| Résumé | Four major paralytic shellfish poisoning (PSP) toxins in pure form—saxitoxin (STX), neosaxitoxin (NEO), gonyautoxin II (GTX II), and decarbamoylsaxitoxin (dcSTX), and mixed gonyautoxin II plus III (GTX II/III)—were toxicologically evaluated in the neuroblastoma cell bioassay and compared with the United States Food and Drug Administration standard reference saxitoxin (FDA STX). Mean relative toxicities of these experimental preparations were 99.5 (STX), 128.0 (NEO), 48.4 (GTX II) and 42.6 (dcSTX) when compared with FDA STX set arbitrarily at 100. Two mixtures of GTX II/III with relative concentrations of 1:2.5 and 4:1 had percentage relative toxicities of 52.4 and 54.5, respectively. Except for GTX II/III, which increased in toxicity, the toxicities of the experimental toxin preparations were not affected by boiling for 5 min in equal volumes of either 0.1 or 1.0 N HCl. Detailed examinations of dose-responses of each individual toxin preparation in the cell bioassay revealed some differences in response profiles. The toxicological data presented here support and extend previous information collected with the mouse bioassay and HPLC. The EC₅₀ values of STX and GTX II/III obtained under different conditions of matrix (acetic acid ν. ethanol), filtration (filtered 0.22 μm or unfiltered) and time in storage at 5 °C after opening of the sealed ampoules were largely unaffected by any of the experimental treatments. |
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