Hypoglycaemic activity of ethanolic leaf extract and fractions of Holarrhena floribunda (Apocynaceae)

Abstract

Holarrhena floribunda is a common plant that has traditionally been used in Africa to treat many diseases such as fever, dysentery, sterility and diabetes. This study was set out to evaluate the hypoglycaemic properties of ethanolic leaf extract of Holarrhena floribunda and various fractions of this extract in normal fasted and fed-hyperglycaemic rats. Blood glucose  levels (g L^-1) were deter-mined at the following times: 1) after a 12 hours period prior to drug administration, 2) An hour after the oral administration of the extract (250-1000 mg kg^-1), its fractions (1000 mg kg^-1), Glibenclamide (10 mg kg^-1) or the vehicle and 3) one and four hours after the oral overload of anhy-drous glucose (4 g kg^-1 body weight). The extract showed a remarkable dose-dependent down-regulation of blood glucose in fasted rats at 1000 mg kg^-1 (p<0.05) and significantly reduced or totally prevented the induction of hyperglycaemia at 500 and 1000 mg kg^-1 respectively. This Glibenclamide-like hypoglycaemic activity of the extract was found to be present in the dichloromethane and ethyl acetate fractions of the plant. Our results show that the leaves of H. floribunda possess hypoglycaemic properties and strongly suggest that its usage in traditional and to a larger extent orthodox medicine may be fully explored.