Central nervous system depressant activity of ethanol extract of Motandra guineensis (Thonn) AD. aerial parts in mice

Abstract

Background: Motandra guineensis Thonn AD. (Apocynaceae) is used for the management of pain and as a sedative in the treatment of insanity in Nigerian traditional medicine. The study investigated the neuropharmacological activities of the aerial parts of M. guineensis in mice. Methods: Classical models of tail suspension, forced swim, open field, hole board, elevated plus maze, and sodium pentobarbital-induced sleeping time tests were employed and the extract was administered at doses of 50,100 and 200 mg/kg, p.o. Oral acute toxicity test was done at the dose of 2000 mg/kg. The extract was also subjected to phytochemical tests and GC–MS analysis. Results: In tail suspension test, the extract at the dose of 200 mg/kg significantly reduced immobility time of mice compared to control while in the forced swim test, immobility time of the mice decreased in a dose-dependant manner. In the open field test, there was a significant and dose-dependant reduction in the number of lines and squares crossed compared with control. The number of head dips in the hole-board test was decreased in the extract treated groups compared to control. The extract significantly increased the time spent in the open arms of elevated plus-maze apparatus at higher doses (100 and 200 mg/kg) compared to control. The phenobarbitone-induced sleeping time was prolonged by the extract at all doses compared to control. There was no death recorded for the extract at the dose of 2000 mg/kg. Conclusion: The results indicate possible CNS depressant effect of the ethanol extract of M. guineensis, thus support the use of the plant as a sedative in the treatment of insanity in Nigerian traditional medicine.

Keywords

• Motandra guineensis
• Apocynaceae
• CNS depressant
• Acute toxicity
• GC–MS