There are several reports proving t

There are several reports proving turmeric to also possess antibacterial properties at high concentration whilst at lower concentrations it tends to supress the physiological traits without reducing growth, thus suggesting that curcumin interferes the metabolic pathways even at lower concentrations [28]. For the present study, the concentration of curcumin tested upon P. aeruginosa AM26 for biofilm inhibition studies was kept up to 3.0 µg/mL. The in vitro studies showed the biofilm formation by AM26 was reduced significantly whilst there was no reduction in the growth density. This reflects that curcumin in the PPM levels can interfere with the QS of the bacteria. Similarly, for V. alginolyticus PBR1 the same concentration of curcumin was found to be inhibiting bioluminescence without affecting its growth. From all the studies so performed, it can be deduced that (i) the active site of LuxR bears striking similarity to LasR, (ii) curcumin exhibits identical effects on both—LuxR and LasR—being antagonist to their actual ligand OhHSL and OdDHL, respectively, (iii) curcumin reduces biofilm formation in P. aeruginosa AM26, and (iv) curcumin causes substantial reduction in bioluminescence in V. alginolyticus PBR1 that may be attributed by inhibition of QS. In a nutshell, the authors conclude spontaneous binding of anti-QS curcumin with AHL receptors may alter their conformation, failing them to transcriptionally activate cassette of genes establishing curcumin as QSI.