Antinociceptive activities of the hydroalcoholic extracts from Erythrina velutina and Erythrina mulungu in mice.

This work studied the antinociceptive effects of the hydroalcoholic extracts (HAEs) from Erythrina velutina (Ev) and Erythrina mulungu (Em) in three experimental models of nociception in mice. The extract was administered intraperitoneally to female mice at the doses of 200 and 400 mg/kg. Inhibitions of abdominal contractions were observed with the doses of 200 (88.6%; 86.8%) and 400 (95.5%; 83.5%) mg/kg of E. velutina and E. mulungu, respectively, as compared to controls. E. velutina and E. mulungu, at both doses, reduced the nociception produced by formalin in the 1st and 2nd phases and this effect was not reversed by the pretreatment with naloxone. In the hot plate test an increase of the reaction time was observed only at 60 (Ev=18.0+/-2.2; Em=20.8+/-2.52) and 90 min (Ev=20.4+/-1.71; Em=23.7+/-2.32) after the treatment with E. velutina and E. mulungu at the dose of 400 mg/kg as compared to controls (T60=11.1+/-0.74; T90=11.9+/-0.86). This effect was not reversed by naloxone. We conclude that E. velutina and E. mulungu presents antinociceptive effects, which are independent of the opioid system.