title: Antioxidant and ACE Inhibitory Bioactive Peptides Purified from Egg Yolk Proteins.
abstract: Protein by-products from the extraction of lecithin from egg yolk can be converted into value-added products, such as bioactive hydrolysates and peptides that have potential health enhancing antioxidant, and antihypertensive properties. In this study, the antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of peptides isolated and purified from egg yolk protein were investigated. Defatted egg yolk was hydrolyzed using pepsin and pancreatin and sequentially fractionated by ultrafiltration, followed by gel filtration to produce egg yolk gel filtration fractions (EYGF). Of these, two fractions, EYGF-23 and EYGF-33, effectively inhibited the peroxides and thiobarbituric acid reactive substance (TBARS) in an oxidizing linoleic acid model system. The antioxidant mechanism involved superoxide anion and hydroxyl radicals scavenging and ferrous chelation. The presence of hydrophobic amino acids such as tyrosine (Y) and tryptophan (W), in sequences identified by LC-MS as WYGPD (EYGF-23) and KLSDW (EYGF-33), contributed to the antioxidant activity and were not significantly different from the synthetic BHA antioxidant. A third fraction (EYGF-56) was also purified from egg yolk protein by gel filtration and exhibited high ACE inhibitory activity (69%) and IC50 value (3.35 mg/mL). The SDNRNQGY peptide (10 mg/mL) had ACE inhibitory activity, which was not significantly different from that of the positive control captopril (0.5 mg/mL). In addition, YPSPV in (EYGF-33) (10 mg/mL) had higher ACE inhibitory activity compared with captopril. These findings indicated a substantial potential for producing valuable peptides with antioxidant and ACE inhibitory activity from egg yolk.
authors.affiliation: Faculty of Health and Medical Sciences, the University of Surrey, Guildford, Surrey GU2 7XH, UK. marwa_yousr@yahoo.co.uk.
authors.forename: Marwa
authors.initials: M
authors.lastname: Yousr
authors.affiliation: Faculty of Health and Medical Sciences, the University of Surrey, Guildford, Surrey GU2 7XH, UK. n.howell@surrey.ac.uk.
authors.forename: Nazlin
authors.initials: N
authors.lastname: Howell
mesh_terms: D000806:Angiotensin-Converting Enzyme Inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D000818:Animals; D001713:Biphenyl Compounds / Q000737:chemistry; D002850:Chromatography, Gel; D004527:Egg Proteins / Q000737:chemistry* / Q000302:isolation & purification; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000302:isolation & purification; D006861:Hydrogen Peroxide / Q000737:chemistry; D006868:Hydrolysis; D017665:Hydroxyl Radical / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D019787:Linoleic Acid / Q000737:chemistry; D010084:Oxidation-Reduction; D010194:Pancreatin / Q000737:chemistry; D010434:Pepsin A / Q000737:chemistry; D007703:Peptidyl-Dipeptidase A / Q000737:chemistry; D010851:Picrates / Q000737:chemistry; D059748:Proteolysis; D020539:Sequence Analysis, Protein; D013481:Superoxides / Q000737:chemistry; D017392:Thiobarbituric Acid Reactive Substances / Q000737:chemistry; D013861:Thiocyanates / Q000737:chemistry
chemical_list: D000806:Angiotensin-Converting Enzyme Inhibitors; D001713:Biphenyl Compounds; D004527:Egg Proteins; D016166:Free Radical Scavengers; D010851:Picrates; D017392:Thiobarbituric Acid Reactive Substances; D013861:Thiocyanates; D013481:Superoxides; D017665:Hydroxyl Radical; C103724:ferric thiocyanate; D010194:Pancreatin; D019787:Linoleic Acid; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl; D007501:Iron; D007703:Peptidyl-Dipeptidase A; D010434:Pepsin A
keywords: ACE inhibition; DPPH (1,1-Diphenyl-2-Picrylhydrazyl); antioxidant activity; chelating activity; egg yolk peptides; hydroxyl radical; malondialdehyde