Antihyperglycemic and hypoglycemic activities of the aqueous leaf extract of Rubus Erlangeri Engl (Rosacea) in mice

Background: The prevalence of diabetes mellitus is on the inexorable rise despite the promises of a wide range of conventional medications. Thus, there is a need to scientifically investigate plants for antidiabetic effect. Methods: After the Rubus Erlanrige Engl (Rosaceae) leaf has been decocted, the plant extract's antidiabetic activity was first investigated in vitro and then in vivo. The in vitro activity was assessed using 3, 5-Dinitrosalicylic acid, and 2,2-diphenyl-1-picrylhydrazine method for α-amylase inhibition and antioxidant effect respectively. On the other hand, the in vivo antidiabetic activity was carried out in normoglycemic, glucose loaded (2.5 g/kg) and single dose streptozotocin (200 mg/kg) induced diabetic mice. Results: Acute toxicity study showed the extract is safe with ≥2 g/kg. The in vitro results demonstrated the extract has an IC50 of 7.34 ± 0.02 and 10.38 ± 0.0.62 μg/ml for antioxidant and α-amylase inhibition activity respectively. On the other hand, the in vivo study revealed that the extract significantly reduced blood glucose level following glucose loading. The extract did not, however, produce a significant reduction of glucose level in normal mice indicating low risk of hypoglycemia. The extract also significantly decreased blood glucose levels in streptozotocin-induced diabetic mice. In the single dose study, the extract lowered blood glucose level all except by lower dose at the 3rd and 4th h (p < 0.05). In repeated dose studies, the reduction in fasting blood glucose was significant with all doses of the extract from the 2nd week onwards. In addition, the extract produced less reduction in body weight after diabetic induction. Conclusion: The findings collectively indicate that the extract has an antidiabetic activity, with low risk of hypoglycemia, probably mediated by various secondary metabolites that act in synergy.