Effets pharmacologiques d’un extrait aqueux de Bidens pilosa L. (Asteraceae) sur le système cardiovasculaire de mammifères

Pharmacological effects of an aqueous extract of Bidens pilosa L.(Asteraceae) on the cardiovascular system of mammalsThe crude aqueous extract of Bidens pilosa L. (Asteraceae), for concentrations ranging from 1x10-3 to 1.4x10-2 g/kg of body weight (b. w.) induced a transient dose dependant hypotension in the rabbit whereas the respiratory wide range and frequency were lessaffected. On the isolated heart of rat, this natural substance caused negative inotropic and chronotropic effects from the concentration of 10-10 mg/mL. These effects reached their maximum values at 10-8 mg/mL and then decreased at 10-6 mg/mL. At 10-4 mg/mL,no major changes were noticed in the recordings. These results suggest that the hypotension induced by Bidens pilosa L. could result, onthe one hand, from the relaxing effects observed by some authors on the vascular smooth muscle and on the other hand, from the cardiodepressant effects of the active principles contained in the plant.Three kinds of active principles were revealed in the presence of atropine, a muscarinic cholinoceptors antagonist. These are : 1) Muscarinic cholinomimetic active principles inhibited by atropine.2) Cardiodepressant principles insensible to atropine.3) Cardioactive principles acting at high doses of Bidens pilosa.At the dose of 1.3x10-1 g/kg of b.w., the crude extract of Bidens pilosa caused a deep hypotension followed by a respiratory arrest lethal for the rabbit. The results obtained justify the use of Bidens pilosa in traditional medicine to treat hypertension