Comprehensive physicochemical, spectroscopic, and biological evaluation of Rosmarinus officinalis essential oil: From GC-MS profiling to ADMET prediction

The essential oil (EO) of Rosmarinus officinalis collected from Ouarzazate, Morocco, showed significant antibacterial, antioxidant and antibiofilm activities. A comprehensive physicochemical characterization identified the major bioactive compounds responsible for these effects. The EO was obtained through hydrodistillation, and the chemical composition of the extracted EO was analysed using gas chromatography-mass spectrometry (GC-MS). Physicochemical characterization included Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) spectroscopy, UV-Vis spectrophotometry, optical rotation (°), refractive index, solubility, and density measurements. The major EO constituents were identified as α-pinene, eucalyptol, and camphor, with physicochemical properties such as an optical rotation of + 6.5°, a refractive index of 1.47, and a density of 0.792. Antioxidant activity, assessed using the DPPH radical scavenging assay, showed 52 % inhibition, while antibacterial tests demonstrated strong inhibitory activity against Gram-positive and Gram-negative bacteria growth, with inhibition zones ranging from 7.33 mm ( P. aeruginosa ) to 20.83 mm ( K. pneumoniae ), while MICs varied from 0.20 µL/ml ( B. clausii ) to 6.45 µL/ml ( Enterococcus spp . and MDR E. coli ). Additionally significant antibiofilm activity was observed with highest against S. aureus (96 % inhibition at MIC) and lowest against E. coli (46 % at MIC/4). Molecular docking and ADMET in silico studies were consistent with previous in vitro findings, revealing favourable binding affinities and pharmacokinetic properties. This study confirms rosemary EO's potential as an effective antioxidant, antibacterial, and antibiofilm agent. Therefore R. officinalis essential oil may serve as a promising natural therapeutic component for use in traditional medicine, aromatherapy, and future pharmaceutical formulations. • Comprehensive physicochemical and bioactivity analysis of rosemary EO. • Essential oil rich in eucalyptol and camphor identified by GC-MS. • Exhibits strong antioxidant and antibacterial activities. • Effectively inhibits bacterial biofilm formation. • Major compounds exhibit high docking affinity toward bacterial proteins, with ADMET profiling confirming favorable pharmacokinetic properties.