title: Antioxidant and anti-fatigue activities of egg white peptides prepared by pepsin digestion.
abstract: BACKGROUND
  Some hydrolyzed peptides derived from food proteins possess antioxidant and anti-fatigue activities. In this study, egg white protein powder (EWPP) was hydrolyzed with pepsin for various times, and four peptide fractions were separated from the hydrolysates by ultrafiltration. The antioxidant activity of the four peptide fractions was determined. The peptide fraction with the strongest antioxidant activity was used to evaluate its anti-fatigue effect and probable mechanisms.
  
  
  RESULTS
  The egg white peptides (EWPs) fraction with molecular weight 2-5 kDa (named EWPs2) showed stronger antioxidant activity than the other peptide fractions (P < 0.05). The swimming time to exhaustion of mice administered EWPs2 was longer (P < 0.05) than that of the control group. EWPs2 increased the levels of blood glucose (by 28.4-42.2%), muscle glycogen (by 6.4-10.6%) and liver glycogen (by 10.7-23.8%) and significantly decreased the levels of lactic acid in muscle and urea nitrogen in blood (P < 0.05).
  
  
  CONCLUSIONS
  Among the four peptide fractions, EWPs2 possessed the strongest antioxidant activity and exhibited an anti-fatigue effect. The experimental data could clarify partially the anti-fatigue mechanisms of EWPs and provide an important basis for developing EWPs as safe and natural antioxidants and anti-fatigue agents for wide use.
authors.affiliation: National Engineering Laboratory for Rice and Byproduct Process, Faculty of Food Science and Engineering, Center South University of Forestry and Technology, Changsha, 410004, China; National R&D Center for Egg Processing, Huazhong Agricultural University, 1 Shizishan Street, Wuhan, Hubei, 430070, China.
authors.forename: Shuguo
authors.initials: S
authors.lastname: Sun
authors.forename: Huihui
authors.initials: H
authors.lastname: Niu
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: Qinlu
authors.initials: Q
authors.lastname: Lin
authors.forename: Feijun
authors.initials: F
authors.lastname: Luo
authors.forename: Meihu
authors.initials: M
authors.lastname: Ma
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001786:Blood Glucose / Q000032:analysis; D004527:Egg Proteins / Q000737:chemistry* / Q000378:metabolism*; D016166:Free Radical Scavengers; D006003:Glycogen / Q000032:analysis; D006868:Hydrolysis; D019344:Lactic Acid / Q000032:analysis; D015227:Lipid Peroxidation / Q000187:drug effects; D008112:Liver Glycogen / Q000032:analysis; D008297:Male; D051379:Mice; D008970:Molecular Weight; D018763:Muscle Fatigue / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000737:chemistry; D010434:Pepsin A / Q000378:metabolism*; D010455:Peptides / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology*; D013550:Swimming; D014462:Ultrafiltration
chemical_list: D000596:Amino Acids; D000975:Antioxidants; D001786:Blood Glucose; D004527:Egg Proteins; D016166:Free Radical Scavengers; D008112:Liver Glycogen; D010455:Peptides; D019344:Lactic Acid; D006003:Glycogen; D010434:Pepsin A
keywords: anti-fatigue mechanism; antioxidant activity; egg white peptides (EWPs); free radicals; liver glycogen