Antibiofilm and quorum sensing inhibitory potential of Cuminum cyminum and its secondary metabolite methyl eugenol against Gram negative bacterial pathogens

Quorum sensing inhibitory (QSI) activity of common South Indian spices and vegetables were evaluated using the bacterial model Chromobacterium violaceum. Among the 22 samples tested the QSI compound present in the methanolic extract of Cuminum cyminum at 2 mg/ml inhibited violacein production in C. violaceum. Further, the outcome of the present investigation reveals that C. cyminum extract strongly interferes with acyl homoserine lactone (AHL) regulated physiological functions coupled with biofilm formation such as flagellar motility and exopolysaccharides (EPS) production. It promotes the loosening of biofilm architecture and powerfully inhibits in vitro biofilm formation in Pseudomonas aeruginosa PAO1, Proteus mirabilis and Serratia marcescens at sub-MIC levels. The result of molecular docking analysis attributes the QSI activity exhibited by C. cyminum to methyl eugenol (ME). The ability of ME to interfere with quorum sensing (QS) systems of various Gram-negative bacterial pathogens comprising diverse AHL molecules was also assessed and ME was found to reduce the AHL dependent production of violacein, bioluminescence and biofilm formation. (C) 2011 Elsevier Ltd. All rights reserved.