Phytochemical and antiemetic studies on aqueous ethanol extract of the root of <i>Senna occidentalis</i> (L.) link

Abstract

Senna occidentalis (Caesalpiniaceae) is a pan tropical shrub plant widely distributed in warm regions of the world. The root infusion of the plant has been used for the treatment of gastro-intestinal disorders including emesis. The current research is aimed at evaluating the antiemetic property of the aqueous ethanol extract and solvent fractions of the root and also verifying the classes of phytochemicals in the extract and fractions. The LD₅₀ of the extract and its solvent fractions was determined. The antiemetic property was evaluated using copper sulphate induced emesis in chicks while phytochemical screening was carried out using standard methods. The three doses of the extract (300, 150 and 75mg/kg) conferred dose-independent protection and inhibition against retching compared to the control group. At a dose of 150mg/kg, the extract completely (100%) prevented copper sulphate-induced emesis comparable to promethazine at 150mg/kg, the standard antiemetic used. Other doses of the extract 300 and 75mg/kg showed lower effect relatively. Two of the three fractions of the ethanol extract; Hexane and n-butanol fractions at 150mg/kg dose protected against retching in a similar degree (100%) demonstrated by the crude ethanol extract and the standard antiemetic promethazine at 150mg/kg, while ethyl acetate fraction exhibited its maximum protection (100%) at the lowest dose used (75mg/kg).The extract and all of its solvent fractions were found to be non-lethal at up a dose of 5000mg/kg via the oral route. Identified phytochemicals in the ethanol extract include; unsaturated steroids, cardiac glycosides, saponins and tannins. These phytochemicals were found to be distributed across different fractions of the extract in order of their polarity; Steroids and resins in the n-hexane fraction, Cardiac glycosides, unsaturated sterols, saponins and tannins in the Ethylacetate and N-butanol fractions. In addition to the ones mentioned, ethyl acetate fraction contains flavonoids. The observed antiemetic activity of the extract and fractions could be due to one or some of these phytochemicals present.

Keywords: Antiemetic, Copper sulphate, Phytochemicals, Senna occidentalis