Characterization of an irritant 4-deoxyphorbol diester from Euphorbia tirucalli.

Latex of Euphorbia tirucalli, collected in Colombia, yielded 12-O-2Z-4E-octadienoyl-4-deoxyphorbol-13-acetate (1), which exhibited an irritant potency equivalent to that of the standard irritant, phorbol-12-tetradecanoate-13-acetate, in a mouse ear test system. The unsaturated 4-deoxyphorbol diesters recently reported in E. tirucalli grown in South Africa were not observed in the present study.