Identification of Pinnatoxins
and Discovery of Their
Fatty Acid Ester Metabolites in Mussels (Mytilus edulis) from Eastern Canada
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Abstract
Pinnatoxins are a group of fast-acting cyclic imine toxins
previously
identified in shellfish from Asia, the southern Pacific, and northern
Europe. In this work pinnatoxins were detected in mussels from locations
across the eastern coast of Canada. Pinnatoxin G (<b>6</b>)
was the major structural variant present, sometimes at levels >80
μg/kg, whereas much lower levels of pinnatoxin A (<b>1</b>) were detected in some samples. Increased concentrations were observed
following base hydrolysis of extracts, leading to the discovery by
LC-MS of a range of fatty acid esters of <b>6</b>. Information
on the structures of these acylated derivatives was provided through
a series of mass spectrometric experiments, supported by partial synthesis,
and it is proposed that the compounds are 28-<i>O</i>-acyl
esters of <b>6</b>. Although acyl esters of a range of other
phycotoxins are known to form as metabolites in shellfish, this is
the first report of their existence for this particular toxin class.
The occurrence of pinnatoxins in North American shellfish further
highlights the international distribution of these toxins