Oligo‐ and macrocyclic diterpenes in thymelaeaceae and Euphorbiaceae occurring and utilized in Yunnan (Southwest China). 6. Tigliane type diterpene esters from latex of Euphorbia prolifera

Abstract Five tigliane type diterpene esters were isolated from the latex of Euphorbia prolifera Buch‐Hom by means of Craig distribution followed by thin layer chromatography. Structural elucidations were done by spectroscopic methods (MS, NMR) and revealed the following Euphorbia factors: Pr1 to be a 12,13‐diester of 4,20‐dideoxyphorbol (12‐benzoate‐13‐isobutyrate), Pr2, Pr3: to be 12,13‐diesters of 4,20‐dideoxy‐5ξ‐hydroxyphorbol (12‐benzoate‐13‐isobutyrate and 12,13‐diisobutyrate, respectively), Pr4/Pr5: to be a mixture of 12,13‐diesters of 4‐deoxyphorbol [12‐(2,4‐decadienoate)‐13‐isobutyrate/12‐(2,4,6‐decatrienoate)‐13‐isobutyrate]. All compounds were assayed on the mouse ear for irritant activity: Pr1 was weakly and the mixture Pr4/Pr5 was highly active, Pr2 and Pr3 were practically inactive.