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During surveillance on the toxicity of invertebrates such as bivalves inhabiting the coasts of Hiroshima Bay in 2001 and 2002, the carnivorous gastropod rapa whelk Rapana venosa collected in the estuary of Nikoh River, was found to contain toxins which showed paralytic actions in mice; the maximum toxicities (as paralytic shellfish poison, PSP) were 4.2 MU/g (May 2001) and 11.4 MU/g (April 2002). Their total toxicities were 224 and 206 MU/viscera of one specimen throughout the monitoring period. Attempts were made to identify the toxic principle in the gastropod. The viscera 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 gastropod toxin was rather unexpectedly identified as PSP. It was comprised of high toxic component (gonyautoxin-3; GTX3, GTX2, saxitoxin; STX) as the major components, which accounted for approximately 91 mol% of all components along with C1 and C2, which are N-sulfocarbamoyl derivatives. Judging from their toxin patterns, it is suggested that the PSP toxification mechanism of the gastropod that PSP toxins produced by phytoplankton such as Alexandrium tamarense, are transferred to and accumulated in plankton feeders such as the short-necked clam, and then transferred to this carnivorous rapa whelk R. venosa through predation.

Trace metals in the viscera of Turbo marmoratus, a huge conical spire, in the coral reef of Ryukyu Island were analyzed. The highest amount of Zn and Fe was detectable in the midgut gland known to be polluted by saxitoxin. This intestine maintained a considerable amount of Si (higher than Ca) which fluctuated in parallel with the taurine amount. These data suggest that the viscera of the alimentary tract accumulate some metals, especially Zn and Fe.

A series of pirardixanthin derivatives, 1, 2, 3, 4, and 5, possessing the 5,6-dihydro-beta-end group were isolated from the spindle shell Fusinus perplexus.(1,2) Their structures and absolute configurations were determined by modern spectroscopic analysis to be (4S,5S,6S,4'S,5'S,6'S)-5,6,5',6'-tetrahydro-beta,beta-carotene-4,4'-diol (1), (3S,4R,5S,6S,4'S,5'S,6'S)-5,6,5',6'-tetrahydro-beta,beta-carotene-3,4,4'-triol (2), (3S,4R,5S,6S,3'S,4'R,5'S,6'S)-5,6,5',6'-tetrahydro-beta,beta-carotene-3,4,3',4'-tetrol (3), (5S,6S,4'S,5'S,6'S)-4'-hydroxy-5,6,5',6'-tetrahydro-beta,beta-caroten-4-one (4), and (4'S,5'S,6'S)-4'-hydroxy-5',6'-dihydro-beta,beta-caroten-4-one (5).