ALKALOIDS IN MADAGASCAN FROGS (MANTELLA) - PUMILIOTOXINS, INDOLIZIDINES, QUINOLIZIDINES, AND PYRROLIZIDINES

Brightly colored ranid frogs of the genus Mantella are found only in m in forests of Madagascar. Gc-ms and gc-Ft-ir analyses of skin alkaloid s of seven different species, including four populations of Mantella m adagascariensis, are reported. All contain one or more representatives of the pumiliotoxin A (PTX-A) class with the 13,14-dihydro derivative s 309A and 325A found in major amounts in the four populations of M. m adagascariensis, while 307A (PTX-A) is found in two populations of M. madagascariensis and in three additional species, Mantella aurantiaca, Mantella viridis, and Mantella crocea. The latter three species also contain appreciable quantities of 323A (PTX-B). The four populations o f M. madagascariensis show major amounts of two 1,4-disubstituted quin olizidines, 217A and 231A, and a 5,8-disubstituted indolizidine, 217B, in addition to many minor or trace quinolizidines and indolizidines. Such disubstituted quinolizidines and indolizidines are present as tra ce alkaloids in the six other species of Mantella, along with 3,5-disu bstituted indolizidines, 3,5-disubstituted pyrrolizidines, the decahyd roquinoline cis-195A, tricyclic alkaloids, and homopumiliotoxins. A ne w alkaloid class, which appears to contain a quinolizidine moiety, is seen in M. aurantiaca and M. crocea and is represented by 235C and sev eral congeners.