Two Lathyrane Diterpenoid Stereoisomers Containing An Unusual Trans-Gem-Dimethylcyclopropane From The Seeds Of Euphorbia Lathyris

Two novel lathyrane-type diterpenoids, the Euphorbia factors L-2a (1) and L-2b (2), and their stereoisomer Euphorbia factor L-2 (3) were obtained from seeds of Euphorbia lathyris. Both Euphorbia factors L-2a and L-2b possess an unprecedented trans-gem-dimethylcyclopropane as structural feature. Also, the Euphorbia factor L-2a is the first example of a lathyrane diterpenoid with an endocyclic 12(Z)-double bond. The structures of the molecules and their absolute configurations were elucidated by comprehensive spectroscopic analyses, Cu-K alpha radiation X-ray diffraction, and comparison with calculated electronic circular dichroism (ECD) data. The Euphorbia factor L-2b exhibited an inhibitory effect against U937 cell line with an IC50 value of 0.87 mu M.