Glycoprotein of Zanthoxylum piperitum DC has a hepatoprotective effect via anti-oxidative character in vivo and in vitro

This study was carried out to investigate the anti-oxidative and hepatoprotective effects of glycoprotein isolated from Zanthoxylum piperitum DC fruit (ZPDC glycoprotein). ZPDC glycoprotein showed a single band with molecular weight of 24 kDa on the 18% sodium dodecyl sulfate-polyacrylamide gel and consists of a carbohydrate component (18%) and a protein component (82%). We found that ZPDC glycoprotein has a strong scavenging activity against DPPH, superoxide anion, and hydroxyl radicals without any pro-oxidant activity in the cell-free system. In hepatocyte cell lines (Chang liver and BNL CL.2 cells), the results showed that ZPDC glycoprotein has an inhibitory effect on hypoxanthine/xanthine oxidase- or glucose/glucose oxidase-induced cytotoxicity in a dose-dependent manner. In addition, administration of ZPDC glycoprotein (20 mg/kg) lowers the levels of lactate dehydrogenase, alanine transaminase, and thiobarbituric acid reactive substances, whereas increases that of nitric oxide, accompanying the normalizing effects on the activity of hepatic anti-oxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) in mouse model of carbon tetrachloride-stimulated acute liver injury. On the whole the results suggest that ZPDC glycoprotein can be a potent hepatoprotective agent as a natural anti-oxidant.