Investigating the in vitro antimicrobial potential and comprehensive computational studies of new Schiff base derivatives

• HSB-5 identified as multi-target antimicrobial lead via integrated in silico screening. • Combined MD, docking, DFT & ADMET validate Schiff base interactions • Stable target binding (LasR, CYP51, and DHFR) confirmed by 100-ns MD simulations. • DFT reveals HSB-5′s optimal HOMO-LUMO gap (3.74 eV) for reactivity. • ADMET flags Ames+ and hepatotoxicity, guiding lead optimization. Antimicrobial resistance (AMR) is growing global health threat driven by multidrug-resistant bacteria ( Staphylococcus aureus, Pseudomonas aeruginosa ), and fungi ( Candida albicans , and C. parapsilosis ). This study evaluated six novel Schiff base derivatives ( HSB-1 to HSB-6 ) through integrated in-vitro antimicrobial activity and comprehensive computational studies. In-vitro disk diffusion assay demonstrated the largest zones of inhibition against S. aureus for HSB-6 and HSB-1 (15–17 mm), activity against P. aeruginosa for HSB-5 and HSB-6 (12 mm), and moderate antifungal activity for HSB-4 (8–11 mm). Molecular docking results correlated with the in-vitro findings with the binding energy ΔG = −12.3 kcal/mol for HSB-5 against LasR ( P. aeruginosa ), showing key interactions involving hydrogen bonding and hydrophobic contacts. Molecular dynamics (MD) simulations of 100 ns validated protein-ligand complex stability (low RMSD, compact R g , and persistent hydrogen bonds). DFT calculations at the B3LYP/6-311G (d, p) level revealed electronic properties consistency with the reactivity: HSB-5 highlighted an intermediate HOMO-LUMO gap (ΔE = 3.74 eV) while HSB-6 and HSB-1 displayed lower gaps (3.09 and 3.12 eV, respectively); NBO and Fukui analyses identified electrophilic nitro/imine groups and nucleophilic π-carbons as likely interaction sites. ADMET profiling indicated drug-likeness for most compounds: high GI absorption for five derivatives, LogP 2.4–4.5; predicted BBB permeability for HSB-2 to HSB–4 , CYP inhibition profiles consistent with metabolic stability, and LogS −3.4 to −5.9. Safety flags include Ames positivity for HSB-4 to HSB-6 and predicted hepatotoxicity for HSB-1 . Overall, HSB-5 emerges as a balanced lead combining in-vitro efficacy and favorable computational profiles which supports its further prioritization for further optimization against anti-microbial resistance. Diagrammatic illustration of the synthesis of Schiff bases, their antimicrobial activity, and computational evaluation via molecular docking, MD simulations, ADMET, and DFT analysis