Antioxidant and orofacial anti-nociceptive activities of the stem bark aqueous extract of Anadenanthera colubrina ( Velloso) Brenan ( Fabaceae)

The anti-nociceptive and antioxidant activities of the Anadenantheracolubrina stem bark aqueous extract (AEAC) were investigated. AEAC (30g/mL) reduced 94.8% of 2,2-diphenyl-1-picrylhydrazyl radical and prevented 64% (200g/mL) of lipid peroxidation caused by 2,2-azobis(2-methylpropionamidine) dihydrochloride-induced peroxyl radicals. AEAC treatment (200 and 400mg/kg) significantly (p<0.001) reduced mice orofacial nociception in the first (61.4% and 62.6%, respectively) and second (48.9% and 61.9%, respectively) phases of the formalin test. Nociception caused by glutamate was significantly (p<0.001) reduced by up to 79% at 400mg/kg, while 56-60% of the nociceptive behaviour induced by capsaicin was significantly inhibited by AEAC (100-400mg/kg). Mice treated with AEAC did not show changes in motor performance in the Rota-rod apparatus. It appears that AEAC is of pharmacological importance in treating pain due to its anti-nociceptive effects, which were shown to be mediated by central and peripheral mechanisms.