Aspirin analogues as dual cyclooxygenase-2/5-lipoxygenase inhibitors: synthesis, nitric oxide release, molecular modeling, and biological evaluation as anti-inflammatory agents

Aspirin vs. ibuprofen: unveiling the distinct cyclooxygenase-1/2 behaviour and dual efficacy of their synthesized analogues via molecular modeling and in vitro biological assessment

Dual inhibition of cyclooxygenase isozymes along with the platelet aggregation activities via the arachidonic acid pathway may offer a better anti-inflammatory agent with enhanced cardiac safety. Although the literature is more focused on COX-2 selectivity, sufficient or improved COX-1/COX-2 selectivity has garnered significant attention recently since it can ensure cardiovascular safety. Herein, in this regard, novel derivatives of non-steroidal anti-inflammatory drugs containing amide, thiourea, thiosemicarbazide, and triazole functionalities were synthesized and characterized. Calculations on the in silico drug-likeness and toxicological properties demonstrated the suitability of the compounds for oral administration. Meanwhile, the molecular docking results suggested two different mechanistic pathways for the anti-inflammatory and anti-platelet effects via COX-2 and COX-1 inhibition. Compounds 3 and 12 were shown to be the most efficient based on their excellent docking scores and favorable interactions, particularly with the selective side-pocket residues of COX-2 and main catalytic residues of COX-1. Furthermore, molecular dynamics simulation confirmed that compounds 3 and 12 exhibited good interactions at the active sites, having stable binding throughout 100 ns. Overall, two major findings were made in the current study. (i) Compound 12 bearing the triazole moiety proved to be the most effective cyclooxygenase inhibitor with IC50 values of 95.11 and 98.73 μM against COX-1 and COX-2 isozymes, respectively. It also maintained its anti-platelet activity (IC50 = 277.67 μM), confirming the dual functioning of compound 12. (ii) Compound 3 purely behaved as an anti-platelet agent (IC50 = 261.0 μM) in contrast to aspirin with fare inhibitory effects against COX-2.

New pyrazole-pyridazine hybrids as selective COX-2 inhibitors: design, synthesis, molecular docking, in silico studies and investigation of their anti-inflammatory potential by evaluation of TNF-α, IL-6, PGE-2 and NO in LPS-induced RAW264.7 macrophages

Hybrid-based design has gained significant interest in the development of novel active substances with anti-inflammatory properties. In this study, two series of new pyrazole-pyridazine-based hybrids, 5a-f and 6a-f, were designed and synthesized. Molecules containing pyrazole and pyridazine pharmacophores in a single molecule, each with a unique mechanism of action and different pharmacological characteristics, are believed to exert higher biological activity. The cell viability of all compounds was evaluated using MTT assay in LPS-induced RAW264.7 macrophages. In vitro COX-1 and COX-2 inhibition assays were performed for the investigation of the anti-inflammatory activity of target compounds. Trimethoxy derivatives 5f and 6f were the most active candidates, demonstrating higher COX-2 inhibitory action than celecoxib, with IC50 values of 1.50 and 1.15 μM, respectively. Bromo derivative 6e demonstrated a COX-2 inhibitory activity comparable to celecoxib. Further, the ability of compounds 5f, 6e, and 6f to inhibit the generation of specific pro-inflammatory cytokines and mediators, including nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and prostaglandin-E2 (PGE-2), in RAW264.7 macrophages stimulated by LPS was also estimated. Compounds 5f and 6f demonstrated the most potent activity. Morover, according to the investigation using molecular modeling studies, derivatives 5f and 6f showed respectable binding affinity towards the COX-2 active site compared to the reference ligand. Moreover, the ADME parameters, physicochemical characteristics, pharmacokinetic characteristics, and l of the most potent compounds were also computed.

Hypothesis-generating proteome perturbation to identify NEU-4438 and acoziborole modes of action in the African Trypanosome

NEU-4438 is a lead for the development of drugs against Trypanosoma brucei, which causes human African trypanosomiasis. Optimized with phenotypic screening, targets of NEU-4438 are unknown. Herein, we present a cell perturbome workflow that compares NEU-4438's molecular modes of action to those of SCYX-7158 (acoziborole). Following a 6 h perturbation of trypanosomes, NEU-4438 and acoziborole reduced steady-state amounts of 68 and 92 unique proteins, respectively. After analysis of proteomes, hypotheses formulated for modes of action were tested: Acoziborole and NEU-4438 have different modes of action. Whereas NEU-4438 prevented DNA biosynthesis and basal body maturation, acoziborole destabilized CPSF3 and other proteins, inhibited polypeptide translation, and reduced endocytosis of haptoglobin-hemoglobin. These data point to CPSF3-independent modes of action for acoziborole. In case of polypharmacology, the cell-perturbome workflow elucidates modes of action because it is target-agnostic. Finally, the workflow can be used in any cell that is amenable to proteomic and molecular biology experiments.

Design of Dual COX-2 and 5-LOX Inhibitors with Iron-Chelating Properties Using Structure-Based and Ligand-Based Methods

Background:

Inflammation is a critical component of many disease progressions, such as malignancy, cardiovascular and rheumatic diseases. The inhibition of inflammatory mediators synthesis by modulation of cyclooxygenase (COX) and lipoxygenase (LOX) pathways provides challenging strategy for development of more effective drugs.

Objective:

The aim of this study was to design dual COX-2 and 5-LOX inhibitors with iron-chelating properties using a combination of ligand-based (three-dimensional quantitative structure-activity relationship (3D-QSAR)) and structure-based (molecular docking) methods.

Methods:

The 3D-QSAR analysis was applied on a literature dataset consisting of 28 dual COX-2 and 5- LOX inhibitors in Pentacle software. The quality of developed COX-2 and 5-LOX 3D-QSAR models were evaluated by internal and external validation methods. The molecular docking analysis was performed in GOLD software, while selected ADMET properties were predicted in ADMET predictor software.

Results:

According to the molecular docking studies, the class of sulfohydroxamic acid analogues, previously designed by 3D-QSAR, were clustered as potential dual COX-2 and 5-LOX inhibitors with ironchelating properties. Based on the 3D-QSAR and molecular docking, 1j, 1g and 1l were selected as the most promising dual COX-2 and 5-LOX inhibitors. According to the in silico ADMET predictions, all compounds had ADMET_Risk score less than 7 and CYP_Risk score lower than 2.5. Designed compounds were not estimated as hERG inhibitors and 1j had improved intrinsic solubility (8.704) in comparison to the dataset compounds (0.411-7.946).

Conclusion:

By combining 3D-QSAR and molecular docking, three compounds (1j, 1g and 1l) were selected as the most promising designed dual COX-2 and 5-LOX inhibitors, for which good activity, as well as favourable ADMET properties and toxicity, are expected.

Evaluation of the Inhibitory Effects of Pyridylpyrazole Derivatives on LPS-Induced PGE2 Productions and Nitric Oxide in Murine RAW 264.7 Macrophages

A series of thirteen triarylpyrazole analogs were investigated as inhibitors of lipopolysaccharide (LPS)-induced prostaglandin E₂ (PGE₂) and nitric oxide (NO) production in RAW 264.7 macrophages. The target compounds 1a-m have first been assessed for cytotoxicity against RAW 264.7 macrophages to determine their non-cytotoxic concentration(s) for anti-inflammatory testing to make sure that the inhibition of PGE₂ and NO production would not be caused by cytotoxicity. It was found that compounds 1f and 1m were the most potent PGE₂ inhibitors with IC₅₀ values of 7.1 and 1.1 μM, respectively. In addition, these compounds also showed inhibitory effects of 11.6% and 37.19% on LPS-induced NO production, respectively. The western blots analysis of COX-2 and iNOS showed that the PGE₂ and NO inhibitory effect of compound 1m are attributed to inhibition of COX-2 and iNOS protein expression through inactivation of p38.

How Physiologic Targets Can Be Distinguished from Drug-Binding Proteins

In clinical trials, some drugs owe their effectiveness to off-target activity. This and other observations raise a possibility that many studies identifying targets of drugs are incomplete. If off-target proteins are pharmacologically important, it will be worthwhile to identify them early in the development process to gain a better understanding of the molecular basis of drug action. Herein, we outline a multidisciplinary strategy for systematic identification of physiologic targets of drugs in cells. A drug-binding protein whose genetic disruption yields very similar molecular effects as treatment of cells with the drug may be defined as a physiologic target of the drug. For a drug developed with a rational approach, it is desirable to verify experimentally that a protein used for hit optimization in vitro remains the sole polypeptide recognized by the drug in a cell. SIGNIFICANCE STATEMENT: A body of evidence indicates that inactivation of many drug-binding proteins may not cause the pharmacological effects triggered by the drugs. A multidisciplinary cell-based approach can be of great value in identifying the physiologic targets of drugs, including those developed with target-based strategies.

Current computer-aided drug design methodologies in discovery of novel drug candidates for neuropsychiatric and inflammatory diseases

Drug discovery and development is a very challenging, expensive and time-consuming process. Impressive technological advances in computer sciences and molecular biology have made it possible to use computer-aided drug design (CADD) methods in various stages of the drug discovery and development pipeline. Nowadays, CADD presents an efficacious and indispensable tool, widely used in medicinal chemistry, to lead rational drug design and synthesis of novel compounds. In this article, an overview of commonly used CADD approaches from hit identification to lead optimization was presented. Moreover, different aspects of design of multitarget ligands for neuropsychiatric and anti-inflammatory diseases were summarized. Apparently, designing multi-target directed ligands for treatment of various complex diseases may offer better efficacy, and fewer side effects. Antipsychotics that act through aminergic G protein-coupled receptors (GPCRs), especially Dopamine D2 and serotonin 5-HT2A receptors, are the best option for treatment of various symptoms associated with neuropsychiatric disorders. Furthermore, multi-target directed cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) inhibitors are also a successful approach to aid the discovery of new anti-inflammatory drugs with fewer side effects. Overall, employing CADD approaches in the process of rational drug design provides a great opportunity for future development, allowing rapid identification of compounds with the optimal polypharmacological profile.

Inhibition of key enzymes in the inflammatory pathway by hybrid molecules of terpenes and synthetic drugs: In vitro and in silico studies

The aim of this work was to compare the anti-inflammatory activity of compounds prepared from terpenes and the synthetic drugs ibuprofen and naproxen. The anti-inflammatory activity of the hybrid compounds was compared with the activity of the parent compounds. This was accomplished using in vitro inhibition of lipoxygenases (LOX) and COX-2, and in silico docking studies in 15-LOX and COX-2. The synthesized hybrids showed an inhibition of COX-2 and LOX between 9.8%-57.4% and 0.0%-97.7%, respectively. None of the hybrids showed an improvement in the inhibitory effect toward these pro-inflammatory enzymes, compared to the parent terpenes and non-steroidal anti-inflammatory drugs. The docking studies allowed us to predict the potential binding modes of hybrids 6-15 within COX-2 and 15-LOX active sites. The relative affinity of the compounds inside the binding sites could be explained by forming non-covalent interactions with most important and known amino acids reported for those enzymes. A good correlation (r²  = 0.745) between docking energies and inhibition percentages against COX-2 was found. The high inhibition obtained for compound 10 against COX-2 was explained by hydrogen bond interactions at the enzyme binding site. New synthetic possibilities could be obtained from our in silico models, improving the potency of these hybrid compounds.

Safer anti-inflammatory therapy through dual COX-2/5-LOX inhibitors: A structure-based approach

Inflammatory mediators of the arachidonic acid cascade from cyclooxygenase (COX) and lipoxygenase (LOX) pathways are primarily responsible for many diseases in human beings. Chronic inflammation is associated with the pathogenesis and progression of cancer, arthritis, autoimmune, cardiovascular and neurological diseases. Traditional non-steroidal anti-inflammatory agents (tNSAIDs) inhibit cyclooxygenase pathway non-selectively and produce gastric mucosal damage due to COX-1 inhibition and allergic reactions and bronchospasm resulting from increased leukotriene levels. 'Coxibs' which are selective COX-2 inhibitors cause adverse cardiovascular events. Inhibition of any of these biosynthetic pathways could switch the metabolism to the other, which can lead to fatal side effects. Hence, there is undoubtedly an urgent need for new anti-inflammatory agents having dual mechanism that prevent release of both prostaglandins and leukotrienes. Though several molecules have been synthesized with this objective, their unfavourable toxicity profile prevented them from being used in clinics. Here, this integrative review attempts to identify the promising pharmacophore that serves as dual inhibitors of COX-2/5-LOX enzymes with improved safety profile. A better acquaintance of structural features that balance safety and efficacy of dual inhibitors would be a different approach to the process of understanding and interpreting the designing of novel anti-inflammatory agents.

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Synthesis of New Tricyclic and Tetracyclic Fused Coumarin Sulfonate Derivatives and Their Inhibitory Effects on LPS-Induced Nitric Oxide and PGE2 Productions in RAW 264.7 Macrophages: Part 2

The synthesis of a new series of 21 fused coumarin derivatives is described, and the biological evaluation of their in vitro antiinflammatory effects as inhibitors of lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E₂ (PGE₂ ) production in RAW 264.7 macrophages. The target compounds 1a-u were first tested for cytotoxicity to determine a non-toxic concentration for antiinflammatory screening, so that the inhibitory effects against NO and PGE₂ production would not be caused by cytotoxicity. Compounds 1f and 1p were the most active PGE₂ inhibitors with IC₅₀ values of 0.89 and 0.95 µM, respectively. Western blot and cell-free COX-2 screening showed that their effects were due to inhibition of both COX-2 protein expression and COX-2 enzyme activity. Their IC₅₀ values against the COX-2 enzyme were 0.67 and 0.85 µM, respectively, which is more potent than etoricoxib. The selectivity indexes of compounds 1f and 1p against COX-2 compared to COX-1 were 41.1 and 42.5, respectively. Compound 1f showed strong inhibitory effects at 5 µM concentration on COX-2 mRNA expression in LPS-induced RAW 264.7 macrophages. Moreover, the tricyclic compounds 1l and 1n as well as the tetracyclic analog 1u were the most potent NO inhibitors, with one-digit micromolar IC₅₀ values. They showed dose-dependent inhibition of inducible nitric oxide synthase (iNOS) protein expression. The tetracyclic derivative 1u was the most potent inhibitor of NO production. It also exhibited a strong inhibitory effect on iNOS mRNA expression in LPS-induced RAW 264.7 macrophages.

Selective COX-2 Inhibitory Properties of Dihydrostilbenes from Liquorice Leaves–In Vitro Assays and Structure/Activity Relationship Study

Three dihydrostilbenes belonging to the polyphenol pool characterized in the leaves of Sicilian liquorice ( Glycyrrhiza glabra L.) have been tested for their antioxidant and anti-inflammatory activity. The three dihydrostilbenes (PA-82, GA-23, DO-07) were in vitro tested to evaluate their capability to scavenge the stable radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), and to decrease thromboxane B2 (TxB2) and prostaglandin E2 (PGE2) release in human whole blood samples. On the basis of the observed capability of these compounds to affect the cell COX-1/COX-2 pathway, a molecular docking study was carried out in order to understand in detail the ability of these compounds to bind to COX-1 and COX-2. The results show that the liquorice dihydrostilbenes are preferred ligands for COX-2 rather than for COX-1, providing a good rational for the observed selectivity in ex vivo experiments. Therefore, they appear to be good candidates for employment in human therapy against inflammation-related pathological conditions.

Novel di-tertiary-butyl phenylhydrazones as dual cyclooxygenase-2/5-lipoxygenase inhibitors: synthesis, COX/LOX inhibition, molecular modeling, and insights into their cytotoxicities

Although dual inhibition of Cyclooxygenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) enzymes is highly effective than targeting COX or LOX alone, there are only a few reports of examining such compounds in case of colorectal cancers (CRC). In the present work we report that the novel di-tert-butyl phenol-based dual inhibitors DTPSAL, DTPBHZ, DTPINH, and DTPNHZ exhibit significant cytotoxicity against human CRC cell lines. Molecular docking studies revealed a good fit of these compounds in the COX-2 and 5-LOX protein cavities. The inhibitors show significant inhibition of COX-2 and 5-LOX activities and are effective against a panel of human colon cancer cell lines including HCA-7, HT-29, SW480 and intestinal Apc10.1 cells as well as the hyaluronan synthase-2 (Has2) enzyme over-expressing colon cancer cells, through inhibition of the Hyaluronan/CD44v6 cell survival pathway. Western blot analysis and qRT-PCR analyses indicated that the di-tert-butyl phenol-based dual inhibitors reduce the expression of COX-2, 5-LOX, and CD44v6 in human colon cancer HCA-7 cells, while the combination of CD44v6shRNA and DTPSAL has an additional inhibitory effect on CD44v6 mRNA expression. The synergistic inhibitory effect of Celecoxib and Licofelone on CD44v6 mRNA expression suggests that the present dual inhibitors down-regulate cyclooxygenase and lipoxygenase enzymes through CD44v6. The compounds also exhibited enhanced antiproliferative potency compared to standard dual COX/LOX inhibitor, viz. Licofelone. Importantly, the HA/CD44v6 antagonist CD44v6shRNA in combination with synthetic compounds had a sensitizing effect on the cancer cells which enhanced their antiproliferative potency, a finding which is crucial for the anti-proliferative potency of the novel synthetic di-tert-butyl phenol based dual COX-LOX inhibitors in colon cancer cells.

Fluorophore-labeled cyclooxygenase-2 inhibitors for the imaging of cyclooxygenase-2 overexpression in cancer: synthesis and biological studies

A group of cyclooxygenase-2 (COX-2)-specific fluorescent cancer biomarkers were synthesized by linking the anti-inflammatory drugs ibuprofen, (S)-naproxen, and celecoxib to the 7-nitrobenzofurazan (NBD) fluorophore. In vitro COX-1/COX-2 inhibition studies indicated that all of these fluorescent conjugates are COX-2 inhibitors (IC₅₀ range: 0.19-23.0 μM) with an appreciable COX-2 selectivity index (SI≥4.3-444). In this study the celecoxib-NBD conjugate N-(2-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)amino)ethyl)-4-(5-(p-tolyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonamide, which displayed the highest COX-2 inhibitory potency and selectivity (COX-2 IC₅₀ =0.19 μM; SI=443.6), was identified as an impending COX-2-specific biomarker for the fluorescence imaging of cancer using a COX-2-expressing human colon cancer cell line (HCA-7).

1,4-Diaryl-substituted triazoles as cyclooxygenase-2 inhibitors: Synthesis, biological evaluation and molecular modeling studies

A novel group of 1,4-diaryl-substituted triazoles was designed and synthesized by introducing the cyclooxygenase-2 (COX-2) pharmacophore SO2NH2 attached to one aryl ring and various substituents (H, F, Cl, CH3 or OCH3) attached to the other aryl ring. The effects of size and flexibility of the compounds upon COX-1/COX-2 inhibitory potency and selectivity was studied by increasing the size of an alkyl linker chain [(-CH2)n, where n=0, 1, 2]. In vitro COX-1/COX-2 inhibition studies showed that all compounds (14-18, 21-25 and 28-32) are more potent inhibitors of COX-2 isozyme (IC50=0.17-28.0μM range) compared to COX-1 isozyme (IC50=21.0 to >100μM range). Within the group of 1,4 diaryl-substituted triazoles, 4-{2-[4-(4-chloro-phenyl)-[1,2,3]triazol-1-yl]-ethyl}-benzenesulfonamide (compound 30) displayed highest COX-2 inhibitory potency and selectivity (COX-1: IC50=>100μM, COX-2: IC50=0.17μM, SI >588). Molecular docking studies using the catalytic site of COX-1 and COX-2, respectively, provided complementary theoretical support for the obtained experimental biological structure-activity relationship data. Results of molecular docking studies revealed that COX-2 pharmacophore SO2NH2 in compound 30 is positioned in the secondary pocket of COX-2 active site; with the nitrogen atom of the SO2NH2 group being hydrogen bonded to Q192 (N⋯OC=2.85Å), and one of the oxygen atoms of SO2NH2 group forming a hydrogen bond to H90 (SO⋯N=2.38Å).

Prodrugs of nonsteroidal anti-inflammatory drugs (NSAIDs), more than meets the eye: a critical review

The design and the synthesis of prodrugs for nonsteroidal anti-inflammatory drugs (NSAIDs) have been given much attention by medicinal chemists, especially in the last decade. As a therapeutic group, NSAIDs are among the most widely used prescribed and over the counter (OTC) medications. The rich literature about potential NSAID prodrugs clearly shows a shift from alkyl, aryalkyl or aryl esters with the sole role of masking the carboxylic acid group, to more elaborate conjugates that contain carefully chosen groups to serve specific purposes, such as enhancement of water solubility and dissolution, nitric oxide release, hydrogen sulfide release, antioxidant activity, anticholinergic and acetylcholinesterase inhibitory (AChEI) activity and site-specific targeting and delivery. This review will focus on NSAID prodrugs that have been designed or were, later, found to possess intrinsic pharmacological activity as an intact chemical entity. Such intrinsic activity might augment the anti-inflammatory activity of the NSAID, reduce its side effects or transform the potential therapeutic use from classical anti-inflammatory action to something else. Reports discussed in this review will be those of NO-NSAIDs, anticholinergic and AChEI-NSAIDs, Phospho-NSAIDs and some miscellaneous agents. In most cases, this review will cover literature dealing with these NSAID prodrugs from the year 2006 and later. Older literature will be used when necessary, e.g., to explain the chemical and biological mechanisms of action.

N-1 and C-3 substituted indole Schiff bases as selective COX-2 inhibitors: synthesis and biological evaluation

A group of N-1 and C-3 disubstituted-indole Schiff bases bearing an indole N-1 (R'=H, CH(2)Ph, COPh) substituent in conjunction with a C-3 -C=HN-C(6)H(4)-4-X (X=F, Me, CF(3), Cl) substituent were synthesized and evaluated as inhibitors of cyclooxygenase (COX) isozymes (COX-1/COX-2). Within this group of Schiff bases, compounds 15 (R(1)=CH(2)Ph, X=F), 17 (R(1)=CH(2)Ph, X=CF(3)), 18 (R(1)=COPh, X=F) and 20 (R(1)=COPh, X=CF(3)) were identified as effective and selective COX-2 inhibitors (COX-2 IC(50)'s=0.32-0.84 μM range; COX-2 selectivity index (SI)=113 to >312 range). 1-Benzoyl-3-[(4-trifluoromethylphenylimino)methyl]indole (20) emerged as the most potent (COX-1 IC(50) >100 μM; COX-2 IC(50)=0.32 μM) and selective (SI >312) COX-2 inhibitor. Furthermore, compound 20 is a selective COX-2 inhibitor in contrast to the reference drug indomethacin that is a potent and selective COX-1 inhibitor (COX-1 IC(50)=0.13 μM; COX-2 IC(50)=6.9 μM, COX-2 SI=0.02). Molecular modeling studies employing compound 20 showed that the phenyl CF(3) substituent attached to the CN spacer is positioned near the secondary pocket of the COX-2 active site, the CN nitrogen atom is hydrogen bonded (N···NH=2.85 Å) to the H90 residue, and the indole N-1 benzoyl is positioned in a hydrophobic pocket of the COX-2 active site near W387.