Piperine Exhibits Potential Antibiofilm Activity Against Pseudomonas aeruginosa by Accumulating Reactive Oxygen Species, Affecting Cell Surface Hydrophobicity and Quorum Sensing.

Gram-positive and Gram-negative bacteria often develop biofilm through different mechanisms in promoting pathogenicity. Hence, the antibiofilm molecule needs to be examined separately on both organisms to manage the biofilm threat. Since the antibiofilm activity of piperine against Staphylococcus aureus was already reported; here, we aimed to examine the antibiofilm activity of it against Pseudomonas aeruginosa. P. aeruginosa is an opportunistic Gram-negative pathogen that can cause several healthcare-associated infections by exploiting biofilm. Several experiments like crystal violet assay, estimation of total protein, measurement of extracellular polymeric substance, and microscopic analysis confirmed that lower concentrations (8 and 16 µg/mL) of piperine could inhibit the microbial biofilm formation considerably. Besides, it could also reduce the secretion of virulence factors from P. aeruginosa. Further investigation showed that the cell surface hydrophobicity and microbial motility of the test organism got reduced under the influence of piperine. Piperine exposure was found to increase the accumulation of reactive oxygen species (ROS) that resulted in the inhibition of biofilm formation. Furthermore, the molecular simulation studies suggested that piperine could affect the quorum sensing network of P. aeruginosa. Towards this direction, we noticed that piperine treatment could decrease the expression of the quorum sensing gene (lasI) that resulted in the inhibition of biofilm formation. Besides biofilm inhibition, piperine was also found to disintegrate the pre-existing biofilm of P. aeruginosa without showing any antimicrobial property to the test organism. Thus, piperine could be used for the sustainable protection of public-healthcare by compromising the biofilm assembly of P. aeruginosa.