Chemical composition and antibacterial properties of eucalyptus camaldulensis dehn essential oil on pathogenic bacteria: exploring the mechanism of action

The uncontrolled use of antibiotics has led to the emergence of multi-resistant bacteria affecting human health. Many solutions have been sought in the hope of developing alternative andeffective molecules, includingmedicinalplants. The aim of the present study is to evaluate the membrane destabilization potential of the essential oil extracted from fresh leaves of Eucalyptus camaldulensis harvested in Benin. For this purpose, the essential oil was extracted by steam stripping. It was separated and identified by gas chromatography coupled to a mass spectrophotometer. This oil was subjected to physicochemical characterisation and sensitivity tests on reference and clinical bacterial strains. Subsequently, the minimum inhibitory concentrations, minimum bactericidal concentrations and antibiotic power were determined. The mode of action of the antibacterial effect of Eucalyptus camaldulensis essential oil was explored using the outer membrane destabilization test of bacterial strains. The average extraction yield was 0.57%, and its major compound was Terpinolene. All strains tested were sensitive to the essential oil except Klebsiella oxytoca NCTC 13442. The inhibition diameters of the essential oil ranged from 7 to 16 mm. The minimum inhibitory concentrations ranged from 3.106 to 12.5 mg/ml. In addition, the essential oil affected the bacterial strains tested by destabilizing their outer membrane. The percentage of outer membrane destabilization of Salmonella typhi and Klebsiella pneumoniae by the essential oil was significantly better than that of Imipenem used as a reference. The present study revealed that the essential oil of Eucalyptus camaldulensis has a remarkable inhibitory activity on Gram negative bacteria with a better percentage of membrane destabilization than the reference molecule. This essential oil is therefore a good alternative to counteract antibiotic resistance.