New Bioactive Macrocyclic Diterpenoids from Euphorbia helioscopia

Three new macrocyclic diterpenoids, euphoscopoids A – C ( 1 – 3 ), including two new jatrophanes and a new lathyrane, were isolated from the whole plant of Euphorbia helioscopia . Their structures were elucidated by spectroscopic methods. Antifeedant and cytotoxic activities of these isolates were evaluated. All compounds showed significant antifeedant activity against a generalist plant‐feeding insect, Helicoverpa armigera , with EC 50 values ranging from 2.05 to 4.34 μg/cm 2 . In addition, compound 2 showed moderate cytotoxicity against tumor cell lines NCI ‐H1975, HepG2, and MCF ‐2, while compounds 1 and 3 were not active at 80 μ m . The results suggested not only the defensive function of macrocyclic diterpenoids in E. helioscopia against insect herbivores, but also their potential applications as new natural insect antifeedants.