Protective effect of Porphyra yezoensis glycoprotein on D-galactosamine-induced cytotoxicity in Hepa 1c1c7 cells

The present study aimed to examine the signaling pathways and enzyme activity associated with the protective effect of Porphyra yezoensis glycoprotein (PYGP) on D-galactosamine (D-GaIN)-induced cytotoxicity in Hepa 1c1c7 cells. D-GaIN is commonly used to induce hepatic injury models in vivo as well as in vitro. PYGP was extracted from Porphyra yezoensis, a red algae distributed along the coasts of Republic of Korea, China and Japan. In the present study, Hepa 1c1c7 cells were pre-treated with PYGP (20 and 40 mu g/ml) for 24 h and then the media was replaced with D-GaIN (20 mM) and PYGP (20 and 40 mu g/ml). The results demonstrated that D-GaIN induced Hepa 1c1c7 cell death and pretreatment with PYGP was found to attenuate D-GaIN toxicity. In addition, D-GaIN decreased the antioxidant activity and increased lipid peroxidation processes; however, pre-treatment with PYGP reduced the generation of lipid peroxidation products, such as thiobarbituric acid reactive substances, as well as increased the activity of antioxidant enzymes, including superoxide dismutase, catalase and glutathione-s-transferase (GST). PYGP was shown to suppress the overexpression of extracellular signal-regulated kinase, c-jun N-terminal kinase and p38 mitogen-activated protein kinase (MAPK) phosphorylation induced by D-GaIN. Furthermore, PYGP increased the protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2), quinine oxidoreductase 1, GST and heme oxygenase 1 protein expression. These results suggested that PYGP had cytoprotective effects against D-GaIN-induced cell damage, which may be associated with MAPKs and the Nrf2 signaling pathway.