Evaluation of nigerian ethnomedical plants for anti-infective and antidiabetic properties

Abstract

There is need for more scientific justifications for many African plants used ethnomedically in treating infections and diabetes. Extracts and ashes of some of them were evaluated for these activities using standard methods while their active constituents were identified using spectroscopy. Leaves of Jatropha tanjorensis, Eugenia uniflora, Bauhinia monandra, Stachytarpheta cayennensis, Gongronema latifolium stem and root, and Clausena lansium stem bark had antihyperglycaemic actions that were due to insulin release. Insulin stimulation was reported as an unreported mechanism of their actions. Insulinotropic quercetin, isoverbascoside, 1:1 mixture of α- and β-amyrin cinnamates, and chalepin and imperatorin were the active constituents of the last four plants. HPLC confirmed their relative proportions in the active fractions, while synergism in some of the constituents and active fractions were also observed. Rutin from B. monandra was a pro-drug. Murraya koenigii was slow acting due to its insulin inhibitory carbazoles. The various plants may help in the management of either type 2 diabetes due to insulin resistance or its insufficiency. Six plants with higher activities than glibenclamide gave the hope of discovering new templates for drug development. Ashes containing “antidiabetic” trace elements had better activities than their extracts, which were attributable to their insulinotropic effects. The most active antiplasmodial compound of G. latifolium was lupenyl acetate. Larvicidal plants may complement anti-malarial activities in malarial control. Absence of toxic elements may confirm the safety of these herbal drugs. Their additional hepatoprotective, anti-microbial, -trichomonal, -inflammatory and trypanocidal properties may account for reduced death of African sufferers using herbal drugs singly or co-administered with orthodox drugs. Implications of these results in the management of diabetes will be presented.