Phytochemical Profile and In Vitro–In Silico Antibacterial Activity of Melia azedarach Leaf and Twig Extracts Obtained Using Solvents of Different Polarities

Melia azedarach L. (Meliaceae) exhibits potential as a source of bioactive antibacterial compounds. In this study, the effect of solvent polarity on ultrasound-assisted extraction of M. azedarach leaves and twigs was evaluated in relation to their phytochemical composition and antibacterial activity against both non-resistant and multidrug-resistant bacteria. The results showed that solvent polarity significantly affected the extraction yield, with methanol and water producing yields above 10%. The methanol extracts of twigs and leaves exhibited the strongest antibacterial activity, showing greater potency against Escherichia coli than Bacillus subtilis. Consistent with these findings, the methanol extracts inhibited the growth of multidrug-resistant enteropathogenic E. coli K1-1, resulting in inhibition zone diameters of 10.93 mm (leaf) and 7.73 mm (twig). Furthermore, the methanol extract contained the highest levels of phenolic, flavonoid, and hydroxyl-rich compounds, which were associated with its antibacterial properties. In silico analysis further revealed that isofucosterol, meliasenin, and melianone exhibited strong predicted binding affinities to key antibacterial proteins, particularly those involved in multidrug-resistant bacterial mechanisms.