Antinociceptive effects of a hydroethanolic stem bark extract of Burkea africana

INTRODUCTION: Pain is a major symptom of many clinical disorders and its relief has long been a concern for individuals across the globe. There is therefore an unmet need to search for new efficacious agents for the effective management of pain. The stem bark of the savanna tree Burkea africana (Hook) (Family: Leguminosae) is used in the Ghanaian traditional medicine for the treatment and management of various pain-related diseases. METHOD: An acute oral toxicity study in mice was conducted by administering BAE (50–5000 mg kg(−1)p.o.). Antinociceptive effect of BAE (50–1000 mg kg(−1)p.o.) was evaluated using the acetic acid-induced abdominal constriction, acidic saline-induced muscle pain and formalin-induced pain models. The antinociceptive mechanism of BAE was also assessed using the formalin-induced pain model. RESULTS: The LD(50) of BAE was thus estimated to be above 5000 mg kg(−1) since none of the animals died in the acute toxicity study. Pretreatment with BAE (50–1000 mg kg(−1)p.o.) significantly reduced the number of writhes after acetic-acid administration compared to the vehicle treated group. BAE also produced a significant and dose-dependent reversal of mechanical hyperalgesia induced by the injection of the acidic saline. Administration of BAE was able to significantly suppress both phases of the formalin test. This effect of the extract was however reversed by pretreatment with naloxone and granisetron. CONCLUSIONS: BAE exhibits antinociceptive effects in rodent pain models with a possible involvement of 5-HT(3) receptors and opioidergic pathways.