The major components of tea may be significantly influenced according to the type of fermentation, and consequently the effects of different teas will differ. We examined whether green tea fermented with Aquilariae Lignum (fGT) shows a stronger anti-diabetic effect than unfermented green tea (GT) on mice with type 2 diabetes. To evaluate the anti-obesity effect of fGT, we assessed body weight, fecal excretion, serum leptin levels, exocrine pancreatic zymogen granule contents, and periovarian fat weight and adiponectin contents. Blood glucose levels, pancreatic weight, and numbers of pancreatic islet insulin- and glucagon-producing cells were determined to evaluate anti-hypoglycemic effects, while total cholesterol, triglyceride, and low- and high-density lipoprotein levels were determined to evaluate anti-hyperlipidemic effects. The antioxidant effect of fGT was detected by measuring malondialdehyde and glutathione contents and the activities of catalase and superoxide dismutase. fGT showed anti-obesity, anti-hypoglycemic, anti-hyperlipidemia, and antioxidant effects. Additionally, fGT exerted stronger anti-diabetic effects compared with GT. Collectively, these results suggested that fGT fermented with the appropriate amounts of Aquilariae Lignum (49:1) has a stronger effect compared with GT. Thus, fGT is a promising and potent new therapeutic agent for type 2 diabetes.

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Tryptanthrin (6,12-dihydro-6,12-dioxoindolo-(2,1-b)-quinazoline) has been reported to have a variety of pharmacological activities. Present study investigated the cytoprotective effects of tryptanthrin on arachidonic acid (AA) + iron-mediated oxidative stress and the molecular mechanisms responsible. In HepG2 cells, pretreatment with tryptanthrin inhibited the cytotoxic effect of AA + iron in a concentration-dependent manner. In addition, tryptanthrin prevented the changes in the levels of apoptosis-related proteins, and attenuated reactive oxygen species production, glutathione depletion, and mitochondrial membrane impairment induced by AA + iron. Mechanistic investigations showed that tryptanthrin increased the phosphorylations of AMP-activated protein kinase (AMPK) and of p38 mitogen-activated protein kinase (p38). Furthermore, inhibition of AMPK or p38 reduced the ability of tryptanthrin to prevent AA + iron-induced cell death and mitochondrial dysfunction. Transfection experiments using AMPK mutants indicated that p38 phosphorylation by tryptanthrin was dependent on AMPK activation. In a phenylhydrazine-induced acute liver injury model, tryptanthrin decreased serum levels of alanine aminotransferase, aspartate aminotransferase, and bilirubin in mice. Additionally, tryptanthrin reduced numbers of degenerating hepatocytes, infiltrating inflammatory cells, 4-hydroxynonenal-, and nitrotyrosine-positive cells in hepatic tissues. Thus, these results suggest tryptanthrin has therapeutic potential to protect cells from oxidative injury via AMPK-dependent p38 activation.