title: Purification and characterization of antioxidant peptides from leukocyte extract of Crocodylus siamensis.
abstract: Antioxidant peptides were isolated from the leukocyte extract of the Siamese crocodile, Crocodylus siamensis. Crocodile leukocyte was extracted by a combination of methods including freeze-thawing, acetic acid extraction and homogenization. The peptides in the leukocyte extract were purified by anion exchange chromatography and reversed phase-high performance liquid chromatography. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay was used to evaluate the antioxidant activity of the elution peaks at each purification step. As a result, there were two purified peptides exhibiting strong antioxidant activity in reducing free radicals on DPPH molecules. The amino acid sequences of these peptides were determined by LC-MS/MS as TDVLGLPAK (912.5 Da) and DPNAALPAGPR (1,148.6 Da), and their IC₅₀ values were 153.4 and 95.7 μM, respectively. The results of this study therefore indicate that leukocyte extract of C. siamensis contains peptides with antioxidant activity which could be used as a novel antioxidant.
authors.affiliation: Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen, 40002, Thailand.
authors.forename: Tinnakorn
authors.initials: T
authors.lastname: Theansungnoen
authors.forename: Nualyai
authors.initials: N
authors.lastname: Yaraksa
authors.forename: Sakda
authors.initials: S
authors.lastname: Daduang
authors.forename: Apisak
authors.initials: A
authors.lastname: Dhiravisit
authors.forename: Sompong
authors.initials: S
authors.lastname: Thammasirirak
mesh_terms: D000489:Alligators and Crocodiles; D000595:Amino Acid Sequence; D000818:Animals; D000975:Antioxidants / Q000737:chemistry* / Q000302:isolation & purification; D001713:Biphenyl Compounds / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry; D007962:Leukocytes / Q000737:chemistry; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification; D010851:Picrates / Q000737:chemistry; D053719:Tandem Mass Spectrometry; D014020:Tissue Extracts / Q000737:chemistry
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D010455:Peptides; D010851:Picrates; D014020:Tissue Extracts; C004931:1,1-diphenyl-2-picrylhydrazyl