Quorum Sensing Modulation of Pseudomonas aeruginosa by Emblica officinalis Seed Extract

Quorum sensing (QS) is a key regulatory mechanism in bacterial pathogens, controlling the production of virulence factors and biofilm formation in plants, animals, and humans. Targeting QS has recently emerged as a promising strategy for combating multidrug-resistant infections without exerting selective pressure on microbial growth. The objective of this study was to evaluate the quorum sensing modulation potential of hydroalcoholic seed extract of Emblica officinalis against Pseudomonas aeruginosa, specifically by analyzing its effect on pyoverdine and pyocyanin production while monitoring bacterial growth. In the present work, P. aeruginosa was isolated from soil samples collected from Girnar Hill, Junagadh, and confirmed through growth on King' s B agar, Gram staining, and biochemical characterization. Hydroalcoholic extracts of E. officinalis seeds were prepared and subjected to antibacterial screening to evaluate their potential as QS modulators. The assay was performed using pseudo-broth medium, with appropriate controls including sterility (SC), growth (GC), negative (NC), positive (PC), and test control (TC). Pigment extraction and quantification of QS-regulated metabolites, pyocyanin and pyoverdine, were carried out using chloroform-based methods. Results demonstrated a 36% reduction in pyoverdine production (OD decreased from 1.10 to 0.70) in the presence of E. officinalis seed extract, while bacterial growth remained unaffected, indicating a targeted inhibition of quorum sensing rather than general antimicrobial activity. These findings suggest that E. officinalis seed extract has potential as a natural, eco-friendly quorum sensing inhibitor that could contribute to sustainable antimicrobial strategies under the framework of circular economy and waste valorization