Taxodinoids A-D, four heptacyclic C40 diterpene dimers from the seeds of Taxodium distichum

Taxodinoid A (1), an unprecedented bis-diterpenic anhydride featuring a 6/6/7/6/6/6 heptacyclic core skeletons, and three novel pyrane-fused abietane-type diterpene dimers (2–4), were obtained from the seeds of Taxodium distichum. Their structures were elucidated by spectroscopic data, X-ray crystallograph and electronic circular dichroism calculation. A biosynthetic pathway and suppressing migration activity against U2 OS cells were also discussed.