HYPOTENSIVE EFFECT OF LAURELIA SEMPERVIRENS (MONIMIACEAE) ON NORMOTENSIVE RATS

The leaves of Laurelia sempervirens (Monimiaceae), an endemic Chilean tree known as 'Laurel', were used by the Mapuche Amerindians for treat ing headache and as a diuretic. Intravenous administration of a hydroa lcoholic L. sempervirens extract to rats, elicited a hypotensive respo nse of -27.0% +/- 2.0% in the mean blood pressure of normotensive anim als at a dose of 5 mg crude extract X kg body weight. Bioassay-guided isolation of the active 'Laurel' metabolites led to the alkaloid lauro tetanine as the main hypotensive principle of L. sempervirens leaves. At 1 mg/kg body weight, laurotetanine produced a hypotensive response of -29.0% +/- 2.1% in the mean blood pressure of normotensive rats, wi th a duration of 2 min, both comparable to those elicited by the crude extract at 5 mg/kg. In the acute oral toxicity study, 'Laurel' proved to be a very low toxicity crude drug at doses up to 3 g crude extract /kg body weight. The data obtained support the use of L. sempervirens in Mapuche traditional medicine.