Picrotoxanes norditerpenes

Nagahisa M, Koike K, Narita M, Ohmoto T (1994) Novel Picrotoxane Norditerpene Lactones from Picrodendron baccatum. Tetrahedron 50 10859... 

The most thorough examination of a species in the Picrodendraceae was conducted by Koike, Ohmoto, and coworkers on P. baccatum (36,46,53-56,77,78). This tree is endemic to the West Indies. The plants investigated by the authors were harvested in the Botanical Garden of Bogor, Indonesia in 1986. In the next 15-20 years this Japanese group isolated 9 monolactone sesquiterpenes and 19 norditerpene picrotoxanes from this plant material. At first, these researchers examined a relatively small sample of the bark of the tree to determine the structural type of the toxins. Thus, 1.2 kg of dried bark were extracted successively with n-hexane. 

EPC-synthesis of methyl picrotoxate (42). Trost s syntheses were the last attempts toward sesquiterpene picrotoxanes. No efforts to s)mthesize C-18-or C-19-picrotox-anes ( norditerpene picrotoxanes) have been reported so far. 

Although investigations of biosynthesis have become considerably more convenient by shifting to stable isotopes and nondestructive spectroscopic methods, the pioneering work was never continued. Thus, the pathway from copabomeol (474) to dendrobine (82), mono- and dilactone picrotoxanes, and norditerpene picrotox-anes is stiU unknown and no enzymes of this biosynthetic pathway have been defined or isolated. There is mention of genes of the dendrobine bios3mthesis isolated and expressed in Escherichia coli (233). 

Like H. globosa the Jamaica walnut or blackwood or bitter plum (P. baccatum) contains sesquiterpenes as well as norditerpenes of the picrotoxane type. Picro-dendrin Q (74), the most toxic picrotoxane for mammals, is found in the bark of this tree. In the Dominican Republic, the tree is also called mata becerro (calf killer) and its bark is used to kill lice and bed bugs (239). 

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