Abstract Medicinal plants contain substances that are used for therapeutic purposes or as precursors for synthesis of useful drugs. Since time past, they have been used in virtually all cultures as a source of medicine. The present study is to determine the total phenolic/flavonoid contents and analgesic properties of different leaf extracts of Cochlospermum planchonii Hook. F (Cochlospermaceae) using acetic acid induced writhings in both sexes of Swiss albino mice. From the results, the total phenolic content of the hexane, ethyl acetate and methanol extracts calculated from the calibration curve (r2=0.997, 0.998, 0.999) were 50.45±1.66, 47.33±15.23 and 239.11±36.60 Gallic Acid Equivalents/g respectively, while the total flavonoid content (r2=0.992, 0.993, 0.997) were 4.94±0.50, 23.60±0.16 and 26.75±0.41 Rutin Equivalents/g respectively. The quantitative values of these secondary metabolites are quite appreciable and are used as the basis for screening the drug for antioxidant activity. The analgesic activity associated with the different leaf extracts for n-hexane, ethyl acetate and methanol extracts were also determined. From the results, the different extracts showed a significant difference (p< 0.05) in the percentage inhibition of the acetic acid induced writhing in mice in a dose related pattern with the methanol extract giving the highest activity. This extract is rich in phenolic compounds which are known to exhibit analgesic effects in animal models. It can therefore be concluded that the analgesic activity claimed by the traditional medical practitioners may have a scientific basis.
Keywords Antioxidant, Analgesic, Medicinal Plants, Cochlospermum planchonii, Phenolic.