Identification of ACE-inhibitory peptides from <i>Phaseolus vulgaris</i> after <i>in vitro</i> gastrointestinal digestion

The objective of this study was to identify the angiotensin I-converting enzyme (ACE)-inhibitory peptides released from thermally treated <i>Phaseolus vulgaris</i> (pinto) whole beans after <i>in vitro</i> gastrointestinal digestion. The degree of hydrolysis increased during digestion reaching a value of 50% at the end of the pancreatic digestion. The &lt;3 kDa fraction of the postpancreatic sample showed high ACE-inhibitory activity (<i>IC</i>₅₀ = 105.6 ± 2.1 μg of peptides/mL). Peptides responsible for the ACE-inhibitory activity were isolated by reverse-phase high-performance liquid chromatography (HPLC). Three fractions, showing the highest inhibitory activity, were selected for tandem mass spectrometry (MS/MS) experiments. Eleven of the identified sequences have previously been described as ACE-inhibitors. Most of the identified bioactive peptides have a hydrophobic amino acid, (iso)leucine or phenylalanine, or proline at the C-terminal position, which is crucial for their ACE-inhibitory activity. The sequence of some peptides allowed us to anticipate the presence of ACE-inhibitory activity.