Transepithelial transport of faba bean peptides across a Caco-2 and HT29-MTX co-culture monolayer after gastrointestinal digestion

Abstract: Faba bean peptides generated after gastrointestinal digestion have revealed promising health beneficial activities, particularly in terms of antioxidant activity. To better anticipate their bioactive potential in vivo, the assessment of faba bean peptides bioavailability is needed. In this study, the transportation of faba bean peptides across the intestinal barrier was investigated using a Caco‑2 and HT29-MTX co-culture monolayer cultivated on a permeable support. Peptides from three faba bean varieties (Fabelle, Malik and Snowbird) were compared to those from pea and soy, two largely consumed legume proteins. The results revealed no significant differences (p > 0.05) in peptides transport on a quantitative level between faba bean, pea and soy. For all legumes, the Oxygen Radical Absorbance Capacity (ORAC) value significantly decreased after transepithelial transport (24-36% reduction), indicating a reduction of the antioxidant activity. A different trend was observed with the 2.2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. The transported peptides from all legumes had lower median effective concentrations (EC50) (p < 0.05) than the initial peptide fraction. The different trend observed in the results could be attributed to the different free radical scavenging mechanisms between ORAC and the ABTS assays. The transported peptides across the intestinal cell monolayer were identified by mass spectrometry and their bioactive properties were predicted in silico. Sixty-seven percent of faba bean transported peptides had antioxidant fragments in their sequence, confirming the experimental findings. This study shows for the first time that faba bean peptides generated after gastrointestinal digestion can be transported intact across the intestinal barrier while maintaining their antioxidant activity. Thereby, suggesting a strong potential to be bioavailable in-vivo and to induce beneficial health effects.