Solenostemon monostachyus P. Beauv (Lamiaceae) is a medicinal plant used traditionally in the treatment of central nervous system (CNS) disorders. The leaf extract was investigated for antidepressant effect on the CNS. The ethanol leaf extract of S. monostachyus (75-225 mg/kg) was evaluated for CNS effect in mice using open field test, Tail suspension tests and Forced swimming test models. The extract was found to significantly (p<0.05-0.01) increased the frequency of line crossing, rearing and walling activities of mice in open field test and also decreased significantly (p<0.05-0.001) duration of immobility time of mice in force swimming and tail suspension tests. The findings of this study show that the leaf extract of S. monostachyus has a significant psychotomotor effect with a weak antidepressant activity and this supports its use in ethnomedicine for the treatment of central nervous system disorders.
KEYWORDS: Solenostemon monostachyus, antidepressant, CNS