Diuretic activity of some Withania aristata Ait. fractions.

We previously reported on the significant dose-dependent diuretic effects produced in laboratory rats by hot water infusions and methanol extracts of Withania aristata Ait., where notable increases were observed in the excretion of water and sodium, with an interesting potassium-saving effect. The present study gives the results of the diuretic effects in rats of the hexane, dichloromethane, ethyl acetate, butanol and methanol-water fractions of the previously studied methanol extract. Water excretion rate, pH, density, conductivity and content of Na(+), K(+) and Cl(-) were measured in the urine of the rats when subjected to hypersaline conditions. Of the above fractions, the methanol:water extract (100mg/kg) showed the most interesting diuretic activity (25%; p<0.01), which suggested that increase in the polarity of the extracting solvent led to an increase in the concentration of the polar compounds responsible for the diuretic effect. These data, together with previous results on the aqueous and methanol extracts, reaffirm assertions made regarding the effectiveness of the extracts of this plant against urinary pathologies in the Canary Islands folk medicine.