Pseudophryne frogs

Spande, T. E., Edeards, M. W., Pannell, L. K., Daly, J. W., Erspamer, V. and Melchiorri, P. 1988. Pseudophrynamine A An unusual prenylated pyrrol[2,3,-(3]indole ester from an Australian frog, Pseudophryne coriacea (Myobatrachidae). Journal of Organic Chemistry, 53 1222-1226. 

The European fire salamander (Salamandra salamandra) and the alpine salamander (Salamandra atra) are the only amphibians known to contain samandarine alkaloids. These are the only two species in this genus. The proposal that extracts of the brilliant black and yellow Australian myobatrachid frog Pseudophryne corroboree contained samandarine alkaloids (52) has proved to be incorrect, and this and other frogs of the genus Pseudophryne instead contain pumiliotoxins and pseudophrynamines (see Sections III,C and VII, A). The major alkaloids of Salamandra salamandra are samandarine, samandarone, and 0-acetylsamandarine. There do not... 

Fig. 7. Structures of allopumiliotoxins. Absolute configurations are known for 267A, 339A, and 339B and are assumed to be the same for the others. All occur in dendrobatid frogs. Some also occur in ranid (Mantella), bufonid (Melanophryniscus), and myobatrachid (Pseudophryne) amphibians (73,73,8))-...

A pumiliotoxin B-like alkaloid has been reported to be present in fractions purified from the Australian myobatrachid frog Pseudophryne coria-cea (113). Effects on the cardiovascular system and cardiac, smooth, and striated muscle preparations were reported (113-118). The pumiliotoxin B-like alkaloid appeared to facilitate neurotransmitter release. In these... 

A major class of amphibian alkaloids was recently discovered in frogs of the myobatrachid genus Pseudophryne (86,119). These represent the unidentified indolic compounds first noted by Erspamer and co-workers in 1976 (169). Isolation of two of these indole alkaloids from partially purified extracts of Pseudophryne coriacea allowed structure elucidation of pseudophrynaminol (XIV) and pseudophrynamine A (XV) by nuclear magnetic resonance spectral analysis (119). Methoxide cleavage of pseudophrynamine A yielded pseudophrynaminol and a methyl ester... 

The structures of other alkaloids of the pseudophrynamine class (3a-prenylpyrrolo[2,3-6]indoles) were deduced from mass spectral analysis (86). The pseudophrynamines are tabulated below. In addition to the listed pseudophrynamines, other trace analogs of pseudophrynamine A (XV) with molecular ions at miz 526,540, and 542 were detected. The structures of the alkaloids of the pseudophrynamine class from frogs of the genus Pseudophryne are shown in Fig. 22. 

The pseudophrynamines have not been detected elsewhere in Nature. In myobatrachid frogs of the genus Pseudophryne, they occur in varying amounts in all species examined (56). The pair of dimeric indole alkaloids, chimonanthine/calycanthine, have been detected in amphibians only in the dendrobatid frog Phyllobates terribilis and, tentatively, as a trace alkaloid in Phyllobates bicolor (14). 

Other comparable examples are known. The main alkaloid in a Nova Scotia collection of Flustra foliacea, dihydroflustramine C, is related to pseudophrynaminol from the skin of the myobatrachid burrowing frog Pseudophryne coriacea. Both classes of alkaloids are based on the 3a-prenyl pyrrolo[2,3- >]indole skeleton (31). 

Scheme 16. Pseudophrynamines from frogs of the genus Pseudophryne.

However, it looks as if some other frogs can, indeed, make their own alkaloids. Australian myobatrachid frogs of the genus Pseudophryne contain two types of alkaloids in their skin extracts, some of which they get from their diets of formicine ants, but some they synthesis themselves. 

The skins of Australian myobatrachid frogs of the genus Pseudophryne contain pseudophrynamines (l,2,3,3a,8,8a-hexahydropyrrolo[2,3-l)]indole alkaloids), which appear to be biosynthesized by the animals themselves, and also varying quantities of pumifrotoxins sequestered from dietary... 

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