| Summary: | 碩士 === 國立嘉義大學 === 食品科學系研究所 === 103 === Methylglyoxal (MG) is a highly reactive dicarbonyl aldehyde which formed during glucose, protein and fatty acid metabolism. This metabolite is a major precursor of advanced glycation end-products (AGEs). Excessing of MG formation can increase reactive oxygen species (ROS) production and cause oxidative stress (OS). OS plays an important role in the pathogenesis of liver damage. Graptopetalum paraguayense E. Walther belongs to the family Crassulaceae. The previous study demonstrated that water extracts of G. paraguayense E. Walther (WGP) exerts hepatoprotection via promoting antioxidant and anti-inflammatory properties against CCl4-induced oxidative liver damage and a series of studies on it bioactivity in the hepatoprotective effect were also conducted. This research was conducted to investigate the protective effect and potential mechanisms of G. paraguayense E. Walther in a MG-induced liver damage rat model. The results show that activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were increased. The level of cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) reached up to 102.8 mg/dL and 76.5 mg/dL, and oral administration WGP could lower down to 79.8 mg/dL and 50.1 mg/dL, but no significant differences in renal function parameters. On the antioxidative activities, the rats induced by MG decreased the activities of catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR). Treatment with WGP could elevate the antioxidant enzyme activities and reduce the contents of liver malondialdehyde (MDA). Besides, evaluated the degree of inflammation by cytokine, results show that the content of TNF-α increased to 5.09 pg/mL and 6.48 pg/mg protein in serum and liver after treated with MG in rats, while feeding WGP effectly reduced the formation of pro-inflammatory cytokine. Furthermore, intraperitoneal injection MG in rats made the MG contents 1.61 and 1.73 times more than normal group’s liver and serum. However, medium-dose WGP (250 mg/kg/bw) could normalize MG level and elevate 30.7% D-lactate contents. The results from histological detections also indicated that the rats induced by MG had a tendency to liver damage. Accompanying with western blot data, the expression of TGF-β1 on MG-induced rats enhanced 1.9 times more than normal groups. Nevertheless, WGP markedly suppressed TGF-β1 expression and had the dose-response effect. In summary, WGP ameliorated liver damage in rats by bringing down the release of LDL, augmenting antioxidant defense as well as inhibiting the generation of pro-inflammatory cytokine and TGF-β1 expression.
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