Screening for antimicrobial activity of essential oils of Ocimum, Lamiaceae

Abstract

     In order to screen the antimicrobial activity of essential oils of the genus Ocimum, microdilution on liquid medium was performed to determine the minimum inhibitory concentration of bacteria and fungi (MIC, the minimum bactericidal concentration (MBC), and the minimum fungicidal concentration (MFC) of the essential oils of 4 species of lemon basil, basil, clove basil and holy basil. Besides, the main chemical composition of essential oils was determined via gas chromatography-mass spectrometry GC-MS at the Institute of Chemical Technology. The results of the study identified the main chemical compositions of 4 essential oil samples: citral (28.69 %) of lemon basil, estragole (79.18 %) of basil, eugenol (23.49 %) of holy basil and camphor (25.67 %) of clove basil. The essential oils of lemon basil and holy basil have the best inhibitory effect on methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) with MICs of 2.5 µL/mL, and lemon basil essential oil had the best inhibitory effect on Gram-negative bacteria E.coli and P.aeruginosa, both C.albicans and C.tropicalis strains with MICs of 5 µL/mL and 0.625 µL/mL, respectively. At the same time, basil essential oil has good bactericidal properties (MBC ≈ MIC) on C. albicans with MFC of 5 µL/mL, while lemon basil essential oil has good bactericidal properties on E.coli and P. aeruginosa with MBC of 5 µL/mL