Studies on the mechanisms of anti-inflammatory activity of the extracts and fractions of Alchornea floribunda leaves

Objective: Alchornea floribunda leaves are widely used in ethnomedicinal management of inflammatory disorders. The present work is aimed at investigating this folkloric use. Methods The anti-inflammatory effect of the leaf extracts and fractions was investigated in experimental animal models of acute and chronic inflammation. The possible mechanisms by which the two most active fractions, hexane (HE) and ethyl acetate (EF) exert their effects were also investigated. Results The crude extract (200 mg/kg) showed moderate inhibition of egg albumen-induced edema in rats (To edema inhibition = 54.69) at 4 h. HE and EF showed very high activity (% edema inhibition of 81.25 and 67.19 respectively at 200 mg/kg) at 4h as compared to the control. Both fractions ameliorated arthritis induced by formaldehyde in rats. At 400 mg/kg, HE evoked a significant irritation of gastric mucosa in rats. EF (200 mg/kg, p.o.) significantly inhibited leucocytes ( % inhibition=36.79) migration in vivo, but could not stabilize heat and hypotonicity-induced lysis of human erythrocyte at 200 and 400 mu g/mL in vitro. Phytochemical investigation revealed the presence of terpenoids and steroids in HE and flavonoids, tannins and saponins in EF. Conclusion These results suggest that the leaves of Alchornea floribunda possess anti-inflammatory activity in acute and chronic inflammation. The activity may derive from a combination of inhibition of prostaglandin synthesis and leucocytes migration. The phytochemical constituents detected in HE and EF may account for the anti-inflammatory activity.