2013 Volume 19 Issue 3 Pages 399-407
With the aim of elucidating the hypotensive effects of Apios americana Medikus tuber, active ingredients with angiotensin-converting enzyme (ACE)-inhibitory activity were identified and their hypotensive effects in spontaneously hypertensive rats (SHR) were investigated. From a pepsin digest of A. americana showing strong activity, two ACE-inhibitory peptides were isolated and identified as YRLPNL and YQLP. Although the ACE-inhibitory activity of YQLP was weak, YRLPNL showed strong ACE-inhibitory activity (IC50 value 7.7 nM) equal to those of lisinopril and captopril. After a single oral administration of YRLPNL, SHR showed a significant decrease in blood pressure. These results suggest that YRLPNL, isolated from A. Americana, is a hypotensive peptide having ACE-inhibitory activity. This is the first report of a food peptide having ACE-inhibitory activity equal to that of pharmaceuticals.