pqsr

4-(tert-Butyl)-benzhydroxamic Acid is a PqsR antagonist with IC50s of 12.5 μM and 23.6 μM for E. coli and P. aeruginosa, respectively, and it reduces the production of the virulence factor pyocyanin in P. aeruginosa with an IC50 of 87.2 μM[1].

PqsR-IN-3 (compound 16e) is a selective inhibitor of the pqs system (IC50=3.7 μM) and its associated virulence factor pyocyanin (IC50=2.7 μM). This compound inhibits the synthesis of bacterial biofilms and is significantly cytotoxic to Pseudomonas aeruginosa. Additionally, PqsR-IN-3 exhibits synergistic effects with various antibiotics, such as Ciprofloxacin and Tobramycin.

PqsR/LasR-IN-3 (Compound 7a) inhibits hERG with an IC50 of 109.01 μM and also functions as a PqsR and LasR systems inhibitor in P. aeruginosa [1].

PqsR-IN-1 (Compound 18) is a potent inhibitor of PqsR, a transcriptional regulator in the quorum sensing mechanism of Pseudomonas aeruginosa, that effectively reduces pyocyanin production and exhibits minimal cytotoxicity [1].

PqsR-IN-2 (Compound 19) is a highly potent inhibitor of PqsR, the transcriptional regulator of quorum sensing in Pseudomonas aeruginosa. It efficiently suppresses pyocyanin production without significant cytotoxicity, making it a promising candidate for therapeutic applications [1].

PqsR/LasR-IN-1 (Compound 2a) is a potent inhibitor of LasR and PqsR systems in P. aeruginosa. PqsR/LasR-IN-1 is also a inhibitor of hERG (IC50= 6.77 μM).

HHQ (2-heptylquinolin-4(1H)-one) is a PqsR antagonist.

Quorum sensing-IN-9 (Compound 7d) inhibits quorum sensing in Pseudomonas aeruginosa by binding to the PqsR protein. It suppresses the expression of quorum sensing system-related genes lasB, rhlA, and pqsA, thereby preventing the production of virulence factors elastase, pyocyanin, and rhamnolipid. Quorum sensing-IN-9 disrupts the motility of P. aeruginosa, inhibits biofilm formation, and reduces the bacterium's virulence and pathogenicity. Additionally, it exhibits anti-infective activity in the Galleria mellonella larval model.

Antibacterialagent 176 (Compound 6f) is a potent PqsR antagonist. It effectively inhibits Pseudomonas aeruginosa (P. aeruginosa CF), demonstrating significant suppression of pyocyanin and 2-alkyl-4(1H)-quinolone production.

Antibacterialagent 210 (compound A9) is an amide derivative that acts as a quorum sensing inhibitor (QSI) for Pseudomonas aeruginosa. It functions by binding particularly to PqsR, and also to LasR, thereby inhibiting the quorum sensing system.

RhlR antagonist 1 is a highly effective antagonist of the RhlR protein, showing an IC50 value of 26 μM. It exhibits selective antagonistic activity against RhlR, with minimal effect on LasR and PqsR. RhlR antagonist 1 strongly inhibits biofilm formation in both static and dynamic environments and reduces the production of virulence factors, such as rhamnolipid and pyocyanin, in P. aeruginosa. These characteristics make RhlR antagonist 1 a valuable tool for the development of molecules that modulate quorum sensing and control P. aeruginosa infections [1].

F-17 is a promising virulence factor inhibitor, displaying substantial inhibitory effects on biofilm formation, elastase activity, pyocyanin production, and swarming motility. Additionally, F-17 exhibits a strong binding affinity towards LasR and PqsR. Notably, F-17 does not exhibit any discernible cytotoxicity [1].

QZN34 is a PqsR inhibitor which prevents S. aureus biofilm formation, severely damaged established S. aureus biofilms, and perturbed P. aeruginosa biofilm development. The mechanism of action of QZN 34 toward Gram-positive bacteria is shown to involve membrane perturbation and dissipation of transmembrane potential.