COX-2) a molecular docking study was performed using AutoDock 4.2.6 software. Based on docking results, COX-2 inhibitors were designed and 6o appears as the most selective derivative which showed an improved selective index compared with indomethacin (IND) and diclofenac (DCF), used as reference drugs. The biological evaluation of 6a-s, using in vitro assays has included the anti-inflammatory and antioxidant effects as well as the nitric oxide (NO) release. Referring to the anti-inflammatory effects, the most active compound was 6i, which was more active than IND and aspirin (ASP) in term of denaturation effect, on bovine serum albumin (BSA), as indirect assay to predict the anti-inflammatory effect. An appreciable anti-inflammatory effect, in reference with IND and ASP, was also showed by 6k, 6c, 6q, 6o, 6j, 6d. The antioxidant assay revealed the compound 6n as the most active, being 100 times more active than IND. The compound 6n showed also the most increase capacity to release NO, which means is safer in terms of gastro-intestinal side effects. The ADME-Tox study revealed also that the NO-IND-TZDs are generally proper for oral administration, having optimal physico-chemical and ADME properties. We can conclude that the compounds 6i and 6n are promising agents and could be included in further investigations to study in more detail their pharmaco-toxicological profile.

Ibuprofen-based advanced therapeutics: breaking the inflammatory link in cancer, neurodegeneration, and diseases

Ibuprofen is a classical nonsteroidal anti-inflammatory drug (NSAID) highly prescribed to reduce acute pain and inflammation under an array of conditions, including rheumatoid arthritis, osteoarthritis, dysmenorrhea, and gout. Ibuprofen acts as a potential inhibitor for cyclooxygenase enzymes (COX-1 and COX-2). In the past few decades, research on this small molecule has led to identifying other possible therapeutic benefits. Anti-tumorigenic and neuroprotective functions of Ibuprofen are majorly recognized in recent literature and need further consideration. Additionally, several other roles of this anti-inflammatory molecule have been discovered and subjected to experimental assessment in various diseases. However, the major challenge faced by Ibuprofen and other drugs of similar classes is their side effects, and tendency to cause gastrointestinal injury, generate cardiovascular risks, modulate hepatic and acute kidney diseases. Future research should also be conducted to deduce new methods and approaches of suppressing the unwanted toxic changes mediated by these drugs and develop new therapeutic avenues so that these small molecules continue to serve the purposes. This article primarily aims to develop a comprehensive and better understanding of Ibuprofen, its pharmacological features, therapeutic benefits, and possible but less understood medicinal properties apart from major challenges in its future application.KEY POINTSIbuprofen, an NSAID, is a classical anti-inflammatory therapeutic agent.Pro-apoptotic roles of NSAIDs have been explored in detail in the past, holding the key in anti-cancer therapies.Excessive and continuous use of NSAIDs may have several side effects and multiple organ damage.Hyperactivated Inflammation initiates multifold detrimental changes in multiple pathological conditions.Targeting inflammatory pathways hold the key to several therapeutic strategies against many diseases, including cancer, microbial infections, multiple sclerosis, and many other brain diseases.

Potency of Bone Marrow-Derived Mesenchymal Stem Cells and Indomethacin in Complete Freund's Adjuvant-Induced Arthritic Rats: Roles of TNF-α, IL-10, iNOS, MMP-9, and TGF-β1

Rheumatoid arthritis (RA) is an autoimmune syndrome affecting joint spaces, leading to the disabled state. Currently, there is no optimal therapy for RA except for systemic immunosuppressants that have variable undesirable effects after long-term use. Hence, the need for other treatment modalities has emerged in an attempt to develop a treating agent that is effective but without bad effects. Bone marrow-derived mesenchymal stem cells (BM-MSCs) may be an alternative medicine since they may differentiate into a variety of mesenchymal tissues including bone and cartilage. Indomethacin (IMC) could be suggested as an analgesic, anti-inflammatory, and antirheumatic potential agent against the course of RA since it possesses significant palliative effects and antipyretic properties. Therefore, our target of this study was to explore and compare the effect of BM-MSCs (1 × 10⁶ cells/rat at the 1^st, 6^th, 12^th, and 18^th days) and IMC (2 mg/kg b.w./day for 3 weeks) either alone or in combination on arthritic rats. The model of rheumatoid arthritis in rats was induced by subcutaneous injection of 0.1 mL/rat CFA into the footpad of the right hind paw. The BM-MSC intravenous injection and IMC oral administration significantly reduced the elevated right hind leg paw diameter and circumference, serum anti-CCP, and ankle joint articular tissue expressions of TNF-α, iNOS, MMP-9, and TGF-β1 while they significantly increased the lowered articular IL-10 expression in CFA-induced arthritic rats. The combinatory effect of the two treatments was the most potent. In conclusion, the treatment of RA with BM-MSCs and IMC together is more effective than the treatment with either BM-MSCs or IMC. The Th1 cytokine (TNF-α), Th2 cytokine (IL-10), iNOS, MMP-9, and TGF-β1 are important targets for mediating the antiarthritic effects of BM-MSCs and IMC in CFA-induced arthritis in rats.

Non-ulcerogenic pyrazolyl 2-hydroxychalcones and pyrazolylpyrazolines derived from naturally existing furochromone (khellin): semi-synthesis, docking study and anti-inflammatory activity

Novel pyrazolyl 2-hydroxychalcone derivatives 3a-e and pyrazolylpyrazoline derivatives 4a-e and 5a-j derived from the naturally existing furochromone (Khellin) were synthesized and evaluated for their in vivo anti-inflammatory activity. Most of the synthesized compounds showed better or comparable activity to that of Diclofenac as reference drug. Twelve compounds were evaluated for their ulcerogenic potential and exhibited no ulcerogenic effect. In addition compounds 3c, 5c and 5h as examples showed PGE₂ inhibition % 88.86, 65.87 and 44.06, respectively and TNFα inhibition % 48.62, 31.11 and 16.02, respectively in rat serum samples. Compounds 3c, 5c, 5h and Celecoxib were subjected to in vitro COX-1 and COX-2 inhibition assay, showed selectivity index 45.04, 102.04, 131.58 and 185.18, respectively. The computational finding supported those of in vitro, where the pyrazolylpyrazolines interacted with the COX-2 enzyme in a similar orientation to that of Celecoxib, while chlacones were found to exhibit similar orientation to that of Diclofenac.

DEG/ENaC/ASIC channels vary in their sensitivity to anti-hypertensive and non-steroidal anti-inflammatory drugs

The degenerin channels, epithelial sodium channels, and acid-sensing ion channels (DEG/ENaC/ASICs) play important roles in sensing mechanical stimuli, regulating salt homeostasis, and responding to acidification in the nervous system. They have two transmembrane domains separated by a large extracellular domain and are believed to assemble as homomeric or heteromeric trimers. Based on studies of selected family members, these channels are assumed to form nonvoltage-gated and sodium-selective channels sensitive to the anti-hypertensive drug amiloride. They are also emerging as a target of nonsteroidal anti-inflammatory drugs (NSAIDs). Caenorhabditis elegans has more than two dozen genes encoding DEG/ENaC/ASIC subunits, providing an excellent opportunity to examine variations in drug sensitivity. Here, we analyze a subset of the C. elegans DEG/ENaC/ASIC proteins to test the hypothesis that individual family members vary not only in their ability to form homomeric channels but also in their drug sensitivity. We selected a panel of C. elegans DEG/ENaC/ASICs that are coexpressed in mechanosensory neurons and expressed gain-of-function or d mutants in Xenopus laevis oocytes. We found that only DEGT‑1d, UNC‑8d, and MEC‑4d formed homomeric channels and that, unlike MEC‑4d and UNC‑8d, DEGT‑1d channels were insensitive to amiloride and its analogues. As reported for rat ASIC1a, NSAIDs inhibit DEGT‑1d and UNC‑8d channels. Unexpectedly, MEC‑4d was strongly potentiated by NSAIDs, an effect that was decreased by mutations in the putative NSAID-binding site in the extracellular domain. Collectively, these findings reveal that not all DEG/ENaC/ASIC channels are amiloride-sensitive and that NSAIDs can both inhibit and potentiate these channels.

Synthesis and Biological Evaluation of 1,3,5-Trisubstituted 2-Pyrazolines as Novel Cyclooxygenase-2 Inhibitors with Antiproliferative Activity

A new series of 1,3,5-trisubstituted 2-pyrazolines for the inhibition of cyclooxygenase-2 (COX-2) were synthesized. The designed structures include a COX-2 pharmacophore SO₂ CH₃ at the para-position of the phenyl ring located at C-5 of a pyrazoline scaffold. The synthesized compounds were tested for in vitro COX-1/COX-2 inhibition and cell toxicity against human colorectal adenocarcinoma cell lines HT-29. The lead compound (4-chlorophenyl){5-[4-(methanesulfonyl)phenyl]-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl}methanone (16) showed significant COX-2 inhibition (IC₅₀ =0.05±0.01 μM), and antiproliferative activity (IC₅₀ =5.46±4.71 μM). Molecular docking studies showed that new pyrazoline-based compounds interact via multiple hydrophobic and hydrogen-bond interactions with key binding site residues of the COX-2 enzyme.

Inhibition of mPGES-1 attenuates efficient resolution of acute inflammation by enhancing CX3CL1 expression

Despite the progress to understand inflammatory reactions, mechanisms causing their resolution remain poorly understood. Prostanoids, especially prostaglandin E2 (PGE2), are well-characterized mediators of inflammation. PGE2 is produced in an inducible manner in macrophages (Mϕ) by microsomal PGE2-synthase-1 (mPGES-1), with the notion that it also conveys pro-resolving properties. We aimed to characterize the role of mPGES-1 during resolution of acute, zymosan-induced peritonitis. Experimentally, we applied the mPGES-1 inhibitor compound III (CIII) once the inflammatory response was established and confirmed its potent PGE2-blocking efficacy. mPGES-1 inhibition resulted in an incomplete removal of neutrophils and a concomitant increase in monocytes and Mϕ during the resolution process. The mRNA-seq analysis identified enhanced C-X3-C motif receptor 1 (CX3CR1) expression in resident and infiltrating Mϕ upon mPGES-1 inhibition. Besides elevated Cx3cr1 expression, its ligand CX3CL1 was enriched in the peritoneal lavage of the mice, produced by epithelial cells upon mPGES-1 inhibition. CX3CL1 not only increased adhesion and survival of Mϕ but its neutralization also completely reversed elevated inflammatory cell numbers, thereby normalizing the cellular, peritoneal composition during resolution. Our data suggest that mPGES-1-derived PGE2 contributes to the resolution of inflammation by preventing CX3CL1-mediated retention of activated myeloid cells at sites of injury.

Design, Synthesis and Comprehensive Investigations of Pyrrolo[3,4-d]pyridazinone-Based 1,3,4-Oxadiazole as New Class of Selective COX-2 Inhibitors

The long-term use of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) in treatment of different chronic inflammatory disorders is strongly restricted by their serious gastrointestinal adverse effects. Therefore, there is still an urgent need to search for new, safe, and efficient anti-inflammatory agents. Previously, we have reported the Mannich base-type derivatives of pyrrolo[3,4-d]pyridazinone which strongly inhibit cyclooxygenase, have better affinity to COX-2 isoenzyme and exert promising anti-oxidant activity. These findings encouraged us to perform further optimization of that structure. Herein, we present the design, synthesis, molecular docking, spectroscopic, and biological studies of novel pyrrolo[3,4-d]pyridazinone derivatives bearing 4-aryl-1-(1-oxoethyl)piperazine pharmacophore 5a,b-6a,b. The new compounds were obtained via convenient, efficient, one-pot synthesis. According to in vitro evaluations, novel molecules exert no cytotoxicity and act as selective COX-2 inhibitors. These findings stay in good correlation with molecular modeling results, which additionally showed that investigated compounds take a position in the active site of COX-2 very similar to Meloxicam. Moreover, all derivatives reduce the increased level of reactive oxygen and nitrogen species and prevent DNA strand breaks caused by oxidative stress. Finally, performed spectroscopic and molecular docking studies demonstrated that new compound interactions with bovine serum albumin (BSA) are moderate, formation of complexes is in one-to-one ratio, and binding site II (subdomain IIIA) is favorable.

In Cellulo Generation of Fluorescent Probes for Live-Cell Imaging of Cylooxygenase-2

Live-cell imaging with fluorescent probes is an essential tool in chemical biology to visualize the dynamics of biological processes in real-time. Intracellular disease biomarker imaging remains a formidable challenge due to the intrinsic limitations of conventional fluorescent probes and the complex nature of cells. This work reports the in cellulo assembly of a fluorescent probe to image cyclooxygenase-2 (COX-2). We developed celecoxib-azide derivative 14, possessing favorable biophysical properties and excellent COX-2 selectivity profile. In cellulo strain-promoted fluorogenic click chemistry of COX-2-engaged compound 14 with non/weakly-fluorescent compounds 11 and 17 formed fluorescent probes 15 and 18 for the detection of COX-2 in living cells. Competitive binding studies, biophysical, and comprehensive computational analyses were used to describe protein-ligand interactions. The reported new chemical toolbox enables precise visualization and tracking of COX-2 in live cells with superior sensitivity in the visible range.

New 1,3,4-Oxadiazole Derivatives of Pyridothiazine-1,1-Dioxide with Anti-Inflammatory Activity

Numerous studies have confirmed the coexistence of oxidative stress and inflammatory processes. Long-term inflammation and oxidative stress may significantly affect the initiation of the neoplastic transformation process. Here, we describe the synthesis of a new series of Mannich base-type hybrid compounds containing an arylpiperazine residue, 1,3,4-oxadiazole ring, and pyridothiazine-1,1-dioxide core. The synthesis was carried out with the hope that the hybridization of different pharmacophoric molecules would result in a synergistic effect on their anti-inflammatory activity, especially the ability to inhibit cyclooxygenase. The obtained compounds were investigated in terms of their potencies to inhibit cyclooxygenase COX-1 and COX-2 enzymes with the use of the colorimetric inhibitor screening assay. Their antioxidant and cytotoxic effect on normal human dermal fibroblasts (NHDF) was also studied. Strong COX-2 inhibitory activity was observed after the use of TG6 and, especially, TG4. The TG11 compound, as well as reference meloxicam, turned out to be a preferential COX-2 inhibitor. TG12 was, in turn, a non-selective COX inhibitor. A molecular docking study was performed to understand the binding interaction of compounds at the active site of cyclooxygenases.

Synthesis, 3D-QSAR, and Molecular Modeling Studies of Triazole Bearing Compounds as a Promising Scaffold for Cyclooxygenase-2 Inhibition

Targeting of cyclooxygenase-2 (COX-2) has emerged as a powerful tool for therapeutic intervention because the overexpression of this enzyme is synonymous with inflammation, cancer, and neurodegenerative diseases. Herein, a new series of 1,2,4-triazole Schiff bases scaffold with aryl and heteroaryl systems 9a–12d were designed, synthesized, structurally elucidated, and biologically evaluated as a potent COX-2 blocker. The rationale beyond the current study is to increase the molecule bulkiness allowing a selective binding to the unique hydrophobic pocket of COX-2. Among the triazole–thiazole hybrids, the one with the para-methoxy moiety linked to a phenyl ring 12d showed the highest In vitro selectivity by COX-2 inhibition assay (IC₅₀ of 0.04 μM) and in situ anti-inflammatory activity when evaluated using the protein denaturation assay (IC₅₀ of 0.88 μM) in comparison with commercially available selective COX-2 inhibitor, Celecoxib (IC₅₀ of 0.05 μM). Towards the COX-2 selectivity, ligand-based three dimensional quantitative structures activity relationship (3D-QSAR) employing atomic-based and field-based approaches were performed and resulted in the necessity of triazole and thiazole/oxazole scaffolds for COX-2 blocking. Furthermore, the molecular modeling study indicated a high selectivity and promising affinity of our prepared compounds to COX-2, especially the hydrophobic pocket and the mouth of the active site holding hydrogen-bonding, hydrophobic, and electrostatic interactions. In Silico absorption, delivery, metabolism, and excretion (ADME) predictions showed that all the pharmacokinetic and physicochemical features are within the appropriate range for human use.

Non-steroidal anti-inflammatory drugs (NSAIDs) and organ damage: A current perspective

Owing to the efficacy in reducing pain and inflammation, non-steroidal anti-inflammatory drugs (NSAIDs) are amongst the most popularly used medicines confirming their position in the WHO's Model List of Essential Medicines. With escalating musculoskeletal complications, as evident from 2016 Global Burden of Disease data, NSAID usage is evidently unavoidable. Apart from analgesic, anti-inflammatory and antipyretic efficacies, NSAIDs are further documented to offer protection against diverse critical disorders including cancer and heart attacks. However, data from multiple placebo-controlled trials and meta-analyses studies alarmingly signify the adverse effects of NSAIDs in gastrointestinal, cardiovascular, hepatic, renal, cerebral and pulmonary complications. Although extensive research has elucidated the mechanisms underlying the clinical hazards of NSAIDs, no review has extensively collated the outcomes on various multiorgan toxicities of these drugs together. In this regard, the present review provides a comprehensive insight of the existing knowledge and recent developments on NSAID-induced organ damage. It precisely encompasses the current understanding of structure, classification and mode of action of NSAIDs while reiterating on the emerging instances of NSAID drug repurposing along with pharmacophore modification aimed at safer usage of NSAIDs where toxic effects are tamed without compromising the clinical benefits. The review does not intend to vilify these 'wonder drugs'; rather provides a careful understanding of their side-effects which would be beneficial in evaluating the risk-benefit threshold while rationally using NSAIDs at safer dose and duration.

Molecular docking study and molecular dynamic simulation of human cyclooxygenase-2 (COX-2) with selected eutypoids

Inflammation is a key factor linked to almost all chronic and degenerative diseases implicit with certain levels of pain. In studies, over the past few years, it has been discovered that prostaglandins are the main cause of this inflammation and therefore could be blocked. Although no steroidal medications can be effective, natural compounds may offer a safer and often an effective alternative treatment for pain relief, especially for long-term use. Hence to find out natural anti-inflammatory compounds, we have highlighted five important butenolides that are eutypoid A, B, C, D and E with structure similar to that of rofecoxib, by ADMET and druglikeness analysis, followed by molecular docking with human COX-2 enzyme. Molecular docking studies revealed the importance of hydrophobic and hydrophilic amino acid residues for the stability of the ligands and that eutypoids C and E are the best candidates for the synthetic drugs with binding energy of -10.39 kcal/mol and -9.87 kcal/mol, respectively. The resulting complexes were then subject to 50 ns molecular dynamics (MD) simulation studies with the GROMACS package to analyze the stability of docked protein-ligand complexes and to assess the fluctuation and conformational changes during protein-ligand interaction. From the RMSD, RMSF, number of hydrogen bonds, SASA, PCA and MM/PBSA binding free energy analysis, we have found that out of five selected compounds eutypoid E showed good binding free energy of -174.45 kJ/mol, which is also good in other structural analyses. This compound displayed excellent pharmacological and structural properties to be drug candidates.Communicated by Ramaswamy H. Sarma.

Development of multitarget inhibitors for the treatment of pain: Design, synthesis, biological evaluation and molecular modeling studies

Multitarget-directed ligands are a promising class of drugs for discovering innovative new therapies for difficult to treat diseases. In this study, we designed dual inhibitors targeting the human fatty acid amide hydrolase (FAAH) enzyme and human soluble epoxide hydrolase (sEH) enzyme. Targeting both of these enzymes concurrently with single target inhibitors synergistically reduces inflammatory and neuropathic pain; thus, dual FAAH/sEH inhibitors are likely to be powerful analgesics. Here, we identified the piperidinyl-sulfonamide moiety as a common pharmacophore and optimized several inhibitors to have excellent inhibition profiles on both targeted enzymes simultaneously. In addition, several inhibitors show good predicted pharmacokinetic properties. These results suggest that this series of inhibitors has the potential to be further developed as new lead candidates and therapeutics in pain management.

Design, synthesis and biological evaluation of novel benzodioxole derivatives as COX inhibitors and cytotoxic agents

Non-steroidal anti-inflammatory drugs are among the most used drugs. They are competitive inhibitors of cyclooxygenase (COX). Twelve novel compounds (aryl acetate and aryl acetic acid groups) were synthesized in this work in order to identify which one was the most potent and which group was most selective towards COX1 and COX2 by using an in vitro COX inhibition assay kit. The cytotoxicity was evaluated for these compounds utilizing MTS assay against cervical carcinoma cells line (HeLa). The synthesized compounds were identified using FTIR, HRMS, ¹H-NMR, and ¹³C-NMR techniques. The results showed that the most potent compound against the COX1 enzyme was 4f with IC₅₀ = 0.725 µM. The compound 3b showed potent activity against both COX1 and COX2 with IC₅₀ = 1.12 and 1.3 µM, respectively, and its selectivity ratio (0.862) was found to be better than Ketoprofen (0.196). In contrast, compound 4d was the most selective with a COX1/COX2 ratio value of 1.809 in comparison with the Ketoprofen ratio. All compounds showed cytotoxic activity against the HeLa Cervical cancer cell line at a higher concentration ranges (0.219–1.94 mM), and the most cytotoxic compound was 3e with a CC₅₀ value of 219 µM. This was tenfold more than its IC₅₀ values of 2.36 and 2.73 µM against COX1 and COX2, respectively. In general, the synthesized library has moderate activity against both enzymes (i.e., COX1 and COX2) and ortho halogenated compounds were more potent than the meta ones.

Systemic bee venom exerts anti-arthritic and anti-inflammatory properties in a rat model of arthritis

Bee venom (BV) is widely used as a traditional China medicine to treat various conditions, including rheumatoid arthritis (RA). The aim of the present study was to evaluate the effects of systemic BV (60 mg/kg) as an anti-arthritic natural product, compare it with Methotrexate and determine the possible underlying mechanisms of BV action using complete Freund's adjuvant-induced arthritic rats. The development of signs of RA signs (knee joint circumference and arthritis scoring index) was evaluated. Erythrocyte sedimentation rate, serum tumor necrosis factor-α (TNF-α) and serum interleukin-1β (IL-1β) levels were measured at the end of the study. Histopathological examination followed by immunostaining of NF-κB (P65) was performed on the affected knee joints. Additionally, in vitro cyclooxygenase (COX) inhibition activity, carrageenan paw edema test and acetic acid writhing tests were performed to evaluate the anti-inflammatory and analgesic effects of the assessed dose and compared with diclofenac. An acute toxicity test was performed to establish the safety of BV at high doses. The results of the present study highlighted the potential of systemic BV on preventing the development of signs of RA. BV also significantly reduced serum levels of TNF-α, IL-1β and NF-κB in the affected joints. In addition to its potent analgesic activity, BV exhibited favorable inhibitory activity of the COX pathway in both in vivo and in vitro models. Therefore, high dose administration of systemic BV displayed safe and promising anti-arthritic, anti-inflammatory and analgesic properties through regulation of different mechanisms associated with the pathogenesis of RA.

Oral Administration of Sodium Nitrate to Metabolic Syndrome Patients Attenuates Mild Inflammatory and Oxidative Responses to Acute Exercise

The beneficial effects of exercise for the treatment and prevention of metabolic syndrome pathologies have been related to its anti-inflammatory and antioxidant effects. Dietary nitrate supplementation is an emerging treatment strategy to alleviate the symptoms of metabolic syndrome affections and to improve vascular function. In this double-blind crossover trial, metabolic syndrome patients performed two exercise tests for 30 min at 60–70% maximal heart rate after the intake of a placebo or a nitrate-enriched beverage. Acute exercise increased the plasma concentration of TNFα, intercellular adhesion molecule ICAM1, PGE1, PGE2 and the newly detected 16-hydroxypalmitic acid (16-HPAL) in metabolic syndrome patients. The cytokine and oxylipin production by peripheral blood mononuclear cells (PBMCs) and neutrophils could be responsible for the plasma concentrations of TNFα and IL6, but not for the plasma concentration of oxylipins nor its post-exercise increase. The intake of sodium nitrate 30 min before exercise increased the concentration of nitrate and nitrite in the oral cavity and plasma and reduced the oxygen cost of exercise. Additionally, nitrate intake prevented the enhancing effects of acute exercise on the plasma concentration of TNFα, ICAM1, PGE1, PGE2 and 16-HPAL, while reducing the capabilities of PBMCs and neutrophils to produce oxylipins.

Structural and Chemical Biology of the Interaction of Cyclooxygenase with Substrates and Non-Steroidal Anti-Inflammatory Drugs

Cyclooxgenases are key enzymes of lipid signaling. They carry out the first step in the production of prostaglandins, important mediators of inflammation, pain, cardiovascular disease, and cancer, and they are the molecular targets for nonsteroidal anti-inflammatory drugs, which are among the oldest and most chemically diverse set of drugs known. Homodimeric proteins that behave as allosterically modulated, functional heterodimers, the cyclooxygenases exhibit complex kinetic behavior, requiring peroxide-dependent activation and undergoing suicide inactivation. Due to their important physiological and pathophysiological roles and keen interest on the part of the pharmaceutical industry, the cyclooxygenases have been the focus of a vast array of structural studies, leading to the publication of over 80 crystal structures of the enzymes in complex with substrates or inhibitors supported by a wealth of functional data generated by site-directed mutation experiments. In this review, we explore the chemical biology of the cyclooxygenases through the lens of this wealth of structural and functional information. We identify key structural features of the cyclooxygenases, break down their active site into regional binding pockets to facilitate comparisons between structures, and explore similarities and differences in the binding modes of the wide variety of ligands (both substrates and inhibitors) that have been characterized in complex with the enzymes. Throughout, we correlate structure with function whenever possible. Finally, we summarize what can and cannot be learned from the currently available structural data and discuss the critical intriguing questions that remain despite the wealth of information that has been amassed in this field.

Anti-inflammatory and ulcerogenic activity of newer phytoisolates of Swertia alata C.B. Clarke

The present study was intended to evaluate the in vitro (COX-1/COX-2) and in vivo anti-inflammatory and ulcerogenic activity of newer phytoconstituents isolated from the aerial parts of Swertia alata C.B. Clarke (Gentianaceae). For isolation of newer phytoconstituents, the ethanolic extract of aerial parts of S. alata was subjected to column chromatography using mixture of petroleum ether and chloroform in various concentrations, which yielded two phytoisolates characterised as nonacosyl triacontanoate (SA-3) and 8-O-glucpyranosyl-(2-acetyl)-1,3-dihydroxy-5-methoxy-xanthone (SA-9). Identification of compounds was based on melting point, UV, FTIR, ¹H-NMR, ¹³C-NMR and mass spectrometric data. The isolates were screened for in vitro COX-1/COX-2 inhibitory activity, in vivo anti-inflammatory and ulcerogenic activity. Among the two compounds, SA-3 was found to be more effective than SA-9. The ulcerogenic study revealed significant gastric tolerance of SA-3 and SA-9 in comparison to indomethacin.

The Pharmaceutical Ability of Pistacia lentiscus L. Leaves Essential Oil Against Periodontal Bacteria and Candida sp. and Its Anti-Inflammatory Potential

BACKGROUND

Given the increasing request for natural pharmacological molecules, this study assessed the antimicrobial capacity of Pistacia lentiscus L. essential oil (PLL-EO) obtained from the leaves of wild plants growing in North Sardinia (Italy) toward a wide range of periodontal bacteria and Candida, including laboratory and clinical isolates sp., together with its anti-inflammatory activity and safety.

METHODS

PLL-EO was screened by gas chromatography/mass spectrometry. The minimal inhibitory concentration (MIC) was determined. The anti-inflammatory activity was measured by cyclooxygenase (COX-1/2) and lipoxygenase (LOX) inhibition, while the antioxidant capacity was determined electro-chemically and by the MTT assay. The WST-1 assay was used to ascertain cytotoxicity toward four lines of oral cells.

RESULTS

According to the concentrations of terpens, PLL-EO is a pharmacologically-active phytocomplex. MICs against periodontal bacteria ranged between 3.13 and 12.5 µg/ml, while against Candida sp. they were between 6.25 and 12.5 µg/mL. Oxidation by COX-1/2 and LOX was inhibited by 80% and 20% µg/mL of the oil, respectively. Antioxidant activity seemed negligible, and no cytotoxicity arose.

CONCLUSIONS

PLL-EO exhibits a broad-spectrum activity against periodontal bacteria and Candida, with an interesting dual inhibitory capacity toward COX-2 and LOX inflammatory enzymes, and without side effects against oral cells.

Computational Methods for the Identification of Molecular Targets of Toxic Food Additives. Butylated Hydroxytoluene as a Case Study

Butylated hydroxytoluene (BHT) is one of the most commonly used synthetic antioxidants in food, cosmetic, pharmaceutical and petrochemical products. BHT is considered safe for human health; however, its widespread use together with the potential toxicological effects have increased consumers concern about the use of this synthetic food additive. In addition, the estimated daily intake of BHT has been demonstrated to exceed the recommended acceptable threshold. In the present work, using BHT as a case study, the usefulness of computational techniques, such as reverse screening and molecular docking, in identifying protein-ligand interactions of food additives at the bases of their toxicological effects has been probed. The computational methods here employed have been useful for the identification of several potential unknown targets of BHT, suggesting a possible explanation for its toxic effects. In silico analyses can be employed to identify new macromolecular targets of synthetic food additives and to explore their functional mechanisms or side effects. Noteworthy, this could be important for the cases in which there is an evident lack of experimental studies, as is the case for BHT.

Thymus algeriensis and Thymus fontanesii: Chemical Composition, In Vivo Antiinflammatory, Pain Killing and Antipyretic Activities: A Comprehensive Comparison

This study aimed to investigate the chemical composition, and evaluate the antioxidant, anti-inflammatory, anti-pyretic, and the analgesic properties of methanol extracts from the leaves of Thymus algeriensis and Thymus fontanesii (Lamiaceae). Thirty-five secondary metabolites were characterized in both extracts using HPLC-PDA-ESI-MS/MS. Phenolic acids, mainly rosmarinic acid and its derivatives, dominated the T. algeriensis extract, while the phenolic diterpene carnosol and the methylated flavonoid salvigenin, prevailed in T. fontanesii extract. Molecular docking study was carried out to estimate the anti-inflammatory potential and the binding affinities of some individual secondary metabolites from both extracts to the main enzymes involved in the inflammation pathway. In vitro enzyme inhibitory assays and in vivo assays were used to investigate the antioxidant and anti-inflammatory activities of the extracts. Results revealed that both studied Thymus species exhibited antioxidant, anti-inflammatory, analgesic, and antipyretic effects. They showed to be a more potent antioxidant than ascorbic acid and more selective against cyclooxygenase (COX-2) than diclofenac and indomethacin. Relatively, the T. fontanesii extract was more potent as COX-2 inhibitor than T. algeriensis. In conclusion, Thymus algeriensis and Thymus fontanesii may be interesting candidates for the treatment of inflammation and oxidative stress-related disorders.

Neuroblastoma SH-SY5Y cytotoxicity, anti-amyloidogenic activity and cyclooxygenase inhibition of Lasianthus trichophlebus (Rubiaceae)

The anti-amyloidogenic potential and cyclooxygenase anti-inflammatory activity of Lasianthus trichophlebus extracts were evaluated. The MeOH extract (LTM) and chloroform extract (LTC) exhibited significant cytotoxic inhibition against the neuroblastoma SH-SY5Y cell with an IC₅₀ of 17.52 μg/mL and 12.28 μg/mL, respectively. Thioflavin T assay indicated the LTC extract inhibition (70.56% at 50 μg/mL) to be statistically comparable (p < 0.05) to the positive control. Cyclooxygenase inhibition against COX-1 and COX-2 enzymes gave IC₅₀ values for the LTM extract to be 18.20 and 29.60 µg/mL, respectively; while, the LTC extract showed 4.11 and 2.78 µg/mL, respectively. LC-MS of the LTM extract identified 22 putative compounds, which may prove to be pharmacologically relevant. This study has provided potential insights into the utilization of L. trichophlebus to develop safer plant-based agents for anti-inflammatory or neurodegenerative diseases.

Maternal cardiac function in women at high risk for pre-eclampsia treated with 150 mg aspirin or placebo: an observational study

OBJECTIVE

To compare maternal haemodynamics in women at low and high risk for preterm pre-eclampsia (PE), and between those at high risk who are randomised to aspirin or placebo.

DESIGN

Prospective, longitudinal observational study.

SETTING

Maternity units in six UK hospitals.

POPULATION

Women participating in the Aspirin for Prevention of Preterm Pre-eclampsia (ASPRE) trial. The population comprised three groups of women: low risk for preterm PE (n = 1362), high risk for preterm PE treated with aspirin (n = 208) and high risk for preterm PE on placebo (n = 220).

METHODS

Women had four visits during pregnancy: 11-14, 19-24, 30-34, and 35-37 weeks' gestation. Blood pressure was measured with a device validated for pregnancy, and PE and maternal haemodynamics were assessed with a bioreactance monitor at each visit. A multilevel linear mixed-effects analysis was performed to examine longitudinal changes of maternal haemodynamic variables, controlling for demographic characteristics, past medical history and medication use.

MAIN OUTCOME MEASURES

Longitudinal changes of cardiac output (CO), mean arterial pressure (MAP), and peripheral vascular resistance (PVR).

RESULTS

The low-risk group demonstrated the expected changes with an increase in CO and reduction in MAP and PVR, with a quadratic change across gestation. In contrast, the high-risk groups had a declining CO, and higher MAP and PVR during pregnancy. The administration of aspirin did not appear to affect maternal haemodynamics.

CONCLUSIONS

Women screened as high risk for preterm PE have a pathological cardiac adaptation to pregnancy and the prophylactic use of aspirin (150 mg oral daily from the first trimester) in this group may not alter this haemodynamic profile.

TWEETABLE ABSTRACT

In women at high risk of pre-eclampsia, prophylactic use of aspirin may not alter the impaired maternal cardiac adaptation.

Synthesis, Biological Activity, and Molecular Modeling Studies of Pyrazole and Triazole Derivatives as Selective COX-2 Inhibitors

Series of diaryl-based pyrazole and triazole derivatives were designed and synthesized in a facile synthetic approach in order to produce selective COX-2 inhibitor. These series of derivatives were synthesized by different reactions like Vilsmeier–Haack reaction and click reaction. In vitro COX-1 and COX-2 inhibition studies showed that five compounds were potent and selective inhibitors of the COX-2 isozyme with IC50values in 0.551–0.002 μM range. In the diarylpyrazole derivatives, compound4bshowed the best inhibitory activity against COX-2 with IC50 = 0.017 μM as one of theN-aromatic rings was substituted with sulfonamide and the other aromatic ring was unsubstituted. However, when theN-aromatic ring was substituted with sulfonamide and the other aromatic ring was substituted with sulfone (compound4d), best COX-2 selectivity was achieved (IC50 = 0.098 μM, SI = 54.847). In the diaryltriazole derivatives, compound15ashowed the best inhibitory activity in comparison to all synthesized compounds including the reference celecoxib with IC50 = 0.002 μM and SI = 162.5 as it could better fit the extra hydrophobic pocket which is present in the COX-2 enzyme. Moreover, the docking study supports the obtained SAR data and binding similarities and differences on both isozymes.

Identification of new potential cyclooxygenase-2 inhibitors: insight from high throughput virtual screening of 18 million compounds combined with molecular dynamic simulation and quantum mechanics

The cyclooxygenase isoenzymes (COX-1 and COX-2) have a critical role in inflammation, fever, and pain. In contrary to COX-1, COX-2 is specifically expressed in inflamed tissues. Because of the subtle difference between both enzyme active sites, targeting COX-2 represents an efficient strategy for the development of novel inhibitors against inflammation with fewer side effects. In order to identify potential inhibitors of COX-2, more than 18,000,000 small molecules were retrieved from the ZINC database and virtually screened against it with a gradual increase in the precision through combined multistep docking. The results were sorted according to the rank-by-rank, induced-fit docking, and MM-GBSA evaluation. Subsequently from the final hit list, two top hits along with an approved selective inhibitor (celecoxib) were further investigated by the molecular dynamics (MD) simulations. The results were indicated that ZINC16934653 and ZINC40484701 demonstrate the highest affinity for the COX-2 binding pocket. Both ligands were bound to the important active-site residues, which are necessary for the correct orientation of inhibitors inside the binding cavity. Their binding free energies were comparable to celecoxib. 100 ns MD simulation is revealed that ZINC40484701 is more preferred in comparison with ZINC16934653 and celecoxib. In addition, non-covalent interactions between the compounds and key residues located in 6 Å distance from the COX-2 binding site show similar patterns of bonding by the reduced density gradient and the independent gradient model. Therefore, ZINC40484701 can be a potential candidate for further in vitro and in vivo analysis after lead-optimization efforts.Communicated by Ramaswamy H. Sarma.

An Activity-Based Sensing Approach for the Detection of Cyclooxygenase-2 in Live Cells

Cyclooxygenase-2 (COX-2) overexpression is prominent in inflammatory diseases, neurodegenerative disorders, and cancer. Directly monitoring COX-2 activity within its native environment poses an exciting approach to account for and illuminate the effect of the local environments on protein activity. Herein, we report the development of CoxFluor, the first activity-based sensing approach for monitoring COX-2 within live cells with confocal microscopy and flow cytometry. CoxFluor strategically links a natural substrate with a dye precursor to engage both the cyclooxygenase and peroxidase activities of COX-2. This catalyzes the release of resorufin and the natural product, as supported by molecular dynamics and ensemble docking. CoxFluor enabled the detection of oxygen-dependent changes in COX-2 activity that are independent of protein expression within live macrophage cells.

Modulation of the immune microenvironment by tumor-intrinsic oncogenic signaling

The development of cancer immunotherapies has been guided by advances in our understanding of the dynamics between tumor cells and immune populations. An emerging consensus is that immune control of tumors is mediated by cytotoxic CD8+ T cells, which directly recognize and kill tumor cells. The critical role of T cells in tumor control has been underscored by preclinical and clinical studies that observed that T cell presence is positively correlated with patient response to checkpoint blockade therapy. However, the vast majority of patients do not respond or develop resistance, frequently associated with exclusion of T cells from the tumor microenvironment. This review focuses on tumor cell-intrinsic alterations that blunt productive anti-tumor immune responses by directly or indirectly excluding effector CD8+ T cells from the tumor microenvironment. A comprehensive understanding of the interplay between tumors and the immune response holds the promise for increasing the response to current immunotherapies via the development of rational novel combination treatments.

Synthesis of Hydroxybenzofuranyl-pyrazolyl and Hydroxyphenyl-pyrazolyl Chalcones and Their Corresponding Pyrazoline Derivatives as COX Inhibitors, Anti-inflammatory and Gastroprotective Agents

Five new series of hydroxybenzofuranyl-pyrazolyl chalcones 3a,b, hydroxyphenyl-pyrazolyl chalcones 6a-c and their corresponding pyrazolylpyrazolines 4a, d, 7a-c and 8a-f have been synthesized and evaluated for their in vitro cyclooxygenase (COX)-1 and COX-2 inhibitory activity. All the synthesized compounds exhibited dual COX-1 and COX-2 inhibitory activity with obvious selectivity against COX-2. The pyrazolylpyrazolines 4a-d and 8a-f bearing two vicinal aryl moieties in the pyrazoline nucleus showed more selectivity towards COX-2. Within these two series, derivatives 4c, d and 8d-f bearing the benzenesulfonamide group were the most selective. Compounds 4a-d and 8a-f were further subjected to in vivo anti-inflammatory screening, ulcerogenic liability and showed good anti-inflammatory activity with no ulcerogenic effect. In addition compounds 4c and 8d as examples showed prostaglandin (PG)E2 inhibition % 44.23 and 51.4 respectively, tumor necrosis factor α (TNFα) inhibition % 33.48 and 41.41 respectively and gastroprotective effect in ethanol induced rodent gastric ulcer model. In addition, to explore the binding mode and selectivity of our compounds, 8d and celecoxib were docked into the active site of COX-1 and COX-2. It was found that compound 8d exhibited a binding pattern and interactions similar to that of celecoxib with COX-2 active site, while bitter manner of interaction than celecoxib to COX-1 active site.

A perspective review on fatty acid amide hydrolase (FAAH) inhibitors as potential therapeutic agents

Fatty acid amide hydrolase (FAAH) is an important enzyme creditworthy of hydrolyzing endocannabinoids and related-amidated signalling lipids, discovery of which has pioneered novel arena of pharmacological canvasses to unwrap its curative potency in various diseased circumstances. It presents contemporary basis for understanding molecules regulating and mediating inflammatory reactions, pain, anxiety, depression, and neurodegeneration. FAAH inhibitors form vital approach for discovery of therapeutic agents that are concerned with local elevation of endocannabinoids under certain stimuli, debarring adverse/unwanted secondary effects from global activation of cannabinoid receptors by exogenous cannabimimetics. During past decades, several molecules with excellent potency developed through tailor-made approaches entered into clinical trials, but none could reach market. Hence, hunt for novel, non-toxic and selective FAAH inhibitors are on horizon. This review summarizes present perception on FAAH in conjunction with its structure, mechanism of catalysis and biological functions. It also foregrounds recent development of molecules belonging to diverse chemical classes as potential FAAH inhibitors bobbing up from in-depth chemical, mechanistic and computational studies published since 2015-November 2019, focusing on their potency. This review will assist readers to obtain rationale on FAAH as potential target for addressing various disease conditions, acquiring significant knowledge on recently established inhibitor scaffolds and their development potentials. New technologies including MD-MM simulations and 3D-QSAR studies allow mechanistic characterization of enzyme. Assessment of in-vitro and in-vivo efficacy of existing FAAH inhibitors will facilitate researchers to design novel ligands utilizing modern drug design methods. The discussions will also impose precaution in decision making process, quashing possibility of late stage failure.

Cyclooxygenase-2 Inhibitors as a Therapeutic Target in Inflammatory Diseases

Inflammation plays a crucial role in the development of many complex diseases and disorders including autoimmune diseases, metabolic syndrome, neurodegenerative diseases, and cardiovascular pathologies. Prostaglandins play a regulatory role in inflammation. Cyclooxygenases are the main mediators of inflammation by catalyzing the initial step of arachidonic acid metabolism and prostaglandin synthesis. The differential expression of the constitutive isoform COX-1 and the inducible isoform COX-2, and the finding that COX-1 is the major form expressed in the gastrointestinal tract, lead to the search for COX-2-selective inhibitors as anti-inflammatory agents that might diminish the gastrointestinal side effects of traditional non-steroidal anti-inflammatory drugs (NSAIDs). COX-2 isoform is expressed predominantly in inflammatory cells and decidedly upregulated in chronic and acute inflammations, becoming a critical target for many pharmacological inhibitors. COX-2 selective inhibitors happen to show equivalent efficacy with that of conventional NSAIDs, but they have reduced gastrointestinal side effects. This review would elucidate the most recent findings on selective COX-2 inhibition and their relevance to human pathology, concretely in inflammatory pathologies characterized by a prolonged pro-inflammatory status, including autoimmune diseases, metabolic syndrome, obesity, atherosclerosis, neurodegenerative diseases, chronic obstructive pulmonary disease, arthritis, chronic inflammatory bowel disease and cardiovascular pathologies.

Free radical-dependent inhibition of prostaglandin endoperoxide H Synthase-2 by nitro-arachidonic acid

Prostaglandin endoperoxide H synthase (PGHS) is a heme-enzyme responsible for the conversion of arachidonic acid (AA) to prostaglandin H₂ (PGH₂). PGHS have both oxygenase (COX) and peroxidase (POX) activities and is present in two isoforms (PGHS-1 and -2) expressed in different tissues and cell conditions. It has been reported that PGHS activity is inhibited by the nitrated form of AA, nitro-arachidonic acid (NO₂AA), which in turn could be synthesized by PGHS under nitro-oxidative conditions. Specifically, NO₂AA inhibits COX in PGHS-1 as well as POX in both PGHS-1 and -2, in a dose and time-dependent manner. NO₂AA inhibition involves lowering the binding stability and displacing the heme group from the active site. However, the complete mechanism remains to be understood. This review describes the interactions of PGHS with NO₂AA, focusing on mechanisms of inhibition and nitration. In addition, using a novel approach combining EPR-spin trapping and mass spectrometry, we described possible intermediates formed during PGHS-2 catalysis and inhibition. This literature revision as well as the results presented here strongly suggest a free radical-dependent inhibitory mechanism of PGHS-2 by NO₂AA. This is of relevance towards understanding the underlying mechanism of inhibition of PGHS by NO₂AA and its anti-inflammatory potential.

Arg-513 and Leu-531 Are Key Residues Governing Time-Dependent Inhibition of Cyclooxygenase-2 by Aspirin and Celebrex

Aspirin and Celebrex are well-known time-dependent inhibitors of the cyclooxygenases (COX). Molecular dynamics simulations suggest that Arg-513 and Leu-531 contribute to the structural mechanisms of COX inhibition. We used mutagenesis and functional analyses to characterize how substitutions at these positions influence time-dependent inhibition by aspirin and Celebrex. We show that substitutions of Leu-531 with asparagine and phenylalanine significantly attenuate time-dependent inhibition of COX-2 by these drugs. The introduction of side chain bulk, rigidity, and charge would disrupt the formation of the initial noncovalent complex, in the case of aspirin, and the "high-affinity" binding state, in the case of Celebrex. Substitution of Arg-513 with histidine (the equivalent residue in COX-1) resulted in a 2-fold potentiation of aspirin inhibition, in support of the hypothesis that the presence of histidine in COX-1 lowers the activation barrier associated with the formation of the initial noncovalent enzyme-inhibitor complex. As a corollary, we previously hypothesized that the flexibility associated with Leu-531 contributes to the binding of arachidonic acid (AA) to acetylated COX-2 to generate 15R-hydroxyeicosatetraenoic acid (15R-HETE). We determined the X-ray crystal structure of AA bound to Co³⁺-protoporphyrin IX-reconstituted V349I murine COX-2 (muCOX-2). V349I muCOX-2 was utilized as a surrogate to trap AA in a conformation leading to 15R-HETE. AA binds in a C-shaped pose, facilitated by the rotation of the Leu-531 side chain. Ile-349 is positioned to sterically shield antarafacial oxygen addition at carbon-15 in a manner similar to that proposed for the acetylated Ser-530 side chain.

Design, synthesis and pharmacological evaluation of CVIB, a codrug of carvacrol and ibuprofen as a novel anti-inflammatory agent

The search for new drugs with anti-inflammatory properties remains a challenge for modern medicine. Among the various strategies for drug discovery, deriving new chemical entities from known bioactive natural and/or synthetic compounds remains a promising approach. Here, we designed and synthesized CVIB, a codrug developed by association of carvacrol (a phenolic monoterpene) with ibuprofen (a non-steroidal anti-inflammatory drug). In silico pharmacokinetic and physicochemical properties evaluation indicated low aqueous solubility (LogP ≥5.0). Nevertheless, the hybrid presented excellent oral bioavailability, gastrointestinal tract absorption, and low toxicity. CVIB did not present cytotoxicity in peripheral blood mononuclear cells (PBMCs), and promoted a significant reduction in IL-2, IL-10, IL-17, and IFN-γ cytokine levels in vitro. The LD₅₀ was estimated to be approximately 5000 mg/kg. CVIB was stable and detectable in human plasma after 24 h. In vivo anti-inflammatory evaluations revealed that CVIB at 10 and 50 mg/kg i.p. caused a significant decrease in total leukocyte count (p < 0.01) and provoked a significant reduction in IL-1β (p < 0.01). CVIB at 10 mg/kg i.p. efficiently decreased inflammatory parameters better than the physical mixture (carvacrol + ibuprofen 10 mg/kg i.p.). The results suggest that the codrug approach is a good option for drug design and development, creating the possibility of combining NSAIDs with natural products in order to obtain new hybrid drugs may be useful for treatment of inflammatory diseases.

Ellagic acid, a plant phenolic compound, activates cyclooxygenase-mediated prostaglandin production

In recent years, ellagic acid (EA), a naturally-occurring phenolic compound richly contained in some of the human food sources such as Longan and Litchi, was reported to have a number of biological effects. Based on our earlier 3D-QSAR/CoMFA models for cyclooxygenase (COX) I and II, we hypothesize that EA may have the potential to modulate the catalytic activity of COX enzymes, and this hypothesis is examined in the present study. The results from both in vitro and in vivo experiments show that EA is an activator of COX enzyme-catalyzed production of prostaglandin E2, a representative prostaglandin tested. Mechanistically, EA can activate the peroxidase active site of COX enzymes by serving as a co-substrate, presumably for the reduction of protoporphorin IX with FeIV inside. The effect of EA is abrogated by the co-presence of galangin, which is known to bind to COX's peroxidase active site and thereby blocks the effect of the reducing co-substrates. In view of the known physiological functions of COX enzymes in the body, it is suggested that some of the pharmacological and/or toxicological effects of EA may result from an increased production of certain prostaglandins and their related derivatives in the body.

Profiling the interaction of 1-phenylbenzimidazoles to cyclooxygenases

In the design of 1-phenylbenzimidazoles as model cyclooxygenase (COX) inhibitors, docking to a series of crystallographic COX structures was performed to evaluate their potential for high-affinity binding and to reproduce the interaction profile of well-known COX inhibitors. The effect of ligand-specific induced fit on the calculations was also studied. To quantitatively compare the pattern of interactions of model compounds to the profile of several cocrystallized COX inhibitors, a geometric parameter, denominated ligand-receptor contact distance (LRCD), was developed. The interaction profile of several model complexes showed similarity to the profile of COX complexes with inhibitors such as iodosuprofen, iodoindomethacin, diclofenac, and flurbiprofen. Shaping of high-affinity binding sites upon ligand-specific induced fit mostly determined both the affinity and the binding mode of the ligands in the docking calculations. The results suggest potential of 1-phenylbenzimidazole derivatives as COX inhibitors on the basis of their predicted affinity and interaction profile to COX enzymes. The analyses also provided insights into the role of induced fit in COX enzymes. While inhibitors produce different local structural changes at the COX ligand binding site, induced fit allows inhibitors in diverse chemical classes to share characteristic interaction patterns that ensure key contacts to be achieved. Different interaction patterns may also be associated with different inhibitory mechanisms.

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 theligands 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.

Long-Lasting Anti-Inflammatory and Antinociceptive Effects of Acute Ammonium Glycyrrhizinate Administration: Pharmacological, Biochemical, and Docking Studies

The object of the study was to estimate the long-lasting effects induced by ammonium glycyrrhizinate (AG) after a single administration in mice using animal models of pain and inflammation together with biochemical and docking studies. A single intraperitoneal injection of AG was able to produce anti-inflammatory effects in zymosan-induced paw edema and peritonitis. Moreover, in several animal models of pain, such as the writhing test, the formalin test, and hyperalgesia induced by zymosan, AG administered 24 h before the tests was able to induce a strong antinociceptive effect. Molecular docking studies revealed that AG possesses higher affinity for microsomal prostaglandin E synthase type-2 compared to type-1, whereas it seems to locate better in the binding pocket of cyclooxygenase (COX)-2 compared to COX-1. These results demonstrated that AG induced anti-inflammatory and antinociceptive effects until 24-48 h after a single administration thanks to its ability to bind the COX/mPGEs pathway. Taken together, all these findings highlight the potential use of AG for clinical treatment of pain and/or inflammatory-related diseases.

Rational Design of Multitarget-Directed Ligands: Strategies and Emerging Paradigms

Due to the complexity of multifactorial diseases, single-target drugs do not always exhibit satisfactory efficacy. Recently, increasing evidence indicates that simultaneous modulation of multiple targets may improve both therapeutic safety and efficacy, compared with single-target drugs. However, few multitarget drugs are on market or in clinical trials, despite the best efforts of medicinal chemists. This article discusses the systematic establishment of target combination, lead generation, and optimization of multitarget-directed ligands (MTDLs). Moreover, we analyze some MTDLs research cases for several complex diseases in recent years and the physicochemical properties of 117 clinical multitarget drugs, with the aim to reveal the trends and insights of the potential use of MTDLs.

[Approach for Producing New 3,3,3-Trifluoropropenylation Reagents: Introduction of a 3,3,3-Trifluoroprop-1-enyl Group for Drug Development]

The chemistry of the 3,3,3-trifluoroprop-1-enyl (TFPE) group has attractive characteristics in medicinal chemistry as a new fluorine motif. However, there are no reports on the properties of this group because it is difficult to construct molecules with it. For the convenient construction of the TFPE group, a new fluorination reagent, CF₃CH=CHTMS (1), was developed from commercially available chemicals with easy purification processes and excellent yields. The utility of 1 as a trifluoropropenylation reagent was exhibited in several types of reaction such as the Sonogashira cross-coupling reaction. Furthermore an indometacin analogue bearing a TFPE group showed greater pharmaceutical activity than the original indometacin. This review describes the details of these research studies under three topics: 1) synthesis of 1; 2) Sonogashira cross-coupling reaction of 1 with acetylene, followed by cyclization into an indole ring; and 3) synthesis of an indometacin analogue with a TFPE group.