Cytotoxic Bisnor- and Norditerpene Dilactones Having 7.ALPHA.,8.ALPHA.-Epoxy-9,11-enolide Substructure from Podocarpus macrophyllus D. DON

Fourteen new bisnor- and norditerpene dilactones, makilactones E-R, having a 7alpha : 8alpha-epoxy-9,11-enolide substructure, were isolated from a methanolic extract of the root and the bark of Podocarpus macrophyllus D. DON (Podocarpaceae) with thirteen known bisnor- and norditerpenoids, and the structures of those new bisnor- and norditerpenoids were determined on the basis of their spectroscopic studies. Of the thirteen known ones isolated, the structures of two, i.e., podolactone B and inumakilactone B, were revised on the basis of X-ray crystallographic analysis and spectroscopic analysis. Many of the compounds of this type isolated in this study showed potent cytotoxic activities against P388 murine leukemia cells.