Isolation and identification of a new ent-kaurane diterpenoid from the leaves of Isodon japonica.

A new ent-kaurane diterpenoid, 3, 14, 16-trihydroxy-ent-kaurane (1), together with seven known diterpenoids (2-8), was isolated from the leaves of Isodon japonica. Their structures were elucidated by spectroscopic methods, including 1D and 2D NMR experiments, IR, HR-ESI-MS and X-ray crystallographic analysis.