Abstract: AIM:To investigate the chemical constituents from the leaves of Broussonetia papyrifera.METHODS:The chemical constituents were isolated and purified by macroporous adsorptive resin D101,silica gel,and ODS column chromatography and preparative HPLC.Their structures were elucidated on the basis of 1D and 2D NMR analyses.In addition,their cytotoxic activity against human hepatoma carcinoma cells(HepG-2) were evaluated by the MTT method.Furthermore,RP-HPLC and colorimetric methods were used for the analysis of cosmosiin and total flavonoids.RESULTS:A new lignan,together with five known compounds were obtained,and their structures were characterized as(+)-pinoresinol-4'-O-β-D-glucopyranosyl-4"-O-β-D-apiofuranoside(1),cosmosiin(2),luteolin-7-O-β-D-glucopyranoside(3),liriodendrin(4),3,5,4'-trihydroxy-bibenzyl-3-O-β-D-glucoside(5),and apigenin-6-C-β-Dglucopyranside(6).Furthermore,RP-HPLC and colorimetric methods were established for the analysis of cosmosiin and total flavonoids.CONCLUSION:Compound 1 was a new lignan,and compounds 5 and 6 were isolated for the first time from the title plant.Compounds 1,4 and 6 showed definite activities against HepG-2,while the other compounds didn't show inhibitory effects.The optimal harvest time of B.papyrifera(L.) Vent.is September.