EVALUATION OF THE POTENTIAL OF FIVE MEDICINAL PLANTS TO INHIBIT ACYL HOMOSERINE LACTONE BASED QUORUM SENSING IN PSEUDOMONAS AERUGINOSA AND ACINETOBACTER BAUMANNII

Abstract

Pseudomonas aeruginosa and Acinetobacter baumannii are common nosocomial pathogens, well recognized for their multidrug resistance. Acyl-homoserine lactone (Acyl-HSL) based Quorum sensing (QS) is known to regulate virulence and biofilm maturation in these organisms; hence, inhibition of QS will help to control their pathogenicity. In the study, 5 plants, Rubia cordifolia, Tinospora cordifolia, Picrorhiza kurroa, Cassia fistula and Bauhinia variegata were screened for QS inhibition. A comparison of different extracts from the above plants, for short and long acyl-HSL inhibition in both pathogens, was carried out using reporter strains, Chromobacterium violaceum ATCC12472 and Escherichia coli MG4/pKDT17 respectively. Ethyl acetate extracts of T. cordifolia inhibited short as well as long acyl-HSLs with about 78% & 71% inhibition of long acyl-HSLs in P. aeruginosa and A. baumannii respectively; higher than the positive control, garlic extract (29% and 33% respectively). Further, absence of antibacterial activity of the plant extract confirmed its QS inhibitory potential.