Ethnopharmacological relevance: Lagopsis supina (Steph.) Ik. -Gal. ex Knorr. has been widely used as a remedy treatment for diuresis and edema in China over 2500 years. Our previous results showed that the aqueous soluble fraction from L. supina (LSB) possessed acute diuretic effect.
Aim of the study: The aim of this study was to appraise the acute (6 h) and prolonged (7 d) diuretic effects, underlying mechanisms, and chemical profiling of LSB.
Materials and methods: The chemical profiling of LSB was performed by ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UHPLC-qTOF-MS/MS). Then, oral administration of LSB (40, 80, 160 and 320 mg/kg) and furosemide (10 mg/kg) once daily for 7 consecutive days to evaluate the diuretic effects in saline-loaded rats. The body weight, food consumption, and water intake were recorded once daily. The urinary volume, pH and electrolyte concentrations (Na+, K+, Cl-, and Ca2+) were measured after administration drugs for acute and prolonged diuretic effects. In addition, the serum levels of Na+-K+-ATPase, angiotensin II (Ang II), anti-diuretic hormone (ADH), aldosterone (ALD), atriopeptin (ANP), aquaporins (AQPs)-1, 2 and 3 were determined by ELISA kits. The mRNA expressions and protein levels of AQPs-1, 2 and 3 were analyzed by real-time quantitative PCR and Western blot assays, respectively.
Results: 30 compounds were identified in LSB based on accurate mass and MS/MS fragmentation compared to literature, among which phenylpropanoids and flavonoids could be partly responsible for the major diuretic effect. Daily administration of LSB (160 or 320 mg/kg) prominently increased urinary excretion volume after the 2 h at the first day of treatment, remaining until the 7th day. LSB did not cause Na+ and K+ electrolyte abnormalities, and has minor effect on Cl- and Ca2+ concentrations at 320 mg/kg. Furthermore, LSB observably suppressed renin-angiotensin-aldosterone system (RAAS) activation, including decreased serum levels of Ang II, ADH, and ALD, and prominently increased serum level of ANP in rats. LSB treatment significantly down-regulated the serum levels, mRNA expressions and protein levels of AQP1, AQP2, and AQP3.
Conclusion: LSB has a prominent acute and prolonged diuretic effects via suppression of AQP and RAAS pathways in saline-loaded rats, and support the traditional folk use of this plant. Taken together, LSB might be a potential diuretic agent.
Keywords: AQP; Diuretic; Electrolytes; LSB; Lagopsis supina; Phytochemical constituents; RAAS.
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