Novel ent-kaurane diterpenoids from Isodon xerophilus

Further investigation on the leaves of Isodon xerophilus afforded three nov el ent-kaurane diterpenoids, xerophilusins D-F (1-3), together with seven k nown compounds, phyllostachysin Lambda (4), oleanolic acid, caffeic acid, r osmarinic acid, rutin, quercetin-3-O-beta -D-glucopyranoside, and quercetin . Structures of 1-3 were elucidated on the basis of their spectral properti es and X-ray crystallographic analysis. Compound 1 showed broad spectra inh ibiting human tumor cells and significant cytotoxicity.