Occurrence of paralytic shellfish poison in the starfish Asterias amurensis in Kure Bay, Hiroshima Prefecture, Japan

Abstract

In May 1996, during surveillance on the toxicity of invertebrates such as bivalves inhabiting the coasts of Hiroshima Bay, the starfish Asterias amurensis collected in the estuary of the Nikoh River was found to contain toxins which showed strong paralytic action in mice; the maximum toxicity (as paralytic shellfish poison, PSP) was 8.0 MU/g for whole body and 28.7 MU/g for viscera throughout the monitoring period, March to July 1996. Attempts were made to identify the paralytic toxins in the starfish. They were extracted with 80% ethanol acidified with acetic acid, followed by defatting with dichloromethane. The aqueous layer obtained was treated with activated charcoal and then applied to a Sep-Pak C18 cartridge. The unbound toxic fraction was analyzed by high-performance liquid chromatography techniques. The starfish toxin was rather unexpectedly identified as PSP. It was comprised of high toxic components (gonyautoxin-1; GTX1, GTX2, GTX3, GTX4, decarbamoyl-GTX3; dcGTX3 and dcSTX) as the major components, which accounted for approximately 77 mole% of all components, along with protogonyautoxin-1, 2, 3 and 4 (PX1–4), which are N-sulfocarbamoyl derivatives. Of the high toxic components, GTX1 was present in the largest amounts. It was concluded that the toxin of starfish collected in the estuary of Nikoh River in May 1996 consisted of PSP, which supposedly came via the food chain from toxic bivalves living in the same area. To our knowledge, this is the first report of the occurrence of PSP in starfish.