Antipsychotic activity of <i>Aframomum melegueta</i> (roscoe) K. Schum (Zingiberaceae) and <i>Bidens pilosa</i> l. (Compositae) in male mice

Mental disorder features unhealthy situations such as sleep disturbance, social withdrawal and impaired role functioning, all of which are treated with herbal formulations, by traditional healers. Aframomum melegueta and Bidens pilosa are medicinal plants applied traditionally to treat psychosis. Hence, this study investigated the antipsychotic effect of the two plants in ketamine induced psychosis in mice. Pulverised plant samples consisting of Aframomum melegueta seeds and leaves, and stem of Bidens pilosa were macerated in absolute methanol for 72 h. Extracts were evaluated in mice for hyper-locomotion in open field and stereotype behaviour in transparent chamber models. Statistical analysis was done using one-way ANOVA at p < 0.05. Aframomum melegueta seeds, and B. pilosa leaves at 500 mg/kg and B. pilosastem at 250 mg/kg, decreased hyperactivity in mice, when compared to the negative control group (ketamine only). Furthermore, the highest dose (500 mg/kg) of Aframomum melegueta seeds, B. pilosa leaves and 250 mg/kg of B. pilosastem gave total tranquilising effect at 60 min into the experiment. Findings from this study revealed that seeds of Aframomum melegueta, and the leaves as well as stem of Bidens pilosa possess constituents responsible for the treatment of psychosis. This in turn justifies the traditional use of both plants in the treatment of mental illness. Different ratios of both plants under study may be combined as formulations and tested in future research, as a step towards drug development.