title: Sub-MICs of Mentha piperita essential oil and menthol inhibits AHL mediated quorum sensing and biofilm of Gram-negative bacteria.
abstract: Bacterial quorum sensing (QS) is a density dependent communication system that regulates the expression of certain genes including production of virulence factors in many pathogens. Bioactive plant extract/compounds inhibiting QS regulated gene expression may be a potential candidate as antipathogenic drug. In this study anti-QS activity of peppermint (Mentha piperita) oil was first tested using the Chromobacterium violaceum CVO26 biosensor. Further, the findings of the present investigation revealed that peppermint oil (PMO) at sub-Minimum Inhibitory Concentrations (sub-MICs) strongly interfered with acyl homoserine lactone (AHL) regulated virulence factors and biofilm formation in Pseudomonas aeruginosa and Aeromonas hydrophila. The result of molecular docking analysis attributed the QS inhibitory activity exhibited by PMO to menthol. Assessment of ability of menthol to interfere with QS systems of various Gram-negative pathogens comprising diverse AHL molecules revealed that it reduced the AHL dependent production of violacein, virulence factors, and biofilm formation indicating broad-spectrum anti-QS activity. Using two Escherichia coli biosensors, MG4/pKDT17 and pEAL08-2, we also confirmed that menthol inhibited both the las and pqs QS systems. Further, findings of the in vivo studies with menthol on nematode model Caenorhabditis elegans showed significantly enhanced survival of the nematode. Our data identified menthol as a novel broad spectrum QS inhibitor.
authors.affiliation: Department of Agricultural Microbiology, Aligarh Muslim University Aligarh, India ; Department of Food Science and Nutrition, College of Food and Agricultural Sciences, King Saud University Riyadh, Saudi Arabia.
authors.forename: Fohad M
authors.initials: FM
authors.lastname: Husain
authors.affiliation: Department of Agricultural Microbiology, Aligarh Muslim University Aligarh, India.
authors.forename: Iqbal
authors.initials: I
authors.lastname: Ahmad
authors.affiliation: Department of Agricultural Microbiology, Aligarh Muslim University Aligarh, India.
authors.forename: Mohammad S
authors.initials: MS
authors.lastname: Khan
authors.affiliation: School of Pharmaceutical Sciences, Sao Paulo State University Araraquara, Brazil.
authors.forename: Ejaz
authors.initials: E
authors.lastname: Ahmad
authors.affiliation: Department of Zoology, Aligarh Muslim University Aligarh, India.
authors.forename: Qudisa
authors.initials: Q
authors.lastname: Tahseen
authors.affiliation: Department of Biochemistry, Protein Research Chair, College of Science, King Saud University Riyadh, Saudi Arabia.
authors.forename: Mohd Shahnawaz
authors.initials: MS
authors.lastname: Khan
authors.affiliation: Department of Food Science and Nutrition, College of Food and Agricultural Sciences, King Saud University Riyadh, Saudi Arabia.
authors.forename: Nasser A
authors.initials: NA
authors.lastname: Alshabib
keywords: C. elegans; anti-quorum sensing activity; biofilm; menthol; molecular docking; peppermint oil