Euphorbesulins A–P, Structurally Diverse Diterpenoids from Euphorbia esula

Aqueous ethanol extracts of powdered twigs of Euphorbia esula afforded 16 new diterpenoids, named euphorbesulins A–P. These euphorbesulins included presegetane (1–3), jatrophane (4–14), paraliane (15), and isopimarane (16) diterpenoids as well as six known analogues. Compounds 1–3 represent a rare type of presegetane diterpenoid. Their structures were determined by analysis of the spectroscopic data, and the absolute configuration of 1 was established by X-ray crystallography. Diterpenoid 7 showed low nanomolar antimalarial activity, while the remaining compounds showed only moderate or no antimalarial activity.