New lignans and cytotoxic constituents from Wikstroemia lanceolata.

Two new lignans, (-)-aptosimon ( 1) and (-)-diasesamin-di-gamma-lactone ( 2), together with twenty-two known compounds, have been isolated from the stems and roots of Wikstroemia lanceolata. The structures of the new compounds were determined through spectral analyses. The proton and carbon assignments of the known sesquiterpenoid, 1alpha,7alpha,10alpha H-guaia-4,11-dien-3-one ( 24) were revised by 2D NMR techniques. Among the isolates, three compounds, (+)-hinokinin ( 6), 2,6-dimethoxy- p-benzoquinone ( 17), and 1alpha,7alpha,10alpha H-guaia-4,11-dien-3-one ( 24) exhibited effective cytotoxicities (ED50 values < 4.0 microg mL-1) against P-388 and HT-29 tumor cell lines.