title: Purification and antioxidant properties of bigeye tuna (Thunnus obesus) dark muscle peptide on free radical-mediated oxidative systems.
abstract: To produce bioactive peptides from by-products of fish processing, bigeye tuna dark muscle was hydrolyzed using various enzymes (alcalase, alpha-chymotrypsin, neutrase, papain, pepsin, and trypsin), and the hydrolysates were evaluated for antioxidant activity. Considering the results of degree of hydrolysis and antioxidant activities, peptic hydrolysate was used for further studies to identify a potent antioxidant peptide. Antioxidant peptide was purified using consecutive chromatographic methods and was identified as being H-Leu-Asn-Leu-Pro-Thr-Ala-Val-Tyr-Met-Val-Thr-OH (MW 1,222 Da) by quantitative time-of-flight electrospray ionization mass spectrometry. Purified antioxidant peptide from bigeye tuna dark muscle (APTDM) was investigated for its antioxidant activities using both free radical scavenging effects and polyunsaturated fatty acid (PUFA) peroxidation inhibitory activity. The results showed that APTDM effectively quenched with low 50% inhibitory concentration values compared to vitamin C as a positive control against four different free radicals: 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, superoxide, and alkyl radical. APTDM also inhibited PUFA peroxidation in a linoleic acid emulsion system, and the activity was similar to that of alpha-tocopherol. We further investigated its antioxidant activities on cellular systems, and the results showed that APTDM significantly scavenged cellular radicals and enhanced the viability of tert-butyl hydroperoxide-induced cytotoxicity. These results indicate that APTDM or a peptide fraction containing APTDM would be a beneficial ingredient for functional food and/or pharmaceuticals.
authors.affiliation: Division of Food Science and Aqualife Medicine, Chonnam National University, Yeosu, Republic of Korea.
authors.forename: Jae-Young
authors.initials: JY
authors.lastname: Je
authors.forename: Zhong-Ji
authors.initials: ZJ
authors.lastname: Qian
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Hee-Guk
authors.initials: HG
authors.lastname: Byun
authors.forename: Se-Kwon
authors.initials: SK
authors.lastname: Kim
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology*; D002478:Cells, Cultured; D016166:Free Radical Scavengers / Q000302:isolation & purification / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D018482:Muscle, Skeletal; D010455:Peptides / Q000302:isolation & purification / Q000494:pharmacology*; D011492:Protein Hydrolysates / Q000302:isolation & purification / Q000494:pharmacology; D014413:Tuna; D020122:tert-Butylhydroperoxide / Q000633:toxicity
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D010455:Peptides; D011492:Protein Hydrolysates; D020122:tert-Butylhydroperoxide