A-type procyanidins from litchi pericarp ameliorate hyperglycaemia by regulating hepatic and muscle glucose metabolism in streptozotocin (STZ)-induced diabetic mice fed with high fat diet

- Chemically well analysed litchi pericarp and lotus seedpod procyanidins were used.
- OPC lowered the blood glucose level and improved the glucose intolerance.
- Anti-diabetic effect of A-OPC is through inhibiting the glucose production and increasing glucose uptake.
- OPC may be a potential natural agent for the prevention and management of type 2 diabetes.

A-type procyanidins is rich in litchi pericarp. This study evaluated the prevention and anti-diabetic effect of A-type oligomeric procyanidins (A-OPC). The results showed A-OPC was more effective than B-type oligomeric procyanidins (B-OPC) of lotus seedpod. AMP-activated protein kinase (AMPK) was activated in liver and skeletal muscle. The protein levels of glucokinase (GK), glucose transporter type 2 (GLUT2, in liver), glucose transporter type 4 (GLUT4, in skeletal muscle) and insulin receptor α (INSR) improved significantly with treatment of A-OPC or B-OPC (p <0.05). Furthermore, the glycolytic key gene expressions of phosphofructokinase (PFK), pyruvate kinase (PK) in liver and skeletal muscle and pyruvate dehydrogenase (PDH) in skeletal muscle were notably up-regulated, while gene expressions, rate-limiting enzymes of gluconeogenesis, of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G-6-Pase) were down-regulated. Both A-OPC and B-OPC improved glucose homeostasis by inhibiting the glucose production in liver, regulating the expression of proteins involved in glucose transport system and increasing glycolysis.