Potential analgesic activity of the methanolic F4 fraction of leaf extracts of Annona senegalensis Pers. (Annonaceae)

Objectives: Pain management is provided by analgesics. While considerable progress has been made in recent years due to better knowledge of the pathophysiology and mechanism of pain, the search for new, more effective analgesics with fewer side effects remains relevant. Previous work carried out at the pharmacology laboratory of the Faculty of Medicine, Pharmacy and Odontology of UCAD (Senegal) had shown an anti-inflammatory activity of the ether extract, as well as that of the methanolic fraction and of ethyl acetate from Annona senegalensis leaves. This study concerns the fractionation of the total methanolic and ethyl acetate fractions by chromatography on a Sephadex column. A phytochemical characterization of the fractions obtained, followed by the study of the analgesic activity of the derivative fractions of the methanolic and ethyl acetate extracts carried out in mice. Methods: Sephadex gel fractionation yielded ten fractions. Characterization tests were carried out on the total extracts and the different derivatives fractions. Results: Phytochemical characterization of the fractions revealed the presence of tannins, alkaloids, flavonoids, sterols and triterpenes. The F4 and F'4 fractions, rich in sterols and triterpenes, significantly reduced the number of cramps at low doses (1 mg/kg and 3 mg/kg). Conclusion: The presence of sterols and triterpenes in the methanolic F4 fraction of the leaves of Annona senegalensis could be the cause of the analgesic activity of the plant. Keywords: Annona senegalensis, phytochemistry, sterols and triterpenes, analgesic.