Evaluation of the blood pressure lowering activity of leaf extract of Acalypha torta Muell

The leaf of Acalypha torta Muell. (Euphorbiaceae) is used as folk remedy in Nigeria for the treatment of hypertension. Effects of extracts of A. torta leaf on the blood pressure of anaesthetized cats were studied to examine this claim. The ethanol extract produced a significant (p < 0.0001) and dose - dependent fall in arterial blood pressure. The extract inhibited adrenaline - induced contraction of isolated rabbit aortic strips and produced a significant (p < 0.0001) and dose - dependent increase in the rate of flow of physiologic fluid through the rat hind-quarters preparation. Both evidences indicate relaxant effect of the ethanol extract on vascular smooth muscle. Calcium chloride - induced tachycardia was abolished following administration of the extract. It had no effect on the rate of contraction of the isolated rabbit heart, but reduced the force of contraction. Column chromatography was performed and Fraction L, eluted with distilled water, was found to be responsible for the reduction in blood pressure.   Key words: Acalypha torta, hypertension, antihypertensive, cat.