Campylopin from Delphinium campylocentrum, the first hetidane C20-diterpene, suggests a new alkaloid biogenetic pathway

A novel C20-diterpene, campylopin (1), was isolated from the whole herb of Delphinium campylocentrum. The elucidation of its structure was accomplished through extensive spectroscopic methods. Compound 1 represents the first hetidane-type diterpene skeleton, which may imply a new biosynthetic pathway from the atisane or hetidane-type diterpene to the hetidine-type diterpenoid alkaloid.