Anti-Quorum Sensing Activity of 12 Essential Oils on chromobacterium violaceum and Specific Action of cis-cis-p-Menthenolide from Corsican Mentha suaveolens ssp. Insularis.

Jean-Pierre Poli,Liliane Berti,Yann Quilichini,Sylvain Sutour,Elodie Guinoiseau,Mathieu Paoli,Félix Tomi,Vannina Lorenzi,Dominique De Rocca Serra

doi:10.3390/molecules23092125

Abstract

Quorum sensing (QS) is a bacterial communication mechanism used to express various survival or virulence traits leading to enhanced resistance. Chromobacterium violaceum is a commonly used strain that highlights anti-QS action of bioactive substances. Here, we wanted to see if 12 selected essential oils (EO) could exert anti-QS activity. We measured the sublethal minimal QS inhibitory concentration (MQSIC) by assessing violacein production of C. violaceum along with bacterial growth. To confirm the QS disruption, we also proceed to surface bacterial observations using scanning electron microscopy (SEM). We showed that cis-cis-p-menthenolide extracted and isolated from a plant endemic to occidental Mediterranean Sea islands, Mentha suaveolens ssp. insularis, acts as an inhibitor of violacein production and biofilm formation. Measured MQSIC was much lower than the minimal inhibitory concentration (MIC): 0.10 mg·mL−1 vs. 3.00 mg·mL−1. Moreover, disturbance of QS-related traits was confirmed by the degradation of C. violaceum biofilm matrix. There is a clear structure–activity relationship between cis-cis-p-menthenolide and anti-QS activity. Indeed, its isomer molecule (mintlactone) exerts a poor anti-QS action. These results indicate that inhibition of violacein production and biofilm formation by cis-cis-p-menthenolide might be related to a disruption in the QS mechanism.

Highlights

Nowadays, bacterial resistance to antibiotics is a major public health issue
quorum sensing (QS) is a bacterial cell-to-cell communication pathway. This specific signal-response system relies on the synthesis, release, and uptake of specific molecules known as autoinducers [1]
Twelve essential oils (EO) were tested for their anti-QS activity on C. violaceum

Summary

Introduction

Bacterial resistance to antibiotics is a major public health issue. Development of new antibiotics with new modes of action is very limited. One potential strategy to override this problem is to restore antibiotic activity. Inhibition of quorum sensing (QS) may be a suitable solution. QS is a bacterial cell-to-cell communication pathway. This specific signal-response system relies on the synthesis, release, and uptake of specific molecules known as autoinducers [1]. When a specific concentration is reached in the outer medium, which is correlated to population concentration, autoinducers are the starting point to trigger and synchronize QS-related behaviors or traits expression

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