Design, synthesis and characterization of new amide-linked Chromone-Isoxazole Hybrids: In Vitro anti-bacterial and antioxidant evaluation, DFT calculations, ADMET profiling, docking and molecular dynamics simulation

In the present study, we report the synthesis, and biological evaluation of a new series of amide-linked chromone-isoxazole hybrids synthesized through a highly regioselective 1,3-dipolar cycloaddition (1,3-DC) reaction in a reproducible manner. The resulting products structures were identified by means of several spectroscopic techniques, including 13 C NMR, 1 H NMR, IR and MS spectrometry. In addition, the regio- and chemoselective synthesis of the newly synthesized chromone-isoxazole carboxamide hybrids were investigated via Density Functional Theory (DFT) calculations at the B3LYP/6-311G(d,p) level, which provided insights into molecular reactivity. Global and local reactivity indexes as well as the non-covalent interactions (NCI) analyses, and the findings explain the observed selectivity of the corresponding product. The antioxidant activity of all the new compounds was examined through the DPPH free radical scavenging assay, and the findings demonstrated a significant free radical scavenging power for the tested compounds. Notably, products 5c and 5e exhibited encouraging antioxidant effect. Antibacterial screening of the chromone-isoxazole hybrids against Escherichia coli, Porteus mirabilis, Bacillus subtilis and Staphylococcus aureus showed moderate activity, with compound 1 demonstrating the most promising antibacterial efficacy. To further explore the compound 1 ' s antibacterial potential, we employed molecular docking, dynamics simulations, ligand-protein contact analysis and ADMET profiling. Docking results revealed that compound 1 forms specific hydrogen bonds and hydrophobic interactions with bacterial targets 2W9S and 10FO, distinct from the interaction observed with standard antibacterial drug. Molecular dynamics simulation indicated stable protein-ligand conformations, despite slight ligand flexibility, and contact analysis identified a critical interaction stabilizing the complex. ADMET analysis confirmed thatcompound 1 possesses good drug-like properties, including oral bioavailability and low toxicity, indicating its potential as an effective antibacterial agent.