title: Hepatoprotective effects of soluble rice protein in primary hepatocytes and in mice.
abstract: BACKGROUND
  The production of rice-derived by-products has increased owing to the growing use of processed rice products. The objective of this study was to isolate highly purified proteins from a rice by-product, rice syrup meal, and to examine their hepatoprotective effects in vitro and in vivo.
  
  
  RESULTS
  Soluble rice protein (SRP70) was obtained via enzymatic processing of rice syrup meal using Termamyl SC and Alcalase. Mass spectrometry analysis showed that SRP70 contained low-molecular-weight (<600 Da) peptides. SRP70 did not affect the viability of rat primary hepatocytes and ameliorated tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity. t-BHP-induced elevations in hepatocyte alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase activities were reduced by SRP70 in a dose-dependent manner. In addition, t-BHP exposure increased the level of malondialdehyde, a toxic reactive aldehyde, which was dose-dependently decreased by SRP70 treatment. These SRP70-induced decreases in biochemical parameters were also observed in vivo in mice. In particular, SRP70 increased the activities of liver antioxidant enzymes in t-BHP-treated mice, including catalase and glutathione peroxidase, as well as increasing the level of glutathione, an antioxidant peptide. SRP70-mediated activation of antioxidant enzymes was shown to be due to the up-regulation in their gene expressions, while nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase 4 (NOX4), a pro-oxidant enzyme, was down-regulated by SRP70. Hematoxylin and eosin staining also showed that SRP70 protected the liver from histopathological changes induced by t-BHP.
  
  
  CONCLUSIONS
  Taken together, these data showed that SRP70, which is derived from a rice-processing by-product, had hepatoprotective effects in vitro and in vivo.
authors.affiliation: BK Bio Co. Ltd, Sungnam, 462-819, Republic of Korea.
authors.forename: Bok-Kyung
authors.initials: BK
authors.lastname: Han
authors.affiliation: Department of Food and Nutrition, Korea University, Seoul, 130-701, Republic of Korea.
authors.forename: Yooheon
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Food Science and Technology, Seoul Women's University, Seoul, 139-774, Republic of Korea.
authors.forename: Hyeon-Son
authors.initials: HS
authors.lastname: Choi
authors.affiliation: Department of Food and Nutrition, Korea University, Seoul, 130-701, Republic of Korea.
authors.forename: Hyung Joo
authors.initials: HJ
authors.lastname: Suh
mesh_terms: D000818:Animals; D000975:Antioxidants; D002374:Catalase / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D056486:Chemical and Drug Induced Liver Injury / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D005979:Glutathione Peroxidase / Q000378:metabolism; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D008107:Liver Diseases / Q000517:prevention & control*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D012275:Oryza / Q000737:chemistry*; D010936:Plant Extracts / Q000494:pharmacology; D010940:Plant Proteins / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility; D020122:tert-Butylhydroperoxide / Q000633:toxicity
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D010940:Plant Proteins; D020122:tert-Butylhydroperoxide; D002374:Catalase; D005979:Glutathione Peroxidase
keywords: SRP70; hepatoprotective effect; mice; primary hepatocytes; t-BHP