Chemical characterization and mode of action of Ligustrum lucidum flower essential oil against food-borne pathogenic bacteria

Current research analyzes the chemical composition of Ligustrum lucidum flower essential oil obtained by the hydrodistillation, and examines its antimicrobial mode of action against food-borne pathogenic bacteria. Gas chromatography-mass spectrometry analysis of the oil resulted in the determination of 44 different compounds, representing 85.2% of the total oil. The oil (1 mg/disc) showed significant antibacterial effect as diameters of inhibition zones (14.6 +/- 0.2 - 19.7 +/- 0.3 mm), as well as minimum inhibitory and minimum bactericidal concentrations values (250-1000 and 250-2000 mu g/mL), respectively. Based on the susceptibility, L. lucidum flower oil revealed its mode of action on membrane integrity as confirmed by increased release of extra-cellular ATP (2.5 and 2.2 pg/mL), leakage of potassium ions (950 and 900 mM/L), loss of 260-nm absorbing materials (4.2 and 3.9 optical density), and increase in relative electrical conductivity (10.6 and 9.8%) against Staphylococcus aureus KCTC-1621 (Gram-positive) and Salmonella enterica ATCC-4731 (Gram-negative), respectively.