title: Antioxidant activity of zein hydrolysates in a liposome system and the possible mode of action.
abstract: Maize zein was hydrolyzed for 0.5-5 h by alcalase or papain. Protein solubility increased (P < 0.05) with the degree of hydrolysis (DH) and was higher for alcalase-hydrolyzed zein than for papain-hydrolyzed zein. The zein hydrolysates with both enzymes consisted mostly of small peptides or amino acids nondetectable by 15% acrylamide gel electrophoresis. Alcalase-hydrolyzed zein exhibited a stronger (P < 0.05) antioxidant activity than papain-hydrolyzed zein, as indicated by peroxide and thiobarbituric acid-reactive substance values in a liposome-oxidizing system. Zein hydrolysates possessed strong Cu(2+) chelation ability and marked reducing power, both of which were accentuated with hydrolysis time. The protein hydrolysates also showed strong radical-scavenging ability, which was not influenced by hydrolysis time. The antioxidant activity of alcalase-hydrolyzed zein at some specific low concentrations was close or comparable to those of butylated hydroxyanisole, alpha-tocopherol, and ascorbate. Although intact zein displayed an antioxidative effect, it was far less potent than hydrolyzed zein. The results demonstrated that enzyme-hydrolyzed zein can act as a metal ion chelator or a hydrogen donor, as well as a radical stabilizer to inhibit lipid oxidation. The effectiveness of the protein hydrolysates appeared to depend on both the concentration and the peptide/amino acid composition of the soluble protein fraction.
authors.affiliation: Department of Food Science, Northeast Agricultural University, Harbin, China.
authors.forename: Baohua
authors.initials: B
authors.lastname: Kong
authors.forename: Youling L
authors.initials: YL
authors.lastname: Xiong
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000975:Antioxidants / Q000494:pharmacology*; D003300:Copper / Q000737:chemistry; D006868:Hydrolysis; D015227:Lipid Peroxidation / Q000187:drug effects; D008081:Liposomes / Q000737:chemistry*; D010206:Papain / Q000378:metabolism; D011492:Protein Hydrolysates / Q000494:pharmacology*; D021122:Protein Subunits / Q000378:metabolism; D012995:Solubility; D013381:Subtilisins / Q000378:metabolism; D015028:Zein / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D000975:Antioxidants; D008081:Liposomes; D011492:Protein Hydrolysates; D021122:Protein Subunits; D003300:Copper; D015028:Zein; D013381:Subtilisins; D010206:Papain