title: Defensin protein from sweet potato (Ipomoea batatas [L.] Lam 'Tainong 57') storage roots exhibits antioxidant activities in vitro and ex vivo.
abstract: This study was designed to investigate the antioxidant activities of sweet potato defensin (SPD1) in vitro and ex vivo. Antioxidant status [2,2'-azinobis[3-ethylbenzthiazoline-6-sulphonic acid (ABTS) assay], scavenging activity against DPPH (1,1-dipheny-2-picrylhydrazyl) radical method, reducing power method, Fe(2+)-chelating ability, FTC (ferric thiocyanate) method, and protection of calf thymus DNA against hydroxyl radical-induced damage were studied in vitro. The ex vivo experiments revealed that SPD1 could decrease the production of intracellular peroxide in HepG2 cells. Four peptides, namely GFR, GPCSR, CFCTKPC and MCESASSK for testing antioxidative activity, were synthesized according to tryptic hydrolysis simulation. In the TEAC assay CFCTKPC performed the best (13.5±0.3μmol TE/g dw), even better than reduced glutathione (7.3±0.2μmol TE/g dw). In the DPPH radical assay (%), [IC(50) (μM) (the concentration required for scavenging 50% activity)] CFCTKPC again had the highest antioxidant activity (IC(50) is 11.3±3.2μM) even better than reduced glutathione (IC(50) is 74.3±2.4μM). In the lipid peroxidation assay, once again CFCTKPC performed the best, with an IC(50) value of 0.5±0.0μM better than reduced glutathione (1.2±0.1μM). These findings mean that cysteine residue is most important in antioxidant activities. It was suggested that SPD1 might contribute its antioxidant activities against hydroxyl and peroxyl radicals.
authors.affiliation: School of Chinese Pharmaceutical Sciences and Chinese Medicine Resources, College of Pharmacy, China Medical University, Taichung 404, Taiwan.
authors.forename: Guan-Jhong
authors.initials: GJ
authors.lastname: Huang
authors.forename: Jeng-Shyan
authors.initials: JS
authors.lastname: Deng
authors.forename: Hsien-Jung
authors.initials: HJ
authors.lastname: Chen
authors.forename: Shyh-Shyun
authors.initials: SS
authors.lastname: Huang
authors.forename: Jung-Chun
authors.initials: JC
authors.lastname: Liao
authors.forename: Wen-Chi
authors.initials: WC
authors.lastname: Hou
authors.forename: Yaw-Huei
authors.initials: YH
authors.lastname: Lin
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects*; D004249:DNA Damage / Q000187:drug effects; D023082:Defensins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D027723:Ipomoea batatas / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism
chemical_list: D000975:Antioxidants; D023082:Defensins; D010940:Plant Proteins