Anti-biofilm, anti-hemolysis, and anti-virulence activities of black pepper, cananga, myrrh oils, and nerolidol against Staphylococcus aureus
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The long-term usage of antibiotics has resulted in the evolution of multidrug-resistant bacteria. Unlike antibiotics, anti-virulence approaches target bacterial virulence without affecting cell viability, which may be less prone to develop drug resistance. Staphylococcus aureus is a major human pathogen that produces diverse virulence factors, such as α-toxin, which is hemolytic. Also, biofilm formation of S. aureus is one of the mechanisms of its drug resistance. In this study, anti-biofilm screening of 83 essential oils showed that black pepper, cananga, and myrrh oils and their common constituent cis-nerolidol at 0.01 % markedly inhibited S. aureus biofilm formation. Furthermore, the three essential oils and cis-nerolidol at below 0.005 % almost abolished the hemolytic activity of S. aureus. Transcriptional analyses showed that black pepper oil down-regulated the expressions of the α-toxin gene (hla), the nuclease genes, and the regulatory genes. In addition, black pepper, cananga, and myrrh oils and cis-nerolidol attenuated S. aureus virulence in the nematode Caenorhabditis elegans. This study is one of the most extensive on anti-virulence screening using diverse essential oils and provides comprehensive data on the subject. This finding implies other beneficial effects of essential oils and suggests that black pepper, cananga, and myrrh oils have potential use as anti-virulence strategies against persistent S. aureus infections.
KeywordsAnti-virulence Biofilm Black pepper oil Essential oil Hemolysis Staphylococcus aureus
The 83 essential oils used in this study were kindly provided by Prof. Young-Joon Ahn of Seoul National University. We thank Professor Sang Woo Joo of the World Class University Nano Research Center at Yeungnam University for the use of the scanning confocal laser microscope. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (Grant nos. 2012R1A1A3010534 and 2010-0021871 to J-H. Lee and J. Lee, respectively).
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