Screening for novel quorum-sensing inhibitors to interfere with the formation of Pseudomonas aeruginosa biofilm

The objective of this study was to screen for novel quorum-sensing inhibitors (QSIs) from traditional Chinese medicines (TCMs) that inhibit bacterial biofilm formation. Six of 46 active components found in TCMs were identified as putative OS's based on molecular docking studies. Of these, three compounds inhibited biofilm formation by Pseudomonas aeruginosa and Stenotrophomonas maltophilia at a concentration of 200 mu M. A fourth compound (emodin) significantly inhibited biofilm formation at 20 mu M and induced proteolysis of the quorum-sensing signal receptor TraR in Escherichia coli at a concentration of 3-30 mM. Emodin also increased the activity of ampicillin against P. aeruginosa. Therefore, emodin might be suitable for development into an antivirulence and antibacterial agent.