Anti-diabetic effect of the polyphenol-rich extract from Tadehagi triquetrum in diabetic mice

Abstract

Purpose: To clarify the diabetes-reducing abilities of the polyphenol-rich extract from Tadehagi triquetrum (HC) in diabetic ob/ob mice. Methods: Aerial parts of T. triquetrum were extracted under reflux and partitioned by n-butanol to generate HC. The effects of HC consumption on blood glucose and lipids, insulin resistance, and liver glucose metabolism were evaluated in vivo. The main compounds of HC were tested for their effects on stimulating glucose consumption and uptake by HepG2 hepatocytes and C2C12 myotubes. Results: After HC treatment, body fat, subcutaneous fat, and epidydimal fat masses decreased (p < 0.05), while mean daily food intake was unaffected. HC (200–400 mg/kg) decreased fasting blood glucose, glycosylated serum protein (GSP), and glycosylated hemoglobin (HbAlc); it also lowered hyperinsulinemia, improved oral glucose tolerance, and reduced hyperlipidemia and liver fat content (p < 0.05). HC treatment markedly elevated liver glycogen content and activity of hepatic glucokinase and pyruvate kinase (p < 0.05). Eight polyphenols were isolated from HC, six of which potently stimulated glucose consumption and uptake in vivo. Conclusion: HC has potent antidiabetic activities. Polyphenols are the main compounds accounting for these effects. Chronic oral administration of HC may be an alternative therapy for managing diabetes, but this has to be subjected first to clinical studies.