Bio-enhancing Effect of Piperine with Metformin on Lowering Blood Glucose Level in Alloxan Induced Diabetic Mice

Background: Diabetes mellitus is the most rampant metabolic pandemic of the 21st century. Piperine, the chief alkaloid of Piper nigrum (black pepper) is widely used in alternative and complementary therapies has been extensively studied for its bio-enhancing property. Objective: To evaluate the bio-enhancing effect of piperine with metformin in lowering blood glucose levels in alloxan-induced diabetic mice. Materials and Methods: Piperine was isolated from an extract of fruits of P. nigrum. Alloxan-induced (150 mg/kg intraperitoneal) diabetic mice were divided into four groups. Group I (control 2% gum acacia 2 g/100 mL), Group II (metformin 250 mg/kg), Group III (metformin and piperine 250 mg/kg + 10 mg/kg), and Group IV (metformin and piperine 125 mg/kg + 10 mg/kg). All the drugs were administered orally once daily for 28 days. Blood glucose levels were estimated at day 0, day 14, and end of the study (day 28). Results: The combination of piperine with therapeutic dose of metformin (10 mg/kg + 250 mg/kg) showed significantly more lowering of blood glucose level as compared to metformin alone on both 14th and 28th day (P < 0.05). Piperine in combination with sub-therapeutic dose of metformin (10 mg/kg + 125 mg/kg) showed significantly more lowering of blood glucose as compared to control group and also showed greater lowering of blood glucose as compared to metformin (250 mg/kg) alone. Conclusion: Piperine has the potential to be used as a bio-enhancing agent in combination with metformin which can help reduce the dose of metformin and its adverse effects.