Alkaloids from Bufonid Toads (Melanophryniscus): Decahydroquinolines, Pumiliotoxins and Homopumiliotoxins, Indolizidines, Pyrrolizidines, and Quinolizidines

Abstract

Skins of bufonid toads of the genus Melanophryniscus contain several classes of alkaloids: decahydroquinolines, pumiliotoxins, allopumiliotoxins, homopumiliotoxins, both 3,5- and 5,8-disubstituted indolizidines, 3,5-disubstituted pyrrolizidines, and a 1,4-disubstituted quinolizidine. Tricyclic alkaloids, including precoccinelline [193A] and alkaloid 236, an oxime methyl ether, are present in one population of Melanophryniscus stelzneri.