Hypotensive activity of aqueous leaf extract of Croton zambesicus Linn Euphorbiaceae

Croton zambesicus is a highly valued medicinal plant in Nigeria and in the West African sub-region. It is used by traditional medicine practitioners in the treatment of various ailments including hypertension. This study aims to determine the hypotensive activity of the aqueous leaf extract of Croton zambesicus in experimental animals. The hypotensive activity of the aqueous extract was assessed in anaesthetized normotensive cats and effect of the extract on isolated right atrium of the guinea pig and isolated perfused heart of the rabbit were also determined. The aqueous extract (20-40 mg/kg i.v.) produced a significant (P<0.001) reduction in the blood pressure of the anaesthetized normotensive cat. The extract (2.5 mg/ml) produced a significant (P<0.05) reduction in the tone and rate of contraction of the isolated right atrium of the guinea pig. In addition, the extract (6.4 mg/ml) inhibited isoprenaline (10 nM)induced contraction of the isolated rabbit heart. The data obtained from this study revealed that the aqueous leaf extract of Croton zambesicus has hypotensive and cardiac depressant activities. These findings provide a pharmacologic basis for use of the plant in management of hypertension in traditional medicine.