Green tea polyphenols ameliorate non-alcoholic fatty liver disease through upregulating AMPK activation in high fat fed Zucker fatty rats.

AIM: To investigate protective effects and molecular mechanisms of green tea polyphenols (GTP) on non-alcoholic fatty liver disease (NAFLD) in Zucker fatty (ZF) rats. METHODS: Male ZF rats were fed a high-fat diet (HFD) for 2 wk then treated with GTP (200 mg/kg) or saline (5 mL/kg) for 8 wk, with Zucker lean rat as their control. At the end of experiment, serum and liver tissue were collected for measurement of metabolic parameters, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), inflammatory cytokines and hepatic triglyceride and liver histology. Immunoblotting was used to detect phosphorylation of AMP-activated protein kinase (AMPK) acetyl-CoA carboxylase (ACC), and sterol regulatory element-binding protein 1c (SREBP1c). RESULTS: Genetically obese ZF rats on a HFD presented with metabolic features of hepatic pathological changes comparable to human with NAFLD. GTP intervention decreased weight gain (10.1%, P = 0.052) and significantly lowered visceral fat (31.0%, P < 0.01). Compared with ZF-controls, GTP treatment significantly reduced fasting serum insulin, glucose and lipids levels. Reduction in serum ALT and AST levels (both P < 0.01) were observed in GTP-treated ZF rats. GTP treatment also attenuated the elevated TNFα and IL-6 in the circulation. The increased hepatic TG accumulation and cytoplasmic lipid droplet were attenuated by GTP treatment, associated with significantly increased expression of AMPK-Thr172 (P < 0.05) and phosphorylated ACC and SREBP1c (both P < 0.05), indicating diminished hepatic lipogenesis and triglycerides out flux from liver in GTP treated rats. CONCLUSION: The protective effects of GTP against HFD-induced NAFLD in genetically obese ZF rats are positively correlated to reduction in hepatic lipogenesis through upregulating the AMPK pathway.

In vitro investigation of anti-diabetic effect of Taxus cuspidate extracts by ultrasound assisted method.

Extracting active components from Chinese medicinal herbs efficiently is a key step in the investigation of their pharmacological effects and modes of action. In this project, we compared the ultrasound-assisted method and the conventional solvent method for extracting the active compound of Taxus cuspidate (dong bei hong dou shan). Through the analysis of various extractions with a quadruple time-of-fight (Q-TOF) LC/MS, we demonstrated that the ultrasound-assisted method reduced solvent consumption and had shorter extraction time, while the extraction yields of the active compound (taxol) were equivalent to or even higher than those obtained with the conventional solvent extraction method. Through the comparison of Taxus cuspidate extracts (TCEs) with different concentrations of acetone and ethanol, we proved that 50% ethanol was an optimal solvent for extracting taxol from Taxus cuspidate. Based on traditional Chinese medicine (TCM) literature, we further determined whether TCEs possess antidiabetic effects by testing glucose uptake in 3T3-L1 adipocytes treated with TCEs from Taxus cuspidate bark and twigs under insulin stimulation (100 nM). The results showed that neither taxol (10 µg/ml) nor TCEs (1 and 0.1 mg/ml) changed glucose uptake significantly compared with insulin alone. This study demonstrated that the ultrasound-assisted method with 50% ethanol is a highly efficient approach for extracting Taxus cuspidate, which may be applicable for extraction of other Chinese medicinal herbs. Extracts of Taxus cuspidate bark and twigs had no effect on insulin stimulated-glucose uptake in vitro. This result conflicts with the description in TCM literature. Further in vivo study to clarify Taxus cuspidate's metabolic actions is necessary.