Potential anti-bacterial agents: montmorillonite clay-catalyzed synthesis of novel 2-(3,5-substituted-1H-pyrazol-1-yl)-3-substituted quinolines and their in silico molecular docking studies

A series of 2-(3,5-substituted-1 H -pyrazol-1-yl)-3-substituted quinolines 5a–g , were obtained from 2-chloro-3-(1,3-dioxolan-2-yl) quinolines 2a–c and diketones 3a–c with great yields by utilizing Montmorillonite clay K-10 as a catalyst in an eco-friendly methodology. All the synthesized compounds were characterized by FTIR, 1 H-NMR, 13 C-NMR and HRMS spectral techniques. Antibacterial screening of the compounds revealed that some of the compounds demonstrate moderate to good results. Amongst all, compound 2c displayed a good inhibitory profile against P. aeruginosa and B. subtilis , while compound 5c exhibited remarkable activity against S. aureus , B. subtilis and P. aeruginosa with an MIC value of 25 μg mL −1 . Moreover, compound 5c presented a MIC value of 50 μg mL −1 against E. coli and K. pneumoniae , which was comparable to that of the standard. In addition, compound 5f was demonstrated good viability against S. aureus and P. aeruginosa with a MIC value of 25 μg mL −1 . Compounds 2c and 5f , however, showed relatively moderate inhibition against S. aureus , while the latter had a moderate activity against B. subtilis . To further demonstrate the antibacterial efficacy of 2c , 5c and 5f , molecular docking studies were done, confirming that compound 5c possesses good binding interaction with the peptide deformylase protein, with a binding energy of −8.1 kcal mol −1 —more prominent than that of standard ampicillin (−7.5 kcal mol −1 )—while compounds 2c and 5f have moderate binding affinity.