Effects of medicagenic acid metabolites, originating from biotransformation of an Herniaria hirsuta extract, on calcium oxalate crystallization in vitro.

ETHNOPHARMACOLOGICAL RELEVANCE

Herniaria hirsuta is traditionally used in Moroccan folk medicine for treatment of urinary stones and as a diuretic. It is rich in saponins, which are known to be deglycosylated in the colon, whereafter aglycones such as medicagenic acid are absorbed and further metabolized in the liver.

AIM OF THE STUDY

A sample of hepatic metabolites of medicagenic acid, with medicagenic acid glucuronide as the most abundant one, was evaluated for in vitro activity against urinary stones. A crystallization assay and a crystal-cell interaction assay were used to evaluate in vitro activity of hepatic metabolites of medicagenic acid on CaCO (calciumoxalate) crystals, present in the majority of urinary stones.

MATERIALS AND METHODS

In the crystallization assay the effects on nucleation of Ca and CO and aggregation of the CaCO crystals are studied. In the crystal-cell interaction assay crystal retention is investigated by determining the amount of Ca bound to injured monolayers of MDCK I cells.

RESULTS

Results of the crystallization assay showed a tentative effect on crystal aggregation. The crystal-cell interaction assay showed a significant inhibition of crystal binding, which may reduce crystal retention in the urinary tract.

CONCLUSIONS

As both formation of crystals by inhibiting aggregation and retention of crystals is affected, the beneficial effect of H. hirsuta against urinary stones may at least in part be attributed to medicagenic acid metabolites, indicating that saponins containing medicagenic acid may act as prodrugs.