Structural and functional characterization of yellow field pea seed (Pisum sativum L.) protein-derived antihypertensive peptides

• Five peptides were identified to be present in a pea protein hydrolysate.
• LTFPG and FEGTVFENG showed moderate renin inhibition.
• IIPLEN, LSSGDVF, and IFENLQN had nil to poor renin inhibition.
• IFENLQN and FEGTVFENG had strong ACE inhibition.
• LTFPG and FEGTVFENG had the highest blood pressure reducing effects.

The aim of this study was to identify and test the in vivo effectiveness of antihypertensive peptides present in a pea protein hydrolysate. Yellow field pea protein isolate was digested with thermolysin and the hydrolysate passed through a 3 kDa ultrafiltration membrane. The permeate was collected as the PPH-3 and separated on a reverse-phase HPLC column into 10 peptide fractions. Fractions 3–8 showed inhibition of in vitro renin activity that ranged from approx. 21–68% while ACE activity was inhibited by fractions 2–10 in the range of 22–95%. Fraction 7 had the highest dual inhibitions of the two enzymes with 52.16 and 95.17% for renin and ACE, respectively. Fraction 7 was therefore, chosen for peptide characterization by tandem mass spectrometry, which led to sequencing of the following five peptides: LTFPG (534 Da); IIPLEN (698 Da); LSSGDVF (724 Da); IFENLQN (877 Da); and FEGTVFENG (999 Da). LTFPG, IFENLQN and FEGTVFENG had significantly (P < 0.05) higher inhibitions of ACE and renin activities and were orally administered to spontaneously hypertensive rats at a dose of 30 mg/kg body weight. LTFPG showed significantly (P < 0.05) the fastest decrease in systolic blood pressure (SBP) with a maximum of − 37 mmHg after 2 h. In contrast the maximum effects of IFENLQN (− 37 mmHg) and FEGTVFENG (− 25 mmHg) were observed after 4 h. Overall, the three peptides had significantly (P < 0.05) better SBP-reducing effects than the PPH-3, which gave a maximum of − 14 mmHg after 6 h.