In vitro and in silico studies on the structural and biochemical insight of anti-biofilm activity of andrograpanin from Andrographis paniculata against Pseudomonas aeruginosa

Microbial infections have become a global threat to drug-tolerant phenomena due to their biofilm formatting capacity. In many cases, conventional antimicrobial drugs fail to combat the infection, thus necessitating the discovery of some alternative medicine. Over several decades, plant metabolites have played a critical role in treating a broad spectrum of microbial infections due to its low cytotoxicity. Andrograpanin, a secondary metabolite, is a diterpenoid present in the leaf ofAndrographis paniculata.In this study, andrograpanin (0.15 mM) exhibited significant inhibition on biofilm production byPseudomonas aeruginosain the presence of gentamicin (0.0084 mM). The impaired production of extracellular polymeric substances and several virulence factors ofPseudomonas aeruginosawere investigated to understand the mechanism of action mediated by andrograpanin. The structural alteration of biofilm was evaluated by using fluorescence microscopy, atomic force microscopy and field emission scanning electron microscopy. The in silico molecular simulation studies predicted interaction of andrograpanin with quorum sensing proteins such as RhlI, LasI, LasR, and swarming motility protein BswR ofPseudomonas aeruginosa. Overall the studies indicate that andrograpanin could be used as a therapeutic molecule against biofilm development byPseudomonas aeruginosa.