Synthesis, in vivo anti-inflammatory, COX-1/COX-2 and 5-LOX inhibitory activities of new 2,3,4-trisubstituted thiophene derivatives

In Vitro Enzymatic and Computational Assessments of Pyrazole-Isatin and Pyrazole-Indole Conjugates as Anti-Diabetic, Anti-Arthritic, and Anti-Inflammatory Agents

Background/Objectives: Recently, the prevalence of diseases such as diabetes, arthritis, and inflammatory diseases, along with their complications, has become a significant health problem. This is in addition to the various biomedical applications of pyrazole, isatin, and indole derivatives. Accordingly, cooperation will continue between chemistry scientists, pharmaceutical scientists, and human doctors to produce hybrid compounds from pyrazole with isatin or indole possessing biological activities as anti-diabetic, anti-arthritic, and anti-inflammatory agents. Methods: The two series of pyrazole-isatin conjugates 12a-h and pyrazole-indole conjugates 14a-d were prepared from our previous works via the direct reaction of 5-amino-pyrazoles 10a-d with N-alkyl isatin 11a,b, and 1H-indole-3-carbaldehyde (13), respectively, using the previously reported procedure. The potential biological activities of 12a-h and 14a-d as anti-diabetic, anti-arthritic, and anti-inflammatory agents were assessed through estimated inhibition percentage (%) and the median inhibitory concentrations (IC50) using methods described in the literature. Further, the computational assessments of 12a-h and 14a-d such as toxic doses (the median lethal dose, LD50), toxicity classes, drug-likeness model scores (DLMS), molecular lipophilicity potential (MLP) maps, polar surface area (PSA) maps, and topological polar surface area (TPSA) values were predicted using available free websites. Results: The in vitro enzymatic assessment results showed that pyrazole-indole conjugate 14b possesses powerful activities against (i) α-amylase (% = 65.74 ± 0.23, IC50 = 4.21 ± 0.03 µg/mL) and α-glucosidase (% = 55.49 ± 0.23, IC50 = 2.76 ± 0.01 µg/mL); (ii) the protein denaturation enzyme (% = 49.30 ± 0.17) and against the proteinase enzyme (% = 46.55 ± 0.17) with an IC50 value of 6.77 ± 0.01 µg/mL; (iii) the COX-1, COX-2, and 5-LOX enzymes with an IC50 of 5.44 ± 0.03, 5.37 ± 0.04, and 7.52 ± 0.04, respectively, which is almost close to the IC50 of the indomethacin and zileuton drugs. Also, the computational assessment results showed (i) the conjugate 14b possesses lipophilic surface properties thus can cross cell membranes, and is effective for treatment; (ii) all the conjugates possess a TPSA value of more than 140 Å2 thus possess good intestinal absorption. Conclusions: The two series of pyrazole-isatin conjugates 12a-h and pyrazole-indole conjugates 14a-d were synthesized from our previous works. The results of these in vitro enzymatic and computational assessments concluded that the pyrazole-indole conjugate 14b possesses powerful activities against various studied enzymes and possesses good computational results. In the future, our research team will present in vitro, in vivo biological, and computational assessments to hopefully obtain effectual agents such as anti-diabetic, anti-arthritic, and anti-inflammatory.

New Diaryl-1,2,4-triazolo[3,4-a]pyrimidine Hybrids as Selective COX-2/sEH Dual Inhibitors with Potent Analgesic/Anti-inflammatory and Cardioprotective Properties

COX-2-selective drugs were withdrawn from the market just a few years after their development due to cardiovascular side effects. As a result, developing a selective COX-2 inhibitor as an anti-inflammatory agent with cardioprotective characteristics has become a prominent objective in medicinal chemistry. New 15 diaryl-1,2,4-triazolo[3,4-a]pyrimidine hybrids 8a-o were synthesized and investigated in vitro as dual COX-2/sEH inhibitors. Compounds 8b, 8m, and 8o have the highest potency and selectivity as COX-2 inhibitors (IC50 = 15.20, 11.60, and 10.50 μM, respectively; selectivity index (COX-1/COX-2) = 13, 20, and 25, respectively), compared to celecoxib (COX-2; IC50 = 42 μM; SI = 8). The 5-LOX inhibitory activity of compounds 8b, 8m, and 8o was further examined in vitro. Compounds 8m and 8o, the most effective COX-2 selective inhibitors, demonstrated stronger 5-LOX inhibitory action than the reference quercetin, with IC50 values of 2.90 and 3.05 μM, respectively. Additionally, compounds 8b, 8m, and 8o were the most potent dual COX-2/sEH inhibitors, with IC50 values against sEH of 3.20, 2.95, and 2.20 nM, respectively, and were equivalent to AUDA (IC50 = 1.2 nM). In vivo investigations also demonstrated that these compounds were the most efficacious as analgesic/anti-inflammatory derivatives with a high cardioprotective profile against cardiac biomarkers and inflammatory cytokines. The docking data analysis inquiry helped better understand the binding mechanisms of the most active hybrids within the COX-2 active site and supported their COX-2 selectivity. Compounds 8b, 8m, and 8o exhibited a similar orientation to rofecoxib and celecoxib, with a larger proclivity to enter the selectivity side pocket than the reference compounds.

Preliminary Investigation of Astragalus arpilobus subsp. hauarensis: LC-MS/MS Chemical Profiling, In Vitro Evaluation of Antioxidant, Anti-Inflammatory Properties, Cytotoxicity, and In Silico Analysis against COX-2

The search results offer comprehensive insights into the phenolic compounds, antioxidant, anti-inflammatory, cytotoxic effects, LC-MS/MS analysis, molecular docking, and MD simulation of the identified phenolic compounds in the Astragalus arpilobus subsp. hauarensis extract (AAH). The analysis revealed substantial levels of total phenolic content (TPC), with a measured value of 191 ± 0.03 mg GAE/g DM. This high TPC was primarily attributed to two key phenolic compounds: total flavonoid content (TFC) and total tannin content (TTC), quantified at 80.82 ± 0.02 mg QE/g DM and 51.91 ± 0.01 mg CE/g DM, respectively. LC-MS/MS analysis identified 28 phenolic compounds, with gallic acid, protocatechuic acid, catechin, and others. In the DPPH scavenging assay, the IC50 value for the extract was determined to be 19.44 ± 0.04 μg/mL, comparable to standard antioxidants like BHA, BHT, ascorbic acid, and α-tocopherol. Regarding anti-inflammatory activity, the extract demonstrated a notably lower IC50 value compared to both diclofenac and ketoprofen, with values of 35.73 µg/mL, 63.78 µg/mL, and 164.79 µg/mL, respectively. Cytotoxicity analysis revealed significant cytotoxicity of the A. arpilobus extract, with an LC50 value of 28.84 µg/mL, which exceeded that of potassium dichromate (15.73 µg/mL), indicating its potential as a safer alternative for various applications. Molecular docking studies have highlighted chrysin as a promising COX-2 inhibitor, with favorable binding energies and interactions. Molecular dynamic simulations further support chrysin's potential, showing stable interactions with COX-2, comparable to the reference ligand S58. Overall, the study underscores the pharmacological potential of A. arpilobus extract, particularly chrysin, as a source of bioactive compounds with antioxidant and anti-inflammatory properties. Further research is warranted to elucidate the therapeutic mechanisms and clinical implications of these natural compounds.

Synthesis, molecular docking, analgesic, anti-inflammatory, and ulcerogenic evaluation of thiophene-pyrazole candidates as COX, 5-LOX, and TNF-α inhibitors

The thiophene bearing pyrazole derivatives (7a-j) were synthesized and examined for their in vitro cyclooxygenase, 5-lipoxygenase, and tumour inducing factor-α inhibitory activities followed by the in vivo analgesic, anti-inflammatory, and ulcerogenic evaluations. The synthesized series (7a-j) were characterized using 1H NMR, 13C NMR, FT-IR, and mass spectral analysis. Initially, the compounds (7a-j) were evaluated for their in vitro cyclooxygenase, 5-lipoxygenase, and tumour inducing factor-α inhibitory activities and the compound (7f) with two phenyl substituents in the pyrazole ring and chloro substituent in the thiophene ring and the compound (7g) with two phenyl substituents in the pyrazole ring and bromo substituent in the thiophene ring were observed as potent compounds among the series. The compounds (7f and 7g) with effective in vitro potentials were further analyzed for analgesic, anti-inflammatory, and ulcerogenic evaluations. Also, to ascertain the binding affinities of compounds (7a-j), docking assessments were carried out and the ligand (7f) with the highest binding affinity was docked to know the interactions of the ligand with amino acids of target proteins.

The Potential of Usnic-Acid-Based Thiazolo-Thiophenes as Inhibitors of the Main Protease of SARS-CoV-2 Viruses

Although the COVID-19 pandemic caused by SARS-CoV-2 viruses is officially over, the search for new effective agents with activity against a wide range of coronaviruses is still an important task for medical chemists and virologists. We synthesized a series of thiazolo-thiophenes based on (+)- and (-)-usnic acid and studied their ability to inhibit the main protease of SARS-CoV-2. Substances containing unsubstituted thiophene groups or methyl- or bromo-substituted thiophene moieties showed moderate activity. Derivatives containing nitro substituents in the thiophene heterocycle-just as pure (+)- and (-)-usnic acids-showed no anti-3CLpro activity. Kinetic parameters of the most active compound, (+)-3e, were investigated, and molecular modeling of the possible interaction of the new thiazolo-thiophenes with the active site of the main protease was carried out. We evaluated the binding energies of the ligand and protein in a ligand-protein complex. Active compound (+)-3e was found to bind with minimum free energy; the binding of inactive compound (+)-3g is characterized by higher values of minimum free energy; the positioning of pure (+)-usnic acid proved to be unstable and is accompanied by the formation of intermolecular contacts with many amino acids of the catalytic binding site. Thus, the molecular dynamics results were consistent with the experimental data. In an in vitro antiviral assay against six strains (Wuhan, Delta, and four Omicron sublineages) of SARS-CoV-2, (+)-3e demonstrated pronounced antiviral activity against all the strains.

Synthesis and In vitro and In silico Anti-inflammatory Activity of New Thiazolidinedione-quinoline Derivatives

BACKGROUND

Inflammation is a series of complex defense-related reactions. The inflammation cascade produces various pro-inflammatory mediators. Unregulated production of these pro-inflammatory mediators can lead to a wide range of diseases, including rheumatoid arthritis, sepsis, and inflammatory bowel disease. In the literature, the anti-inflammatory action of quinoline and thiazolidinedione nuclei are well established, alone, and associated with other nuclei. The synthesis of hybrid molecules is a strategy for obtaining more efficient molecules due to the union of pharmacophoric nuclei known to be related to pharmacological activity.

OBJECTIVES

Based on this, this work presents the synthesis of thiazolidinedione-quinoline molecular hybrids and their involvement in the modulation of cytokines involved in the inflammatory reaction cascade.

METHODS

After synthesis and characterization, the compounds were submitted to cell viability test (MTT), ELISA IFN-γ and TNF-α, adipogenic differentiation, and molecular docking assay with PPARy and COX-2 targets.

RESULTS

LPSF/ZKD2 and LPSF/ZKD7 showed a significant decrease in the concentration of IFN- γ and TNF-α, with a dose-dependent behavior. LPSF/ZKD4 at a concentration of 50 μM significantly reduced IL-6 expression. LPSF/ZKD4 demonstrates lipid accumulation with significant differences between the untreated and negative control groups, indicating a relevant agonist action on the PPARγ receptor. Molecular docking showed that all synthesized compounds have good affinity with PPARγ e COX-2, with binding energy close to -10,000 Kcal/mol.

CONCLUSION

These results demonstrate that the synthesis of quinoline-thiazolidinedione hybrids may be a useful strategy for obtaining promising candidates for new anti-inflammatory agents.

Development of Novel Pyrrole Derivatives and Their Cinnamic Hybrids as Dual COX-2/LOX Inhibitors

Molecular hybridization has emerged as a promising approach in the treatment of diseases exhibiting multifactorial etiology. With regard to this, dual cyclooxygenase-2/lipoxygenase (COX-2/LOX) inhibitors could be considered a safe alternative to traditional non-steroidal anti-inflammatory drugs (tNSAIDs) and selective COX-2 inhibitors (coxibs) for the treatment of inflammatory conditions. Taking this into account, six novel pyrrole derivatives and pyrrole-cinnamate hybrids were developed as potential COX-2 and soybean LOX (sLOX) inhibitors with antioxidant activity. In silico calculations were performed to predict their ADMET (absorption, distribution, metabolism, excretion, toxicity) properties and drug-likeness, while lipophilicity was experimentally determined as RM values. All synthesized compounds (1-4, 5-8) could be described as drug-like. The results from the docking studies on COX-2 were in accordance with the in vitro studies. According to molecular docking studies on soybean LOX, the compounds displayed allosteric interactions with the enzyme. Pyrrole 2 appeared to be the most potent s-LOX inhibitor (IC50 = 7.5 μM). Hybrids 5 and 6 presented a promising combination of in vitro LOX (IC50 for 5 = 30 μM, IC50 for 6 = 27.5 μM) and COX-2 (IC50 for 5 = 0.55 μM, IC50 for 6 = 7.0 μM) inhibitory activities, and therefore could be used as the lead compounds for the synthesis of more effective multi-target agents.

Promising anti-Helicobacter pylori and anti-inflammatory metabolites from unused parts of Phoenix dactylifera CV 'Zaghloul': in vitro and in silico study

CONTEXT

Date palm waste is an agricultural waste that accumulates in massive amounts causing serious pollution and environmental problems.

OBJECTIVES

Date palm trees, Phoenix dactylifera Linn CV 'Zaghloul' (Arecaceae) grown in Egypt, leave behind waste products that were investigated to produce compounds with anti-Helicobacter pylori and anti-inflammatory activities.

MATERIALS AND METHODS

Chromatographic workup of P. dactylifera aqueous methanol extract derived from fibrous mesh and fruit bunch (without fruit) afforded a new sesquiterpene lactone derivative, phodactolide A (1), along with ten known compounds (2-11), primarily identified as polyphenols. Chemical structures were unambiguously elucidated based on mass and 1D/2D NMR spectroscopy. All isolated compounds were assessed for their activities against H. pylori using broth micro-well dilution method and clarithromycin as a positive control. The anti-inflammatory response of isolated compounds was evaluated by inhibiting cyclooxygenase-2 enzyme using TMPD Assay followed by an in silico study to validate their mechanism of action using celecoxib as a standard drug.

RESULTS

Compounds 4, 6 and 8-10 exhibited potent anti-H. pylori activity with MIC values ranging from 0.48 to 1.95 µg/mL that were comparable to or more potent than clarithromycin. For COX-2 inhibitory assay, 4, 7 and 8 revealed promising activities with IC₅₀ values of 1.04, 0.65 and 0.45 μg/mL, respectively. These results were verified by molecular docking studies, where 4, 7 and 8 showed the best interactions with key amino acid residues of COX-2 active site.

CONCLUSION

The present study characterizes a new sesquiterpene lactone and recommends 4 and 8 for future in vivo studies as plausible anti-ulcer remedies.

Design, synthesis, and molecular docking of novel pyrazole-chalcone analogs of lonazolac as 5-LOX, iNOS and tubulin polymerization inhibitors with potential anticancer and anti-inflammatory activities

Uncontrolled inflammation predisposes to pleiotropic effects leading to cancer development thanks to promoting all stages of tumorigenesis. Therefore, cancer-associated inflammation has been delegated as the seventh hallmark of cancer. Thus, raging the war against both inflammation and cancer via the innovation of bioactive agents with dual anti-inflammatory and anticancer activities is a necessity. Herein, a novel series of pyrazole-chalcone analogs of Lonazolac (7a-g and 8a-g) have been synthesized and investigated for their in vitro anticancer activity against four cancer cell lines using the MTT assay method. Among all, hybrid 8g was the most potent against three cancer cell lines, HeLa, HCT-116, and RPMI-822 with IC₅₀ values of 2.41, 2.41, and 3.34 µM, respectively. In contrast, hybrid 8g showed moderate inhibitory activity against MCF-7 with IC₅₀ 28.93 μM and with a selectivity profile against MCF-10A (non-cancer cells). Mechanistically, hybrid 8g was the most potent inhibitor against tubulin polymerization (IC₅₀ = 4.77 µM), suggesting tubulin as a molecular target and explaining the observed cytotoxicity of hybrid 8g. This was mirrored by the detected potent pre-G1 apoptosis induction and G2/M cell cycle arrest. Moreover, hybrid8gexhibited selectivity against COX-2 (IC₅₀ = 5.13 µM) more than COX-1 (IC₅₀ = 33.46 µM), indicating that 8g may have lower cardiovascular side effects, but is still not potent as celecoxib (COX-2 IC₅₀ = 0.204 µM, COX-1 = 35.8 µM). Notably, hybrid 8g showed promising inhibitory activity towards 5-LOX (IC₅₀ = 5.88 µM). Finally, the anti-inflammatory activity of hybrid8 g was confirmed by high iNOS and PGE2 inhibitory activities in LPS-stimulated RAW cells with IC₅₀ values of4.93 µM and 10.98 µM, respectively, that accompanied by showingthe most potent inhibition of NO release (70.61 % inhibition rate). Molecular docking studies of hybrid 8g confirmed good correlations with the executed biological results. Furthermore, hybrid 8g had good drug-likeness and suitable physicochemical properties. Taken together, the combined results suggested hybrid8gas a promising orally administered candidate in the journey of repurposing NSAIDs for cancer chemopreventionand treatment.

Novel 5,6-diphenyl-1,2,4-triazine-3-thiol derivatives as dual COX-2/5-LOX inhibitors devoid of cardiotoxicity

A novel series of 5,6-diphenyl-1,2,4-triazine-3-thiol derivatives were designed, synthesized, and screened for their inhibitory potential against COX-2 and 5-LOX enzymes. The compounds from the series have shown moderate to excellent inhibitory potential against both targets. Compound 6k showed the inhibitions against COX-2 (IC₅₀ = 0.33 ± 0.02 μM) and 5-LOX inhibition (IC₅₀ = 4.90 ± 0.22 μM) which was better than the standard celecoxib (IC₅₀ = 1.81 ± 0.13 μM) for COX-2 and zileuton (IC₅₀ = 15.04 ± 0.18 μM) for 5-LOX respectively. Further investigation on the selected derivative 6k in rat paw edema models revealed significant anti-inflammatory efficacy. Compound 6k has also shown negligible ulcerogenic liability as compared to indomethacin. Moreover, in vivo biochemical analysis also established the compound's antioxidant properties. Compounds 6c and 6k were also observed to be devoid of cardiotoxicity post-myocardial infarction in rats. The molecular docking and dynamics simulation studies of the most active derivative 6k affirmed their consentient binding interactions with COX-2 specific ravine and cleft of 5-LOX.

A study on the cellular and cytotoxic effects of S and Se heterocycles on the myeloid leukemia cell line PLB-985

This paper describes the synthesis of several halogenated S and Se heterocycles and tests their biological activity by measuring the effects on the myeloid leukemia cell line, PLB-985 cells. We report that select compounds exhibit significant increases in mitochondria membrane potential and increased oxidative stress in PLB-985 cells. Our results contribute to the foundational knowledge of different S and Se containing compounds and their possible impacts on human cells.

Novel quinoxaline derivatives as dual EGFR and COX-2 inhibitors: synthesis, molecular docking and biological evaluation as potential anticancer and anti-inflammatory agents

Novel quinoxaline derivatives (2a–d, 3, 4a, 4b and 5–15) have been synthesized via the reaction of 4-methyl-3-oxo-3,4-dihydroquinoxaline-2-carbohydrazide (1) with different aldehydes, ketones, diketones, ketoesters, as well as hydrazine, phenyl isothiocyanate, carbon disulphide. The synthesized products have been screened for their in vitro anticancer and COX inhibitory activities. Most of the synthesized compounds exhibited good anticancer and COX-2 inhibitory activities. MTT assay revealed that compounds 11 and 13 were the most potent and exhibited very strong anticancer activity against the three cancer cell lines with IC₅₀ values ranging from 0.81 μM to 2.91 μM. Compounds 4a and 5 come next and displayed strong anticancer activity against the three cancer cell lines with IC₅₀ values ranging from 3.21 μM to 4.54 μM. Mechanistically, compounds 4a and 13 were the most active and potently inhibited EGFR with IC₅₀ = 0.3 and 0.4 μM, respectively. Compounds 11 and 5 come next with IC₅₀ = 0.6 and 0.9 μM, respectively. Moreover, compounds 11 and 13 were the most potent as COX-2 inhibitors and displayed higher potency against COX-2 (IC₅₀ = 0.62 and 0.46 μM, respectively) more than COX-1 (IC₅₀ = 37.96 and 30.41 μM, respectively) with selectivity indexes (SI) of 61.23 and 66.11, respectively. Compounds 4a and 5 comes next with IC₅₀ = 1.17 and 0.83 μM and SI of 24.61 and 48.58, respectively. Molecular docking studies into the catalytic binding pocket of both protein receptors, EGFR and COX-2, showed good correlation with the obtained biological results. Parameters of Lipinski's rule of five and Veber's standard were calculated and revealed that compounds 4a, 5, 11 and 13 had a reasonable drug-likeness with acceptable physicochemical properties. Therefore, based on the obtained biological results accompanied with the docking study and physicochemical parameters, it could be concluded that compounds 4a, 5, 11 and 13 could be used as promising orally absorbed dual anti-inflammatory agents via inhibition of COX-2 enzyme and anticancer candidates via inhibition of EGFR enzyme and could be used as a future template for further investigations.

Novel quinoxaline derivatives (2a–d, 3, 4a, 4b, 5–15) have been synthesized and screened for their in vitro anticancer and COX-2 inhibitory activities. Compounds 4a, 5, 11 and 13 proved to be the most potent anticancer and COX-2 inhibitors.

Synthetically-tailored and nature-derived dual COX-2/5-LOX inhibitors: Structural aspects and SAR

Inflammation is a most complex pathological process that gives birth to different diseases. Different inflammatory mediators are released during an inflammation responsible for acute pain and chronic inflammatory diseases like cancer, asthma, rheumatoid arthritis, osteoarthritis, neurodegenerative diseases, metabolic and cardiovascular disorders. The arachidonic acid pathway, which results in the production of inflammatory mediators, provides several targets for anti-inflammatory intervention. The most popularly used medications for inflammation are non-steroidal anti-inflammatory agents (NSAIDs) but it has some limitations, in particular traditional NSAIDs which inhibit the COX pathway non-selectively, producing gastrointestinal side effects, and other adverse effects like stroke and renal failure. On the other hand, selective COX-2 inhibitors commonly known as 'coxibs' produce cardiovascular side effects. Frequent inhibition of either cyclooxygenase or lipoxygenase enzyme switches the metabolism of arachidonic acid from one to another which could lead to serious consequences. Therefore, a need to develop novel, effective and safe anti-inflammatory agents which can inhibit the release of both prostaglandins and leukotrienes from the respective cyclooxygenase and lipoxygenase pathways has emerged. This resulted in the discovery of new anti-inflammatory agents derived from natural and synthetic sources as dual COX-2/5-LOX inhibitors. To further contribute towards the discovery in this field, we have attempted to summarize structural features and pharmacological activities of heterocyclic scaffolds and natural products explored as dual COX-2/5-LOX inhibitors. We have emphasized the designing of the dual inhibitors inspired by the previously reported COX-2 and 5-LOX inhibitors. This outline could render us to identify the best pharmacophores catering to dual COX-2/5-LOX inhibitory activity while improving their efficiency as anti-inflammatory agents.

Novel chalcone/aryl carboximidamide hybrids as potent anti-inflammatory via inhibition of prostaglandin E2 and inducible NO synthase activities: design, synthesis, molecular docking studies and ADMET prediction

Two series of chalcone/aryl carboximidamide hybrids 4a-f and 6a-f were synthesised and evaluated for their inhibitory activity against iNOS and PGE2. The most potent derivatives were further checked for their in vivo anti-inflammatory activity utilising carrageenan-induced rat paw oedema model. Compounds 4c, 4d, 6c and 6d were proved to be the most effective inhibitors of PGE2, LPS-induced NO production, iNOS activity. Moreover, 4c, 4d, 6c and 6d showed significant oedema inhibition ranging from 62.21% to 78.51%, compared to indomethacin (56.27 ± 2.14%) and celecoxib (12.32%). Additionally, 4c, 6a and 6e displayed good COX2 inhibitory activity while 4c, 6a and 6c exhibited the highest 5LOX inhibitory activity. Compounds 4c, 4d, 6c and 6d fit nicely into the pocket of iNOS protein (PDB ID: 1r35) via the important amino acid residues. Prediction of physicochemical parameters exhibited that 4c, 4d, 6c and 6d had acceptable physicochemical parameters and drug-likeness. The results indicated that chalcone/aryl carboximidamides 4c, 4d, 6c and 6d, in particular 4d and 6d, could be used as promising lead candidates as potent anti-inflammatory agents.

Novel 1,2,4-oxadiazole-chalcone/oxime hybrids as potential antibacterial DNA gyrase inhibitors: Design, synthesis, ADMET prediction and molecular docking study

New antibacterial drugs are urgently needed to tackle the rapid rise in multi-drug resistant bacteria. DNA gyrase is a validated target for the development of new antibacterial drugs. Thus, in the present investigation, a novel series of 1,2,4-oxadiazole-chalcone/oxime (6a-f) and (7a-f) were synthesized and characterized by IR, NMR (¹H and ¹³C) and elemental analyses. The title compounds were evaluated for their in-vitro antimicrobial activity by the modified agar diffusion method as well as their E. coli DNA gyrase inhibitory activity. The minimum inhibitory concentration (MIC) and the structure activity relationships (SARs) were evaluated. Among all, compounds 6a, 6c-e, 7b and 7e were the most potent and proved to possess broad spectrum activity against the tested Gram-positive and Gram-negative organisms. Additionally, compounds 6a (against S. aureus), 6c (against B. subtilis and E. hirae), 6e (against E. hirae), 6f, 7a and 7c (against E. coli) and 7d (against B. subtilis), with MIC value of 3.12 μM were two-fold more potent than the standard ciprofloxacin (MIC = 6.25 μM). Mechanistically, compounds 6c, 7c, 7e and 7b had good inhibitory activity against E. coli gyrase with IC₅₀ values of 17.05, 13.4, 16.9, and 19.6 µM, respectively, in comparison with novobiocin (IC₅₀ = 12.3 µM) and ciprofloxacin (IC₅₀ = 10.5 µM). The molecular docking results at DNA gyrase active site revealed that the most potent compounds 6c and 7c have binding mode and docking scores comparable to that of ciprofloxacin and novobiocin suggesting their antibacterial activity via inhibition of DNA gyrase. Finally, the predicted parameters of Lipinski's rule of five and ADMET analysis showed that 6c and 7c had good drug-likeness and acceptable physicochemical properties. Therefore, the hybridization of the chalcone and oxadiazole moieties could be promising lead as antibacterial candidate which merit further future structural optimizations.