Polyphenols and tri-terpenoids from Olea europaea L. in alleviation of enteric pathogen infections through limiting bacterial virulence and attenuating inflammation

Olea europaea L. was known associated with health benefits, however the role of single bioactive component remains to be elucidated. This study was to investigate the operational feasibility of maslinic/oleanolic acid, hydroxytyrosol, and oleuropein from olive in control and alleviation of enteric pathogen infections. Our results indicated that the growth of Lactobacillus was stimulated by maslinic/oleanolic acid up to 4% (w/v) in dose-dependent manner. Hydroxytyrosol (>0.05%) and oleuropein (>0.5%) significantly reduced Salmonella Typhimurium/EHEC within 12 h, altered their physicochemical properties, influenced host cell-pathogen interactions, and especially 0.6-6.0 folds down-regulated the virulence gene expressions. Further molecular analysis revealed that these olive compounds up-regulated anti-inflammatory cytokine IL-10 gene by 3.0-8.0 folds and down-regulated multiple inflammation related genes at various levels. These results suggest that polyphenols in olive may serve as potential preservatives in post-harvest food processing while tri-terpenoids may assist in modulation of gut microflora and reduction of enteric pathogen colonization.