Analgesic, anti-inflammatory and antipyretic activities of methanolic leaf extract of Maerua crassifolia

Objective: To investigate the the analgesic, anti-inflammatory and antipyretic activities of the methanolic leaf extract of Maerua crassifolia in mice and rats. Methods: Acetic acid-induced writhing and tail immersion methods were used to assess analgesic activity, while xylene and carrageenan-induced paw oedema methods were used to evaluate the anti-inflammatory effect of the leaf extract. Yeast and amphetamine-induced pyrexia were used to investigate the antipyretic activity. The phytochemical analysis and oral acute toxicity of the methanolic leaf extract of Maerua crassifolia were also evaluated. Results: The leaf extract (100, 200, and 400 mg/kg) showed a dose dependent and significant (P < 0.05) inhibition of pain in acetic acid-induced writhing and tail immersion tests. The extract also produced significant (P < 0.05) anti-inflammatory activity in both paradigms. A significant (P < 0.05) reduction in hyperpyrexia was also observed with the leaf extract. The phytochemical screening revealed the presence of alkaloids, flavonoids, terpenoids, tannins, steroids, resins, saponins and cardiac glycosides. The oral median lethal dose of the leaf extract was estimated to be greater than 5 000 mg/kg in rats. Conclusions: The findings confirmed its ethnomedical use in the treatment of pains and feverish conditions.