Antiedematogenic and Free Radical Scavenging Activity of Swertiamarin Isolated from Enicostemma axillare

Swertiamarin, a secoiridoid isolated from the ethyl acetate extract of Enicostemma axillare, was evaluated for antiedematogenic activity using carrageenan-, formalin-, and histamine-induced paw edema methods in rats. In the carrageenan-induced method, the percentages of edema inhibition obtained after 5 h induction were 38.60, 52.50, and 45.44, respectively, for 100 and 200 mg/kg bw swertiamarin and 100 mg/kg bw of standard diclofenac sodium given orally. The activity of swertiamarin at 200 mg/kg bw was found to be superior to that of standard diclofenac sodium in all these methods. Swertiamarin was also screened for in vitro antioxidant activity using seven different methods: good activity was observed in ABTS and hydrogen peroxide methods, and moderate activity was observed in hydroxyl radical by deoxyribose and lipid peroxidation methods, with IC50 values of 2.83, 5.70, 52.56, and 78.33 mu g/mL, respectively. The total antioxidant capacity was found to be 4.51 mM of ascorbic acid per gram of swertiamarin. Swertiamarin possesses antiedematogenic and in vitro antioxidant activities, and it may be the active constituent responsible for the anti-inflammatory activity of E. axillare.