Euphorbia, phorbols

Tumor promotion is preferential proliferation of a cell damaged by transformation, it is a very slow process that can take many years. Certain substances are able to strongly accelerate it—e.g., phorbol esters. These occur in plants (e. g.. Euphorbia species) and act as activators of protein kinase C (see p. 386). 

Several studies have examined the chemistry of Euphorbia species. A majority of these investigations have focused on the chemical character of the plant latex relative to taxonomy (, ) or mammalian toxicity Toxic Ingenane diterpenes (phorbols) have also been... 

Plants of the Euphorbiaceae family and particularly members of the Euphorbia genus have long been known to yield latexes with irritant and carcinogenic properties and these properties have been associated with diter-penes of the phorbol class. Members of the Euphorbia genus also contain diterpenes with other skeletons, among them the ingenane derivative PEP005 (38). " ... 

The major stmctural types known are the phorbol esters [e.g., a tigliane from Sapium japonicum (17)] Croton, Sap-ium, Aleurites, Mancinella, Baliospermum, and Euphorbia), ingenol esters [e.g., ingenane (18)] Euphorbia), and daph-nanes [e.g., daphnetoxin (19)] Euphorbia, Hura, Hip-pomane, Excoecaria, Baliospermum, Thymelaeaceae) (Fig. 22.7) most of the plants that contain these diterpenes are in subfamilies Crotonoideae and Euphorbioideae (Kinghom, 1979 Webster, 1975). 

Ingenol derivatives are restricted to several species of the genus Euphorbia. These compounds exhibit toxicological and cocarcinogenic properties similar to those of the phorbol compounds. 

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