INHIBITION OF QUORUM SENSING BY EXTRACTS OF ALPINIA GALANGA

Abstract

Bacteria communicate with each other by producing and responding to diffusible signal molecules known as auto inducers by a phenomenon called Quorum sensing. Quorum sensing controls virulons in many infectious bacteria. The pathogenicity of an infectious agent can be prevented by blocking this mechanism and thereby attenuate the infectious agents. The lyophilized aqueous and ethanolic extracts of A. galanga were subjected to the inhibition of violacein a pigment produced in Chromobacterium violaceum under quorum sensing by broth dilution method. There was a concentration dependent inhibition observed from a concentration of 2mg/ml. The aqueous extract A. galanga inhibited violacein production completely at a concentration of 2mg/ml & 1mg/ml. The ethanolic extracts of A. galanga inhibited violacein production till a concentration of 125µg/ml. Germ tube inhibition was also attempted. The ethanolic extracts of A. galanga was found to inhibit germ tube of Candida albicans at tested concentration. The lyophilized extracts did not show any significant antibacterial activity. Eighteen bioactive compounds were found in the GC-MS analysis of the ethanolic extracts of A. galanga. Cytotoxic results revealed that the extracts were non-toxic from 500µg/ml. The results of the present study identified that the rhizome extracts of A. galanga have potential to replace antibiotics because of its quorum sensing inhibitory activity against C. violaceum and C. albicans.