Antidiabetic Properties of an Aqueous-Methanolic Stem Bark Extract of Spathodea campanulata (Bignoniaceae) P. Beauv

Abstract

Spathodea campanulata (Bignoniaceae) P. Beauv. is a common medicinal plant in the central and south- western regions of Uganda. It is popular for its use primarily in the treatment of diabetes and some other ailments. In this study the antidiabetic properties of an aqueous methanolic extract (SCE) of the stem bark were explored using experimental rat models. In normoglycemic rats, the extract reduced blood glucose levels with a significant effect (p<0.05) after 2 h at the 800 mg/kg dose. The standard chlorpropamide also produced significant lowering of normal blood glucose at all the time intervals studied (0.5, 1, 2, 4 h.). In the oral glucose tolerance test (OGTT), SCE reduced glucose-induced glycemia in a moderate manner. SCE 200, 400, 800 mg/kg bodyweight caused reduction in glycemia by 62, 63 and 35% respectively. SCE (200, 400 and 800 mg/kg) caused reduction in hyperglycemia by 10, 29 and 4% respectively, in the alloxan-induced hyperglycemia. The standard drug Chlorpropamide (400 mg/kg) significantly (p<0.05) reduced hyperglycemia by 85%. Prolonged treatment (daily dose for 17days) with SCE reduced alloxan diabetes as well; 33% by the 200 mg/kg dose, 66% by the 400 mg/kg dose and 42.9% by the 800 mg/kg dose. Both single dose and multiple dose effects were not significant (p<0.05). Therefore, SCE has hypoglycemic and antihyperglycemic effects in the experimental diabetic models used and at the doses applied. Further purification of the crude extract may improve on the potency. Toxicity studies are also required to standardize its safety.