Analgesic and anti-inflammatory activity of methanolic fraction of total ethereal leaf extract of Annona senegalensis Pers. (Annonaceae)

Annona senegalensis leaves are used in African Traditional Medicine as analgesic and anti-inflammatory drugs. This study aimed to investigate the analgesic and anti-inflammatory activities of total ethereal leaf extract (TEE) of A. senegalensis and its methanolic fraction (MF). Experiments were performed in acetic acid induced contortions in mice and carrageenan rat paw edema. The preventive effect of TEE (100 mg/kg, per os) and MF (1 mg/kg, 3 mg/kg and 10 mg/kg, per os) was evaluated in carrageenan induced edema at 1, 3 and 5 h. The analgesic effect of MF (1, 3 and 10 mg/kg, per os) was tested in mice contortions. Oral administration of MF (3 mg/kg) showed an analgesic activity less similar than 100 mg/kg of acetylsalicylic acid (ASA) administered in the same conditions (17.60±6.74 vs26.80±4.66 contortions). The analgesic activity of MF is dose dependent at the lower doses (1 and 3 mg/kg, per os). However, the prevention of mice contortions with MF is less important at a higher dose (30 mg/kg, per os). In rat paw edema, TEE (100 mg/kg, per os) and MF (1 and 3 mg/kg, per os), significantly prevented carrageenan induced edema, as compared to the control and ASA groups. The dose of 3 mg/kg per os of MF induced an edema percentage inhibition similar to 100 mg/kg per os of ASA. Similarly to analgesic activity, the prevention of rat paw edema with MF is less important at a higher dose (10 mg/kg, per os). These results show an analgesic and anti-inflammatory activity of A. senegalensis leaf extracts, justifying the use of this plant leaves in African Traditional Medicine to prevent or treat pain and inflammation.   Keys words: Annona senegalensis, leaves, pain, inflammation.