Cytotoxic Lignan Esters from Cinnamomum osmophloeum

! The bark and roots of Cinnamomum osmophloeum are widely used in Taiwan as spice substitutes for C. cassia. We have isolated three novel lignan esters, one dibenzylbutane-type ligan ester [9,9'di- O-feruloyl-(+)-5,5'-dimethoxy secoisolariciresinol (3)] and two cyclolignan esters [(7' S, 8' R, 8R) -lyoniresinol-9-O-(E)-feruloyl ester (5) and (7' S, 8' R, 8R)-lyoniresinol-9,9'-di-O-(E) -feruloyl ester (6)], and several known lignans from the heartwood and roots of C. osmophloeum. We identified these compounds using 1D and 2D NMR spectroscopy and mass spectrometry. Cytotoxicity assays of these novel lignan esters revealed that compound 6 has strong activities against human liver cancer (HepG2 and Hep3B) and oral cancer (Ca9-22) cells, with IC50 values of 7.87, 4.31, and 2.51 mu g/mL, respectively.