Baicalein attenuates the quorum sensing-controlled virulence factors of Pseudomonas aeruginosa and relieves the inflammatory response in P. aeruginosa-infected macrophages by downregulating the MAPK and NFκB signal-transduction pathways

Abstract

Burgeoning antibiotic resistance and unfavorable outcomes of inflammatory injury after Pseudomonas aeruginosa infection have necessitated the development of novel agents that not only target quorum sensing (QS) but also combat inflammatory injury with the least risk of resistance. This study aimed to assess the anti-QS and anti-inflammatory activities of baicalein, a traditional herbal medicine that is widely used in the People’s Republic of China, against P. aeruginosa infection. We found that subminimum inhibitory concentrations of baicalein efficiently interfered with the QS-signaling pathway of P. aeruginosa via downregulation of the transcription of QS-regulated genes and the translation of QS-signaling molecules. This interference resulted in the global attenuation of QS-controlled virulence factors, such as motility and biofilm formation, and the secretion into the culture supernatant of extracellular virulence factors, including pyocyanin, LasA protease, LasB elastase, and rhamnolipids. Moreover, we examined the anti-inflammatory activity of baicalein and its mode of action via a P. aeruginosa-infected macrophage model to address its therapeutic effect. Baicalein reduced the P. aeruginosa-induced secretion of the inflammatory cytokines IL-1β, IL-6, IL-8, and TNFα. In addition, baicalein suppressed P. aeruginosa-induced activation of the MAPK and NFκB signal-transduction pathways in cocultured macrophages; this may be the mechanism by which baicalein inhibits the production of proinflammatory cytokines. Therefore, our study demonstrates that baicalein represents a potential treatment for P. aeruginosa infection because it clearly exhibits both antibacterial and anti-inflammatory activities.

Chitosan nanoencapsulation of flavonoids enhances their quorum sensing and biofilm formation inhibitory activities against an E.coli Top 10 biosensor

“…Figure 2 ii-b) [7,56]. Overall, our findings concur with previous studies that have documented that these phytochemicals can inhibit biofilm formation [19,37]. For instance, baicalein has been reported to inhibit P. aeruginosa PA01 biofilm formation at concentrations of 32-128 µg/mL [37], while quercetin at concentrations of 16 µg/mL produced the highest inhibitory antibiofilm formation effect against PA01 among the concentrations used -8, 16, 32 and 64 µg/mL [19].…”

“…In fact, at higher concentration it was observed that both free flavonoids seem to be toxic towards the E. coli Top 10 biosensor. Both phytochemicals had been reported to inhibit quorum sensing-dependent processes in a P. aeruginosa PA01 strain, but this is only achieved at higher concentrations too [19,37]. However, in their encapsulated forms, our results demonstrate that their QS inhibition ability improves when tested in our E. coli Top 10 biosensor.…”

A medicinal herbCassia alataattenuates quorum sensing inChromobacterium violaceumandPseudomonas aeruginosa

“…Molecules with QS inhibitory activity are of special interest against P. aeruginosa due to the burgeoning antibiotic resistance and unfavourable outcomes of inflammatory injury after the infection (Luo et al . ).…”

“…3d). Biofilm has clinical significance as it plays a key role in the ability of organisms to resist antibiotics and persist in long-term infections such as cystic fibrosis and indwelling medical devices (Singh et al 2000;Donlan 2001;Popat et al 2012 special interest against P. aeruginosa due to the burgeoning antibiotic resistance and unfavourable outcomes of inflammatory injury after the infection (Luo et al 2016).…”

Evaluation of Natural and Botanical Medicines for Activity against Growing and Non-growing Forms ofB. burgdorferi

“…This current study adds to the research on the anti- Borrelia activity of Scutellaria baicalensis . This botanical and/or baicalein have also been shown to have antimicrobial activity (133, 134), synergistic effects with antibiotics (135–139) and reduce biofilm formation in Pseudomonas aeruginosa models (140, 141).…”