Cardiovascular effect of Artemisia afra and its constituents

The cardiovascular effects of a mixture of long chain fatty esters (C44H88O2) and scopoletin isolated from Atemisia afra and an aqueous extract of the plant were investigated in rabbits. The long chain fatty esters induced hypotensive effects at doses of 0.5, 1.0, 1.5 and 3 mg/kg. The diastolic pressure was affected more than the systolic. Aqueous A. afra extract (10-45 mg/kg) had a hypotensive effect in vivo and a dose-dependent biphasic effect on the heart in vitro. Lower doses induced an initial cardiostimulation followed by cardiodepression, whereas higher doses were mainly cardiodepressant. Scopoletin, a coumarin derivative, at a dose of 1.0-2.5 mg, induced a dose-dependent decrease in inotropic activity plus an appreciable decrease in chronotropic effects, especially at higher dose levels. These results suggest that A. afra and its constituents are potentially useful for the management of hypertensive conditions.