Cytotoxic lignans from Viburnum foetidum.

Two new lignans, 3,4,4'-trihydroxy-3',9-dimethoxy-9,9'-epoxylignan (1), 3,4'-dihydroxy-3',4, 9-trimethoxy-9,9'-epoxylignan (2), together with one known compound, 4,4'-dihydroxy-3,3',9-trimethoxy-9,9'-epoxylignan (3), were isolated from the 95 % EtOH extract of Viburnum foetidum. The structures of the two new compounds were elucidated on the basis of 1D, 2D-NMR, and mass spectral analysis. All the lignans were in vitro evaluated for their cytotoxic activities against four tumor cell lines (A549, SK-OV-3, SKMEL-2 and HCT15).