Abstract
Pseudomonas aeruginosa- major group of an aerobic bacteria associated with nosocomial and other life threatening infections. Diverse virulence factors produced by P. aeruginosa is due to distinct molecular cell signaling mechanism termed as quorum sensing (QS). Interfering with normal QS mechanism by active biomolecules is an effective strategy for attenuating its virulence. With this objective, the present study is undertaken to evaluate the inhibition of quorum sensing of clinical isolate of P. aeruginosa by repression of Las R-a transcriptional regulator for QS by ethanol extract of Terminalia chebula and Ficus racemosa. Las R repression by the plant extracts was measured in inhibition of various virulence factors like biofilm, pyocyanin production, total proteolytic activity, swarming and twisting motility. Fabrication of the extracted metabolites on the wound dressing and its effect on anti bacterial activity was also investigated. Compatibility of plant extracts on zebra fish development and blood cells was further studied. P. aeruginosa was isolated from the post operative patient and the isolated pure culture was identified by cultural, biochemical, molecular characteristics. Active principles of both the plants were readily extracted in ethanol and effectively repressed the expression of Las R. Both the tested plant extracts effectively repressed Las R expression which in turn affect the production of various virulence factors like biofilm formation, pyocyanin production, swarming motility, twisting motility, total proteolytic activity, cell adhesion and signaling molecule acyl honoserine lactone (AHL) production. Plant extract treatment brought about drastic reduction of all the tested virulence factors and AHL production. Extracted metabolites were fabricated on the wound dressing material adopting simple dip or immersion method reveals uniform coating, effective embedding of phytochemicals with the fibers and retained the anti bacterial activity against P. aeruginosa. Biocompatibility studies with zebra fish model shows both the tested plant extracts treatment was not exhibited any sign of toxicity on the developmental stages of Zebra fish. Hemolysis and changes in anti oxidative enzymes were not recorded in the plant extracts treated blood which demonstrated the best biocompatibility of the tested plant extracts. These results shows that the presence of potential phytochemicals in the ethanolic extract of Terminalia chebula and Ficus racemosa effectively represses the Las R followed by inhibition of quorum sensing mediated virulence factors production may be useful in the lead of anti bacterial drugs.
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