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Title: Bioactive properties of peptides derived from egg yolk proteins
Author: Yousr, Marwa Nasr
ISNI:       0000 0004 5348 1012
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2014
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Bioactive peptides can be released, during gastrointestinal digestion or food processing, from many plant and animal proteins and represent an important source of potential health_enhancing components. Therefore, the aim of tIus study is to investigate antioxidant, anticancer and antihypertensive activities of proteins and peptides extracted from egg yolk. Defatted egg yolk (EY) was hydrolysed using pepsin and pancreatin and sequentially fractionated by ultrafiltration, followed by gel filtration (EYGF), resulting in tlu'ee different fractions of which two (EYGF-23 and EYGF-33) effectively inhibited the oxidation of linoleic acid in a dose-dependent malmer. Both fractions (80 mglml) exhibited antioxidant activity comparable to trolox and butylated hydroxytoluene (0.2 mg/ml). The antioxidant mechanism involved superoxide anion and hydroxyl radicals scavenging, fenous chelating and reducing ability. The protective effect of one of the fractions (EYGF-23) was also tested in Caco-2 colon cancer epithelial cells, exposed to 3 mM of tert-butyl hydroperoxide (t-BHP) to induce oxidative stress. Induced cell toxicity by t-BHP was significantly inhibited when Caco-2 cells were treated with 1.0 mglml of the fraction for 24 hours. This fiaction protected the cells by inhibiting intracellular ROS as well as lipid peroxidation products by 60.0% (p <0.001) and 24.15%, (p <0.05). In addition, total glutathione level and superoxide dismutase activity were significantly elevated to 0.29 IlM (p <0.001) and 55.10% (p <0.01), respectively, in comparison to cells treated with t-BHP alone. Amino acids lysine, proline, tyrosine and tryptophan in this fraction may be responsible for antioxidant activity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available