Sulfated diesters of okadaic acid and DTX-1: Self-protective precursors of diarrhetic shellfish poisoning (DSP) toxins

Many toxic secondary metabolites used for defense are also toxic to the producing organism. One important way to circumvent toxicity is to store the toxin as an inactive precursor. Several sulfated diesters of the diarrhetic shellfish poisoning (DSP) toxin okadaic acid have been reported from cultur...

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Bibliographic Details
Published in:Harmful algae 2017-03, Vol.63, p.85-93
Main Authors: Hu, Tingmo, LeBlanc, Patricia, Burton, Ian W., Walter, John A., McCarron, Pearse, Melanson, Jeremy E., Strangman, Wendy K., Wright, Jeffrey L.C.
Format: Article
Language:English
Subjects:
Animals
Dinoflagellida - metabolism
Diol esters
DSP toxins
DTX-1
Marine Toxins - analysis
Okadaic acid
Okadaic Acid - analysis
Pyrans - analysis
Shellfish Poisoning
Sulfated diesters
Toxin storage
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Summary:Many toxic secondary metabolites used for defense are also toxic to the producing organism. One important way to circumvent toxicity is to store the toxin as an inactive precursor. Several sulfated diesters of the diarrhetic shellfish poisoning (DSP) toxin okadaic acid have been reported from cultures of various dinoflagellate species belonging to the genus Prorocentrum. It has been proposed that these sulfated diesters are a means of toxin storage within the dinoflagellate cell, and that a putative enzyme mediated two-step hydrolysis of sulfated diesters such as DTX-4 and DTX-5 initially leads to the formation of diol esters and ultimately to the release of free okadaic acid. However, only one diol ester and no sulfated diesters of DTX-1, a closely related DSP toxin, have been isolated leading some to speculate that this toxin is not stored as a sulfated diester and is processed by some other means. DSP components in organic extracts of two large scale Prorocentrum lima laboratory cultures have been investigated. In addition to the usual suite of okadaic acid esters, as well as the free acids okadaic acid and DTX-1, a group of corresponding diol- and sulfated diesters of both okadaic acid and DTX-1 have now been isolated and structurally characterized, confirming that both okadaic acid and DTX-1 are initially formed in the dinoflagellate cell as the non-toxic sulfated diesters.
ISSN:1568-9883
1878-1470
DOI:10.1016/j.hal.2017.01.012