Hepatoprotective compounds of the roots of Cudrania tricuspidata on tacrine-induced cytotoxicity in Hep G2 cells

The bioassay-guided fractionation of the MeOH extract of the root barks of Cudrania tricuspidata furnished three hepatoprotective compounds, gerontoxanthone A (2), cudraflavone B (4), gericudranin E (5), together with four prenylated Xanthones, cudraxanthone B (3), isocudraxanthone K (6), cudraxanthone C (7), cudraxanthone H (8), and a prenylated flavanone, euchrestaflavanone C (1). Compounds 4 and 5 showed significant hepatoprotective effects with the EC50 values of 37.39+/-0.4 and 39.87+/-0.7 microM, respectively, and compound 2 showed moderate hepatoprotective effect with an EC50 value of 125.9+/-1.5 microM, against tacrine-induced cytotoxicity in Hep G2 cells. Silybin as positive control showed an EC50 value of 84.76+/-0.5 microM. Isocudraxanthone K (6) is a new compound.