Antidiabetic and Toxicity Studies of the Extract of Four Nigerian Medicinal Plants

Aims: To evaluate the anti-hyperglycaemic efficacy and safety of the methanol extract of the combination of Senecio biafrae leaf, Xylopia aethiopica fruit, Carica papaya seed and Spondias mombin stem bark mixed together in ratio 1:1:1:1 Study Design: Extract of medicinal plants was assayed using glucose and streptozotocin-induced herperglycaemic rats model. Place and Duration of Study: Department of Pharmacognosy, Obafemi Awolowo University, IleIfe, Nigeria, between May, 2019 and January, 2022. Methodology: The extract of the combined plant parts was tested for toxicity in rats while its effects on glucose level, blood and biochemical components were also assessed. Its in-vitro anti-hyperglycaemic activity was assayed in α-amylase and α-glucosidase inhibitory models while its in-vivo effects were tested in glucose and streptozotocin-induced hyperglycaemic rats. The antioxidant activity of the extract was also carried out. Results: The extract did not show any adverse effects on blood sugar levels, haematological and biochemical parameters in normal rats in sub acute toxicity tests. The extract gave comparable (p > 0.05) α-amylase and α-glucosidase inhibitory effects to acarbose. In glucose-induced hyperglycaemic rats, its 100 mg/kg was the most effective dose with 19, 40, 43, and 57%  activity  that was significantly higher (p < 0.05) than the 10, 18, 24, and 40%  activity given by glibenclamide (5 mg/kg) at the same time points. In streptozotocin-induced diabetic assay, its 50 mg/kg showed 31, 85, 85 and 82 % effects on days 4, 7, 10 and 14, respectively that was significantly higher than its 100 mg/kg and glibenclamide on days 7 and 10.  The extract also elicited high free radical scavenging effects in all the antioxidant assays. Conclusion: The extract of the combination of four Nigerian antidiabetic plants mixed together in equal ratio gave significantly better antidiabetic activity at low doses than the individual plants without toxic effects.