Antidiabetic effect of flavones from Cirsium japonicum DC in diabetic rats

Cirsium japonicum DC is a traditional Chinese herb used along with other herbs to treat hypertension, traumatic hemorrhage, inflammation, and renal cellular injury. Here, we isolated two flavones from Cirsium japonicum DC , pectolinarin and 5,7-dihydroxy-6,4′-dimethoxy flavone (DDMF), and investigated their antidiabetic effect in diabetic rats established by intravenous injection with streptozotocin followed by feeding with high-carbohydrate/high-fat diet. Both pectolinarin and DDMF showed antidiabetic effect in diabetic rats. However, FECJ, a mixture of pectolinarin and DDMF, is more effective than pectolinarin and DDMF in improving the plasma glucose, cholesterol and triglycerides levels in diabetic rats. The altered activities of glucose metabolism-related enzymes in diabetic rats were well reversed after flavone treatment. The plasma adiponectin level was greatly increased in diabetic rats treated with FECJ, while no obvious effect of the flavones on the dysregulated plasma insulin level and expressions of leptin and glucose transporter 4 (GLUT4) was observed. Our data indicated that the flavones improved adiponectin expression, accompanied by restoring of the dysregulated activities of the glucose metabolism-related enzymes, ultimately resulting in well improved glucose and lipid homeostasis. Thus, an antidiabetic effect of Cirsium japonicum DC was revealed in diabetic rats, suggesting the potential benefit of the Cirsium japonicum DC as an alternative in treating diabetes mellitus.