Cytotoxic constituents of Isodon rubescens var. lushiensis

Five new ent-kaurane diterpenoids, ludongnins F-J (1-5), along with 10 known compounds, guidongnins A-C (6-8), angustifolin (9), 6-epiangustifolin (10), sculponeatin J (11), gardenin D, 5,3',4'-trihydroxy-6,7,8-trimethoxyflavone, pedalitin, and quercetin, were isolated from the leaves of Isodon rubescens var. lushiensis. The structures of 1-5 were determined by spectroscopic analysis, as well as X-ray crystallographic analysis of 1. Compounds 1-11 were evaluated against K562 leukemia cells for their cytotoxic effects.