In vivo efficacy of pyochelin-mediated delivery of zingerone in Pseudomonas aeruginosa-induced peritonitis.

Aim: The efficacy of a pyochelin-zingerone conjugate (PZC) against Pseudomonas aeruginosa in vivo in a mouse model of peritonitis, as well as mode of action in vitro, were investigated. Methods & results: Intraperitoneal administration of PZC (220 mg kg-1 b.wt.) resulted in a significant reduction in bacterial count in liver tissue by 2 log10 on the 4th day post infection. This was supported by reduced levels of inflammatory markers, liver function, inflammatory cytokines and improved histopathology. PZC showed its ability to disrupt the cellular membrane, increase permeability of the membrane and leakage of intracellular contents of P. aeruginosa, resulting in its death. Conclusion: The present study reports the hepatoprotective potential of PZC in an experimental model of P. aeruginosa-induced peritonitis.

Novel Vanillin-based hybrids inhibit quorum sensing and silences phenotypical expressions in Pseudomonas aeruginosa.

In this study, we report the chemical synthesis, computational analysis, and anti-virulent studies of five Vanillin-based hybrids employing phytochemicals. Vanillin (V) is known to have substantial anti-quorum sensing activity against the gram-negative pathogen Pseudomonas aeruginosa. Therefore, with the aim to further enhance the potency of Vanillin, it was chemically conjugated via a triazole (T) linker with five phytochemicals- Zingerone (Z), Eugenol (E), Guaiacol (G), Cinnamaldehyde (C), and Ferulic acid (F) to form the hybrids named as VTZ (1), VTE (2), VTG (3), VTC (4), and VTF (5), respectively. Molecular docking studies revealed the strong binding affinity of the designed hybrids with quorum-sensing receptors (LasR, Rh1R, and PqsR). The synthesized hybrids were also evaluated for anti-quorum sensing activities to examine the efficacy against P. aeruginosa bacterial strains PAO1. The hybrids VTE (2), VTG (3), and VTC (4) displayed improved anti-quorum activity relative to Vanillin. Furthermore, the attenuation of virulence factors of P. aeruginosa (Las-A protease, Las-B elastase, pyocyanin pigmentation, and motility) in the presence of VTE (2), VTG (3), and VTC (4) further authenticated the anti-virulent activity of the hybrids. The new design strategy of the phytochemical-phytochemical scaffolds and their biological evaluation provides a proof of concept for the simultaneous perturbation of well-established anti-virulent targets. This appears to be highly promising and effective strategy to ameliorate the enigma of antimicrobial resistance.

Guaiacol augments quorum quenching potential of ciprofloxacin against Pseudomonas aeruginosa.

AIM: The present study aims to investigate the antimicrobial as well as antivirulence potential and the principle mechanism of action of guaiacol against Pseudomonas aeruginosa. METHODS AND RESULTS: Quorum sensing inhibition and membrane disruption studies were performed to check the effect of guaiacol on the virulence of P. aeruginosa. Production of various virulence factors and biofilm formation was studied at a sub-MIC concentration of guaiacol alone (1/8 MIC) and in combination with ciprofloxacin (1/2 FIC). Guaiacol exhibited synergistic interactions with ciprofloxacin and further reduced the production of all virulence factors and biofilm formation. Using crystal violet (CV) assay and quantification of exopolysaccharide, we observed weak biofilm formation, together with reduced motilities at sub-MIC, which was further visualized by confocal laser microscopy and Field Emission Scanning Electron Microscopy. The antibacterial activity of guaiacol against P. aeruginosa upon 2 × MIC exposure coincided with enhanced membrane permeability leading to disruption and release of cellular material as quantified by CV uptake assay and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The results demonstrated that sub-MICs of guaiacol in combination with ciprofloxacin can act as a potent alternate compound for attenuation of quorum sensing in P. aeruginosa. CONCLUSION: The study reports that guaiacol in combination with ciprofloxacin at 1/2 FIC significantly compromised the bacterial growth and motilities alongside inducing quorum quenching potential. This was accompanied by inhibition of biofilm which subsequently decreased EPS production at sub-MIC concentration. Furthermore, guaiacol in combination displayed a severe detrimental effect on bacterial membrane disruption, thereby enhancing cellular material release. NOVELTY IMPACT STATEMENT: For the first time, the potential of guaiacol in combination with ciprofloxacin in attenuation of virulence factors, and biofilm formation in Pseudomonas aeruginosa was described. Results corroborate how plant bioactive in synergism with antibiotics can act as an alternate treatment regime to tackle the menace of drug resistance.

Design, Synthesis, and Quorum Quenching Potential of Novel Catechol-Zingerone Conjugate to Find an Elixir to Tackle Pseudomonas aeruginosa Through the Trojan Horse Strategy.

To address the issue of multidrug resistance in Pseudomonas aeruginosa, a novel catechol-zingerone conjugate (1) linked via a non-hydrolyzable 1,2,3-triazole linker was synthesized and subjected to biological evaluation based on the Trojan horse strategy. To enhance the efficacy, catechol, a xenosiderophore, utilized by P. aeruginosa for iron assimilation, and the dietary phytochemical zingerone, known for its anti-virulent activity against Pseudomonas aeruginosa, were exploited in the present study. Theoretical validation of conjugate (1) was conducted by in silico molecular docking analysis to determine the interaction with outer membrane transport receptor PirA and quorum sensing signal receptors. In addition, nine-fold binding affinity of Conjugate (1) toward PirA (5FP2) in comparison to its natural ligand catechol with D-score -1.13 Å authenticated the designed Trojan horse drug. Conjugate (1) showed stronger anti-virulent activity than zingerone; hence, it exhibited a promising anti-biofilm efficacy as assessed by crystal violet assay and visualized by FESEM toward P. aeruginosa. Encouraging results against P. aeruginosa in terms of quorum sensing regulated virulence factors, motility phenotypes, and biofilm formation with no cell cytotoxicity and could help open hitherto unexplored possibilities of establishing Trojan horse drugs as a successful approach against multidrug resistance in P. aeruginosa.

Natural bioactives versus synthetic antibiotics for the attenuation of quorum sensing-regulated virulence factors of Pseudomonas aeruginosa.

Aim: To study the influence of plant volatiles, bioactives and synthetic antibiotics on the attenuation of the quorum sensing (QS)-regulated virulence factors of Pseudomonas aeruginosa. Materials & methods: QS inhibition; the QS-regulated virulence factors pyocyanin, hemolysin, elastase, protease, alginate and pyochelin; and motility phenotypes were performed at sub-MIC to check the attenuation effect of 24 agents on the virulence of P. aeruginosa. Results: Eighteen out of 24 assayed compounds exhibited anti-QS activity and reduced the production of all virulence factors. Cinnamaldehyde, zingerone and lavender oil exhibited a significant reduction in motility phenotypes. Conclusion: Natural phytomolecules as a whole or their bioactives could be used to develop antivirulence drugs after in vivo evaluation.