Polyzonium rosalbum Polyzonimine

Last but not least, a very intriguing terpenoid pyrrolidine alkaloid, poly-zonimine was milked from the millipede Polyzonium rosalbum (148). The structural formula of polyzonimine (118) is based on an X-ray crystallographic analysis of its perchlorate and by a total synthesis. 

Perhaps the most interesting arthropodan defensive compounds from the point of view of structural diversity are the alkaloids. While alkaloids had long been believed to arise only as a consequence of plant secondary metabolism, it has become apparent over the last few decades that arthropods are both prolific and innovative alkaloid chemists. The millipede Polyzonium rosalbum, once thought to secrete camphor (20), in fact gives off a camphoraceous/earthy aroma produced by the spirocyclic isoprenoid imine polyzonimine (21). 

Another millipede, Polyzonium rosalbum, contains two alkaloids, poly-zonimine (19) and nitropolyzonamine (49), in its defensive secretion (Tables II and IV). Polyzonimine (19) is repellent to such natural enemies as ants and might effect the deterrence of various insects by acting as a topical irritant 113). 

The defence secretion of the milliped Polyzonium rosalbum contains the spiro-monoterpenoid polyzonimine (35) 97 the isolation of the spirocyclic nitro-compound (36)98 might suggest a non-geranyl pyrophosphate biogenetic route from a pyr-rolizidine alkaloid. The production of verbenone in the bark beetle Dendroctonus sp. may be associated with chemical communication.99... 

The pyrrolizidine oximes are unknown in Nature except in amphibians. There are, however, two closely related natural products, nitropoly-zonamine (the oxime of236 is replaced by a j3-nitro substituent in nitropo-lyzonamine) and its proposed bicyclic precursor polyzonimine, both of which were isolated from defensive secretions of the millipede Polyzonium rosalbum 154,155). Nitropolyzonamine, like the amphibian pyrrolizidine oximes, is dextrorotatory 155). Neither nitropolyzonamine nor polyzonimine has been detected in amphibians. 

Polyzonimine, C10H17N, occurs in the defence secretion of the millipede Polyzonium rosalbum. It is a liquid, monoterpenoid, tertiary base containing an imino nitrogen atom, revealed by spectroscopy [i (C=N) 1626 cm ]. An X-ray diffraction analysis of a perchloric acid derivative revealed structure (4) for the alkaloid, confirmation being provided by synthesis (Scheme 1). Tests on the compound demonstrated its irritancy towards various insects. ... 

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