Highly irritant ingenane type diterpene esters fromEuphorbia cyparissias L.

Summary From the roots ofEuphorbia cyparissias L. a highly irritant diterpene ester fraction was isolated and further resolved into its constituents. Together with some less active and some inactive isomers, the pure Euphorbia factors were characterized as new diesters of 13-hydroxyingenol and as triesters of the new 13,19-dihydroxyingenol. The Euphorbia factorsCy₆,Cy₁₁ andCy₁₄ are the strongest irritants of the ingenane ester type hitherto known,Cy₁₁ being at least as active as the standard diterpene ester type irritant 12-O-tetradecanoylphorbol-13-acetate (TPA).Acknowledgments. We are greatly indebted to the Wilhelm and Maria Meyenburg Foundation for financial support for the supply of plant material required for this investigation.The results were partially presented by H.H.O. at the 17. Hauptversammlung der Gesellschaft Deutscher Chemiker. München, 12.–16.9.1977. PhD-thesis. University of Heidelberg, 1978.