John
W. Daly*#, Tetsuo Kaneko*
Jason Wilham*, H. Martin Garraffo*
Thomas F. Spande*, Alex Espinosa F#
Maureen A. Donnelly
*Laboratory of Bio-organic
Chemistry,
National Institute of Diabetes and Digestive and Kidney Diseases,
National Institutes of Health, Bethesda, MD 20892;
#Ciflorpan, Universidad de Panam¶, Panam¶, Republica de
Panam¶;
Department of Biological Sciences, Florida International University, Miami, PL
33199.
Nearly 500 alkaloids have been detected in skin extracts from frogs of the family Dendrobatidae. All seem to have been sequestered unchanged into skin glands from alkaloid-containing arthropods. Ants, beetles, and millipedes seem to be the source of decahydroquinolines, certain izidines, coccinellines, and spiropyrrolizidine oximes. But the dietary source for a major group of frog-skin alkaloids, namely the pumiliotoxins (PTXs), alloPTXs, and homoPTXs, remained a mystery. In hopes of revealing an arthropod source for the PTX group, small arthropods were collected from eight different sites on a Panamanian island, where the Dendrobatid frog (Dendrobates pumilio) was known to contain high levels of two PTXs. |
The mixed arthropod collections from several sites, each representing up to 20 arthropod taxa, contained PTX 307A and/or alloPTX 323B. In addition, the mixed arthropod collections from several sites contained a 5,8-disubstituted indolizidine (205A or 235B), representing another class of alkaloids previously unknown from an arthropod.
An ant alkaloid, decahydroquinoline 195A, was detected in the mixed arthropod collections from several sites. Thus, 'combinatorial bioprospecting' demonstrates that further collection and analysis of individual taxa of leaf-litter arthropods should reveal the taxa from which PTXs, alloPTXs, and 5,8-disubstituted indolizidines are derived.
Dendrobates pumilio: Summers, K., Cronin, T.W., and Kennedy, T., 2003, Variation in spectral reflectance among populations of Dendrobates pumilio, the strawberry poison frog, in the Bocas del Toro Archipelago, Panama:
Journal of Biogeography, v. 30, p. 35-53.