Diuretic herb Gomphrena celosioides Mart. (Amaranthaceae) promotes sustained arterial pressure reduction and protection from cardiac remodeling on rats with renovascular hypertension.

ETHNOPHARMACOLOGICAL RELEVANCE: Gomphrena celosioides Mart., belonging to the Amaranthaceae family, is a weed known as "perpétua," and its ethnopharmacological use is to treat of urinary tract disorders and kidney stones. Urinary tract disorders and kidney stones could include several pathological conditions such hypertension, diuretic and lithiasic problems. In the present work a model of renovascular hypertension was developed in vivo to investigate its usefulness as an antihypertensive drug. AIM OF THE STUDY: Evaluate the effect of acute and 28 day oral administration of G. celosioides extract on systemic arterial pressure and diuresis of renovascular-hypertensive rats, as well as its effect on cardiac remodeling and vascular reactivity. MATERIALS AND METHODS: Ethanolic extract of G. celosioides (EEGC) was used. To induce renovascular hypertension, adult male Wistar rats were submitted to Goldblatt 1K1C or 2K1C surgery. The mean arterial pressure (MAP) of 1K1C animals was directly assessed by cannulation of the carotid artery before and after intraduodenal acute administration of 30, 100 or 300 mg/kg of EEGC. For the 4-week assay, 2K1C animals received daily treatments with water (control group), 100 mg/kg EEGC or 15 mg/kg enalapril for 28 days. Diuresis and caudal blood pressure were assessed weekly, and at the 28th day of treatment, the MAP was directly quantified shortly before euthanasia. Internal organs were removed, weighed and routinely processed for histology and the left ventricle wall was measured. Blood was collected for biochemical analysis and mechanism investigation by quantification of angiotensin converting enzyme (ACE) activity and aldosterone, nitrite and thiobarbituric acid reactive substances (TBARS) concentration. The rats' mesenteric beds were isolated and cannulated to have their pressure variation assessed after crescent doses of phenylephrine (Phe), acetylcholine (ACh) and sodium nitroprusside (SNP). RESULTS: EEGC acutely reduced MAP the dose of 100 mg/kg. In the 4-week assay, EEGC acted as diuretic after acute administration after 1, 2, 3 and 4 weeks of treatment. EEGC also acted as an antihypertensive and it showed significant difference already after 1 week (and after 3 and 4 weeks) compared to control, with its MAP close to pre-surgery values at the end of the experiment. It promoted ACE inhibition, which led to lower aldosterone levels. The lower TBARS and higher nitrite concentration found in the EEGC group suggest antioxidant activity and NO maintenance. Moreover, EEGC counteracted the impairment of vascular reactivity induced by renovascular hypertension. The extract group presented thinner left ventricle wall compared to the control, meaning reduced hypertension-induced cardiac remodeling. CONCLUSIONS: The G. celosioides diuretic effect is maintained on renovascular hypertensive rats and can reduce the blood pressure after the first week of treatment by inhibiting ACE and these effects are longstanding and strong enough to promote protection against cardiac remodeling. Therefore, it shows potential as an antihypertensive drug.

Mechanisms underlying the diuretic effect of Gomphrena celosioides Mart. (Amaranthaceae).

ETHNOPHARMACOLOGICAL RELEVANCE: Gomphrena celosioides (Amaranthaceae) is a native medicinal plant found in Mato Grosso do Sul State that is used for treating urinary tract and kidney stones. This study aimed to evaluate the diuretic effects of ethanolic extract from G. celosioides (EEGC) on acute and extended diuresis to provide a pharmacological basis for its use in traditional medicine. AIM OF THE STUDY: To evaluate the diuretic and natriuretic activity of EEGC and its mechanism of action in an animal model. MATERIALS AND METHODS: EEGC (30, 100 and 300mg/kg) was orally administered in male Wistar rats, and urinary excretion was measured at intervals of up to 8h after administration. To evaluate participation of the nitric oxide (NO), prostaglandin and bradykinin pathways in its effect, respective inhibitors were also administered together with effectives doses of EEGC and compared with control groups. A 7-day model with daily administration and urine measurement was also carried out. RESULTS: Oral administration of doses of 100 and 300 significantly increased urine output after 8h compared to the control group. It was observed this effect is dependent on the NO, prostaglandin and bradykinin pathways because their inhibitors reduced the diuretic effects of EEGC. Moreover, after 7 days of treatment, the effect was sustained and a decrease in serum aldosterone was observed in the extract group. CONCLUSION: According to the results, G. celosioides extract showed diuretic and natriuretic effects associated with more than one mechanism of action. Considering that all diuretic drugs are currently available for the treatment of volume and electrolyte disturbances, especially hypertensive status, the present results may have clinical relevance and open new possibilities for the development of new natural diuretics from G. celosioides.