Alibertia edulis (L.C. Rich.) A.C. Rich - A potent diuretic arising from Brazilian indigenous species.

ETHNOPHARMACOLOGICAL RELEVANCE: Although Alibertia edulis (L.C. Rich.) A.C. Rich decoction is used in Brazilian folk medicine due to its possible antihypertensive effect, this species has never been critically investigated as a hypotensive drug. So, the aim of this study was to evaluate the possible hypotensive and antihypertensive effects of the oral administration of Alibertia edulis aqueous extract (AEAE) in normotensive and hypertensive rats, and evaluate its inter-relation with a possible diuretic activity. MATERIAL AND METHODS: Different doses of AEAE (20, 65 and 200mg/kg) were tested on the mean arterial pressure (MAP) of normotensive Wistar rats and after induction of renovascular hypertension (two-kidney, one-clip Goldblatt model). In addition, the diuretic effects of AEAE were compared with hydrochlorothiazide (HCTZ) in an acute and repeated-dose treatment for 7 days. Volume, sodium, potassium, chloride, calcium contents, pH and density were estimated in urine samples collected after 8 or 24h. Plasma sodium, potassium, total protein, urea, creatinine, AST and ALT concentrations were measured in samples collected at the end of the experimental period (seventh day). Finally, the antioxidant activity of the AEAE was assessed using the DPPH radical scavenging and ferric ions reducing power assay. RESULTS: The intraduodenal administration of the HCTZ and AEAE significantly reduced, in a dose-dependent manner, the MAP in both normotensive and hypertensive rats. Otherwise, the heart rate was not affected by any treatment. Acute and prolonged oral administration of AEAE (200mg/kg) and HCTZ caused a significant increase in volume and urinary concentrations of sodium, potassium and chloride. Moreover, urinary calcium concentration was significantly increased after administration of AEAE (200mg/kg). Finally, AEAE was able to present important in vitro antioxidant properties. CONCLUSION: The results obtained have shown that AEAE presents potent diuretic activity and significant hypotensive and antihypertensive effect. In addition, this study may confirm part of the pharmacological activity popularly attributed to this species and opens perspective for the future use in various renal and cardiovascular diseases.

Acute and subacute toxicity of the aqueous extract of Alibertia edulis (Rich.) A. Rich. ex DC. in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Alibertia edulis, popularly known as "marmelo do Cerrado" is a native plant from the brazilian Cerrado. It has high food and ornamental potential and the tea leaves are currently used as hypoglycemic, antihypertensive and diuretic. AIM OF THE STUDY: In order to evaluate the safety of the aqueous extract of Alibertia edulis leaves (AEAE), the acute and subacute toxicity tests were performed in male and female Wistar albino rats. MATERIALS AND METHODS: The experiments were performed in accordance with the OECD guidelines 425 and 407. For the acute toxicity, one single dose of the AEAE (2000mg/kg) was administered by gavage to five female rats. The animals were observed for 14 days for any signs of toxicity and death. In the subacute toxicity, four different doses (125, 250, 500 and 1000mg/kg) of the AEAE were administered to male and female rats for 28 consecutive days. A satellite group received the maximum dose (1000mg/kg) for 28 days and remained untreated for 14 more days in order to observe reversibility, persistence, or delayed occurrence of toxic effects. The five parameters of the Hippocratic screening, body weight, food and water intake were daily observed. At the end of the experiment, blood samples were collected for the hematological and biochemical analysis. The vital and reproductive organs were inspected for any histopathological changes. RESULTS: No deaths or behavioral changes were observed during both experiments as well as no changes on organ weights, biochemical, hematological and histopathological parameters that could indicate any signs of toxicity. CONCLUSION: All doses tested can be considered safe in rats and the LD50 is higher than 2000mg/kg. Therefore, further assessments are required in order to proceed to clinical studies in humans.