title: Peptide fractionation and free radical scavenging activity of zein hydrolysate.
abstract: Alcalase-treated zein hydrolysate (ZH) was separated by gel filtration, ultrafiltration, and reversed-phase HPLC, and the scavenging activities for 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+), 1,1-diphenyl-2-picrylhydrazyl (DPPH*), and superoxide anion (O2*-) radicals of different peptide fractions were measured to establish the antioxidant efficacy. Results showed that the ability to stabilize water-soluble free radicals (ABTS*+) by ZH components was insensitive to the peptide size, whereas that against ethanol-soluble free radicals (DPPH*) and O2*- was molecular weight dependent. Antioxidative peptides of <1 kDa were further separated by HPLC into 30 components, of which those with great hydrophobicity exhibited strong DPPH* and O2*- scavenging ability and those with intermediate hydrophobicity displayed the maximum ABTS*+ scavenging activity. Two dominant components (fractions 8 and 17) were further purified and identified by LC-PDA-ESI-MS to be Tyr-Ala and Leu-Met-Cys-His, respectively. The results demonstrated that the free radical scavenging activity of ZH depended on the radical species and was strongly related to the molecular weight and hydrophobicity of the constituting peptides.
authors.affiliation: State Key Laboratory of Food Science and Technology and School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Xueyan
authors.initials: X
authors.lastname: Tang
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: He
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Dai
authors.forename: Youling L
authors.initials: YL
authors.lastname: Xiong
authors.forename: Mingyong
authors.initials: M
authors.lastname: Xie
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
mesh_terms: D016166:Free Radical Scavengers / Q000737:chemistry* / Q000302:isolation & purification*; D005609:Free Radicals / Q000737:chemistry; D006868:Hydrolysis; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification*; D013381:Subtilisins / Q000737:chemistry; D015028:Zein / Q000737:chemistry*
chemical_list: D016166:Free Radical Scavengers; D005609:Free Radicals; D010455:Peptides; D015028:Zein; D013381:Subtilisins