Deciphering the molecular mechanisms underlying anti-pathogenic potential of a polyherbal formulation Enteropan® against multidrug-resistant Pseudomonas aeruginosa.

Objective: Anti-pathogenic potential of a polyherbal formulation Enteropan® was investigated against a multidrug-resistant strain of the bacterium Pseudomonas aeruginosa.

Methods: Growth, pigment production, antibiotic susceptibility, etc., were assessed through appropriate in vitro assays. Virulence of the test pathogen was assessed employing the nematode worm Caenorhabditis elegans as a model host. Molecular mechanisms underlining the anti-pathogenic activity of the test formulation were elucidated through whole transcriptome analysis of the extract-exposed bacterial culture.

Results: Enteropan-pre-exposed P. aeruginosa displayed reduced (~70%↓) virulence towards the model host C. elegans. Enteropan affected various traits like biofilm formation, protein synthesis and secretion, quorum-modulated pigment production, antibiotic susceptibility, nitrogen metabolism, etc., in this pathogen. P. aeruginosa could not develop complete resistance to the virulence-attenuating activity of Enteropan even after repeated exposure to this polyherbal formulation. Whole transcriptome analysis showed 17% of P. aeruginosa genome to get differentially expressed under influence of Enteropan. Major mechanisms through which Enteropan exerted its anti-virulence activity were found to be generation of nitrosative stress, oxidative stress, envelop stress, quorum modulation, disturbance of protein homeostasis and metal homeostasis. Network analysis of the differently expressed genes resulted in identification of 10 proteins with high network centrality as potential targets from among the downregulated genes. Differential expression of genes coding for five (rpoA, tig, rpsB, rpsL, and rpsJ) of these targets was validated through real-time polymerase chain reaction too, and they can further be pursued as potential targets by various drug discovery programmes.