Identification of bioactive peptides from a papain hydrolysate of bovine serum albumin and assessment of an antihypertensive effect in spontaneously hypertensive rats

Inhibition of angiotensin-I-converting enzyme (ACE-I), renin, and dipeptidyl peptidase-IV (DPP-IV) plays a key role in the treatment of hypertension and type-2 diabetes. The aim of this study was to isolate and characterize novel ACE-I, renin, and DPP-IV inhibitory peptides from a papain hydrolysate of bovine serum albumin (BSA). BSA was obtained from whole bovine blood and hydrolyzed with the food-grade enzyme papain. The generated hydrolysate was further purified using ultrafiltration and high performance liquid chromatography (HPLC), and a number of novel bioactive peptides were identified using de novo peptide sequencing. These included SLR, YY, ER, and FR which inhibited the activity of the enzyme ACE-I by half at a concentration of 0.17 ± 0.02, 0.18 ± 0.04, 0.27 ± 0.01, and 0.42 ± 0.02 mM, respectively. In addition, the 1 kDa fraction of the papain hydrolysate was assessed for antihypertensive activity in vivo using spontaneously hypertensive rats (SHRs) and reduced sys- tolic blood pressure over a 24 h period when compared with the control (p b 0.001). Results demonstrated the potential of bovine serum albumin as a source of bioactive peptides with health-promoting properties and poten- tial for use as functional food ingredients.