Anti-bacterial and anti-quorum sensing activity of thai traditional medicinal plants in Nakhon-Ratchasima province, Thailand

Quorum sensing is an intercellular signaling system in bacteria in response to cell population. Several physiological processes in pathogenesis of medically important bacteria are associated with quorum sensing. As quorum sensing controls bacterial virulences, the inhibition of the system is being considered as a novel approach for antibacterial substance. This research determined the effect of 47 Thai medicinal plant species on bacterial quorum sensing, Chromobacterium violaceum. Anti-quorum sensing activity was indicated by the inhibition of violacein pigment producing of biomonitor strain, C. violaceum DMST 21761. Screening test by disc diffusion assay revealed that five plant extracts exhibited anti-quorum sensing activity including Alpinia galanga Sw., Feronia limonia (L.) Swing, Millingtonia hortensis Linn., Oroxylum indicum (L.) Kurz., and Sesbania grandiflora (L.) Poiret. All extracts, except A. galanga, reduced violacein production. Sixteen extracts produced pronounced inhibitory activity. This result may reveal the mode of action of botanical plants including anti-quorum sensing property and this activity should be further examinations.