Protective Effect of Procyanidin-Rich Grape Seed Extract against Gram-Negative Virulence Factors.

Biofilm formation and lipopolysaccharide (LPS) are implicated in the pathogenesis of gastrointestinal (GI) diseases caused by Gram-negative bacteria. Grape seeds, wine industry by-products, have antioxidant and antimicrobial activity. In the present study, the protective effect of procyanidin-rich grape seed extract (prGSE), from unfermented pomace of L. cv Bellone, on bacterial LPS-induced oxidative stress and epithelial barrier integrity damage has been studied in a model of Caco-2 cells. The prGSE was characterized at the molecular level using HPLC and NMR. The in vitro activity of prGSE against formation of biofilm of subsp. serovar Typhimurium and was investigated. In vivo, prGSE activity using infected larvae has been evaluated. The results show that the prGSE, if administered with LPS, can significantly reduce the LPS-induced permeability alteration. Moreover, the ability of the extract to prevent Reactive Oxygen Species (ROS) production induced by the LPS treatment of Caco-2 cells was demonstrated. prGSE inhibited the biofilm formation of and In terms of in vivo activity, an increase in survival of infected larvae after treatment with prGSE was demonstrated. In conclusion, grape seed extracts could be used to reduce GI damage caused by bacterial endotoxin and biofilms of Gram-negative bacteria.