Activities and mechanisms of eugenol and cinnamaldehyde against Legionella pneumophila

作者：Ma, Jiangwei; Jiang, Luxi; Chen, Yu^*; Kang, Jian^*

来源：International Journal of Clinical and Experimental Medicine, 2017, 10(12): 16460-16467.

• Eugenol
• cinnamaldehyde
• legionella pneumophila
• antimicrobial activity
• antibacterial mechanism

Background: Legionella pneumophila (L. pneumophila) is a primary human pathogenic gram-negative bacterium and is the causative agent of legionellosis, with an associated death rate of 5-10%. Eugenol and cinnamaldehyde were found to demonstrate antimicrobial properties, and are derived from aromatic plant-derived essential oils. Objectives: The aim of this study was to investigate the antibacterial activities and mechanisms of eugenol and cinnamaldehyde against L. pneumophila. Methods: Antibacterial activity was determined by broth microdilution method, and a time-kill curve plotted. The mechanism of antibacterial action was assessed by the measurement of release of 260 nm-absorbing material, SDS-PAGE and silver staining, and transmission electron microscopy (TEM). Results: The minimum inhibitory concentration (MIC) of eugenol to L. pneumophila was equal to its minimum bactericidal concentration (MBC) with a concentration of 0.0125% (v/v) or 133 mu g mL(-1) (w/v), whereas the MIC of cinnamaldehyde against L. pneumophila was 15-31 mu g mL(-1) and its MBC was 31-62 mu g mL(-1). Eugenol completely inactivated L. pneumophila (6 x 10(5) CFU mL(-1)) at a concentration of >= 8xMIC in 0.5 h. Cinnamaldehyde was demonstrated to have similar activity at a concentration of >= 32xMIC in 1.5 h. Eugenol kills L. pneumophila by the disruptive action on the bacterial cell envelope, while cinnamaldehyde has no effect on bacterial membrane. Conclusions: Our study showed that both eugenol and cinnamaldehyde can inhibit the growth of L. pneumophila, which provides the potential for preventing and treating L. pneumophila contamination and infection.

• 出版日期2017
• 单位中国医科大学