In China, porcine blood has a long history as a food with medicinal effects and for treating strokes, an obvious clinical consequence of hypertension. However, the active ingredients are still unknown and need to be clarified. This study described the isolation, characterization and animal experiments of angiotensin converting enzyme (ACE)-inhibitor peptides derived from porcine blood. The highly active low-molecular-weight hydrolysates were obtained from pepsin digestion of discolored porcine blood. After isolation of the hydrolysate, an active fraction containing three peptides was obtained. These peptides were analyzed by MALDI-TOF-MS. They were WVPSV (P1), YTVF (P2), VVYPW (P3), with median inhibitory concentrations of 0.368, 0.226, 0.254 mg/ml, respectively. They were first found in porcine blood. Additionally, a digestion test was performed to verify the antihypertensive effect of the peptides in vitro. After digestion with gastrointestinal proteases, the ACE-inhibitor activity of these peptides was enhanced. When these peptides were administered orally to spontaneously hypertensive rats at a dose of 10 mg/kg, a temporary antihypertensive activity was observed at 3 and 15 h after administration. These findings suggested that the peptides in porcine blood might have potential as antihypertensive agents.
Key words: Angiotensin I-converting enzyme, inhibitor activity, peptide, porcine hemoglobin.
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