Diuretic activity of ethanolic extract and fraction enriched in saponins from Solanum sisymbriifolium Lam. root in rats.

Objective: Solanum sisymbriifolium Lam. is a native perennial plant with chemical characteristics of therapeutic importance. In Paraguayan traditional medicine, it is attributed to antihypertensive and diuretic activities. For this reason, the objective of the study was to evaluate the effect of acute oral administration of the ethanolic extract and fraction enriched in saponins obtained from the root of S. sisymbriifolium on the diuresis profile of rats.

Materials and methods: Male Wistar rats were used, randomly distributed in 6 groups to evaluate the diuretic activity. The control group received distilled water; the diuretic group was treated with 20 mg/kg of furosemide. Two groups were treated with 50 and 100 mg/kg of the ethanolic extract of S. sisymbriifolium, and two other groups were treated with 1 and 10 mg/kg with the fraction enriched in saponins. The animals were placed in individual metabolic cages for a period of 24 h. Urine volume was determined at 5 and 24 h, and urinary electrolytes, pH, and glomerular filtration rate at 24 h.

Results: The findings indicated that both doses of the ethanolic extract and the saponin-enriched fraction significantly increased diuresis after 24 hours of treatment. Urinary pH was not affected. A significant increase in the urinary excretion of Na+ and Cl- was observed without affecting the elimination of K+ with both doses of the extracts. In addition, a significant increase in GFR was evidenced.

Conclusions: Both ethanolic extract and saponins enriched fraction, presented natriuretic and saluretic effects with a possible mechanism of action mediated, at least partially, by the inhibition of carbonic anhydrase. Furthermore, it was possible to demonstrate the participation of the COX/PG pathway in the diuretic mechanism of the extracts in male rats.