RESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Acanthospermum hispidum DC. is an important medicinal herb that belongs to family Asteraceae, popularly used as a diuretic and hypotensive in the region of Pantanal, state of Mato Grosso do Sul, Brazil. Despite the relevance of this species throughout the country, there are no detailed studies about its possible ethnobotanical indication. AIM: To carry out a detailed ethnopharmacological investigation of the cardio-renal properties of A. hispidum. MATERIALS AND METHODS: First, a detailed morpho-anatomical study with the purpose of characterizing and providing quality control parameters for the species was carried out. Then, purified aqueous extract (ESAH) was obtained and a detailed phytochemical investigation about its main secondary metabolites was performed. In addition, a thorough acute toxicological study was conducted to evaluate the actual toxic effects of this preparation. Finally, the possible diuretic and hypotensive effects of ESAH on male Wistar rats (30, 100, 300mg/kg; intraduodenally) were evaluated, and using pharmacological antagonists or inhibitors, the involvement of prostaglandin/cAMP and nitric oxide/cGMP pathway and potassium channels in ESAH-induced hypotension was investigated. RESULTS: The analyses performed by liquid chromatography-mass spectrometry showed that the main secondary metabolites present in ESAH were phenolic compounds, such as caffeoylquinic acids (chlorogenic acid), dicaffeoylquinic acids and glycosylated flavonoids (quercetin glucoside and galactoside). ESAH did not induce any acute toxic effects and did not affect the urinary volume or renal excretion of electrolytes in Wistar rats. On the other hand, intraduodenal administration of ESAH induces a significant acute hypotensive effect. Previous treatment with N(G)-nitro-L-arginine methyl ester, methylene blue, or tetraethylammonium fully avoided the hypotensive effect of ESAH. All other parameters were not affected by treatment with ESAH. CONCLUSION: Data obtained in this study allow us to suggest that ESAH obtained from A. hispidum presents an important acute hypotensive effect, which appears to be dependent on the nitric oxide/cGMP pathway. This study presents new evidences about the therapeutic potential of this species when acute hypotensive response is required.
