Analgesic effect of methanolic extract of Erica Arborea in mice by using hot plate test

Erica arborea L. (EA, Ericaceae) is a topical shrub or small tree predominantly found in all around the Mediterranean area such as Çanakkale, Turkey, which is used traditionally as a diuretic, urinary antiseptic, anorexiant and against constipation. However, its other pharmacological effects have not been yet elucidated clearly. The aim of this study was to investigate the analgesic effect of its hydroalcoholic-extract on hot plate test, as a model of thermal acute pain. Study was carried out on male Swiss mice weighing 30-35 g. In order to study acute pain, hot plate test with set point 50±1 °C and cut off time 50 Sec was used. Methanolic extract of aerial parts was prepared by maceration method and then its analgesic effect was studied at the doses of 10, 20 and 30 mg/kg, i.p. In addition, the methanolic fractions of 20, 40, 60, 80 and 100% were prepared by solid phase extraction method, and then their analgesic effect was investigated at the dose of 5 mg/kg, i.p. The effect of methanolic extract and fractions were compared with the analgesic effect of morphine (10 mg/kg, i.p.) as a standard analgesic drug. Results obtained from this study showed that methanolic extract of EA had analgesic effect (P<0.05) at the dose of 10 mg/kg, i.p. The analgesic effect of extract was less than (P<0.05) morphine 10 mg/kg, i.p.). Among the prepared-methanolic fractions, only the fraction 20% (10 mg/kg, i.p.) caused significant (P<0.05) analgesia. Moreover, the methanolic extract (10 mg/kg, i.p.) has not any motor deficit effect in rotarod test. We conclude that total methanolic extract and faction 20% of EA have a good pain relief effect in hot plate test. The analgesic effect of EA was also comparable to that of morphine, as a well known analgesic drug. In order to relate the analgesic effect of EA to particular phytochemicals, further investigations should be done.