Mechanism of action and bioactivities of Cinnamomum zeylanicum essential oil against some pathogenic microbes

Abstract

Background and objective The emergence of multiple drug-resistant pathogenic microorganisms leads to the search for new, safe, and effective therapeutic substances. Essential oils (EOs) of the cinnamon species are known for their biological antimicrobial and antioxidant properties. Therefore, in our study, the EO extracted from the bark of wild Cinnamomum zeylanicum grown in the green mountains of Oman was investigated to study both the aspects. Materials and methods Chemical composition of the EO was analyzed by gas chromatography–mass spectrometry, and then its antimicrobial potential was tested against different Gram-positive, Gram-negative bacteria and fungi. The minimum inhibitory concentration (MIC) was detected and a further in-depth study on the antimicrobial mode of action of the EO at the MIC concentration was studied, in addition to the determination of the antioxidant potential of the studied EO. Results and conclusion Thirty compounds were identified, and the major constituents were cinnamaldehyde (81.78%), bornyl acetate (5.33%), and cinnamyl acetate (2.82%). The antimicrobial results showed a highly significant activity against all tested microbes. The MIC of our EO ranged from 3.3 μl/ml for Gram-positive bacteria and fungi to 10 μl/ml for Gram-negative ones. The mode of action of EO at MIC concentration showed that it had a strong effect on cell viability, permeability of cell membrane, and leakage of cell constituents such as DNA, RNA, and protein from the cell membrane to outside with the lethal percent reaching 99.99%. Moreover, it was observed that the bactericidal and fungicidal effects act in a dose- and time-dependent manner and they depend on the culture condition. Finally, the EO had a strong antioxidant effect with IC50 equaling 2.3 mg. Cinnamon essential oil has a great potential as a useful agent help in combating resistant microorganisms coupled with healing of wounds according to its antioxidant activity.