In recent years, compounds with biological properties produced by plants have received attention as an alternative to control microorganisms. Essential oils extracted from green leaves of Eucalyptus sp. have shown antimicrobial activities. However, to date there are no reports of antimicrobial activity of essential oils extracted from dried Eucalyptus staigeriana leaves. The objective of this study was to determine the chemical composition of the essential oils obtained from dried leaves of E. staigeriana and to evaluate in vitro their antimicrobial and antibiotic activity against gram-positive and gram-negative and also resistant and multiresistant Enterococcus faecalis isolated from samples. of food and clinics. The characterization of E. staigeriana was performed by GC-MS. For this study 26 bacterial strains were used, which included 11 reference strains and 15 antibiotic resistant E. faecalis strains. The antimicrobial activity of E. staigeriana against gram positive and gram negative was determined using the disc diffusion method. The minimum inhibitory concentration values were evaluated by the microdilution technique. Antibiofilm effects were evaluated by the microtiter plate method. As a result, 21 compounds were identified, being oxygenated monoterpenes (69.58%) the large chemical family. E. staigeriana showed only antimicrobial activity against gram-positive strains. Resistant and multiresistant E. faecalis strains showed the lowest minimum inhibitory concentration (3.12 to 6.25%) when compared to the reference E. faecalis strain. AND. Staigeriana showed the ability to inhibit biofilm formation, but little or no ability to inhibit preformed biofilm. This study demonstrates that the essential oil obtained from dried E. staigeriana leaves is a promising alternative for important control of resistant gram-positive food and clinical bacteria.
Reference: Correa, M. S., J. Schwambach, M. B. Mann, J. Frazzon and A. P. G. Frazzon (2019). “Antimicrobial and antibiofilm activity of the essential oil from dried leaves of Eucalyptus staigeriana.” Arquivos do Instituto Biológico 86.