Screening for Quorum Sensing Inhibitors from Edible Leaves and Oils
The increasing occurrence of multi drug resistant pathogenic bacterial strains has gradually rendered traditional antimicrobial treatment ineffective. Today a global concern has emerged that we are entering a post antibiotic era with a reduced capability to combat microbes, and hence the development of novel therapeutic approaches to the treatment of bacterial infections constitute a focal point of modern research. The alternative to antibiotic mediated bacteria killing or growth inhibition is attenuation of bacterial virulence such that the organism fails to establish successful infection. Compounds with such abilities are the result of rational drug design and are termed antipathogenic drugs .Antipathogenic drugs target key regulatory bacterial systems that govern the expression of virulence factors. Quorum sensing is ubiquitous in bacteria, and have been found to regulate diverse cellular functions including luminescence, biofilm formation, antibiotic production, virulence factors expression, pigment production, plant microbe interaction and motility. The observation that QS is linked to virulence factor production, suggest that many virulent microbes could potentially be rendered nonpathogenic by inhibition of their quorum sensing systems. Research into quorum sensing, and inhibition there of, may provide means of treating many common and damaging chronic infections without the use of growth inhibitory agents. The primary objective of this investigation was to determine if extracts of edible leaves such as Sauropus androgynus,Manihot utiisim, Murraya koenigi,Mentha arrensis,Coccinia grandis,Trigonella foenum-graceum,Camellia
sinensis,Spinacea oleracea,Citrus aurantifolia and oils such as coconut oil, sesame oil, ground nut oil and mustard oil, have any QS inhibition activity. The bacterial strain used was Chromobacterium violaceum. Loss of purple pigment in Chromobacterium violaceum is indicative of quorum sensing inhibition by the extract introduced. The experiments were done in triplicate using standard methods. 6 fruit extracts, viz., Quantitative assessment of pigment inhibition indicated that the quorum quenching activity of the fruits is concentration dependent .Among the leaves only green tea shows quorum quenching property. None of the commonly used oils shows QSI property. Since tea is a common house hold product, its antiquorum sensing property opens up an a new category of antipathogenic drugs with reduced toxicity.