Chemical Class: Diterpenes: Tiglianes (etc)

Di-terpenes are hydrocarbons with 20 carbon atoms [monoterpenes have 10, Sequiterpenes 15, tri-terpenes 30 and tetra-terpenes (the carotenes) 40].

DITERPENES: TIGLIANES (and relatives) The Phorbol esters found in most Euphorbs are based on the Tigliane Series. These have many hydroxyly groups attached around the rings in various places, conferring various toxicities to the compounds. They too have the cyclo-propane ring. The Daphnane Series lack the cyclo-propane ring and have a propene group attached at carbon atom number 13, but this does not make them less toxic. It can be seen that the Daphnanes are identical to the Tiglianes but where the cyclopropane unit has broken the lower bond. Some of the Daphnanes exhibit the most irritant properties of any chemicals in the plant world: Mezereon (Daphne Mezereum) being one of those plants. Huratoxin is a daphnane from the (non-native) Sandbox Tree. The Ingenane Series are slightly different in having no six-membered ring and instead two seven-membered rings. They still retain the strained cyclo-propane 3-membered ring. The molecule is highly strained and non-planar, being somewhat twisted and because of this adopts either the cis- or trans-conformation. Similarly, not all ingenanes are found in Euphorbs; Milliamine A is an ingenane produced in the Crown of Thorns. The five series are all derived from the pre-cursors, the Lathyranes, which have an incompleted ring but possess the energetic cyclo-propane ring. Apart from a missing bond, they already possess the polycyclic structure of a three-membered, five-membered, seven-membered and a six-membered ring structure of the whole series. In the Ingenane series, the six-membered ring has become a second seven-membered ring by straddling the resident seven-membered ring. The Jatrophane Series (first found in the non-native species Jatropha) are simply the Lathyrane Series but without the cyclo-propane ring. Missing this energetic ring, these compounds do not illicit skin irritation. Jatrophanes exhibit microtubule binding activities similar to those induced by Paclitaxel, further research is necessary. The Pepluane series are diterpenoids first found in Petty Spurge (Euphorbia Peplus) and have fused 5-, 6-, 5- and 6-membered rings. They too lack the cyclo-propane unit. The Paraliane Series are diterpenoids first found in Sea Spurge (Euphorbia Paralias, from which they obtain their name) and have fused three fused 5-membered rings and one 6-membered ring. They too lack the cyclo-propane unit. The Segetane series are rare diterpenoids recently found in Sea Spurge (Euphorbia Paralias) and have fused 5-, 7-, 6- and 5-membered rings. They lack the cyclo-propane unit.