Anti-quorum sensing activity of Syzygium jambos (L.) Alston against Pseudomonas aeruginosa PAO1 and identification of its bioactive components

The multidrug-resistant opportunistic pathogen, Pseudomonas aeruginosa is recognized to causes severe chronic infection in immune-compromised individuals. The production of numerous virulence factors and biofilm formation in P. aeruginosa is regulated by cell-to-cell communication system known as Quorum sensing (QS). The anti-QS property of the ethanolic leaf extract of Syzygium jambos in inhibiting the QS-regulated virulence traits was studied. At sub-MIC concentration, the test extract strongly attenuated the QS signaling circuit of P. aeruginosa resulting in significant decrease in the production of virulence determinants and biofilm formation. The ethanolic leaf extract was fractionated and separated using HPLC based activity profiling. The bioactive components contributing to the anti-QS efficacy of S. jambos were identified. Molecular docking of the active compounds revealed relatively strong binding affinity of the phytoconstituents for the transcriptional activators of the QS circuit in P. aeruginosa, i.e., LasR and RhlR, as compared to the natural ligands, 3-oxo-C12-HSL and C4-HSL. The findings indicated the potential of S. jambos and its bioactive components as QS antagonist in the treatment of chronic infections caused by P. aeruginosa.