The presence of Tetrodotoxin in amphibians

Schwartz, C. A.(1)

(1)Laboratóriode Toxinologia – Universidade de Brasília, Brasília, DF, Brasil.

Tetrodotoxin (TTX) is one of the most potent marine toxin already isolated. TTX occurs in a wide range of marine animals. Among terrestrial animals TTX is known only in the Amphibia class, occurring in a few families of salamanders and anurans. Recently, the occurrence of tetrodotoxin and analogues was examined in three braquicephalid species: Brachycephalus ephippium, B. nodoterga and B. pernix. In toxicity assay with intra-peritonial injection in mice, B. nodoterga extract shown poisonless, while B. pernix extract had the highest toxicity among the studied species. The tissues extracts showed differences in their toxicities. The skin showed be the most toxic tissue, followed by the liver. The presence of TDA, TTX, 4-epiTTX and anhydroTTX were suggested by comparison of retention time in LC-FLD system. The presence of 6-epiTTX, 11-oxoTTX, 11-norTTX(S)-ol and 5-deoxiTTX were identified by LC-ESI/MS system. Mass spectrometry MALDI-TOF and LC-ESI/MS, confirm the family Brachycephalidae as the fourth anuran family to contain TTX. The fragmentation spectra obtained by LC-ESI/MS/MS of TTXs showed a fragmentation patterns that can be used to characterize this family of compounds. Bacteria, as TTX source in amphibian was suggested by analysis in LC-FLD system of the semi-purified bacteria extracts and its culture medium. Peaks with the same time of retention of TTXs, suggest the presence of these compounds. However it is not discarded the diet origin. Since the first detection of TTX in terrestrial vertebrates, the number of identified TTX-containing amphibian species increased. There are almost 4.000 species of amphibians in 26 recognised families, among these, only six were described containing TTX (Urodela: Salamandridae and Ambystomatidae; Anura: Bufonidae, Dendrobatidae, Brachycephalidae and Rhacophoridae), probable TTX are not limited to these few families of amphibians.

CORRESPONDENCE TO:

Schwartz, C. A., Laboratório de Toxinologia, CFS, IB, Universidade de Brasília, Brasília, DF, 70910-900, Brasil, Email: schwartz@unb.br