Inhibition of Quorum Sensing in Pseudomonas aeruginosa by N -Acyl Cyclopentylamides

Abstract

N -Octanoyl cyclopentylamide (C8-CPA) was found to moderately inhibit quorum sensing in Pseudomonas aeruginosa PAO1. To obtain more powerful inhibitors, a series of structural analogs of C8-CPA were synthesized and examined for their ability to inhibit quorum sensing in P. aeruginosa PAO1. The lasB - lacZ and rhlA - lacZ reporter assays revealed that the chain length and the ring structure were critical for C8-CPA analogs to inhibit quorum sensing. N -Decanoyl cyclopentylamide (C10-CPA) was found to be the strongest inhibitor, and its concentrations required for half-maximal inhibition for lasB - lacZ and rhlA - lacZ expression were 80 and 90 μM, respectively. C10-CPA also inhibited production of virulence factors, including elastase, pyocyanin, and rhamnolipid, and biofilm formation without affecting growth of P. aeruginosa PAO1. C10-CPA inhibited induction of both lasI - lacZ by N -(3-oxododecanoyl)- l -homoserine lactone (PAI1) and rhlA - lacZ by N -butanoyl- l -homoserine lactone (PAI2) in the lasI rhlI mutant of P. aeruginosa PAO1, indicating that C10-CPA interferes with the las and rhl quorum-sensing systems via inhibiting interaction between their response regulators (LasR and RhlR) and autoinducers.