Alchornea floribunda (Euphorbiaceae) leaves are widely used in African ethnomedicine for the management of acute and chronic inflammatory disorders. In the present study, bioactivity-guided fractionation led to the isolation of two known (1 and 3) and one new (2) stigmastane steroids from the hexane extract of Alchornea floribunda leaves. The anti-inflammatory activities of these compounds were evaluated using IN VITRO and IN VIVO animal models. The compounds 1, 2, and 3 at 50 and 100 microg/ear significantly (p < 0.05) inhibited xylene-induced ear edema in mice in a dose-dependent manner. The topical anti-inflammatory effect of 1 and 2 are significantly (p < 0.05) higher than that of indomethacin and prednisolone. At 20 mg/kg (i. p.), all the compounds significantly (p < 0.05) inhibited acute inflammation induced by subplantar injection of egg albumen in rats. Compound 1 exhibited an anti-inflammatory effect (50.9 % edema inhibition) comparable (p < 0.05) to that of prednisolone (48.0 % edema inhibition) at 3 h. Compounds 1, 2, and 3 (50 microg/mL) significantly (p < 0.05) inhibited heat-induced haemolysis of human erythrocytes in vitro, but had no effect on hypotonicity-induced hemolysis. The compounds were elucidated as (24R)-5alpha-stigmast-3,6-dione ( 1), 5alpha-stigmast - 23-ene-3,6-dione ( 2), and 3beta-hydroxy-5alpha-stigmast-24-ene ( 3) by spectral analysis. The results of this study show that these compounds may, in part, account for the anti-inflammatory effect of Alchornea floribunda leaves. This is the first report on the isolation and structure elucidation of these anti-inflammatory steroids from Alchornea floribunda leaves.
Georg Thieme Verlag KG Stuttgart . New York.