DIETARY SOURCE FOR SKIN ALKALOIDS OF POISON FROGS (DENDROBATIDAE)

A wide range of alkaloids, many of which are unknown elsewhere in natu re, occur in skin of frogs. Major classes of such alkaloids in dendrob atid frogs are the batrachotoxins, pumiliotoxins, histrionicotoxins, g ephyrotoxins, and decahydroquinolines. Such alkaloids are absent in sk in of frogs (Dendrobates auratus) raised in Panama on wingless fruit f lies in indoor terraria. Raised on leaf-litter arthropods that were co llected in a mainland site, such terraria-raised frogs contain tricycl ic alkaloids including the beetle alkaloid precoccinelline, 1,4-disubs tituted quinolizidines, pyrrolizidine oximes, the millipede alkaloid n itropolyzonamine, a decahydroquinoline, a gephyrotoxin, and histrionic otoxins. The profiles of these alkaloids in the captive-raised frogs a re closer to the mainland population of Dendrobates auratus at the lea f-litter site than to the parent population of Dendrobates auratus fro m a nearby island site. Extracts of a seven-month sampling of leaf-lit ter insects contained precoccinelline, pyrrolizidine oxime 236 (major) , and nitropolyzonamine (238). The results indicate a dietary origin f or at least some ''dendrobatid alkaloids,'' in particular the pyrroliz idine oximes, the tricyclic coccinellines, and perhaps the histrionico toxins and gephyrotoxins.