Yessotoxins-polycyclic ethers from dinoflagellates: Relationships to diarrhetic shellfish toxins

Diarrhetic shellfish poisoning ( DSP) is known to be caused by okadaic acid ( OA), dinophysistoxin-1 ( DTX-1), and pectenotoxins ( PTX) that are polycyclic ethers produced by marine dinoflagellates, mainly Dinophysis sp. Yessotoxin ( YTX) is also classified as a DSP toxin, because it was first isolated in 1987 from scallops that were implicated in a DSP episode. Twenty two structural analogs of yessotoxin have now been isolated either from shellfish, or the dinoflagellates Protoceratium reticulatum and Lingulodinium polyedrum. Metabolism of YTX to 45-hydroxyYTX, carboxyYTX, and hydroxycarboxyYTX in mussels has been reported. However, most yessotoxin analogs initially isolated from shellfish extractions now also have been isolated from cultures of P. reticulatum. The pharmacological activity of the yessotoxin group is distinctly different from those of OA, DTX-1, and PTX and this has fueled a move to remove YTX from the DSP group. This review focuses on advances in the chemistry, pharmacology, and detection of yessotoxins.