Identification of tetrodotoxin and paralytic shellfish toxins in marine gastropods [Niotha clathrata and Zeuxis scalaris] implicated in food poisoning [incidents in south Taiwan]

Attempts were made to elucidate the responsible toxins in the gastropod Niotha clathrata and Zeuxis scalaris which recently caused food poisoning incidents in south Taiwan. The remained (cooked) and captured (live) specimens of both gastropods were assayed for toxicity (as tetrodotoxin = TTX). The average toxicity of cooked and live specimens was 150 plus or minus 126 (mean plus or minus S.D.) and 345 plus or minus 192 mouse unit (MU) in N. clathrata, and 13 plus or minus 9 and 98 plus or minus 46 MU in Z. scalaris, respectively. The toxin was partially purified from the methanolic extract of the gastropod by ultrafiltration and Bio-Gel P-2 column chromatography. Cellulose acetate membrane electrophoresis, TLC, and HPLC analyses demonstrated that the toxin consisted mainly of TTX (about 80%), along with minor paralytic shellfish poison (PSP, about 20%). The PSP components were identified as gonyautoxin 1-4 and neosaxitoxin in both gastropods. It was concluded from these results that the causative agents of the above food poisoning were TTX and PSP.