One of a family of piperidine alkaloids isolated from the skin of the poison arrow frog Dendrobates histrionicus. Noncompetitive inhibitor of nicotinic acetylcholine receptors characterized by an unusual spirocyclic cis-enyne structure. Virtually nontoxic, the family was originally misnamed because of the source. Isoln: J. W. Daly et al., Proc. Natl. Acad. Sci. USA 68, 1870 (1971). Isoforms: idem et al., Helv. Chim. Acta 60, 1128 (1977). Acetylcholine antagonism: M. Glavinovic et al., Can. J. Physiol. Pharmacol. 52, 1220 (1974); as allosteric inhibitor: S. M. Sine, P. Taylor, J. Biol. Chem. 257, 8106 (1982). Total synthesis: S. C. Carey et al., Tetrahedron Lett. 26, 5887 (1985); stereospecific synthesis: G. M. Williams et al., J. Am. Chem. Soc. 121, 4900 (1999). Review: J. W. Daly, J. Nat. Prod. 61, 162-172 (1997).