Novel click modifiable thioquinazolinones as anti-inflammatory agents: Design, synthesis, biological evaluation and docking study

Design and synthesis of new 1,2,4-oxadiazole/quinazoline-4-one hybrids with antiproliferative activity as multitargeted inhibitors

Introduction

The combination of BRAF and tyrosine kinase (TK) inhibitors has been demonstrated to be highly effective in inhibiting tumor development and is an approach for overcoming resistance in clinical trials. Accordingly, a novel series of 1,2,4-oxadiazole/quinazoline-4-one hybrids was developed as antiproliferative multitargeted inhibitors.

Methods

The structures of the newly synthesized compounds 9a-o were validated using IR, NMR, MS, and elemental techniques. 9a-o were tested as antiproliferative agents.

Results and Discussion

The results showed that the majority of the tested compounds showed significant antiproliferative action with 9b, 9c, 9h, 9k, and 9l being the most potent. Compounds 9b, 9c, 9h, 9k, and 9l were tested as EGFR and BRAFV600E inhibitors. These in vitro tests revealed that compounds 9b, 9c, and 9h are strong antiproliferative agents that may act as dual EGFR/BRAFV600E inhibitors. 9b, 9c, and 9h were further investigated for their inhibitory effect on mutant EGFR (EGFRT790M), and the results showed that the tested compounds had considerable inhibitory action. Cell cycle study and apoptosis detection demonstrated that compound 9b exhibits cell cycle arrest at the G2/M transition. Molecular docking simulations reveal the binding mechanism of the most active antiproliferative agents.

Experimental investigation and molecular simulations of quinone related compounds as COX/LOX inhibitors

Quinone-containing compounds have risen as promising anti-inflammatory targets; however, very little research has been directed to investigate their potentials. Accordingly, the current study aimed to design and synthesize group of quinones bearing different substituents to investigate the effect of these functionalities on the anti-inflammatory activities of this important scaffold. The choice of these substituents was carefully done, varying from a directly attached heterocyclic ring to different aromatic moieties linked through a nitrogen spacer. Both in vitro and in vivo anti-inflammatory activities of the synthesized compounds were assessed relative to the positive standards: celecoxib and indomethacin. The in vitro enzymatic and transcription inhibitory actions of all the synthesized compounds were tested against cyclooxygenase-2 (COX-2), cyclooxygenase-1 (COX-1), and 5-lipoxygenase (LOX) and the in vivo gene expression of Interleukin-1, interleukin 10, and Tumor Necrosis Factor-α (TNF-α) were determined. The IC50 against COX-1 and COX-2 enzymes obtained by the immunoassay test revealed promising activities of sixteen compounds with selectivity indices higher than 100-fold COX-2 selectivity. Out of those, four compounds revealed selectivity indices comparable to celecoxib as a reference drug. Furthermore, all the tested compounds inhibited LOX with an IC50 in the range of 1.59-3.11 µM superior to that of the reference drug used; zileuton (IC50 = 3.50 µM). Consequently, these results highlight the promising LOX inhibitory activity of the tested compounds. The obtained in vivo paw edema results showed high inhibitory percentage for the compounds 9a, 9b, and 11a with the significant lower TNF-α relative mRNA expression for compounds 5a, 5d, 9a, 9b, 12d, and 12e. Finally, in silico docking of the most active compounds (5b, 5d, 9a, 9b) against COX2 enzymes presented an acceptable justification of the obtained in vitro inhibitory activities. As a conclusion, Compounds 5b, 5d, 9a, 9b, and 11b showed promising results and thus deserves further investigation.

Reduction-sensitive polymeric carrier for the targeted delivery of a quinazoline derivative for enhanced generation of reactive oxygen species against cancer

Hepatocellular carcinoma (HCC) is one of the deadliest malignant tumors and the development of effective therapeutics against HCC is urgently needed. A novel quinazoline derivative 04NB-03 (Qd04) has been proved to be highly effective against HCC without obvious toxic side-effects. However, the poor water solubility and low bioavailability in vivo severely limit its clinical application. In addition, Qd04 kills tumor cells by inducing an accumulation of endogenous reactive oxygen species (ROS), which is highly impeded by the overexpression of glutathione (GSH) in tumor cells. Herein, we designed a disulfide cross-linked polyamino acid micelle to deliver Qd04 for HCC therapy. The disulfide linkage not only endowed a tumor-targeted delivery of Qd04 by responding to tumor cell GSH but also depleted GSH to achieve increased levels of ROS generation, which improved the therapeutic efficiency of Qd04. Both in vitro and in vivo results demonstrated that the synthesized nanodrug exerted good anti-hepatoma effects, which provided a potential application for HCC therapy in clinics.

Chromone-based small molecules for multistep shutdown of arachidonate pathway: Simultaneous inhibition of COX-2, 15-LOX and mPGES-1 enzymes

As a new approach to the management of inflammatory disorders, a series of chromone-based derivatives containing a (carbamate)hydrazone moiety was designed and synthesized. The compounds were assessed for their ability to inhibit COX-1/2, 15-LOX, and mPGES-1, as a combination that should effectively impede the arachidonate pathway. Results revealed that the benzylcarbazates (2a-c) demonstrated two-digit nanomolar COX-2 inhibitory activities with reasonable selectivity indices. They also showed appreciable 15-LOX inhibition, in comparison to quercetin. Further testing of these compounds for mPGES-1 inhibition displayed promising activities. Intriguingly, compounds 2a-c were capable of suppressing edema in the formalin-induced rat paw edema assay. They exhibited an acceptable gastrointestinal safety profile regarding ulcerogenic liabilities in gross and histopathological examinations. Additionally, upon treatment with the test compounds, the expression of the anti-inflammatory cytokine IL-10 was elevated, whereas that of TNF-α, iNOS, IL-1β, and COX-2 were downregulated in LPS-challenged RAW264.7 macrophages. Docking experiments into the three enzymes showed interesting binding profiles and affinities, further substantiating their biological activities. Their in silico physicochemical and pharmacokinetic parameters were advantageous.

Click chemistry-aided drug discovery: A retrospective and prospective outlook

Click chemistry has emerged as a valuable tool for rapid compound synthesis, presenting notable advantages and convenience in the exploration of potential drug candidates. In particular, in situ click chemistry capitalizes on enzymes as reaction templates, leveraging their favorable conformation to selectively link individual building blocks and generate novel hits. This review comprehensively outlines and introduces the extensive use of click chemistry in compound library construction, and hit and lead discovery, supported by specific research examples. Additionally, it discusses the limitations and precautions associated with the application of click chemistry in drug discovery. Our intention for this review is to contribute to the development of a modular synthetic approach for the rapid identification of drug candidates.

Dual COX-2/15-LOX inhibitors: A new avenue in the prevention of cancer

Dual cyclooxygenase 2/15-lipoxygenase inhibitors constitute a valuable alternative to classical non-steroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 (cyclooxygenase-2) inhibitors for the treatment of inflammatory diseases, as well as preventing the cancer. Indeed, these latter present diverse side effects, which are reduced or absent in dual-acting agents. In this review, COX-2 and 15-LOX (15-lipoxygenase) pathways are first described in order to highlight the therapeutic interest of designing such compounds. Various structural families of dual inhibitors are illustrated. This study discloses various structural families of dual 15-LOX/COX-2 inhibitors, thus pave the way to design potentially-active anticancer agents with balanced dual inhibition of these enzymes.

Dual-target inhibitors based on COX-2: a review from medicinal chemistry perspectives

Inhibitors of COX-2 constitute a class of anti-inflammatory analgesics, showing potential against certain types of cancer. However, such inhibitors are associated with cardiovascular toxicity. Moreover, although single-target molecules possess specificity for particular targets, they often lead to poor safety, low efficacy and drug resistance due to compensatory mechanisms. A new generation of dual-target drugs that simultaneously inhibit COX-2 and another target is showing strong potential to treat cancer or reduce adverse cardiac effects. The present perspective focuses on the structure and functions of COX-2, and its role as a therapeutic target. It also explores the current state and future possibilities for dual-target strategies from a medicinal chemistry perspective.

Magic shotgun approach to anti-inflammatory pharmacotherapy: Synthesis of novel thienopyrimidine monomers/heterodimer as dual COX-2 and 15-LOX inhibitors endowed with potent antioxidant activity

Emerging evidence points to the intertwining framework of inflammation and oxidative stress in various ailments. We speculate on the potential impact of the magic shotgun approach in these ailments as an attempt to mitigate the drawbacks of current NSAIDs. Hence, we rationally designed and synthesized new tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine monomers/heterodimer as dual selective COX-2/15-LOX inhibitors with potent antioxidant activity. The synthesized compounds were challenged with diverse in vitro biological assays. Regarding the monomeric series, compound 5k exerted the highest COX-2 inhibitory activity (IC50 = 0.068 μM, SI = 160.441), while compound 5i showed the highest 15-LOX inhibitory activity (IC50 = 1.97 μM). Surpassing the most active monomeric members, the heterodimer 11 stemmed as the most potent and selective one in the whole study (COX-2 IC50 = 0.065 μM, SI = 173.846, 15-LOX IC50 = 1.86 μM). Heterodimer design was inspired by the cross-talk between the partner monomers of the COX-2 isoform. Moreover, some of our synthesized compounds could significantly reverse the LPS-enhanced production of ROS and proinflammatory cytokines (IL-6, TNF-α, and NO) in RAW 264.7 macrophages. Again, the heterodimer showed the strongest suppressor activity against ROS (IC50 = 18.79 μM) and IL-6 (IC50 = 4.15 μM) production outperforming the two references, celecoxib and diclofenac. Regarding NO suppressor activity, compound 5j (IC50 = 18.62 μM) surpassed the two references. Only compound 5a significantly suppressed TNF-α production (IC50 = 19.68 μM). Finally, molecular modeling simulated the possible binding scenarios of our synthesized thienopyrimidines within the active sites of COX-2 and 15-LOX. These findings suggest that those novel thienopyrimidines are promising leads showing pharmacodynamics synergy against the selected targets.

Thermogenic Modulation of Adipose Depots: A Perspective on Possible Therapeutic Intervention with Early Cardiorenal Complications of Metabolic Impairment

Cardiovascular complications of diabetes and obesity remain a major cause for morbidity and mortality worldwide. Despite significant advances in the pharmacotherapy of metabolic disease, the available approaches do not prevent or slow the progression of complications. Moreover, a majority of patients present with significant vascular involvement at early stages of dysfunction prior to overt metabolic changes. The lack of disease-modifying therapies affects millions of patients globally, causing a massive economic burden due to these complications. Significantly, adipose tissue inflammation was implicated in the pathogenesis of metabolic syndrome, diabetes, and obesity. Specifically, perivascular adipose tissue (PVAT) and perirenal adipose tissue (PRAT) depots influence cardiovascular and renal structure and function. Accumulating evidence implicates localized PVAT/PRAT inflammation as the earliest response to metabolic impairment leading to cardiorenal dysfunction. Increased mitochondrial uncoupling protein 1 (UCP1) expression and function lead to PVAT/PRAT hypoxia and inflammation as well as vascular, cardiac, and renal dysfunction. As UCP1 function remains an undruggable target so far, modulation of the augmented UCP1-mediated PVAT/PRAT thermogenesis constitutes a lucrative target for drug development to mitigate early cardiorenal involvement. This can be achieved either by subtle targeted reduction in UCP-1 expression using innovative proteolysis activating chimeric molecules (PROTACs) or by supplementation with cyclocreatine phosphate, which augments the mitochondrial futile creatine cycling and thus decreases UCP1 activity, enhances the efficiency of oxygen use, and reduces hypoxia. Once developed, these molecules will be first-in-class therapeutic tools to directly interfere with and reverse the earliest pathology underlying cardiac, vascular, and renal dysfunction accompanying the early metabolic deterioration. SIGNIFICANCE STATEMENT: Adipose tissue dysfunction plays a major role in the pathogenesis of metabolic diseases and their complications. Although mitochondrial alterations are common in metabolic impairment, it was only recently shown that the early stages of metabolic challenge involve inflammatory changes in select adipose depots associated with increased uncoupling protein 1 thermogenesis and hypoxia. Manipulating this mode of thermogenesis can help mitigate the early inflammation and the consequent cardiorenal complications.

In Silico and in Vitro Biological Evaluation of Novel Serial Sulfonate Derivatives on Pancreatic Lipase Activity

The novel benzothiazole sulfonate hybrid derivatives containing azomethine group were synthesized and characterized using 1 H-NMR, 13 C-NMR, and HR-MS analysis. The potential enzyme inhibition activities against pancreatic lipase of the novel benzothiazole sulfonate hybrid derivatives containing azomethine group were screened with in vitro and in silico methods. IC50 values of compounds 5 b (23.89 μM), 5 i (28.87 μM), and 5 f (30.13±4.32) were found to be more effective pancreatic lipase inhibitors than orlistat (57.75 μM) in vitro studies. Also, the binding affinities of compounds 5 b (-8.7 kcal/mol), 5 i (-8.6 kcal/mol), and 5 f (-8.9 kcal/mol) were found potential inhibitors for pancreatic lipase in silico studies. In addition, the absorption distribution, metabolism, and excretion properties (ADME), molecular properties, toxicity estimation, and bioactivity scores of the synthesized compounds were scanned. It was found to have the ability to cross the brain-blood barrier for compounds 5 a, 5 b, 5 c, and 5 d. All compounds were calculated to be taken orally as drugs, suitable for absorption in the intestinal tract and not carcinogenic, as well as very strongly bound to plasma proteins. Finally, compound 5 f was observed to be the best inhibitor for pancreatic lipase according to in vitro and in silico studies.

Synthesis and Biological Evaluation of Some New 3-Aryl-2-thioxo-2,3-dihydroquinazolin-4(1H)-ones and 3-Aryl-2-(benzylthio)quinazolin-4(3H)-ones as Antioxidants; COX-2, LDHA, α-Glucosidase and α-Amylase Inhibitors; and Anti-Colon Carcinoma and Apoptosis-Inducing Agents

Oxidative stress, COX-2, LDHA and hyperglycemia are interlinked contributing pathways in the etiology, progression and metastasis of colon cancer. Additionally, dysregulated apoptosis in cells with genetic alternations leads to their progression in malignant transformation. Therefore, quinazolinones 3a-3h and 5a-5h were synthesized and evaluated as antioxidants, enzymes inhibitors and cytotoxic agents against LoVo and HCT-116 cells. Moreover, the most active cytotoxic derivatives were evaluated as apoptosis inducers. The results indicated that 3a, 3g and 5a were efficiently scavenged DPPH radicals with lowered IC50 values (mM) ranging from 0.165 ± 0.0057 to 0.191 ± 0.0099, as compared to 0.245 ± 0.0257 by BHT. Derivatives 3h, 5a and 5h were recognized as more potent dual inhibitors than quercetin against α-amylase and α-glucosidase, in addition to 3a, 3c, 3f and 5b-5f against α-amylase. Although none of the compounds demonstrated a higher efficiency than the reference inhibitors against COX-2 and LDHA, 3a and 3g were identified as the most active derivatives. Molecular docking studies were used to elucidate the binding affinities and binding interactions between the inhibitors and their target proteins. Compounds 3a and 3f showed cytotoxic activities, with IC50 values (µM) of 294.32 ± 8.41 and 383.5 ± 8.99 (LoVo), as well as 298.05 ± 13.26 and 323.59 ± 3.00 (HCT-116). The cytotoxicity mechanism of 3a and 3f could be attributed to the modulation of apoptosis regulators (Bax and Bcl-2), the activation of intrinsic and extrinsic apoptosis pathways via the upregulation of initiator caspases-8 and -9 as well as executioner caspase-3, and the arrest of LoVo and HCT-116 cell cycles in the G2/M and G1 phases, respectively. Lastly, the physicochemical, medicinal chemistry and ADMET properties of all compounds were predicted.

Design, synthesis, spectroscopic characterizations, in vitro pancreatic lipase as well as tyrosinase inhibition evaluations and in silico analysis of novel aryl sulfonate-naphthalene hybrids

One of the primary purposes of this study is to synthesize new aryl sulfonate-naphthalene hybrid structures possessing divergent electron-withdrawing and electron-releasing functional groups. Following the improved reaction conditions, we successfully gathered ten distinct sulfonate derivatives (3a-j) with good yields. The synthesized naphthalene-based sulfonate derivatives were then characterized using appropriate analytical methods (FT-IR, 1H-NMR, 13C-NMR, HRMS, and elemental analysis). Additionally, in vitro and in silico enzyme inhibitory properties of the prepared aryl sulfonate-naphthalene hybrid structures were evaluated against pancreatic lipase and tyrosinase enzymes. Corresponding in vitro enzyme activity investigations revealed that the produced compounds inhibit pancreatic lipase and tyrosinase enzymes significantly. According to the lowest IC50 values, 3h (95.3 ± 4.0 µM) demonstrated the most effective inhibition against pancreatic lipase, whereas 3a (40.8 ± 3.3 µM) was found as the most effective inhibition against the tyrosinase. According to in silico studies, 3a exhibited the highest affinity value (-9.9 kcal/mol) against pancreatic lipase, whereas 3f demonstrated the best affinity value (-8.7 kcal/mol) against tyrosinase.Furthermore, we investigated various structural and physicochemical properties of the target molecules, namely frontier orbital' (HOMO, LUMO, and bandgap) energies (including their corresponding contour plots), global reactivity descriptors (ionization energy and electron affinity), and electronegativity values gathered from ground-state (GS) density functional theory (DFT) calculations. These investigations demonstrated that the observed electrostatic interactions effectively contributed to the studied molecules' experimentally demonstrated enzyme inhibition potential. Also, ADMET studies were evaluated to enlighten the molecular interactions of the compounds with the enzymes.Communicated by Ramaswamy H. Sarma.

Design, Synthesis, Biological Evaluation, and Molecular Docking Study of 4,6-Dimethyl-5-aryl/alkyl-2-[2-hydroxy-3-(4-substituted-1-piperazinyl)propyl]pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-diones as Anti-Inflammatory Agents with Dual Inhibition of COX and LOX

In the present study, we characterize the biological activity of a newly designed and synthesized series of 15 compounds 2-[2-hydroxy-3-(4-substituted-1-piperazinyl)propyl] derivatives of pyrrolo[3,4-c]pyrrole 3a-3o. The compounds were obtained with good yields of pyrrolo[3,4-c]pyrrole scaffold 2a-2c with secondary amines in C₂H₅OH. The chemical structures of the compounds were characterized by ¹H-NMR, ¹³C-NMR, FT-IR, and MS. All the new compounds were investigated for their potencies to inhibit the activity of three enzymes, i.e., COX-1, COX-2, and LOX, by a colorimetric inhibitor screening assay. In order to analyze the structural basis of interactions between the ligands and cyclooxygenase/lipooxygenase, experimental data were supported by the results of molecular docking simulations. The data indicate that all of the tested compounds influence the activity of COX-1, COX-2, and LOX.

Design and Development of COX-II Inhibitors: Current Scenario and Future Perspective

Innate inflammation beyond a threshold is a significant problem involved in cardiovascular diseases, cancer, and many other chronic conditions. Cyclooxygenase (COX) enzymes are key inflammatory markers as they catalyze prostaglandins production and are crucial for inflammation processes. While COX-I is constitutively expressed and is generally involved in "housekeeping" roles, the expression of the COX-II isoform is induced by the stimulation of different inflammatory cytokines and also promotes the further generation of pro-inflammatory cytokines and chemokines, which affect the prognosis of various diseases. Hence, COX-II is considered an important therapeutic target for drug development against inflammation-related illnesses. Several selective COX-II inhibitors with safe gastric safety profiles features that do not cause gastrointestinal complications associated with classic anti-inflammatory drugs have been developed. Nevertheless, there is mounting evidence of cardiovascular side effects from COX-II inhibitors that resulted in the withdrawal of market-approved anti-COX-II drugs. This necessitates the development of COX-II inhibitors that not only exhibit inhibit potency but also are free of side effects. Probing the scaffold diversity of known inhibitors is vital to achieving this goal. A systematic review and discussion on the scaffold diversity of COX inhibitors are still limited. To address this gap, herein we present an overview of chemical structures and inhibitory activity of different scaffolds of known COX-II inhibitors. The insights from this article could be helpful in seeding the development of next-generation COX-II inhibitors.

Synthesis and anti-inflammatory activity evaluation of NO-releasing furoxan/1,2,4-triazole hybrid derivatives

An efficient synthesis method was developed for furoxan/1,2,4-triazole hybrids 5a-k from methyl 5-(halomethyl)-1-aryl-1H-1,2,4-triazole-3-carboxylates 1 through two-steps reaction including hydrolyzation and esterification. All of the furoxan/1,2,4-triazole hybrid derivatives were characterized by spectroscopy. On the other hand, the influence of newly synthesized multi-substituted 1,2,4-triazoles on the exogenous NO release ability, in vitro and in vivo anti-inflammatory activity, and in silico predictions were experimentally evaluated. Based on the exogenous NO release ability study and SAR studies of in vitro anti-inflammatory activity, all of compounds 5a-k exhibited slightly NO release ability and potential anti-inflammatory activity on LPS-induced RAW264.7 cells (IC₅₀ = 5.74-15.3 μM) compared to Celecoxib (IC₅₀ = 16.5 μM) and Indomethacin (IC₅₀ = 56.8 μM). Furthermore, compounds 5a-k were also subjected to in vitro COX-1/COX-2 inhibition assays. Particularly, compound 5f exhibited extraordinary COX-2 inhibition (IC₅₀ = 0.0455 μM) and selectivity (SI = 209). In addition, compound 5f was also examined in vivo pro-inflammatory cytokine productions and gastric safety and possessed the better inhibition of cytokine and safety compared with Indomethacin at the same concentration. Through the molecular modeling and in silico physicochemical and pharmacokinetic properties prediction, compound 5f was stabilized in COX-2 active binding site and possessed the fundamental strong H-bond interaction with Arg499 to form the significant physicochemical and pharmacological properties as a candidate drug. Following the in vitro, in vivo, and in silico study results, compound 5f demonstrated to be a potential anti-inflammatory agent and had comparable effects with Celecoxib.

New tetrahydropyrimidine-1,2,3-triazole clubbed compounds: Antitubercular activity and Thymidine Monophosphate Kinase (TMPKmt) inhibition

Two series of new tetrahydropyrimidine (THPM)-1,2,3-triazole clubbed compounds were designed, synthesized and screened for their antitubercular (anti-TB) activity against M. tuberculosis H₃₇Rv strain using microplate alamar blue assay (MABA). The most active compounds 5c, 5d, 5e and 5f were further examined for their cytotoxicity against the growth of RAW 264.7 mouse macrophage cells using MTT assay. The four compounds showed safety profiles better than or comparable to that of ethambutol (EMB). These compounds were evaluated for their inhibition activity against mycobacterium tuberculosis thymidine monophosphate kinase (TMPKmt). Compounds 5c and 5e were the most potent exhibiting comparable inhibition activity to that of the natural substrate deoxythymidine monophosphate (dTMP). An in silico study was performed including docking of the most active compounds 5c and 5e into the TMPKmt (PDB: ID 1G3U) binding pocket in addition to prediction of their physicochemical and pharmacokinetic properties to explore the overall activity of these anti-TB candidates. Compounds 5c and 5e are promising anti-TB agents and TMPKmt inhibitors with acceptable oral bioavailability, physicochemical and pharmacokinetic properties.

Novel pyrazole-based COX-2 inhibitors as potential anticancer agents: Design, synthesis, cytotoxic effect against resistant cancer cells, cell cycle arrest, apoptosis induction and dual EGFR/Topo-1 inhibition

Novel differently substituted pyrazole derivatives were designed, synthesized and evaluated for their anticancer activity. All compounds selectively inhibited COX-2 enzyme (IC₅₀ = 0.043-0.56 μM). Compounds 11, 12 and 15 showed superior potency (IC₅₀ = 0.043-0.049 μM) and screened for their antiproliferative effect against MCF-7 and HT-29 cancer cell lines using doxorubicin and 5-FU as reference drugs. Compounds 11, 12 and 15 showed good potency against MCF-7 (IC₅₀ = 2.85-23.99 μM) and HT-29 (IC₅₀ = 2.12-69.37 μM) cell lines. Also, compounds 11, 12 and 15 displayed (IC₅₀ = 56.61-115.75 μM) against non-cancerous WI-38 cells compared to doxorubicin (IC₅₀ = 13.32 μM). Compound 11 showed superior cytotoxicity against both MCF-7 (IC₅₀ = 2.85) and HT-29 (IC₅₀ = 2.12 μM) and was more potent than 5-FU (HT-29: IC₅₀ = 8.77 μM). Besides, it displayed IC₅₀ of 115.75 μM against normal WI-38 cells regarding it as a safe cytotoxic agent. In addition, compound 11 displayed IC₅₀ values of 63.44 μM and 98.60 μM against resistant HT-29 and resistant MCF-7 cancer cell lines sequentially. The most potent compound arrested cell cycle at G1/S phase in HT-29 treated cells displaying accumulation of cells in G0 phase and increase in percentage of cells in both early and late apoptotic stages. Apoptotic induction ability was confirmed via up-regulation of BAX, down-regulation of Bcl-2 and activation of caspase-3/9 protein levels. Compound 11 inhibited both EGFR (IC₅₀ = 0.083 μM) and Topo-1 (IC₅₀ = 0.020 μM) enzymes. Also, compound 11 decreased both total and phosphorylated EGFR concentration in HT-29 cells. Finally, molecular docking study showed good binding interactions between novel compounds and target receptors.

Methyl 2-((3-(3-methoxyphenyl)-4-oxo-3,4-dihydroquinazolin-2-yl)thio)acetate

A green synthetic procedure was developed for the two-step synthesis of methyl 2-((3-(3-methoxyphenyl)-4-oxo-3,4-dihydroquinazolin-2-yl)thio)acetate from anthranilic acid, using two green chemistry approaches: utilization of the DES and microwave-induced synthesis. The first step includes a synthesis of 2-mercapto-3-(3-methoxyphenyl)quinazolin-4(3H)-one which was performed in choline chloride:urea DES. In the second step S-alkylation of 2-mercapto-3-(3-methoxyphenyl)quinazolin-4(3H)-one was performed in a microwave-induced reaction. The desired compound was successfully obtained in a yield of 59% and was characterized by different spectral methods.

Application of Deep Eutectic Solvents in the Synthesis of Substituted 2-Mercaptoquinazolin-4(3H)-Ones: A Comparison of Selected Green Chemistry Methods

In this study, deep eutectic solvents (DESs) were used as green and eco-friendly media for the synthesis of substituted 2-mercaptoquinazolin-4(3H)-ones from different anthranilic acids and aliphatic or aromatic isothiocyanates. A model reaction on anthranilic acid and phenyl isothiocyanate was performed in 20 choline chloride-based DESs at 80 °C to find the best solvent. Based on the product yield, choline chloride:urea (1:2) DES was found to be the most effective, while DESs acted both as solvents and catalysts. Desired compounds were prepared with moderate to good yields using stirring, microwave-assisted, and ultrasound-assisted synthesis. Significantly, higher yields were obtained with mixing and ultrasonication (16-76%), while microwave-induced synthesis showed lower effectiveness (13-49%). The specific contribution of this research is the use of DESs in combination with the above-mentioned green techniques for the synthesis of a wide range of derivatives. The structures of the synthesized compounds were confirmed by 1H and 13C NMR spectroscopy.

An Overview of Recent Advances in Biomedical Applications of Click Chemistry

Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) is a modular and bio-orthogonal approach that is being adopted for the efficient synthesis of organic and bioorganic compounds. It leads to the selective formation of 1,4-disubstituted 1,2,3-triazole units connecting readily accessible building blocks via a stable and biocompatible linkage. The vast array of the bioconjugation applications of click chemistry has been attributed to its fast reaction kinetics, quantitative yields, minimal byproducts, and high chemospecificity and regioselectivity. These combined advantages make click reactions quite suitable for the lead identification and the development of pharmaceutical agents in the fields of medicinal chemistry and drug discovery. In this review, we have outlined the key aspects, the mechanistic details and merits and demerits of the click reaction. In addition, we have also discussed the recent pharmaceutical applications of click chemistry, ranging from the development of anticancer, antibacterial, and antiviral agents to that of biomedical imaging agents and clinical therapeutics.

Challenging inflammatory process at molecular, cellular and in vivo levels via some new pyrazolyl thiazolones

The work reported herein describes the synthesis of a new series of anti-inflammatory pyrazolyl thiazolones. In addition to COX-2/15-LOX inhibition, these hybrids exerted their anti-inflammatory actions through novel mechanisms. The most active compounds possessed COX-2 inhibitory activities comparable to celecoxib (IC₅₀ values of 0.09-0.14 µM) with significant 15-LOX inhibitory activities (IC₅₀s 1.96 to 3.52 µM). Upon investigation of their in vivo anti-inflammatory activities and ulcerogenic profiles, these compounds showed activity patterns equivalent or more superior to diclofenac and/or celecoxib. Intriguingly, the most active compounds were more effective than diclofenac in suppressing monocyte-to-macrophage differentiation and inflammatory cytokine production by activated macrophages, as well as their ability to induce macrophage apoptosis. The latter finding potentially adds a new dimension to the previously reported anti-inflammatory mechanisms of similar compounds. These compounds were effectively docked into COX-2 and 15-LOX active sites. Also, in silico predictions confirmed the appropriateness of these compounds as drug-like candidates.

The Emerging Role of COX-2, 15-LOX and PPARγ in Metabolic Diseases and Cancer: An Introduction to Novel Multi-target Directed Ligands (MTDLs)

Emerging evidence supports an intertwining framework for the involvement of different inflammatory pathways in a common pathological background for a number of disorders. Of importance are pathways involving arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 15-lipoxygenase (15-LOX). Both enzyme activities and their products are implicated in a range of pathophysiological processes encompassing metabolic impairment leading to adipose inflammation and the subsequent vascular and neurological disorders, in addition to various pro- and antitumorigenic effects. A further layer of complexity is encountered by the disparate, and often reciprocal, modulatory effect COX-2 and 15-LOX activities and metabolites exert on each other or on other cellular targets, the most prominent of which is peroxisome proliferator-activated receptor gamma (PPARγ). Thus, effective therapeutic intervention with such multifaceted disorders requires the simultaneous modulation of more than one target. Here, we describe the role of COX-2, 15-LOX, and PPARγ in cancer and complications of metabolic disorders, highlight the value of designing multi-target directed ligands (MTDLs) modifying their activity, and summarizing the available literature regarding the rationale and feasibility of design and synthesis of these ligands together with their known biological effects. We speculate on the potential impact of MTDLs in these disorders as well as emphasize the need for structured future effort to translate these early results facilitating the adoption of these, and similar, molecules in clinical research.

Triazole, imidazole, and thiazole-based compounds as potential agents against coronavirus

The expansion of the novel coronavirus known as SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), COVID-19 (coronavirus disease 2019), or 2019-nCoV (2019 novel coronavirus) is a global concern over its pandemic potential. The need for therapeutic alternatives to stop this new pandemic is urgent. Nowadays, no efficacious therapy is available, and vaccines and drugs are underdeveloped to cure or prevent SARS-CoV-2 infections in many countries. Some vaccines candidates have been approved; however, a number of people are still skeptical of this coronavirus vaccines. Probably because of issues related to the quantity of the vaccine and a possible long-term side effects which are still being studied. The previous pandemics of infections caused by coronavirus, such as SARS-CoV in 2003, the Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, HCoV-229E, and HCoV-OC43 were described in the 1960 s, -HCoV-NL63 isolated in 2004, and HCoV-HKU1identified in 2005 prompted researchers to characterize many compounds against these viruses. Most of them could be potentially active against the currently emerging novel coronavirus. Five membered nitrogen heterocycles with a triazole, imidazole, and thiazole moiety are often found in many bioactive molecules such as coronavirus inhibitors. This present work summarizes to review the biological and structural studies of these compound types as coronavirus inhibitors.

Novel 1,2,4-triazine-quinoline hybrids: The privileged scaffolds as potent multi-target inhibitors of LPS-induced inflammatory response via dual COX-2 and 15-LOX inhibition

Based on the observed pharmacophoric structural features for the reported dual COX/15-LOX inhibitors and inspired by the abundance of COX/LOX inhibitory activities reported for the 1,2,4-triazine and quinoline scaffolds, we designed and synthesized novel 1,2,4-triazine-quinoline hybrids (8a-n). The synthesized hybrids were evaluated in vitro as dual COXs/15-LOX inhibitors. The new triazine-quinoline hybrids (8a-n) exhibited potent COX-2 inhibitory profiles (IC₅₀ = 0.047-0.32 μM, SI ∼ 20.6-265.9) compared to celecoxib (IC₅₀ = 0.045 μM, SI ∼ 326). Moreover, they revealed potent inhibitory activities against 15-LOX enzyme compared to reference quercetin (IC₅₀ = 1.81-3.60 vs. 3.34 μM). Hybrid 8e was the most potent and selective dual COX-2/15-LOX inhibitor (COX-2 IC₅₀ = 0.047 μM, SI = 265.9, 15-LOX IC₅₀ = 1.81 μM). These hybrids were further challenged by their ability to inhibit NO, ROS, TNF-α, IL-6 inflammatory mediators, and 15-LOX product, 15-HETE, production in LPS-activated RAW 264.7 macrophages cells. Compound 8e was the most potent hybrid in reducing ROS and 15-HETE levels showing IC₅₀ values of 1.02 μM (11-fold more potent than that of celecoxib, IC₅₀ = 11.75 μM) and 0.17 μM (about 43 times more potent than celecoxib, IC₅₀ = 7.46 μM), respectively. Hybrid 8h exhibited an outstanding TNF-α inhibition with IC₅₀ value of 0.40 μM which was about 25 times more potent than that of celecoxib and diclofenac (IC₅₀ = 10.69 and 10.27 μM, respectively). Docking study of the synthesized hybrids into the active sites of COX-2 and 15-LOX enzymes ensures their favored binding affinity. To our knowledge, herein we reported the first 1,2,4-triazine-quinoline hybrids as dual COX/15-LOX inhibitors.

Explorations on the electronic structure and spectroscopic IR assignments of 5-methyl-2-(2-oxopropyl)-pyrazolo[5,1-b]quinazolin-9(3H)-one molecule

In the present work, theoretical investigations on a quinazoline derivate, 5-methyl-2-(2-oxopropyl)pyrazolo[5,1-b]quinazolin-9(3H)-one, have been carried out through quantum mechanical density functional B3LYP/6-31G(d,p) method to explore its electronic structure and vibrational features. The normal modes analysis was executed to predict the contributions of different vibrational modes at the required frequencies in the infrared region and the spectral peaks have been assigned accordingly. Besides, certain electronic properties that are associated with chemical reactivity like, HOMO-LUMO energy gap, molecular electrostatic potential, Mulliken partial charges, etc have been estimated and discussed herein. It has been established that the molecule is chemically reactive and may be used in designing drugs as COX-2/5-LOX inhibitor.

Synthesis, biological evaluation and molecular docking studies of novel quinazolinones as antitubercular and antimicrobial agents

In the present study, a series of novel quinazolinone hybrids, viz. triazepino-quinazolinones 4, thiazolo-triazolo-quinazolinones 7 and triazolo-quinazolinones 8 have been synthesized from the key intermediate 3-(substituted phenyl)-2-hydrazinoquinazolin-4(3H)-ones 3. All the newly synthesized compounds were characterized by means of spectral (IR, ¹H NMR, ¹³C NMR) and elemental analysis. The target compounds were biologically screened for their in vitro antimicrobial and antitubercular activities against pathogenic strain. The results of bioassay demonstrated that some of the compounds exhibited pronounced antimicrobial activity comparable to that of standard drugs tested under similar conditions. Compounds 4c, 4e, 7e and 8b showed relatively very good inhibitory activity against pathogenic bacteria with minimum inhibitory concentration (MIC) of 2.6 μg/mL, 5.2 μg/mL, while the rest of the compounds showed moderate activity. Compounds 4c and 8b were found to be nearly equipotent with ciprofloxacin against P. aeruginosa with MIC 5.2 μg/mL, while compound 8b was more potent against pathogenic bacteria S. aureus. It is very remarkable that four compounds, 4c, 4e, 7e and 8b showed pronounced antifungal activity against selected pathogenic fungi, A. niger, C. albicans with MIC 2.6 μg/mL and 5.2 μg/mL. The antitubercular activity of synthesized compounds reveal that compound 8b showed better activity than the other compounds with a MIC of 5.2 μg/mL against M. tuberculosis (H₃₇Rv). Molecular docking studies of the compounds were performed to rationalize the inhibitory properties of these compounds and results showed that these compounds have good binding energy and better binding affinity within the active pocket, thus these compounds may be considered as potent inhibitors towards selective targets.

Synthesis of New 1, 3, 4-Oxadiazole-Incorporated 1, 2, 3-Triazole Moieties as Potential Anticancer Agents Targeting Thymidylate Synthase and Their Docking Studies

Thymidylate synthase (TS) has emerged as a hot spot in cancer treatment, as it is directly involved in DNA synthesis. In the present article, nine hybrids containing 1,2,3-triazole and 1,3,4-oxadiazole moieties (6–14) were synthesized and evaluated for anticancer and in vitro thymidylate synthase activities. According to in silico pharmacokinetic studies, the synthesized hybrids exhibited good drug likeness properties and bioavailability. The cytotoxicity results indicated that compounds 12 and 13 exhibited remarkable inhibition on the tested Michigan Cancer Foundation (MCF-7) and Human colorectal Carcinoma (HCT-116) cell lines. Compound 12 showed four-fold inhibition to a standard drug, 5-fluoruracil, and comparable inhibition to tamoxifen, whereas compound 13 exerted five-fold activity of tamoxifen and 24-fold activity of 5-fluorouracil for MCF-7 cells. Compounds 12 and 13 inhibited thymidylate synthase enzyme, with an half maximal inhibitory concentration, IC₅₀ of 2.52 µM and 4.38 µM, while a standard drug, pemetrexed, showed IC₅₀ = 6.75 µM. The molecular docking data of compounds 12 and 13 were found to be in support of biological activities data. In conclusion, hybrids (12 and 13) may inhibit thymidylate synthase enzyme, which could play a significant role as a chemotherapeutic agent.

New methyl 5-(halomethyl)-1-aryl-1H-1,2,4-triazole-3-carboxylates as selective COX-2 inhibitors and anti-inflammatory agents: Design, synthesis, biological evaluation, and docking study

A new method was developed for synthesis of 1,2,4-triazole-3-carboxylates 5a-p and 6 from nitrilimines 3a-p through amination and heterocyclization two-steps reactions. All of 1,2,4-triazole-3-carboxylates 5 and 6 were characterized by spectroscopy technique. Based on the SAR study of anti-inflammation activity, most of these compounds showed potential anti-inflammatory activity on NO inhibition in LPS-induced RAW 264.7 cells (IC₅₀ < 7.0 µM) compared with Celecoxib and Indomethacin. Several potential compounds 5b-h, 5j, 5l, 5n, and 5o were subjected to in vitro cyclooxygenase COX-1/COX-2 inhibition assays. Compound 5d showed extraordinary COX-2 inhibition (IC₅₀ = 17.9 nM) and the best selectivity (COX-1/COX-2 = 1080). Furthermore, 5 mg/kg compound 5d exhibited better in vivo anti-inflammation and gastric protection results compared to 10 mg/kg Indomethacin. Docking experiments of 5d into COX-2 binding pocket have been evaluated. Following the bioactivities experimental data, the potential drug candidate 5d, significantly exhibited better anti-inflammatory effect than Indomethacin.

Novel tetrazole-based selective COX-2 inhibitors: Design, synthesis, anti-inflammatory activity, evaluation of PGE2, TNF-α, IL-6 and histopathological study

To search for effective and selective COX-2 inhibitors, four novel series of tetrazole derivatives were designed based on bioisosteric replacement of SO₂NH₂ in celecoxib with tetrazole ring incorporating different central moieties as chalcone (2a-f), isoxazole (3a-c) or pyrazole (4a-c & 5a-c). Target tetrazoles were synthesized and their structures were confirmed by spectroscopic techniques and elemental analyses. All target compounds were more selective for COX-2 isozyme than COX-1 when compared to standard drugs indomethacin and celecoxib. Compounds 3b, 3c, 4b, 4c, 5b and 5c exhibited potent in vitro COX-2 inhibitory activity (IC₅₀ = 0.039-0.065 μM). Trimethoxy derivatives 3c, 4c and 5c acquired superior COX-2 selectivity index values (SI = 297.67-317.95) and were 1.1 fold higher than celecoxib (SI = 282.22). The most active six compounds were evaluated for their in vivo anti-inflammatory activity and serum levels of PGE₂, TNF-α and IL-6 in addition to their ulcerogenic liability and histopathological profile. At a dose of 50 mg/Kg, compounds 3c and 5c showed better anti-inflammatory activity (% edema inhibition = 29.209-42.643) than celecoxib (% edema inhibition = 28.694-40.114) at different time intervals and were less ulcerogenic (UI = 0.123 and 0.11 in sequent) than celecoxib (UI = 0.167). Also, they displayed potent inhibitory effect on the production of PGE₂ (% inhibition = 81.042 and 82.724 in sequent) greater than celecoxib (% inhibition = 79.666). Compound 5c decreased rat serum concentrations of both TNF-α (% inhibition = 55.349) and IL-6 (% inhibition = 61.561) in a comparable or better activity to celecoxib as reference drug. Finally, docking poses of the most active compounds showed strong binding interactions and effective overall docking energy scores explaining their remarkable COX-2 inhibitory activity.

Design, synthesis, and biological evaluation of new pyrazoloquinazoline derivatives as dual COX-2/5-LOX inhibitors

A new series of pyrazoloquinazoline derivatives equipped with different chalcones was designed, synthesized, and identified through ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, and infrared spectroscopic techniques. Our design strategy of the quinazolinone-privileged scaffold as a new scaffold was based on merging pharmacophores previously reported to exhibit cyclooxygenase-2 (COX-2)/5-lipoxygenase (5-LOX) inhibitory activity. All the newly synthesized derivatives were biologically evaluated for COX and 5-LOX inhibitory activity and COX-2 selectivity, using celecoxib and zileuton as reference drugs, as they exhibited promising anti-inflammatory activity. Compound 3j was found to be the most promising derivative, with IC₅₀ values of 667 and 47 nM against COX-1 and COX-2, respectively, which are superior to that of celecoxib (IC₅₀ value against COX-2 = 95 nM), showing an SI of 14.2 that was much better than celecoxib. Compounds 3f and 3h exhibited COX-1 inhibition, with IC₅₀ values of 1,485 and 684 nM, respectively. The synthesized compounds showed a significant inhibitory activity against 5-LOX, with IC₅₀ values ranging from 0.6 to 4.3 µM, where compounds 3f and 3h were found to be the most potent derivatives, with IC₅₀ values of 0.6 and 1.0 µM, respectively, in comparison with that of zileuton (IC₅₀  = 0.8 µM). These promising derivatives, 3f, 3h, and 3j, were further investigated in vivo for anti-inflammatory, gastric ulcerogenic effects, and prostaglandin production (PGE2) in rat serum. The molecular docking studies concerning the binding sites of COX-2 and 5-LOX revealed similar orientation, compared with reported inhibitors, which encouraged us to design new leads targeting COX-2 and 5-LOX as dual inhibitors, as a new avenue in anti-inflammatory therapy.

Design, One Pot Synthesis and Molecular Docking Studies of Substituted-1H-Pyrido[2,1-b] Quinazolines as Apoptosis-Inducing Anticancer Agents

Objective:

The present study focused to build pyridine and quinazoline rings in a single molecule and designed a new fused Pyrido[2,1-b] quinazoline to have a better pharmacological activity.

Material and Methods:

A three component, one-pot synthesis of substituted-1H-Pyrido[2,1-b] quinazoline derivatives has been described by conventional and microwave synthesis using triflic acid as catalyst. These compounds were screened for in vitro cytotoxic activity against the panel of cancer cell lines A549, NCI-H460, HT-29, HCT-15, DU-145, and HFL.

Results:

Among the tested compounds, 11-(1-benzyl-1H-indol-3-y1)-2, 3, 4, 11-tetrahydro-1H-pyrido[2,1-b] quinazoline (4i) showed most potent cytotoxicity against A549 and NCI-H460 lung cancer cell lines with IC₅₀ values 4.57±0.25 and 5.53±0.49 µM, respectively. Moreover, compound 4i was found to be most potent considerable cell growth inhibition with GI₅₀ values of 2.70±0.18 and 3.24±0.40 µM against A549 and NCI-H460 cell lines, respectively. In addition, induction of apoptosis for compound 4i on A549 was investigated by morphological changes, Acridine orange/ethidium bromide (AO/EB) and DAPI staining. Furthermore, a strong anti-clonogenic effect of compound 4i on lung cancer cells was observed. The flow cytometric analysis investigation reveals that compound 4i arrests the A549 cancer cell lines at the G0/G1 phase of the cell cycle. Molecular docking were also performed on 4i, 4j, and erlotinib to predict the binding mode towards the EGFR kinase (PDB code: 1M17) and the compounds have displayed similar interactions and compared with erlotinib.

Conclusion:

Overall, these findings could suggest that the compound 4i would be an ideal lead as an anticancer agent.

A Facile One-Pot Synthesis of 3-Methylbenzisoxazoles <i>via</i> a Key Intermediate of <i>ortho</i>-Ethoxyvinyl Nitroaryls by Domino Rearrangement and Their Anti- Inflammatory Activity

BACKGROUND

Recently, there has been a lot of scientific interest in exploring the syntheses of oxygen and nitrogen-containing heterocyclic compounds due to their pharmacological activities. In addition, benzisoxazoles play a very important role in organic synthesis as key intermediates.

OBJECTIVE

In this paper, we focused on developing a novel synthetic route for biologically active arylisoxazoles under normal conditions, and simplified it to get high purities and yields, and also reported their anti-inflammatory activities.

METHODS

An efficient and simple method has been explored for the synthesis of novel 3-methyl arylisoxazoles from o-nitroaryl halides via o-ethoxyvinylnitroaryls, using dihydrated stannous chloride (SnCl2.2H2O) in MeOH / EtOAc (1:1) via Domino rearrangement in one pot synthesis.

RESULTS

We synthesized novel 3-methylarylisoxazoles from o-nitroarylhalides via o-ethoxyvinylnitroaryls, using dihydrated stannous chloride (SnCl2.2H2O) in MeOH / EtOAc (1:1) via domino rearrangement. In this reduction, nitro group and ethoxy vinyl group change to the functional acyl ketones, followed by hetero cyclization. Here, the reaction proceeds without the isolation of intermediates like 2-acylnitroarenes and 2- acylanilines. All the synthesized compounds were completely characterized by the NMR and mass spectra. The compounds were also explored for their anti-inflammatory activity by carrageenan-induced inflammation in the albino rats (150-200 g) of either sex used in this entire study with the use of Diclofenac sodium as the standard drug. The initial evaluations identified leading targets with good to moderate anti-inflammatory activity.

CONCLUSION

A simple, one-pot and convenient method has been explored for the synthesis of novel 3- methylarylisoxazoles with high purity and reaction yields. All the compounds 3a, 3c, 3d, 3f, 3g and 3h exhibited 51-64% anti-inflammatory activities.

1,2,3-Triazole-containing hybrids as leads in medicinal chemistry: A recent overview

The 1,2,3-triazole ring is a major pharmacophore system among nitrogen-containing heterocycles. These five-membered heterocyclic motifs with three nitrogen heteroatoms can be prepared easily using 'click' chemistry with copper- or ruthenium-catalysed azide-alkyne cycloaddition reactions. Recently, the 'linker' property of 1,2,3-triazoles was demonstrated, and a novel class of 1,2,3-triazole-containing hybrids and conjugates was synthesised and evaluated as lead compounds for diverse biological targets. These lead compounds have been demonstrated as anticancer, antimicrobial, anti-tubercular, antiviral, antidiabetic, antimalarial, anti-leishmanial, and neuroprotective agents. The present review summarises advances in lead compounds of 1,2,3-triazole-containing hybrids, conjugates, and their related heterocycles in medicinal chemistry published in 2018. This review will be useful to scientists in research fields of organic synthesis, medicinal chemistry, phytochemistry, and pharmacology.

Novel aryl carboximidamide and 3-aryl-1,2,4-oxadiazole analogues of naproxen as dual selective COX-2/15-LOX inhibitors: Design, synthesis and docking studies

A series of novel naproxen analogues containing 3-aryl-1,2,4-oxadiazoles moiety (4b-g) and their reaction intermediates aryl carboximidamides moiety (3b-g) was synthesized and evaluated in vitro as dual COXs/15-LOX inhibitors. Compounds 3b-g exhibited superior inhibitory activity than celecoxib as COX-2 inhibitors. Compounds 3b-d and 3g were the most potent COX-2 inhibitors with IC50 range of 6.4 - 8.13 nM and higher selectivity indexes (3b, SI = 26.19; 3c, SI = 13.73; 3d, SI = 29.27; 3g, SI = 18.00) comparing to celecoxib (IC50 = 42.60 nM, SI = 8.05). Regarding 15-LOX inhibitory activity, compounds belonging to aryl carboximidamide backbone 3b-e and 3g were the most potent with IC50 range of 1.77-4.91 nM comparing to meclofenamate sodium (IC50 = 5.64 µM). Data revealed that The levels of NO released by aryl carboximidamides 3b-g were more higher than 3-aryl-1,2,4-oxadiazole derivatives 4b-g, which correlated well with their COX-2 inhibitory activities.

Synthesis and biological evaluation of pyridazinone derivatives as selective COX-2 inhibitors and potential anti-inflammatory agents

A series of pyridazinone derivatives, bearing an aryl or pyridyl moiety linked through an ethenyl spacer to position-6 was designed and synthesized. The newly synthesized compounds were screened for preferential inhibition of COX-2 over COX-1 isoforms. Compounds 2c, 2d, 2e, 2f, 3a, 3b, 3c, 3d and 3e are highly potent COX-2 inhibitors with IC₅₀ values in nano-molar range. Moreover, they showed clear preferential COX-2 over COX-1 inhibition with selective indices (SIs) ranging from 4 to 38. Of particular interest, compounds 2d, 2f, 3c and 3d exhibited the most prominent COX-2 inhibitory activity with IC₅₀ values range of 15.56-19.77 nM. They showed SIs of 24, 38, 35 and 24, respectively which were 1.4-2.2 fold higher than celecoxib (SI 17). These four compounds were further investigated in vivo for anti-inflammatory activity using the carrageenan induced rat paw edema method and ulcerogenic liability. Compounds 2f, 3c and 3d demonstrated superior anti-inflammatory activity relative to both indomethacin and celecoxib. None of these compounds showed gastric ulcerogenic effect. On the other hand, compound 2d was found equipotent to celecoxib at the second hour of oral administration. At the fourth hour, it exhibited more potent anti-inflammatory activity than celecoxib, becoming equipotent to indomethacin. It showed mild hyperemia in vivo compared to indomethacin and celecoxib. The molecular docking study of compounds 2d, 2f, 3c and 3d into COX-2 active site revealed a similar binding mode to celecoxib, explaining their remarkable COX-2 inhibitory activity. Taken together, these results indicated that these derivatives are good leads for potential COX-2 inhibitors to be used as potent and safe anti-inflammatory agents.