The occurrence of 11-oxotetrodotoxin, a rare tetrodotoxin analogue, in the brachycephalidae frog Brachycephalus ephippium.

11-oxoTTX is an analogue 4-5 times more toxic than TTX itself, been rare even in marine animals. Two ions at m/z 320 and 336 corresponding to TTX and 11-oxoTTX (M+H(+)), respectively, were detected in the Brachycephalidae frog Brachycephalus ephippium extracts. The fragment ion pattern of 11-oxoTTX is similar to that TTX, although its possible to verify some specific fragments.