Antimalarial and analgesic activities of root extract of Panicum maximum

Background: Panicum maximum is used as malarial remedy traditionally and the leaf extract has been found to possess antimalarial, analgesic and anticancer properties. Objective: The ethanol root extract of Panicum maximum were evaluated for antiplasmodial and analgesic activities in rodents. Methods: The crude root extract (137 – 547mg/kg) of Panicum maximum were investigated for antiplasmodial activity against chloroquine sensitive Plasmodium berghei infections in mice. The antiplasmodial activity during early and established infections as well as prophylactic were investigated. Artesunate 5mg/kg and pyrimethamine 1.2mg/kg were used as positive controls. Analgesic activity of the crude extract/fractions was also evaluated against acetic acid, formalin and heat-induced pains. Results: The extract dose-dependently reduced parasitaemia induced by chloroquine sensitive Plasmodium berghei infection in prophylactic, suppressive and curative models in mice. These reductions were statistically significant (p<0.001). They also improved the mean survival time (MST) from 13 to 28 days relative to control (p<0.001).  The activity of extract was weak compared to that of the standard drugs used (artesunate and pyrimethamine). On chemically and thermally- induced pains, the extract inhibited acetic acid and formalin-induced inflammation as well as hot plate-induced pain in mice. These inhibitions were statistically significant (p<0.001) and in a dose-dependent fashion. Conclusion: Panicum maximum root extract has antiplasmodial and analgesic activities which may in part be mediated through the chemical constituents of the plant. Key words: Panicum maximum, analgesic, antimalaria