In vitro screening for natural quorum sensing inhibitor molecules

Increasing antimicrobial resistance in pathogenic bacteria has created the need for the development of novel therapeutic agents. Having a role in various mechanisms of gene regulation such as biofilm formation and production of virulence factors; quorum sensing (QS), cell-density dependent bacterial intercellular signaling mechanism, has become a target for developing next generation antimicrobials. Recent studies have shown that disrupting the communication between bacteria reduces their pathogenicity and, therefore, attenuate the possible infections. Both Gram negative and positive bacteria use this mechanism to regulate such physiological processes. Among all of them, Pseudomonas aeruginosa, being an opportunistic human pathogen, attracted the greatest focus on QS system investigations.In this study, we aimed to screen some natural compounds (rose absolute, rose oil, clove oil, cinnamon oil and pine turpentine) for their inhibitory effects on Pseudomonas aeruginosa QS system. Therefore, we initially detected these molecules whether they have QS inhibition activity or not. The results showed that all of these compounds were potential QS inhibitors. To test them further, the molecules were probed with a QS reporter system that allow gathering a dose-response relationship. According to our data; rose absolute was found to be the most effective compound on the inhibition of QS. This is the first study demonstrated that rose absolute has inhibitory effects on QS and it can be potential candidate to be used as a therapeutic agent to fight with bacterial infections in the future.