RESUMO
CONTEXT: Solenostemon monostachyus P. Beauv (Lamiaceae) is an important herb used traditionally in the treatment of malaria, fever, and other diseases. OBJECTIVES: Antiplasmodial and antipyretic activities of S. monostachyus aerial extract were evaluated to ascertain the folkloric claim of its antimalarial and antipyretic activities. MATERIALS AND METHODS: The extract (75-225 mg/kg) and fractions (chloroform and aqueous; 150 mg/kg) of S. monostachyus were investigated for suppressive, prophylactic, and curative antiplasmodial activities against chloroquine-sensitive Plasmodium berghei infections in Swiss albino mice and for antipyretic activity against 2,4-dinitrophenol and yeast-induced pyrexia. Artesunate (5 mg/kg) and pyrimethamine (1.2 mg/kg) were used as positive controls for antiplasmodial models. Thin films made from tail blood of each mouse were used to assess the level of parasitaemia of the mice. RESULTS: The extract/fractions progressively reduced parasitaemia induced by chloroquine sensitive P. berghei infection in prophylactic (28.48-71.72%), suppressive (12.52-72.47%), and curative (22.4-82.34%) models in mice. These reductions were statistically significant (p < 0.01-0.001). They also improved significantly (p < 0.01-0.001) the mean survival time (MST) from 12.26 to 25.63 d relative to control (11.36 d). The activities of extract/fractions were incomparable with that of the standard drugs used (artesunate and pyrimethamine). The extract exerted prominent inhibition of pyrexia on dinitrophenol (87.33-90.11%, 5 h) and yeast (56.22-65.33, 5 h) induced pyrexia. Inhibition was significant (p < 0.05-0.001) from 3 to 5 h post-administration of extract and in a dose-dependent fashion. CONCLUSION: The plant may possess antiplasmodial and antipyretic effects which may in part be mediated through the chemical constituents of the plant.
