Chemical Composition and Antibacterial Activity of Essential Oil Extracted from Pinus halepensis Mill. Growing in the Green Mountain Region of Libya

Abstract

Plant-based natural products remain a vital reservoir of bioactive molecules. Among these, Pinus halepensis Mill. is recognized as an essential-oil-rich species exhibiting antimicrobial potential. This study aimed to obtain essential oil from P. halepensis from the Green Mountain area of Libya, characterize its chemical profile by GC-MS, and assess its antibacterial potency against bacterial isolates from a hospital in Benghazi. A cost-effective solvent extraction technique employing n-hexane at a controlled low temperature was used to obtain the oil. Chemical profiling was carried out on an Agilent 7890A GC interfaced with an Agilent 5975C MSD. Antibacterial potential was assessed through the disc diffusion assay against Staphylococcus aureus, Proteus mirabilis, Escherichia coli, and Pseudomonas aeruginosa. The obtained oil displayed pronounced antibacterial effects, particularly toward S. aureus, P. mirabilis, and E. coli. GC-MS profiling enabled the identification of 28 constituents, with α-Pinene (24.35%), β-Pinene (18.72%), and β-Caryophyllene (15.83%) being the most abundant. Inhibition zones enlarged proportionally with increasing oil concentration (a statistically significant dose-response pattern, p < 0.05), reaching maximum values at 30% concentration (35.00 ± 1.73 mm against S. aureus, 30.00 ± 1.00 mm against P. mirabilis, 29.00 ± 1.00 mm against E. coli, and 25.00 ± 1.73 mm against P. aeruginosa). The essential oil derived from Libyan P. halepensis represents a promising reservoir of antibacterial constituents and merits further investigation to establish its clinical usefulness.