In the present study, the essential oil isolated from the buds of Cleistocalyx operculatus by hydrodistillation
was analyzed by GC and GC/MS. A total of 55 compounds representing 93.71% of the oil were identified.
The oil significantly inhibited the growth of food spoilage (FS), food-borne (FB), skin pathogens
(SP), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococci (VRE) and
multiantibiotic-resistant bacteria (MARB). The minimum inhibitory concentration (MIC) and minimum
bactericidal concentration (MBC) of the oil against the tested microorganisms were found in the range
of 1–20 lL/mL. Whereas the ethanol extract exhibited potential antibacterial activity against the entire
tested Gram positive bacteria and one food spoilage Gram negative bacterium P. aeruginosa. The MIC
and MBC values of ethanol extract against the tested bacteria were found in the range of 0.25–32 mg/
mL. The scanning electron microscopic (SEM) studies demonstrated potential detrimental effect of the
essential oil on the morphology of MRSA-P249 and VRE-B2332 at the used MIC values, along with the
potential effect on cell viabilities of the tested bacteria. Moreover, the total antioxidant capacity and
the scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals of the essential oil and the ethanol
extract were also evaluated