Effect of triterpene saponins from roots of Ampelozizyphus amazonicus Ducke on diuresis in rats

Ethnopharmacological relevance: Ampelozizyphus amazonicus Ducke is a plant used in Brazilian folk medicine to both prevent malaria and act as a depurative. Aim of the study: We have investigated the effects of an ethanol crude extract of roots of Ampelozizyphus amazonicus (CEaD)), a chemically characterized saponin mixture (SAPAaD), as well as a saponin-free fraction (SAPlaD-free) obtained from CEAaD on diuresis in rats. Materials and methods: Wistar rats under ad libitum water conditions or water deprivation for 12 h prior to the start of the experiment were volume-expanded with 0.9% NaCl (4% body weight, by gavage) containing either CEAaD, SAPAaD, or SAPAaD-free at the doses indicated in the text. Rats were individually housed in metabolic cages, and urine volume was measured every 30 min throughout the experiment (3 h). Results: CEAaD increased urine volume in rats under conditions of both free access to water and under water deprivation. In the latter condition, CEAaD (150mg/kg) increased the urine volume from zero to 0.9 +/- 0.1 ml/120 min, n = 6). Similarly, the SAPAaD-free (50-200 mg/kg) mixture also increased the urine volume. In contrast, SAPaD (12.5-1000 mg/kg) produced a significant reduction (p<0.01) in diuresis under conditions of both water deprivation and with free access to water prior to the start of the experiment. Conclusion: Our data indicate that CEAaD contains compounds that cause both diuresis and antidiuresis and that the antidiuretic effect is due mainly to the presence of saponins. (C) 2009 Elsevier Ireland Ltd. All rights reserved.