Molecular Docking, In silico ADMET Study and Synthesis of Quinoline Derivatives as Dihydrofolate Reductase (DHFR) Inhibitors: A Solvent-free One-pot Green Approach through Sonochemistry

Background: Quinoline derivatives have evinced their biological importance in targeting bacteria by inhibiting Dihydrofolate reductase. H2SO4 was successfully applied as an acid catalyst for a green, efficient, and one-pot solvent-free synthesis of quinoline derivatives using sonochemistry approach from various aromatic amines and glycerol with affording yield up to 96% within 6-10 min. Objective: In this study, the synthesis, characterization, and biological assessment of fifteen quinoline derivatives (1-15) as potential DHFR inhibitors were carried out. The target compounds were docked to study the molecular interactions and binding affinities with the 1DLS enzyme. Methods: The synthesized molecules were characterized using IR, MASS, and 1H and 13C NMR. The In-silico molecular docking study was carried out through target Human Dihydrofolate Reductase (DHFR) retrieved from a protein data bank having PDB ID: 1DLS and the antimicrobial activity of all synthesized compounds were tested against Human Dihydrofolate Reductase(DHFR) enzyme by using in-vitro DHFR assay kit. Results: The molecular docking results revealed that compounds 2 and 6 have the lowest binding energy and good binding affinity with the DHFR enzyme. In-silico ADMET predictions revealed that all best-scored compounds had good absorption and drug-like properties for potential use as DHFR inhibitors to treat bacterial infection. The in vitro studies revealed that compounds 2 and 6 show potent DFHR inhibitory activity against gram-positive and gram-negative with IC50 = 12.05 +/- 1.55 mu M and 10.04 +/- 0.73 mu M, respectively. While compounds 12, 13, and 15 exhibited moderate antimicrobial activity through DHFR inhibition with IC50= 16.33 +/- 0.73 mu M, 17.02 +/- 1.55 mu M, and 18.04 +/- 1.05 mu M, respectively. Conclusion: This environmentally benign sonochemistry-based approach for synthesizing quinoline derivatives could be affordable for large-scale production and become a potential lead candidate for developing a new quinoline-based antimicrobial agent.