Experimental and molecular docking analyses of antibacterial activity in moroccan Rosmarinus officinalis essential oil

Abstract

Antimicrobial resistance motivates antibacterial agents with multi-target mechanisms. We evaluated Moroccan rosemary essential oil (ROEO) against four pathogens (Escherichia coli, Citrobacter freundii, Staphylococcus aureus, Enterococcus faecalis) by disk diffusion and broth microdilution. ROEO inhibited all strains (zones 11.3-21.0 mm); activity was bactericidal for E. faecalis (MBC/MIC = 2.0) and bacteriostatic for others (MBC/MIC > 4). Bioassay-guided silica chromatography, using E. faecalis as the pre-specified indicator, localised activity to a polar fraction (F8; 18.5% of the oil; 14.0 ± 1.71 mm). GC-MS showed F8 was enriched in oxygenated monoterpenes (97.45%): myrtenol, verbenone, p-cymen-8-ol, γ-terpinen-7-al, carvone, β-thujone. Docking (AutoDock Vina) predicted binding of major constituents to essential enzymes (tyrosyl-tRNA synthetase, L-methionine γ-lyase, DNA gyrase B, and NAD⁺-dependent DNA ligase); native-ligand redocking reproduced crystallographic poses (RMSD ≤ 2.0 Å). In silico ADMET supported drug-like properties with high intestinal absorption and class-typical CNS-penetration and skin-sensitisation alerts. ROEO's antibacterial profile is underpinned by an oxygenated-monoterpene fraction and yields testable hypotheses for enzyme validation, synergy studies, and in vivo efficacy and safety.