Diuretic activity and neuropharmacological effects of an ethanol extract from Senna septemtrionalis (Viv.) H.S. Irwin & Barneby (Fabaceae).

Ethnopharmacological relevance Senna septemtrionalis (Viv.) H.S. Irwin & Barneby (Fabaceae) is a shrub empirically used as diuretic, and for the treatment of neurological disorders. These pharmacological effects have not been previously evaluated.To evaluate the diuretic and CNS effects of a standardized ethanol extract of Senna septemtrionalis aerial parts (SSE).Gas chromatography mass spectrometry was used to perform a chemical analysis with SSE. In all tests, SSE was evaluated from 10 to 100 mg/kg p.o. The diuretic activity of SSE was assessed in mice individually placed in metabolic cages. After 6 h, the urine volume and the electrolyte excretion (Na and K) were measured. The role of prostaglandins and nitric oxide was assessed administrating mice with indomethacin and N(ω)-nitro-L-arginine methyl ester (L-NAME), prior the administration of 100 mg/kg SSE. The sedative effects of SSE were analyzed with the pentobarbital-induced sleeping time test. The effects of SSE on motor coordination in mice were evaluated with the rotarod test. The antidepressant-like activity of SSE was analyzed with the forced swimming test (FST) and the tail suspension test (TST). The role of 5-HT2 receptor, α1-and α2-adrenoceptors, or muscarinic receptors was assessed administrating mice with cyproheptadine, prazosin, yohimbine, and atropine, respectively, prior the administration of 100 mg/kg SSE in the FST. The anxiolytic-like activity of SSE (10-100 mg/kg p.o.) was assessed using the light-dark test (LDB), the elevated plus maze test (EPM), the cylinder exploratory test, and the open field test (OFT). The anticonvulsant effect of SSE (1-100 mg/kg) was evaluated in mice administered with different convulsant agents: strychnine, pentylenetetrazol (PTZ), isoniazid (INH) or yohimbine.

The main compound found in SSE was D-pinitol (42.2%). SSE (100 mg/kg) increased the urinary volume (2.67-fold), as well as the excretion of Na (5.60-fold) and K (7.2-fold). The co-administration of SSE with L-NAME or indomethacin reverted the diuretic activity shown by SSE alone. SSE lacked sedative effects and did not affect motor coordination in mice. SSE (100 mg/kg) showed higher and similar antidepressant-like effect, compared to 20 mg/kg fluoxetine, in the FST and TST, respectively. The co-administration of SSE with yohimbine reverted the antidepressant-like activity shown by SSE alone. SSE (100 mg/kg) showed anxiolytic-like activity in the four models of anxiety, with similar activity with 1.5 mg/kg clonazepam. The seizure-protective effect of SSE was ED₅₀ = 73.9 ± 8.4 mg/kg (INH) and 40.4 ± 5.2 mg/kg (yohimbine).

The diuretic effects of SSE involve the possible contribution of prostaglandins and nitric oxide. SSE showed moderate anxiolytic and anticonvulsant effects, whereas the participation of α2-adrenoceptors is probably associated in the antidepressant-like effects of SSE.