Hiroko Narita

Occurrence of tetrodotoxin in the gastropod mollusk Tutufa lissostoma (frog shell)

Paralytic toxicity was detected in gastropod mollusk Tutufa lissostoma (frog shell) specimens collected from Suruga Bay, Shizuoka Prefecture, Japan. Seventeen of the 22 digestive glands removed were toxic; the highest toxicity, expressed as tetrodotoxin (TTX), being as high as 700 mouse units (MU) per gram. Attempts were made to isolate the toxin from pooled digestive glands by activated charcoal treatment and column chromatography on Amberlite IRC-50, CM-Sephadex C-25 and Bio-Rex 70. The toxin showed a specific toxicity (as TTX) of 4200 MU/mg. It exhibited the same thin-layer chromatographic and electrophoretic behaviors and 1H-NMR spectrum as TTX. The toxin gave the same pattern as the TTX standard when alkali-hydrolyzed and analyzed by GC--MS, indicating that it contains the quinazoline skeleton specific to TTX. From these results the frog shell toxin was identified as TTX.

Migration of Dibutylhydroxytoluene from Plastic Packaging Material into Dried Fishes and Shellfishes

Dibutylhydroxytoluene (BHT) was detected in dried fishes to which it had not been added as a food additive. In order to examine the migration of BHT from the plastic packaging material to the dried fishes, the relationship between the storage conditions (temperature and duration) and the quantity of migration was investigated. Increased quantity of migration was observed at higher temperatures and longer periods of storage.A random survey of foods on the market revealed 2.0-3.6mg/kg of BHT in dry foods and 0.15-1.7μg/cm2 in the plastic wrapping material. BHT was detected more frequently in wrapping with lower gas permeability, namely polyvinilidene chloride, than in other wrapping material.