A Diterpenoid with a New Skeleton and Cytotoxic Terpenoids Isolated from <i>Amentotaxus formosana</i>

Abstract

Abstract The new diterpenoid 6 α ‐hydroxy‐ ent ‐kaur‐16‐en‐15‐one ( 1 ) and a diterpenoid with a new skeleton, i.e. , amentotaxin BB ( 5 ), as well as three new lanostanoids, i.e. , (3 β ,23 R )‐3‐methoxy‐24‐methylenelanost‐8‐en‐23‐ol ( 6 ), (23 S )‐23‐methoxy‐24‐methylenelanost‐8‐en‐3‐one ( 7 ), and (3 β ,24 ξ )‐3‐methoxy‐24‐methyl‐9,19‐cyclolanostan‐25‐ol ( 8 ), were isolated from the bark and leaves of Amentotaxus formosana. Their structures, including the relative configurations, were elucidated from spectroscopic data. Compound 1 and a known compound, ent ‐kaur‐16‐en‐15‐one ( 2 ), showed potent cytotoxic effects against a number of cancer cells in vitro.