Discovery of fatty acid ester metabolites of spirolide toxins in mussels from Norway using liquid chromatography/tandem mass spectrometry

Authors

  • John A. B. Aasen,

    1. Institute for Marine Biosciences, National Research Council of Canada, 1411 Oxford St., Halifax, NS, B3H 3Z1, Canada
    2. Norwegian School of Veterinary Science, Department of Food Safety and Infection Biology, P. O. Box 8146 Dep., 0033 Oslo, Norway
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  • William Hardstaff,

    1. Institute for Marine Biosciences, National Research Council of Canada, 1411 Oxford St., Halifax, NS, B3H 3Z1, Canada
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  • Tore Aune,

    1. Norwegian School of Veterinary Science, Department of Food Safety and Infection Biology, P. O. Box 8146 Dep., 0033 Oslo, Norway
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  • Michael A. Quilliam

    Corresponding author
    1. Institute for Marine Biosciences, National Research Council of Canada, 1411 Oxford St., Halifax, NS, B3H 3Z1, Canada
    • Institute for Marine Biosciences, National Research Council of Canada, 1411 Oxford St., Halifax, NS, B3H 3Z1, Canada.
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  • Dedicated to Dr. Robert Boyd on the occasion of his retirement as Editor-in-Chief of Rapid Communications in Mass Spectrometry.

Abstract

Cultured mussels sampled in the spring of 2002 and 2003 from Skjer, a location in the Sognefjord, Norway, tested positive in the mouse bioassay for lipophilic toxins. In a previous report, it was established that a number of spirolides, cyclic imine toxins produced by the phytoplankton Alexandrium ostenfeldii, were present in the mussels and were responsible for the observed toxicity. The main toxin proved to be a new compound named 20-methyl spirolide G. In subsequent studies, a delayed onset of spirolide-like symptoms in the mouse bioassay exceeding the usual time limit of 20 min was observed in some samples, with symptoms and death appearing as long as 45–50 min after injection. It is well known that shellfish can extensively metabolize other toxins, such as okadaic acid and the dinophysistoxins, to fatty acid acyl esters and it is also known that a delayed onset of toxic symptoms with such metabolites can occur. Analyses performed with liquid chromatography/tandem mass spectrometry (LC/MS/MS) have revealed a complex mixture of esters of 20-methyl spirolide G in the contaminated mussels. Precursor ion scanning has delineated the range of fatty acid esters involved, while product ion scanning has provided information on structure. Identity was also supported through reaction of 20-methyl spirolide G with palmitic anhydride, which produced a derivative with a retention time and spectrum identical with one putative metabolite, 17-O-palmitoyl-20-methyl spirolide G. Copyright © 2006 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

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