Hepatoprotective Triterpene Saponins from the Roots of Glycyrrhiza inflata

Two novel oleanane-type triterpene saponins, licorice-saponin P2 (1) and licorice-saponin Q2 (3), together with nine known compounds 2, 4-11, have been isolated from the water extract of the roots of Glycyrrhiza inflata. The structures of these compounds were elucidated on the basis of spectroscopic analysis, including 2D-NMR experiments (H-1-H-1 COSY, HSQC, HMBC and ROESY). In in vitro assays, compounds 2-4, 6 and 11 showed significant hepatoprotective activities by lowering the ALT and AST levels in primary rat hepatocytes injured by D-galactosamine (D-GalN). In addition, compounds 2-4, 6, 7 and 11 were found to inhibit the activity of PLA(2) with IC50 values of 6.9 M, 3.6 M, 16.9 M, 27.1 M, 32.2 M and 9.3 M, respectively, which might be involved in the regulation of the hepatoprotective activities observed.