Punicalagin inhibits biofilm formation and virulence gene expression of Vibrio parahaemolyticus

Vibrio parahaemolyticus is a major food-borne pathogen and the leading cause of seafood-associated enteric infections worldwide. In addition, imprudent use of antibiotics has contributed to increasing antibiotic resistance in V. parahaemolyticus. Therefore, there is an urgent need to develop novel control strategies to reduce V. parahaemolyticus contamination and infection. V. parahaemolyticus could form biofilm on different surfaces and contains several virulence factors, which together contribute to its persistence and pathogenicity. In this study, anti-biofilm and potential anti-virulence effects of punicalagin against V. parahaemolyticus were investigated. Punicalagin at sub-inhibitory concentrations (3.125–12.5 μg/mL) exerted significant anti-biofilm activity (20.9–74.4% reduction). It decreased bacterial motility, and attenuated metabolic activity of cells inside biofilm. Meanwhile, punicalagin inhibited EPS production and caused reduction of exopolysaccharides in biofilms, and decreased Raman peak intensities of different biofilm components. Moreover, punicalagin significantly inhibited V. parahaemolyticus adhesion to Caco-2 cells (23.8–68.1% reduction) and downregulated expression of genes involved in V. parahaemolyticus biofilm formation and virulence. These findings suggest that punicalagin could be potentially developed as an alternative strategy to control V. parahaemolyticus biofilms in food industry and mitigate diseases caused by this pathogen.