Purification and identification of a novel hypotensive and antioxidant peptide from porcine plasma

BACKGROUND Pig plasma contains a large amount of protein. Porcine plasma polypeptide can be prepared by the enzymatic hydrolysis of porcine plasma protein. The present study investigated the function, structure, and mechanisms of porcine plasma peptides. RESULTS The results showed that WVRQAPGKGL had a major ability to scavenge hydroxyl radical scavenging activity (HRSA) (35.25%), 2,2 '-azino-bis (3-ethylbenzothiazo line-6-sulfonic acid) diammonium salt radical scavenging activity (ABTS RSA) (93.09%) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH RSA) (25.72%), as well as in angiotensin converting enzyme (ACE) inhibition (91.64%). WVRQAPGKGL could inactivate ACE by binding to Zn2+ because of the presence of carboxyl in WVRQAPGKGL. The ACE inhibition, HRSA, and DPPH of synthetic WVRQAPGKGL were improved by 12.70%, 16.06%, and 117.11% respectively after in vitro digestion. It (0.1 mg mL(-1)) also increased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) by 59.78%, 69.05%, and 59.06%, and decreased reactive oxygen species (ROS) and malondialdehyde (MDA) by 22.08% and 50.59%, respectively, to protect HepG2 cells induced by H2O2. Furthermore, in a spontaneously hypertensive rat (SHR) model, the systolic blood pressure (SBP) and diastolic blood pressure (DBP) of the peptide group (30 mg kg(-1)) both decreased by about 33.33% in comparison with captopril. CONCLUSION A new difunctional (antioxidant and hypotensive) peptide, WVRQAPGKGL, derived from porcine plasma hydrolyzate was isolated by gel filtration and reverse phase chromatography, and identified by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS)(-1). The difunctional peptide WVRQAPGKGL from porcine plasma could therefore be used in formulating functional foods or pharmaceuticals. (c) 2022 Society of Chemical Industry.