Analgesic effect of the methanol extract of Erica arborea (L.) in mice using formalin test

Abstract

Background and the purpose of the study: Erica arborea L. (Ericaceae) has been used in Turkey folk medicine as a diuretic, urinary antiseptic and laxative. However, its other pharmacological effects have not been yet elucidated clearly. The aim of this study was to investigate analgesic effects of its methanolic (MeOH) extract in mice using formalin test, as a model of tonic inflammatory pain. Methods: The MeOH extract of aerial parts and its fractions (20, 40, 60, 80 and 100% MeOH in water) were prepared by maceration and solid phase extraction method respectively. Effects of the MeOH extract (10, 20 and 30 mg/kg, i.p.) and different fractions (5 mg/kg, i.p.) were compared with analgesic effects of the morphine (10 mg/kg, i.p.) and indomethacine (5 mg/kg, i.p.) as standard analgesic drugs. Results and major conclusion: Results showed that the MeOH extract of E. arborea (10 mg/kg, i.p.) similar to the morphine (10 mg/kg, i.p.) and indomethacen (5 mg/kg, i.p.) decreased formalin-induced paw licking time,. Among the prepared-fractions of the MeOH extract, only fraction of 20% (5 mg/kg, i.p.) caused significant decrease in paw licking behavior. Moreover, the MeOH extract (10 mg/kg, i.p.) did not produce any motor deficit effects in rotarod test. From the results it may be concluded that the MeOH extract and faction of 20% of E. arborea have a good analgesic effects in formalin test.