Assessment of antidepressant and sedative-hypnotic activities of methanolic crude extracts of Stephania japonica (Thunb.) Miers. whole plants

In this study, methanolic crude extracts of Stephania japonica (Thunb.) Miers. (MESJ) whole plants were examined for possible antidepressant and sedative-hypnotic activities. Herein, the forced swimming test and tail suspension test were conducted to explore the antidepressant activity. In addition, the open field test and hole-board test were performed to evaluate the sedative-hypnotic activities. In the acute toxicity test, the MESJ ensured safety up to a dose of 2000 mg/kg, p.o. The experimental doses were 100 and 200 mg/kg p.o. In both the forced swimming test and tail suspension test, the extract significantly (p<0.01 and p<0.05) inhibited immobility time in a dose dependent manner compared to the control. These results (13.56-26.46% inhibition) indicate the mild antidepressant activity of MESJ compared to nortriptyline (60.4-64.6% inhibition). The open field test and hole-board test demonstrated the dose dependent significant (p<0.001, p<0.01 and p<0.05) and moderate sedative-hypnotic activities of the extract compared to diazepam. However, these activities were found to gradually decrease after 60 min in the open field test and must be considered as short-term activities, compared to diazepam. It can be claimed that the methanolic crude extract of Stephania japonica possesses mild antidepressant and moderate but short-term sedative-hypnotic activities.