Antidepressant-like effect and toxicological parameters of extract and withanolides isolated from aerial parts of Solanum capsicoides All. (Solanaceae).

Abstract

The present work describes the evaluation of the antidepressant-like activity of the extract, fractions, and compounds obtained from the aerial parts of Solanum capsicoides. The methanolic extract (MESC) obtained by conventional maceration was partitioned with solvents of increasing polarities yielding the respective fractions of hexane (HE), dichloromethane (DCM), and ethyl acetate (EA). The dichloromethane and ethyl acetate fractions were submitted to chromatographic and spectroscopic techniques, leading to the isolation and identification of cilistadiol (1), astragalin (2), and cilistol A (3). In relation to the antidepressant activity, the extract was active against the forced swimming test (FST) at a concentration of 300mg/kg an ED50 (deffective dose that reduces 50% of immobility time) of 120.3 (117.3-123.4) mg/kg. Similar values were observed when evaluated in the tail suspension test (TST). In addition, the results showed no influence on motor behavior when evaluated in the open field test (OFT). Based on the observed profile of the MESC, dichloromethane fraction presenting the best profile, in both FST and TST test. Likewise, the fraction also did not present motor impairment when evaluated by the OFT test. Considering that the dichloromethane fraction was more effective, the isolated compounds cilistadiol and cilistol A were evaluated in the same experimental models. In FST, both compounds had a significant antidepressant-like effect, with ED50 values of 0.22 (0.16-0.28) and 1.03 (0.89-1.18) μmol/kg, respectively. When evaluated in the TST, showed ED50 values of 0.30 (0.18-0.52) and 1.49 (1.27-1.73) μmol/kg, respectively. The isolated compounds also did not present significant differences in the motor behavior when evaluated on OFT test in comparison with the control group. No toxicological parameters were observed until the highest dose of MESC (2000mg/kg), demonstrating safety in the use of this plant.