Extraction, identification of chemical compounds and antimicrobial activity of purple basil essential oil on food-born pathogenic bacteria and its comparison with vancomycin and gentamicin antibiotics

The objective of this study was to extract the essential oil of purple basil leaf, to identify its compounds and to investigate its antimicrobial effects on some food-borne pathogenic bacteria through different qualitative and quantitative methods, and eventually, to compare it with some antibiotics including vancomycin and gentamycin in vitro. The essential oil components were identified with GC/MS. The antimicrobial effect of basil essential oil was measured through well diffusion agar (WDA), and finally, the minimum inhibitory concentration (MIC) of the essential oil was determined using microdilution broth and triphenyl tetrazolium chloride. The results revealed that 28 identified compounds constituted 99.28% of the whole essential oil compounds. p-Allylanisole (51.64%) was the most abundant component of the essential oil. In addition, other main components such as n-Tricosane (24.83%) and Linalool (14.81%). In the wall in agar method, the mean free zone diameter was equal to 15.9 mm in the case of Gram-positive bacteria and 11.15 mm in the case of Gram-negative ones. The minimum MIC of purple basil essential oil ranged from 4.6 to 36.8 mg/ml in the case of pathogenic bacteria. Moreover, its minimum bactericidal concentration varied from 4.6 to 73.6. in conclusion, it can be said that purple basil essential oil was effective on Gram-positive bacteria at lower concentrations and could inhibit their growth.