Inhibition of quorum sensing in Pseudomonas aeruginosa by sesquiterpene lactones

Six sesquiterpene lactones (SLs) of the goyazensolide and isogoyazensolide-type isolated from the Argentine herb Centratherum punctatum were evaluated on their ability to inhibit virulence factors of Pseudomonas aeruginosa ATCC 27853. Although compounds were not able to completely inhibit bacterial growth at 200μg/ml, the SLs do altered biofilm formation, elastase activity, and production of N-acyl-homoserinelactones (AHLs) which are known quorum sensing autoinducers at lower concentration. Compounds 2, 3, and 5 displayed significant inhibitory effects on P. aeruginosa biofilm formation at 0.5μg/ml being compound 3 (1.32μM) the most potent (42%). Compounds 2, 3, 4, 5 and 6, inhibited 39, 44, 42, 32 and 35% the production of AHLs at 100μg/ml and inhibited by more than 50% the elastase activity at 0.5μg/ml. Our results clearly indicated that sesquiterpene lactones are good candidates for the development of new antimicrobial agents acting not as bactericidal but as antipathogenic agents.