title: Chemical characteristics and enhanced hepatoprotective activities of Maillard reaction products derived from milk protein-sugar system.
abstract: The objective of this study was to investigate the characteristics, antioxidative properties, and hepatoprotective effects of Maillard reaction products (MRP) from milk protein reacted with sugars. The MRP were obtained from milk protein, whey protein concentrates and sodium caseinate, using 2 types of sugars, lactose and glucose, by heating the mixture at 55°C for 7d in a sodium phosphate buffer (pH 7.4). Changes in the chemical modification of the milk protein were monitored by measuring the protein-bound carbonyls and PAGE protein profiles. The results showed that the amount of protein-bound carbonyls increased after Maillard reaction (MR). In addition, sodium dodecyl sulfate-PAGE analysis indicated a formation of high-molecular weight complexes through MR. The modification sites induced by MR of milk protein were monitored by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of tryptic-digested gel spots of MRP. As a result, modification and their localization in AA sequence of MRP was identified. Also, the MRP showed higher antioxidant activities than the intact milk protein, and they reduced intracellular reactive oxygen species production and inhibited the depletion of the reduced glutathione concentrations in the HepG2 cells. In particular, glucose-sodium caseinate MRP showed the highest biological activities among all MRP. Therefore, these results suggest that the MRP from milk protein reacting with sugars possess effective antioxidant activity and have a protective ability against oxidative damage.
authors.affiliation: R&D Center, Seoul Dairy Cooperative, Ansan, Kyunggi 425-839, South Korea.
authors.forename: Nam Su
authors.initials: NS
authors.lastname: Oh
authors.affiliation: R&D Center, Seoul Dairy Cooperative, Ansan, Kyunggi 425-839, South Korea; Department of Biotechnology, College of Life Science & Biotechnology, Korea University, Seoul 136-713, South Korea.
authors.forename: Ji
authors.initials: J
authors.lastname: Young Lee
authors.affiliation: Department of Biotechnology, College of Life Science & Biotechnology, Korea University, Seoul 136-713, South Korea.
authors.forename: Hyun Ah
authors.initials: HA
authors.lastname: Lee
authors.affiliation: R&D Center, Seoul Dairy Cooperative, Ansan, Kyunggi 425-839, South Korea.
authors.forename: Jae Yeon
authors.initials: JY
authors.lastname: Joung
authors.affiliation: R&D Center, Seoul Dairy Cooperative, Ansan, Kyunggi 425-839, South Korea.
authors.forename: Yong Kook
authors.initials: YK
authors.lastname: Shin
authors.affiliation: Department of Biotechnology, College of Life Science & Biotechnology, Korea University, Seoul 136-713, South Korea.
authors.forename: Sae Hun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: BK21 Plus Graduate Program, Department of Animal Science, Chonbuk National University, Jeonju, 561-756, Korea. Electronic address: ykeys2584@jbnu.ac.kr.
authors.forename: Younghoon
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, College of Life Science & Biotechnology, Korea University, Seoul 136-713, South Korea. Electronic address: kwangwon@korea.ac.kr.
authors.forename: Kwang Won
authors.initials: KW
authors.lastname: Lee
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000737:chemistry; D002364:Caseins / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D005947:Glucose / Q000737:chemistry*; D056945:Hep G2 Cells; D006358:Hot Temperature; D006801:Humans; D007785:Lactose / Q000737:chemistry*; D008107:Liver Diseases / Q000517:prevention & control*; D015416:Maillard Reaction; D013058:Mass Spectrometry; D008894:Milk Proteins / Q000737:chemistry*; D010084:Oxidation-Reduction; D000067816:Whey Proteins / Q000737:chemistry
chemical_list: D000975:Antioxidants; D002364:Caseins; D008894:Milk Proteins; D000067816:Whey Proteins; D005947:Glucose; D007785:Lactose
keywords: Maillard reaction; antioxidant activity; hepatoprotective effect; milk protein