[Euphorbiaceae diterpenes: plant toxins or promising molecules for the therapy?]

Most of the species of Euphorbiaceae are known to be toxic and poisonous plants because their milky latex has strong skin irritant activity, and chronic exposure can result carcinogenic effect. The toxic constituents of Euphorbiaceae species are specific diterpenes, called in common as phorboids. These compounds (tigliane, ingenane and daphnane derivatives) possess extreme pro-inflammatory and tumour promoting effects due to the activation of protein kinase C enzyme. The present article gives a survey about the present estimation of Euphorbiaceae diterpenes on the basis of own experimental results and literature data. The study tries to answer the question whether these compounds can be regarded as plant toxins or they may have therapeutic relevance? It was concluded that one group of diterpenes, such as most of phorbol and ingenol esters can be considered exclusively as toxins without any possible medicinal use. The other group of diterpenes comprises compounds, which display toxicity, but in adequate dose they have therapeutic perspective (e.g. the resiniferatoxin with capsaicine-like effect). The third group of compounds such as diterpenes of non-phorboid type with macrocyclic or polycyclic structures do not have toxic effect or this property is markedly reduced, however demonstrate interesting biological activities (anti-MDR, antiproliferative and tubulin-interacting effects). Thus, these compounds may be promising lead compounds for natural product based drug developments.