Hypoglycemic and Hypolipidemic Effects of Leonotis mollisima Aqueous Leaf Extract in Type 2 Diabetic Rats

Type 2 diabetes is a global health challenge, prevalent in Uganda in about 3.6% of cases. Despite the availability of conventional treatments, there is a growing interest in natural remedies due to their potential efficacy and fewer side effects. This study evaluated Leonotis mollissima aqueous leaf extract for hypoglycemic and hypolipidemic effects in type 2 diabetic rats, given its traditional use and limited scientific validation.

Diabetes was induced in Wistar rats using a high-fat diet (60% fat; 40% carbohydrate, 15% protein, 0.5% cholesterol) and streptozotocin (35 mg/kg). Rats received Leonotis mollissima extract (250, 500, 1000 mg/kg) or glimepiride (5 mg/kg; sulfonylurea insulin secretagogue) for 28 days. Fasting blood glucose, oral glucose tolerance, glycated hemoglobin, lipid profiles, and pancreatic histology were assessed.

Leonotis mollissima (1000 mg/kg) significantly reduced fasting blood glucose levels (p = 0.0172 vs negative control group), improved glucose tolerance (p < 0.0001), and lowered glycated haemoglobin levels in a dose-dependent manner. Leonotis mollissima (1000 mg/kg) also improved lipid profiles by reducing total cholesterol (p = 0.0016 vs negative control), and low-density lipoprotein-cholesterol levels (p = 0.0197 vs negative control). Histological examination revealed that higher doses of the extract restored pancreatic histoarchitecture, with intact acini cells and islets of Langerhans.

Leonotis mollissima aqueous leaf extract exhibits significant hypoglycemic and hypolipidemic effects in type 2 diabetic Wistar rats, supporting its traditional use. The extract's ability to improve glycemic control, lipid profiles, and pancreatic histoarchitecture suggests its potential as a therapeutic agent for managing diabetes and its complications. Further research is recommended to isolate active compounds and evaluate their efficacy in clinical trials.