Hypotensive Effect of an Aqueous Extract of Leaves of Lophira lanceolata (Ochnaceae), A Plant Known to Be Antihypertensive, in Rabbits

Lophira lanceolata (Ochnaceae) is a plant commonly used in traditional African medicine to treat a number of illnesses, including hypertension. The aim of the present study was to evaluate the hypotensive effects of an aqueous extract of leaves of Lophira lanceolata on arterial hypertension in rabbits. A qualitative phytochemical study was conducted to determine the various secondary compounds contained in this extract. Using a Ludwig manometer, consisting of a U-shaped tube containing mercury surmounted by a writing stylus, the blood pressure of rabbits was recorded on smoked paper wound around a cylinder rotating at constant speed. The doses of test substances are administered to the rabbits via its exposed saphenous vein. The qualitative phytochemical study carried out with the aqueous extract of dried Lophira lanceolata leaves revealed the presence of sterols, polyphenols, flavonoids, saponosides, quinone compounds, alkaloids and gall tannins. Aqueous extract of Lophira lanceolata, in doses ranging from 1 to 25 mg/kg body weight, induces dose-dependent hypotension. This hypotension is considerably reduced by atropine, a competitive inhibitor of muscarinic cholinergic receptors. This suggests the presence of muscarinic cholinomimetic active ingredients in the aqueous extract of dried Lophira lanceolata leaves. These principles could be alkaloids and/or flavonoids contained in this extract.