In this work, we report the synthesis of some new pyrazole derivatives via an efficient and practical procedure. The structures of the obtained compounds were established using different spectroscopic techniques such as NMR and FT-IR spectroscopy as well as high resolution mass spectrometry (HRMS). The synthesized compounds were screened for their antimicrobial activity against the following pathogenic microorganisms: Listeria innocua (CECT 4030), Staphylococcus aureus (CECT 976), Escherichia coli (K12), and Candida albicans (ATCC 10231). The results of the in vitro tests reveal that compounds 5c, 9b, and 9c exhibit important antimicrobial activity against some tested microbe strains, and show excellent bactericidal and fungicidal activities. A molecular docking study was performed on the most active compounds against E. coli and C. albicans receptors, in order to determine the modes of hydrogen bonding, and electrostatic and hydrophobic interactions that occur between the selected ligands and the target proteins. Furthermore, the 3D-QSAR study based on CoMFA and CoMSIA analyses ascertained a good correlation between the antibacterial activity of the pyrazole derivatives and their structural parameters. The structural features identified in these analyses were successfully used to design new pyrazole derivatives that show better in silico antimicrobial activity than the synthesized ones. In addition, most of the synthesized and the newly designed compounds show good drug-like properties. The ADME-Tox profiles indicate a good oral bioavailability. The newly designed compounds were subjected to molecular docking, which showed that they could form stable complexes with the E. coli receptor. Therefore, the obtained results in this study might provide important information for designing and synthesizing new pyrazoles with enhanced antimicrobial activity.

This work describes the synthesis, characterization, and in vitro and in silico evaluation of the biological activity of new functionalized isoxazole derivatives. The structures of all new compounds were analyzed by IR and NMR spectroscopy. The structures of 4c and 4f were further confirmed by single crystal X-ray and their compositions unambiguously determined by mass spectrometry (MS). The antibacterial effect of the isoxazoles was assessed in vitro against Escherichia coli, Bacillus subtilis, and Staphylococcusaureus bacterial strains. Isoxazole 4a showed significant activity against E. coli and B. subtilis compared to the reference antibiotic drugs while 4d and 4f also exhibited some antibacterial effects. The molecular docking results indicate that the synthesized compounds exhibit strong interactions with the target proteins. Specifically, 4a displayed a better affinity for E. coli, S. aureus, and B. subtilis in comparison to the reference drugs. The molecular dynamics simulations performed on 4a strongly support the stability of the ligand–receptor complex when interacting with the active sites of proteins from E. coli, S. aureus, and B. subtilis. Lastly, the results of the Absorption, Distribution, Metabolism, Excretion and Toxicity Analysis (ADME-Tox) reveal that the molecules have promising pharmacokinetic properties, suggesting favorable druglike properties and potential therapeutic agents.