The high blood pressure is one of the main causes of death and cardiovascular diseases. Vasodilator medications are frequently used to treat arterial hypertension. The aim of this study was to evaluate vasodilator properties of three plants from North of Morocco then to quantify phenolic compounds and flavonoids in each plant extracts. The leaves of Origanum elongatum, Cistus salviifolius and Cistus laurifolius were extracted with hexane, methanol and ethyl acetate by ultrasonic apparatus. The total phenolic content, analyzed using Folin–Ciocalteu’s reagent, of the samples varied from 46.6 µg/100 mg to 153 µg/100 mg dry weight, expressed as gallic acid equivalents (GAE). The total flavonoid concentrations, detected using 2% aluminum chloride, varied from 3.63 to 5.54 µg equivalents (RE)/mg dry weight. Under different plant growth regulators induce a vasodilator effect on Wistar rat mesenteric vascular bed pre-contracted with norepinephrine. for O.elongatum, the methanolic extracts at (PP = 50 mmHg) were found to be more active than the acetylcholine with a concentration of 10-4 M taken as a reference (PP = 40 mmHg) and The vasodilator activity of methanolic extract of Cistus laurifolius at 100 μg/ml is the same as the reference (PP=40 mmHg). the vasodilator activity found in the three plants studied is due to their antioxidant power
