Production, Analysis and in Vivo Antihypertensive Evaluation of Novel Angiotensin-I-converting Enzyme Inhibitory Peptides from Porcine Brain

This study investigated the angiotensin I-converting enzyme (ACE)-inhibitory activity and antihypertensive effect of alcalase-, flavourzyme-, and protease N-digested porcine brain hydrolysates (PBHs) on spontaneously hypertensive rats (SHRs) after their oral administration. In addition, we investigated whether a peptide fraction with a molecular weight of less than 3 000 Da inhibits ACE in vitro and lowers arterial blood pressure. The results revealed that PBHs obtained after 4 h of hydrolysis with protease N (PBP4H) yielded peptides enriched with ACE-inhibitory activity (86.29 ± 5.76%). Furthermore, PBP4H had the lowest ACE-inhibitory activity IC50 value (1.945 mg/mL). Oral administration of PBP4H-100 (100 mg/kg bw/day) and low-molecular-weight peptide fractions, PBP4H < 3 000 Da (50 mg/kg bw/d) reduced the systolic blood pressure (−30 mmHg) in SHRs. Moreover, the long-term administration of PBP4H-100 and PBP4H < 3 000 Da significantly suppressed hypertension. In addition, results of the plasma ACE activity was positively related with the SBP lowering effects of PBP4Hs. Overall, these results reveal the antihypertensive effect of PBH and as a functional supplement for suppressing hypertension