Evaluation of anti-quorum sensing properties of extracts of Tridax procumbens against potent pathogens Proteus mirabilis and Serratia marcescens.

Medicinal plants play an important role for the development of new drugs and potent therapeutic agents. Tridax procumbens, a widespread weed, is used as an important medicinal plant in Ayurveda. In the current scenario, several pathogenic organisms have become multidrug resistant due to indiscriminate use of antibiotics. There is a need to find out an alternative treatment strategy that will only inhibit the virulence of pathogens without challenging basic cell function so that they do not develop the resistance against antibiotics. Virulence of the pathogens is controlled by a phenomenon called Quorum sensing. The present study was therefore conducted to evaluate the anti-quorum sensing potential of the weed Tridax procumbens. Extracts of the plant were prepared in Soxhlet apparatus using solvents with increasing polarity. The extracts were tested for anti-swarming potential in Proteus mirabilis and pigment inhibition in Serratia marcescens. Petroleum ether and chloroform extracts were found to be the most potent inhibitors of quorum sensing in Proteus mirabilis showing 14% and 37.5% reduction in the diameter of the swarm zones and the number of the swarm rings also was significantly reduced. Dose dependent pigment inhibition in Serratia marcescens was observed in the presence of ethyl acetate and methanol extract with diameter of zones of pigment inhibition ranging from 14-31 mm. Results of the study indicate that the plant Tridax procumbens possess medicinal properties and can be studied further as a potent inhibitor of quorum sensing dependent virulence in pathogenic organisms