Two New Lignans from the Roots of Pulsatilla koreana

Two new lignans, (2R,3R)-2 beta-(4 ''-hydroxy-3 ''-methoxybenzyl)-3 alpha-( 4'-hydroxy-3'-methoxybenzyl)-gamma-butyrolactone 2-O-(beta-D-glucopyranoside) (1) and (1S,2R,3S)-dimethyl-1,2,3,4-tetra-hydro-3,6,7-trihydroxy-1-(3', 4'-dihydroxyphenyl)naphthalene-2,3-dicarboxylate (2) together with nine known compounds (3-11) were isolated from the ethyl acetate fraction of the roots of Pulsatilla koreana. Their chemical structures were established based on physicochemical and spectroscopic data analyses. All isolates were investigated for their inhibition effects against the classical pathway of the complement system. Among them, compound 6 showed significant inhibitory activity with an IC50 value of 75.9 mu M, compounds 8 and 9 had moderate effects with IC50 values of 182.2 and 166.5 mu M, respectively.