Asian Journal
Of Traditional Medicines

Abstract: Inhibition of quorum sensing (QS), a cell density-dependent regulation of virulent bacterial gene expression by autoinducers (AI) or acylated homoserine lactones (AHL) is an attractive strategy for the discovery of novel antimicrobials which can overcome antibiotic resistance. Pseudomonas aeruginosa (PAO1), an opportunistic pathogen in immune compromised patients is under the regulation of the LasR-RhlR system for its QS-mediated expression and development of virulence. Camellia sinensis (Green tea, GT) is well known for its health benefits worldwide. GT extracts have been shown to inhibit PAO1 growth, but few studies have investigated its QS-related antivirulent activities. Our objective was to screen for QS inhibitory properties of different high quality GT samples, to understand their mechanism of action, and to investigate their effect on the expression of QS-regulated virulence factors in PAO1. Our results indicate that GT extracts significantly inhibited QS. The mechanism of inhibition appeared to be a combination of (1). interfering with AHL activity, and of (2). modulating the synthesis of AHL’s. All of the extracts which inhibited QS in these studies also inhibited the expression of virulence factors in PAO1 which are regulated by QS.

Key words: Quorum sensing, autoinducers (AI), acylated homoserine lactones (AHL), Pseudomonas aeruginosa, Camellia sinensis antimicrobial activity, swarming motility