Skin Irritant Ingenol Esters from Euphorbia esula

Abstract

An ethyl acetate fraction of aerial parts of E. esula L. collected in Germany was shown to exhibit irritant and weak tumor promoting but not solitary carcinogenic activity. The diterpene moiety of the irritants and tumor promotors contained in E. esula was identified to be ingenol (I). From aerial parts the irritant 3-0-(2E,4Z)-decadienoylingenol (III, Euphorbia factor E₁) and a mixture E_M of irritant Euphorbia factors shown to contain Euphorbia factor E₁, 3-0-(2,4,6)-decatrienoylingenol (V, Euphorbia factor E₂) and 3-0-(2,4,6,8)-dodecatetraenoylingenol (VI, Euphorbia factor E₃) were isolated. The antileukemic ingenol-3,20-dibenzoate (IX) was not found in the plant material investigated here. IX, a strong irritant, prepared by partial synthesis from ingenol (I) proved to be a weak tumor promoter as well.

Key Word Index

Euphorbia esula - Euphorbiaceae - Irritant diterpenes - Ingenol - Tumor promotion - Antileukemic activity