Evaluation of Diuretic Activities of Hydro-Alcoholic Extract and Solvent Fractions of the Roots Of Withania Somnifera L. (Solanacaea) in Rats

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Addis Ababa University


Background: Withania somnifera (Local name ‘Gisawa’) is used in folkloric medicine for the management of hypertension in different parts of the world including Ethiopia, this may be due to its diuretic activity. However, it has not been yet scientifically validated for its efficacy and safety. Objective: The aim of this study was to investigate the diuretic potential of both hydroalcoholic (80% methanol) extract and solvent fractions of the hydro-alcoholic root extract of W. somnifera in rats. Methods and Materials: The roots of W. somnifera used in this study were collected from Addis Ababa, which was then identified and authenticated by a taxonomist. The plant materials were garbled, dried under shade and grounded which were then macerated in 80% methanol to give the crude extract. A portion of the crude 80% methanol extract was further partitioned sequentially using solvents of increasing polarity to give chloroform, n-butanol fractions and the aqueous residue. Rats were randomly divided into five groups; two control groups (positive and negative controls) and three test groups each comprising six rats. Group I served as negative control and received distilled water 10 ml/kg, Group II served as a positive control and was given a standard drug 10mg/kg hydrochlorothiazide, Group III, IV and V were test groups and received 200, 400 and 600 iv mg/kg of the hydro-alcoholic extract, respectively. And a similar grouping was used for the solvent fractions. Urine output was collected up to 24 h and analyzed for electrolytes. Results: The hydro-alcoholic extract increased diuresis significantly at the doses of 400 and 600 mg/kg (p<0.001), while the solvent fractions of the hydro-alcoholic extract the aqueous and n-butanol fractions significantly increased urine volume (p< 0.01) at 400 mg/kg, with maximum urine output at the highest dose. Regarding electrolyte excretion, the larger doses of both hydro-alcoholic extract and aqueous fraction had increased natriuresis (p<0.001), while the effect on kaliuresis were smaller when compared with the standard. Phytochemical analysis revealed the presence of secondary metabolites; include tannins, terpenoids, flavonoids and saponins, which could be the responsible component (s) for the diuretic activity. Conclusion: The results of the present study indicated that the plant is endowed with significant diuretic activity providing evidence for its traditional claim. The increased diuresis effects of the crude extracts and fractions may be attributable for presence of increased polarity of phytoconstitutents. Key words: Withania somnifera, hydrochlorothiazide, diuresis, natriuresis and kaliuresis



Withania somnifera; Hydrochlorothiazide; Diuresis; Natriuresis and kaliuresis