Comparative Evaluation of the Hypoglycaemic and Antioxidant Effects of Kalanchoe pinnata and Vernonia amygdalina Leaf Extracts (Separate and Combined) in Diabetic Wistar Rats

Abstract

This study comparatively evaluated the hypoglycaemic and antioxidant effects of Kalanchoe pinnata (KPE) and Vernonia amygdalina (VAE) leaf extracts, administered separately and in combination, in streptozotocin-induced diabetic Wistar rats. Following diabetes induction, rats received metformin (100 mg/kg), KPE (100 or 200 mg/kg), VAE (100 or 200 mg/kg), or KPE+VAE (100 mg/kg each) orally for 28 days; biochemical analyses were performed using three rats per group after exclusions. Fasting blood glucose, glycated haemoglobin (HbA1c), serum insulin, glutathione, glutathione peroxidase, superoxide dismutase, catalase, and malondialdehyde were assessed. At Weeks 2 and 4, fasting blood glucose did not differ significantly between treated groups and the diabetic control, although VAE at 200 mg/kg produced the lowest Week 4 value among extract-treated groups. All treated groups had HbA1c values significantly lower than the diabetic control and statistically comparable with the normal control. VAE at 200 mg/kg produced the numerically lowest HbA1c (4.39 ± 0.28%) and showed strong antioxidant responses, including the highest glutathione peroxidase and superoxide dismutase activities. In contrast, KPE at 200 mg/kg and the combined treatment produced markedly reduced serum insulin concentrations of 0.51 ± 0.15 and 0.44 ± 0.03 ng/mL, respectively. The combination did not show a clear advantage over the individual extracts. These findings indicate measurable glycaemic and antioxidant effects, with VAE at 200 mg/kg showing the most consistent overall profile, while the insulin findings warrant cautious dose optimisation.