Tribulus terrestris: preliminary study of its diuretic and contractile effects and comparison with Zea mays.

Objectives: Tribulus terrestris L. (Zygophyllaceae) which is called Al-Gutub (in Iraqi dialect) or Quti;ba (in classical Arabic medicine), and Zea mays were both used alone or in combination by Iraqi herbalists to propel urinary stones. We studied the aqueous extract of the leaves and fruits of T. terrestris and the hair of Z. mays, to determine their diuretic activity and the contractile effect of T. terrestris.

Methods: The aqueous extract was filtered and the solvent was evaporated to produce a dry crude extract. The dry extract was then dissolved in physiological saline to make the required concentrations. Wistar male rats were used for the diuresis test and strips of isolated Guinea pig ileum were used for the contractility test.

Results: The aqueous extract of T. terrestris, in oral dose of 5g/kg elicited a positive diuresis, which was slightly more than that of furosemide. Z. mays aqueous extract did not result in significant diuresis when given alone in oral dose of 5g/kg, while combination of Z. mays and T. terrestris extracts produced the same extent of diuresis as that produced by T. terrestris alone. Na(+), K(+) and Cl(+) concentrations in the urine had also much increased. In addition to its diuretic activity T. terrestris had evoked a contractile activity on Guinea pig ileum.

Conclusion: T. terrestris has long been used empirically to propel urinary stones. The diuretic and contractile effects of T. terrestris indicate that it has the potential of propelling urinary stones and merits further pharmacological studies.