Analgesic effect of the aqueous seed extract of Persea Americana Mill (Lauraceae)

Abstract

Persea americana, Mill (Lauraceae) is one of the medicinal plants used in Nigeria for pain relief. Based on its ethnomedicinal use in pain management, the seed of the plant was extracted with distilled water and screened for analgesic activity. The analgesic screening was done in mice using four models: acetic acid-induced writhing; formalin -induced pain, tail immersion and hot plate methods. The mice were divided into five groups of five each. The first group in all models served as control and received normal saline, the next three groups received either 100, 200 or 400 mg/kg of the extract respectively. The last group was given a reference drug, either pentazocine (10 mg/kg) or aspirin (100 mg/kg). The extract at all doses tested showed a significant reduction of the number of writhes (p < 0.05) compared with the control. The extract also showed significant reduction of the paw licking time in the formalin induced pain test. Its effect was about the same in both phases (p<0.05). A significant increase in the mean reaction time of mice in the tail immersion and hot plate tests (p<0.05) was also produced by the extract in comparison with the control. Inhibition of the synthesis of prostaglandins may account for its peripheral analgesic effect, while its action on central receptors may account for its central analgesic activities. In conclusion, the plant has significant non-dose dependent peripheral and central analgesic effects.

Keywords: Writhes, neurogenic pain, peripheral pain, crude extract, Persea americana

Journal of Pharmaceutical and Allied Sciences, Vol. 10 No. 3 (2013)