Working concentration of AHL in minimal media is 2.5 mM and in water is 5 microM.
Recently, extracts of Dalbergia trichocarpa bark have been shown to disrupt P. aeruginosa PAO1 quorum sensing (QS) mechanisms, which are key regulators of virulence factor expression and implicated in biofilm formation. One of the active compounds has been isolated and identified as oleanolic aldehyde coumarate (OALC), a novel bioactive compound that inhibits the formation of P. aeruginosa PAO1 biofilm and its maintenance as well as the expression of the las and rhl QS systems. Consequently, the production of QS-controlled virulence factors including, rhamnolipids, pyocyanin, elastase and extracellular polysaccharides as well as twitching and swarming motilities is reduced. Native acylhomoserine lactones (AHLs) production is inhibited by OALC but exogenous supply of AHLs does not restore the production of virulence factors by OALC-treated cultures, indicating that OALC exerts its effect beyond AHLs synthesis in the QS pathways. Further experiments provided a significant inhibition of the global virulence factor activator gacA by OALC. OALC disorganizes established biofilm structure and improves the bactericidal activity of tobramycin against biofilm-encapsulated PAO1 cells. Finally, a significant reduction of Caenorhabditis elegans paralysis was recorded when the worms were infected with OALC-pre-treated P. aeruginosa. Taken together, these results show that triterpenoid coumarate esters are suitable chemical backbones to target P. aeruginosa virulence mechanisms.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4505864/
Dear Shamas,
You should prepare a stock solution into acetonitrile or ethyl acetate. Usually we prepare it at 1 mM or 10 mM. We then dilute it to our working concentrations in any kind of broth. However, I do note that you want to test a really high concentration in minimal medium (2.5 mM). I am not sure if you will get complete dilution. For QS purposes, concentrations in the range of nM to microM are enough to activate the phenotypes evaluated. Hope this helps.
Uelinton
Dear Shamas,
I do not know the reason you need so much concentration but I agree with Uelinton about the range of nM to microM is enought to activate the phenotypes depending on QS molecules.
As an example you can see the natural range of AHL production by the pathogen bacteria Edwarsiella tarda.
Article In vitro quenching of fish pathogen Edwardsiella tarda AHL p...
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