Evaluation of Antibacterial, Antifungal, and Anticancer Activities of Essential Oils from Six Species of Eucalyptus

Abstract

:Several Eucalyptus species are traditionally used for a variety of medical purposes. Local communities have used leaves, as well as other parts of the plant for various diseases, including cancer. Recently, a variety of Eucalyptus species have shown potential cytotoxic properties in addition to antimicrobial activities. Considering the lack of available data supporting such reported effects, the goal of this research was to study the in vitro cytotoxic, antibacterial and antifungal activities of the essential oils from six Eucalyptus species, including: Eucalyptus woodwardi, Eucalyptus stricklandii, Eucalyptus salubris, Eucalyptus sargentii, Eucalyptus torquata and Eucalyptus wandoo. The agar diffusion method and the microdiltution test were used to robustly evaluate the antimicrobial activities associated with the different Eucalyptus essential oils against medically important Gram-positive and Gram-negative bacteria. Generally, the examined oils were more effective to eradicate Gram-positive growth than the Gram-negative bacteria. Additionally, essential oil of E. sargentii exhibited significant antifungal activities against Candida albicans and Aspergillus flavus, whereas oil of E. salubris demonstrated moderate activities against both fungi. Regarding the cytotoxic activity, weak to moderate cytotoxicity against non-lymphoma tumor cell lines was demonstrated by the essential oils, whereas potent cytotoxicity was evident against BJAB and Raji lymphoma tumor cell lines. The decrease of cellular DNA content suggests that the observed cytotoxicity is most likely mediated by apoptotic pathways.