Antiobesity Activity of Aqueous Extracts of Rhizoma Dioscoreae Tokoronis on High-Fat Diet-Induced Obesity in Mice

We examined the effects of Rhizoma Dioscoreae Tokoronis extracts (RDTEs) on plasma lipids, body weight, and lipogenic enzymes. Mice were administered a standard chow diet, a 60% high-fat diet, or a high-fat diet with RDTE. Mice that were fed a high-fat diet containing RDTE were found to have lower increases in body and epididymal adipose tissue weights and a lessened occurrence of hepatic steatosis than mice that were fed a high-fat diet. The decreased adiposity that was induced by RDTE accounted for lower plasma levels of tumor necrosis factor-alpha, leptin, and glucose and a higher level of adiponectin. RDTE administration also resulted in a significant decrease in triglyceride, total plasma cholesterol, and low-density lipoprotein-cholesterol when compared to the high-fat group. To identify the mechanism by which RDTE induced its antiobesity effect, we investigated the sterol response element binding protein ( SREBP) transcription system, which was induced in mice that were fed the high-fat diet. RDTE was found to suppress the expression of SREBP-1 as well as that of fatty acid synthase in adipose and liver tissues in mice provided the high-fat diet. These findings suggest that the antiobesity action of RDTE in mice that are fed a high-fat diet may occur in response to suppression of the SREBP-1-dependent lipogenic pathway.