Objective: Hibicus sabdariffa L. is traditionally used in Africa to treat several ailments and associated diseases. Despite the extensive use of these plants in traditional health care, literature provides little information regarding its pharmacological properties even if in the last three decades, a lot of concerted efforts have been channeled into researching this local plant with pharmacological values effects. This work was therefore designed to investigate the hypotensive and antihypertensive therapeutic values effects of aqueous extract of Hibicus sabdariffa L., in order to assess the efficiency of the traditional use of this Malvaceae from Ivory Coast. Methods: The aorta of guinea pig is isolated and dose-effect tests of AEHS are recorded. Different doses of AEHS are injected to the rabbit and the effects recorded. Several drugs with a known pharmacological effect are injected in order to determine the mechanism of action of AEHS. Results: Concentrations ranging from 10-6 mg/ml and 16 mg/ml induce a dose-dependent vasorelaxation. It was estimated that vasorelaxation becomes meaningful between 10-2 mg/ml and 1 mg/ml (25 to 48 %). Under, non-significant difference between 10-6 and 10-4 mg/ml (0 to 4% of relaxation). The vasorelaxation becomes highly significant between 2 mg/ml and 16 mg/ml (from 68 to 100 %). The maximum relaxation is reached from 8 mg/ml, concentration from which the resting tone of the muscle not changing significantly (3.9 to 4.10 -2 mm). The effects of the aqueous extract of Hibicus sabdariffa were observed on blood pressure of the rabbit. The average normal blood pressure measured on animals was 78 ± 3.8 mmHg. The injection at doses from 10-5 g / kg b.w. to 5x10-1 g/kg b.w. shaped to a decrease of 1 to 100%, from 78 ± 3.6 to 38 ± 1.8mmHg, as drop from 1 to 100%. It was found that atropine has no effect on hypotension induced by AEHS. A dose of AEHS 6 x 10-6 g/kg b.w. that has no effect as single treatment, together with simultaneously injected acetylcholine in a dose of 10-6 mg / kg b.w., has been resulted the production of hypotension near 48.71%. Under these treatments blood pressure of the animal passes from 78 ± 3.6 mmHg to 40 ± 2.1 mmHg. Adrenaline injected at a dose of 10-4 mg / kg b.w. causes hypertension. Blood pressure goes from 78.0 ± 3.5 mmHg to 118.0 ± 3.5 mmHg. This pressure is suppressed by simultaneous injection of AEHS in dose of 8x10-3 g / kg b.w. Conclusion: It was suggested that AEHS has an hypotensive effect in normal animals and antihypertensive effect to hypertensive animals.
