Mosloflavone attenuates the quorum sensing controlled virulence phenotypes and biofilm formation in Pseudomonas aeruginosa PAO1: In vitro, in vivo and in silico approach.

Quorum sensing (QS) is the cell density dependent communication network which coordinates the production of pathogenic determinants in majority of pathogenic bacteria. Pseudomonas aeruginosa causes hospital-acquired infections by virtue of its well-defined QS network. As the QS regulatory network in P. aeruginosa regulates the virulence determinants and antibiotic resistance, attenuating the QS system seems to be influential in developing next-generation anti-infective agents. In the current study, the QS attenuation potential of a flavonoid, mosloflavone was investigated against P. aeruginosa virulence and biofilm formation. Mosloflavone inhibited the pyocyanin production, LasB elastase and chitinase by 59.52 ±â€¯2.74, 35.90 ±â€¯4.34 and 61.18 ±â€¯5.52% respectively. The QS regulated biofilm formation and development was also reduced when supplemented with sub-MIC of mosloflavone. The gene expression studies of mosloflavone using RT-PCR depicted its ability to down-regulate the expression levels of QS regulated virulence genes such as lasI (60.64%), lasR (91.70%), rhlI (57.30%), chiC (90.20%), rhlA (47.87%), rhlR (21.55%), lasB (37.80%), phzM (42.40%), toxA (61.00%), aprA (58.4%), exoS (78.01%), algD (46.60%) and pelA (50.45%). The down-regulation of QS virulence phenotypes by mosloflavone could be attributed to its binding affinity with the QS regulatory proteins, LasR and RhlR by competitively inhibiting the binding of natural autoinducers as evidenced from simulation studies. Mosloflavone also exhibited promising potential in controlling bacterial infection in Caenorhabditis elegans model system, in vivo. The anti-biofilm and anti-QS potential of mosloflavone in the current study illustrated the candidature of mosloflavone as a promising biocide.

Antioxidant, anti-quorum sensing and anti-biofilm potential of ethanolic leaf extract of Phrynium capitatum and Dryptes indica

Objective: To investigate the antioxidant and anti-infective potential of Phrynium capitatum and Dryptes indica extract. Methods: The antioxidant potentials were determined by DPPH radical scavenging, reducing power, hydroxyl radical scavenging and total antioxidant assays. We further examined anti-quorum sensing activity and inhibition of synthesis of pathogenic factor of Chromobacterium violaceum and Pseudomonas aeruginosa PAO1. Bioactive compounds were determined using gas chromatography–mass spectrometry analysis. In silico analysis was conducted to determine the binding affinity of bioactive compounds of plant extracts for the quorum sensing regulatory receptor LasR. Results: DPPH assay showed that the ethanolic extract of Phrynium capitatum and Dryptes indica at 500 μg/mL showed (86.96 ± 4.07)％ and (74.83 ± 3.47)％ inhibition, respectively. Hydroxyl radical scavenging assay showed (73.17 ± 3.03)％ and (62.63 ± 4.59)％ activity, respectively. The ethanolic extract of Phrynium capitatum and Dryptes indica showed high level of attenuation of quorum sensing regulated pyocyanin production. Confocal laser scanning microscopic analysis revealed that the extracts had the potential to effectively inhibit biofilm formation of Pseudomonas aeruginosa. Molecular docking analysis showed a better binding affinity of bioactive compounds from the extracts for the structure of LasR protein of Pseudomonas aeruginosa. Conclusions: The ethanolic extracts of Phrynium capitatum and Dryptes indica possess antioxidant activity and the potential to inhibit the quorum sensing system and its regulatory virulence traits in Pseudomonas aeruginosa PAO1.

Determination of Antioxidant Potential of Selected Wild Edible Mushrooms from India in a Saccharomyces cerevisiae Model System.

Wild edible mushrooms are one of the most fascinating nutraceuticals because of their pleasant texture, peculiar aroma, and tremendous therapeutic potential; they have been used since ancient times. In this study we evaluated the antioxidant potential of 4 wild edible mushrooms-Cantharellus tropicalis, C. cibarius, Lentinus edodes, and Russula delica-collected from Mizoram, India. We performed in vitro and in vivo studies using a Saccharomyces cerevisiae stress response mechanism as the model system. Among the 4 mushrooms, C. cibarius exhibited the most significant antioxidant activity both in vitro and in vivo, followed by L. edodes, R. delica, and C. tropicalis. Gas chromatography-mass spectrometry analysis of methanolic extracts of the mushrooms revealed the presence of substantial amounts of fatty acids, fatty acid esters, and other bioactive constituents. The in vitro antioxidant activity was corroborated by in vivo studies using an S. cerevisiae oxidative stress response mechanism. In spot assays, the C. cibarius methanolic extract showed the highest scavenging potential in wild and mutant (sodlΔ and tsalΔ) strains of S. cerevisiae. These results were confirmed further by determining the level of reactive oxygen species through the use of fluorescent microscopy and intensity studies. The results suggested the efficacy of wild edible mushrooms as prominent therapeutic agents and that they have tremendous nutraceutical properties.