Antidiabetic and antioxidant effects of the methanol extract of Bridelia micrantha (Hochst) Baill. (Euphorbiaceae) leaves on alloxan-induced diabetic albino mice

Bridelia micrantha (Hochst) Baill. (Euphorbiaceae), commonly known in English as “coast gold leaf” or “ogaofia” (the boss of the bush) in Igbo, is a semi-deciduous to deciduous tree up to 20 m tall with a dense rounded crown and tall, and bare stem indigenous to southern part of Nigeria. Its stem bark, which is yellow grey and smooth to slightly rough, has been of interest to researchers because of its use in the treatment of various disease conditions in Nigerian traditional medicine. The present study was targeted at investigating the antidiabetic and antioxidant effects of the methanol extract of B. micrantha leaves using alloxan-induced diabetic mice in vivo and in vitro. The extract, at the dose of 250, 500, and 1,500 mg/kg, showed a remarkable time-dependent decrease in blood glucose level in alloxan-induced diabetic mice. There was no significant difference between the extract-treated groups and the groups treated with 10 mg/kg distilled water and glibenclamide (2 mg/kg), respectively. Six hours posttreatment, the blood glucose level for the groups treated with 250 mg/kg of B. micrantha and glibenclamide (2 mg/kg), respectively, were lower than the normal blood glucose level respectively for the groups before the induction of diabetes. B. micrantha showed its optimum antioxidant activity in DPPH spectrophotometric assay at the concentration of 400 μg/ml. The ferric reducing antioxidant power showed a significant concentration-dependent increase in the total antioxidant power. These findings demonstrate that B. micrantha has both antidiabetic and antioxidant effects on experimental model of diabetes in mice and validate its use in Nigerian traditional medicine for the treatment of diabetes. Even in its crude form, the effects were comparable to that of glibenclamide, an oral sulfonylurea with proven antidiabetic activity. This finding suggests that the extract could be a potential source of a novel antidiabetic and antioxidant agent for the management of diabetes mellitus.