Broad Spectrum Anti-Quorum Sensing Activity of Tannin-Rich Crude Extracts of Indian Medicinal Plants.

Varsha Shukla,Zarine Bhathena

doi:10.1155/2016/5823013

Abstract

Quorum sensing (QS) mechanisms have been demonstrated to have significance in expression of pathogenicity in infectious bacteria. In Gram negative bacteria the autoinducer molecules that mediate QS are acyl homoserine lactones (AHL) and in Gram positive bacteria they are peptides called autoinducing peptides (AIP). A screening of tannin-rich medicinal plants was attempted to identify extracts that could interrupt the QS mechanisms in both Gram positive and Gram negative bacteria over a wide range of concentrations and therefore potentially be potent agents that could act as broad spectrum QS inhibitors. Six out of the twelve Indian medicinal plant extracts that were analyzed exhibited anti-QS activity in Chromobacterium violaceum 12472 and in S. aureus strain with agr:blaZ fusion over a broad range of subinhibitory concentrations, indicating that the extracts contain high concentration of molecules that can interfere with the QS mechanisms mediated by AHL as well as AIP.

Highlights

Unlike the early views on unicellular bacteria that suggested solitary behavior and little interactive capacity within a population, recent developments in ecological sciences suggest that communities, rather than individuals, play a major role in the maintenance of ecological stability [1, 2]
Qualitative analysis for condensed tannins showed that the extracts of Acacia arabica, Terminalia arjuna, Casuarina equisetifolia, Thespesia populnea, Mangifera indica, and Embelia ribes were rich in condensed tannins
The discovery of antibiotics has been a boon to human civilization, the current traditional antimicrobials need to be reviewed for their efficacy because of the increasing occurrence of multidrug resistant strains

Summary

Introduction

Unlike the early views on unicellular bacteria that suggested solitary behavior and little interactive capacity within a population, recent developments in ecological sciences suggest that communities, rather than individuals, play a major role in the maintenance of ecological stability [1, 2]. Quorum sensing is a process of communication in bacteria via which bacteria are able to sense whether they have reached a density corresponding to their quorate population At this density they are able to alternate gene expression such that the phenotype will be able to sustain the activities best suited for survival in the new environment [3]. LuxI encodes an autoinducer synthase that catalyzes the formation of the signal molecule, AHL, that on reaching the quorum activates luxR that codes for the receptor of AHL. This complex binds to the QS regulated promoters and leads to transcription of all genes controlled by QS system [3, 4, 7, 8]. P3 codes for RNAIII, which is the regulatory effector of the agr regulon and initiates the transcription of genes that encode a variety of exoproteins responsible for pathogenicity [6, 9,10,11]

Methods

Results

Conclusion