Investigation on anti-pathogenic potential of Panchvalkal and Punica granatum peel extract against certain human-pathogenic bacteria

Abstract

Present study has focused on investigation on anti-pathogenic potential of Panchvalkal (a polyherbal ayurvedic formulation), and Punica granatum peel extract against certain human-pathogenic bacteria. The test extracts were assayed against four bacterial pathogens viz. Pseudomonas aeruginosa, Staphylococcus aureus, Chromobacterium violaceum, and Serratia marcescens. Their effect in vitro on parameters like bacterial growth, quorum sensing, catalase activity, hemolytic activity, susceptibility to antibiotics and serum-dependent lysis, etc. were investigated, followed by demonstration of the in vivo efficacy using the nematode worm Caenorhabditis elegans as the model host. Mode of action of the Panchvalkal formulation was also investigated at the molecular level by studying the differential gene expression of the P. aeruginosa culture exposed to it, through whole transcriptome analysis, wherein ~14% of the genome of this bacterium was found to be expressed differently under influence of Panchvalkal. Major mechanisms through which Panchvalkal seems to exert its anti-virulence effect are generation of nitrosative and oxidative stress, and disturbing iron and molybdenum homeostasis, besides interfering with QS machinery. Some of the constituent phytochemicals of P. granatum peel, were also assayed in their pure form for their possible anti-pathogenic property. However, individual phytochemicals were not found to be as effective as the crude extract. This study validates the anti-infective potential of Panchvalkal and P. granatum peel extract, mentioned in texts of traditional medicine e.g. Ayurved, and also demonstrates therapeutic utility of the ‘polyherbalism’ concept.