Specimens of the Japanese ivory shell Babylonia japonica from Sakajiri Bay, Fukui Prefecture, were all found to be toxic throughout the survey period, Aug. to Nov. 1980; the maximum toxicity (as tetrodotoxin) was 53 MU/g digestive gland.
The responsible toxin was isolated from the digestive gland by a method which essentially consisted of the adsorption onto activated charcoal, chromatography on Amberlite IRC-50 and CM-Sephadex C-25, and finally crystallization from an acidified methanolic solution.
The toxin and its derivatives were indistinguishable from those of tetrodotoxin (TTX) in thin-layer chromatography using 3 solvent systems. The toxin showed the same mobility as that of TTX in cellulose acetate membrane electrophoresis. The C₉-base-trimethylsilyl derivative from the toxin gave the same mass spectrum as that of the corresponding TTX derivative. The dose-death time curves of this toxin and TTX coincided well with each other. It was concluded from those results that the Japanese ivory shell toxin isolated was indeed TTX.