A novel phenolic derivative inhibits AHL-dependent quorum sensing signaling in Pseudomonas aeruginosa

Abstract

Increasing antibiotic resistance and the decline in the pharmaceutical industry’s investments have amplified the need for novel treatments for multidrug-resistant bacteria. Quorum sensing (QS) inhibitors reduce pathogens’ virulence without selective pressure on bacteria and provide an alternative to conventional antibiotic-based therapies. P. aeruginosa uses complex QS signaling to control virulence and biofilm formation. We aimed to identify inhibitors of P. aeruginosa QS acting on acyl-homoserine lactones (AHL)-mediated circuits. Bioluminescence and qRT-PCR assays were employed to screen a library of 81 small phenolic derivatives to reduce AHL-dependent signaling. We identified GM-50 as the most active compound inhibiting the expression of AHL-regulated genes but devoid of cytotoxic activity in human epithelial cells and biocidal effects on bacteria. GM-50 reduces virulence factors such as rhamnolipids, pyocyanin, elastase secretion, and swarming motility in P. aeruginosa PAO1 laboratory strain. By molecular docking, we provide evidence that GM-50 highly interacts with RhlR. GM-50 significantly improved aztreonam-mediated biofilm disruption. Moreover, GM-50 prevents adhesion of PAO1 and inflammatory damage in the human A549 cell line and protects Galleria mellonella from PAO1-mediated killing. GM-50 significantly reduces virulence factors in 20 P. aeruginosa clinical isolates from patients with respiratory tract infections. In conclusion, GM-50 inhibits AHL-signaling, reduces virulence factors, enhances the anti-biofilm activity of aztreonam, and protects G. mellonella larvae from damage induced by P. aeruginosa. Since GM-50 is active on clinical strains, it represents a starting point for identifying and developing new phenolic derivatives acting as QS-inhibitors in P. aeruginosa infections.

MALDI Mass Spectrometry Imaging Reveals the Existence of an N-Acyl-homoserine Lactone Quorum Sensing System in Pseudomonas putida Biofilms

“…These AHLs bind to the transcriptional activators LasR and RhlR and activate target promoters. Both las and rhl have been implicated in the regulation of quinolone-like signaling molecule production in a group of Pseudomonas [29,30]. As C4-HSL and 3-oxo-C12-HSL are quinolone precursors, they could not be detected when quinolones were highly homogenously produced throughout the P. putida biofilm.…”

Glycol Chitosan-Poly(lactic acid) Conjugate Nanoparticles Encapsulating Ciprofloxacin: A Mucoadhesive, Antiquorum-Sensing, and Biofilm-Disrupting Treatment Modality for Bacterial Keratitis

“…The final reaction mixture for RT PCR constitutes 10 μM of forward and reverse primer (1:1, 2 μL), RNase-free water (0.8 μL), and SYBER green (10 μL). The sequence of primers was referred from the reported literature , and listed in Table S4. The RT-PCR was performed as follows: one cycle at 95 °C for 30 s for initial denaturation, followed by 40 cycles, each cycle consisting of denaturation programmed at 95 °C for 30 s followed by annealing and extension at 60 °C for 30 s. The experiments were performed in triplicates.…”

Evaluation of novel compounds as anti-bacterial or anti-virulence agents

“…Findings within this study revealed that most novel compounds were effective anti-bacterial agents, some compounds were potent inhibitors of biofilm formation, whereas compound UA3 has shared significant anti-quorum sensing potential against Chromobacterium pseudoviolaceum ( Rafiq et al., 2022 ). In the study performed by Bernabè et al. (2022) in house library of phenolic derivatives (81 compounds) were tested for anti-QS activity.…”