Occurrence of 11-oxotetrodotoxin in the red-spotted newt, Notophthalmus viridescens, and further studies on the levels of tetrodotoxin and its analogues in the newt's efts.

An analogue of tetrodotoxin (TTX), 11-oxoTTX, was semi-purified from the red-spotted newt, Notophthalmus viridescens, and identified by ESI-MS and 1H NMR spectra. The levels of TTX, 11-oxoTTX and 6-epiTTX in early stage of development (efts) of this newt were investigated by a post-column fluorescent-HPLC system, and compared with those of adult newts. The level of 11-oxoTTX in both of adults and efts were remarkably high, almost close to those of TTX, while 6-epiTTX was a minor component in both stages. The level of 6-epiTTX in efts (1.8+/-1.3 microg/g, SD, n=10) was significantly larger than that in adults (0.51+/-0.26 microg/g, SD, n=12) (p<0.05), while no significant difference was observed in the levels of TTX and 11-oxoTTX between efts (13+/-7.4 and 9.1+/-5.6 microg/g) and adult newts (16+/-6.3 and 13+/-6.2 microg/g, respectively) (p>0.05).