Antioxidant and Angiotensin-Converting Enzyme Inhibitory Activity of Faba Bean-Derived Peptides After In Vitro Gastrointestinal Digestion: Insight into Their Mechanism of Action.

ABSTRACT

Faba bean flour, after in vitro gastrointestinal digestion, showed important antioxidant and angiotensin-converting enzyme (ACE) inhibitory activities. In the present study, 11 faba bean- derived peptides were synthesized to confirm their bioactivities and provide a deeper understanding of their mechanisms of action. The results revealed that 7 peptides were potent antioxidants, namely, NYDEGSEPR, TETWNPNHPEL, TETWNPNHPE, VIPTEPPH, VIPTEPPHA, VVIPTEPPHA, and VVIPTEPPH. Among them, TETWNPNHPEL had the highest activity in the ABTS (EC50 = 0.5 ± 0.2 mM) and DPPH (EC50 = 2.1 ± 0.1 mM) assays (p < 0.05), whereas TETWNPNHPE had the highest activity (p < 0.05) in the ORAC assay (2.84 ± 0.08 mM Trolox equivalent/mM). Synergistic and/or additive effects were found when selected peptides (TETWNPNHPEL, NYDEGSEPR, and VVIPTEPPHA) were combined. Four peptides were potent ACE inhibitors, where VVIPTEPPH (IC50 = 43 ± 1 µM) and VVIPTEPPHA (IC50 = 50 ± 5 µM) had the highest activity (p < 0.05), followed by VIPTEPPH (IC50 = 90 ± 10 µM) and then VIPTEPPHA (IC50 = 123 ± 5 µM) (p < 0.05). These peptides were noncompetitive inhibitors, as supported by kinetic studies and a molecular docking investigation. This study demonstrated that peptides derived from faba beans have multifunctional bioactivities, making them a promising food-functional and nutraceutical ingredient.