Phyllobates terribilis

Very rapid-acting paralytic neurotoxin that binds to sodium channels of nerve and muscle cells depolarizing neurons by increasing the sodium channel permeability. It is obtained from South American poison-dart frogs (Phyllobates aurotaenia, Phyllobates terribilis). It is insoluble in water but soluble in hydrocarbons and other nonpolar solvents. The dried toxin can remain active for at least a year. However, it is relatively nonpersistent in the environment. 

The batrachotoxins were the first class of unique alkaloids to be characterized from skin extracts of frogs of the family Dendrobatidae (see ref. 23 for a review of amphibian alkaloids). Batrachotoxin was detected in only five species of dendrobatid frogs and these frogs were then classified as the monophyletic genus Phyllobates, based in part on the presence of batrachotoxins (24). However, levels of batrachotoxins differ considerably, with the Colombian Phyllobates terribilis containing nearly 1 mg of batrachotoxins per frog, while the somewhat smaller Phyllobates bicolor and Phyllobates aurotaenia, also from the rain forests of the Pacific versant in Colombia, contain 10-fold lower skin levels (8). The two... 

The above three alkaloids are found in the skins of dendrobatid frogs of the genus Phyllobates terribilis, P. aurotaenia, and P. bicolor, all of Colombia, and to a very minor extent in P. vittatus of Costa Rica and P. lugubris of Panama (28). 

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). 

Frog poison. Batrachotoxin (BTX) is a steroidal alkaloid from the skin of Phyllobates terribilis, a poisonous Colombian frog (source of the poison used on blowgun darts). In the presence of BTX, sodium channels in an excised patch stay persistently open when the membrane is depolarized. They close when the membrane is repolarized. Which transition is blocked by BTX ... 

Tetradotoxin is a potent neurotoxin isoiated from the ovaries and liver of many species of Tetradodontidae, especiaiiy the Japanese fugu (or puffer fish). Saxitoxin is a mussel or clam poison produced by certain marine dinoflagellates, Gonyaulax catenella or G. tamarensis, the consumption of which cause the mussels or clams to become poisonous. These poisonous shellfish were connected to a toxic red tide environmental condition on the coastal region of California in early 1970. Batrachotoxin is a cardiotoxic and neurotoxic steroid isolated originally from the poison dart frog, Phyllobates terribilis. It is a lipid soluble neurotoxin that is at least 10-fold more toxic than tetradotoxin. 

Three calycanthine-type alkaloids, (—)-calycanthine (149) (the optical antipode of (+ )-calycanthine (150)), (—)-isocalycanthine (151), and we,so-chimonanthine (152) were isolated from Psychotria forsteriana, from New Caledonia, and complete and NMR assignments were reported (101). This represents the second isolation of the levorotatory isomer of calycanthine (the first was from Pausinystalia macroceras, Rubiaceae, (102)) as well as the first isolation of we,so-chimonanthine. (—)-Calycanthine and (+ )-chimonanthine (153) were also found to occur in the skin of the Colombian poison dart frog, Phyllobates terribilis (103). 

L-Tryptophan derivatives Chimonanthine, calycanthine (D 21) Accumulated in skin secretions of the poison-dart frog Phyllobates terribilis, feeding deterrent... 

For batrachotoxin, the story is similar, but more complex. Captive-born Phyllobates terribilis don t have batrachotoxins in their skins. If poison frogs are caught in the wild, the amount of toxin in their skin often diminishes with keeping. As before, this suggests a dietary... 

Scientists from the National Institutes of Health have Isolated and determined the structures of many of the compounds present In these skin secretions using the techniques of mass spectrometry and NMR spectroscopy. So far the structures of well over 200 different alkaloids have been determined. The most potent of these toxins is batrachotoxin (from Phyllobates terribilis), an example of a steroidal alkaloid. Other toxins include histrionicotoxin (from Dendmbates... 

Recently, two additional batrachotoxin class alkaloids were isolated as minor constituents from skin extracts of Phyllobates terribilis. Mass spectra and proton and carbon-13 magnetic resonance spectra allowed assignment of structures as 4p-hydroxybatrachotoxin and 4P-hydroxyhomobatracho-toxin 254). 

Tokuyama, T., and J. W. Daly Steroidal alkaloids (batrachotoxins and 4-hydoxy-batrachotoxins), indole alkaloids (calycanthine and chimonanthine) and a piperidinyl-dipyridine alkaloid (noranabasamine) in skin extracts from the Colombian poison-dart frog Phyllobates terribilis (Dendrobatidae). Tetrahedron Letters, in preparation (1982). 

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