In vitro renin–angiotensin system inhibition and in vivo antihypertensive activity of peptide fractions from lima bean (Phaseolus lunatus L.)

BACKGROUND The renin–angiotensin system is key in the physiopathology of arterial hypertension because it converts angiotensin I, via angiotensin I‐converting enzyme (ACE), into angiotensin II. In vitro analyses were done of the ACE‐inhibitory and renin‐inhibitory activities of peptide fractions isolated by enzymatic hydrolysis of lima bean ( Phaseolus lunatus ) protein. Antihypertensive activity was confirmed in vivo using a rat model. RESULTS Lima bean protein was hydrolyzed with one of two sequential enzymatic systems (pepsin–pancreatin or Alcalase®–Flavourzyme®). Ultrafiltration of the hydrolysates produced fractions of different molecular weights. The >3 kDa fraction of the pepsin–pancreatin hydrolysate had the highest ACE‐inhibitory activity (60.15%, IC 50: 172.62 µg mL −1 ), while the >3 KDa fraction of the Alcalase®–Flavourzyme® hydrolysate had the highest in vitro renin‐inhibitory activity. A weak correlation ( r = 0.44) was found between ACE‐inhibitory and renin‐inhibitory activities. When tested in vivo , the latter fraction lowered systolic blood pressure by 64% and diastolic blood pressure by 51%. CONCLUSION Peptide fractions from lima bean Phaseolus lunatus protein hydrolysates exhibit both in vitro and in vivo antihypertensive activity. Bioactive peptides from lima bean have potential applications as ingredients in functional foods.