Honey enhances the anti-quorum sensing activity and anti-biofilm potential of curcumin†
Abstract
Both turmeric (Curcuma longa Linn) and honey have been popularly used for treating microbial infections in Asian countries, but their combined effect on bacterial virulence has not been tested thus far. Therefore, in this investigation, the potential of curcumin (50 μg mL−1) plus 1% of honey (ChC) in reducing QS-mediated production of virulence factors and biofilm formation in Pseudomonas aeruginosa PAO1 was studied. Treatment with ChC displayed a significant reduction in the secretion of AHLs, pyocyanin, pyoverdin, pyochelin, LasA protease, LasB elastase, and hemolysin without affecting bacterium growth. The data obtained from β-galactosidase activity revealed that ChC reduced the activity of QS-related genes, namely lasI, lasR, rhlI, and rhlR. The ChC showed strong anti-biofilm activity, inhibiting biofilm formation and also eradicating it. It was also proven that the anti-biofilm activity is associated with the inhibition of rhamnolipid and alginate, as well as the swimming, and swarming motility of PAO1 as a result of ChC treatment. Eventually, it was also documented that ChC enhanced the susceptibility of PAO1 to conventional antibiotics. The results clearly indicated that the combination of curcumin and honey is a good candidate for the development of a new antibacterial agent acting not as a cidal but as an anti-virulence agent.
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