Duckweed (Wolffia globosa) improves intestinal epithelial barrier function induced by gut microbial metabolites in vitro

• Duckweed ( Wolffia globosa ) improves intestinal epithelial barrier function. • Gut bacterial bile acid and protein metabolism could reduce gut barrier function. • Duckweed extracts protect deleterious effects of gut metabolites on barrier function. • Duckweed extracts tend to increase expression of tight junction proteins. Intestinal barrier dysfunction plays an important role in many disease-development risks, and gut microbiota-derived metabolites are an attractive target to influence intestinal homeostasis and barrier function. Dietary intake has been shown to modulate gut microbiota and microbial metabolite production. Here, the effect of gut microbial metabolites on barrier function in an intestinal Caco-2 epithelial monolayer model and the influence of duckweed ( Wolffia globosa ) extract treatments on barrier integrity and the expression of tight junctions (TJs) were investigated. Results demonstrated that the combination of the secondary bile acid sodium deoxycholate (SDC) and p -cresol increased permeability of Caco-2 monolayers as reflected by significantly decreased ( p < 0.05) transepithelial electrical resistance (TEER) and increased ( p < 0.05) fluorescein isothiocyanate-dextran 40 kDa (FITC-D40) flux compared to vehicle control. Alterations induced by SDC and p -cresol were prevented by duckweed polysaccharide (DPS) and protein-enriched extracts (DPT) as evidenced by significantly increased TEER and decreased paracellular flux of FITC-D40. DPS and DPT incubations were also associated with a trend towards increased claudin 1 and occludin expression compared to both control and gut microbial metabolite SDC and p -cresol-treated cells. These results demonstrate that extracts of duckweed protect against the deleterious effects of dysbiotic mediators SDC and p -cresol on intestinal barrier function.