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Chemistry and Chemical Biology of Lipophilic Algal Toxins

Final Report Summary - ALGETOX (Chemistry and chemical biology of lipophilic algal toxins)

A range of algal and shellfish samples from Ireland, Germany, Japan, Norway and New Zealand have been analysed by a range of LC-MS techniques, and a series of novel toxin analogues have been identified.

The fellow is supervising a PhD student in Ireland developing improved methods for isolating azaspiracids, for which there is an acute shortage for use both in toxicological experiments and as an analytical standard.

A viable method for labelling azaspiracids was developed, and then optimised with Canadian collaborators. Labelling methodology could permit development of new chemical and biochemical analytical methods for azaspiracids.

Experiments to determine the source of azaspiracid-3 and -6 in shellfish revealed that these are primarily generated via heat-induced decarboxylation of metabolites (azaspiracid-17 and -19) produced in shellfish, and efficient isotopic labelling of azaspiracid-3 and -6 was achieved by a simple chemical reaction of these metabolites.

A range of yessotoxin analogues were provided to a collaborator for toxicity testing. Structure-activity data from this has provided a basis for developing labelled derivatives that are expected to be biologically active.

Two metabolites of brevetoxins have been prepared and characterised by chemical and biochemical methods. Radiolabelled versions of these metabolites were prepared during a visit to collaborators in the USA in 2009. These radiolabelled analogues are being used in toxicological biochemical experiments and to assess adsorption, metabolism and excretion of these compounds in mammals.

NMR analysis was performed on a known and on a new pectenotoxin analogue in collaboration with Japanese researchers. Full structural analysis of the known pectenotoxin, which is currently regulated, had not previously been reported.

An array of microcystin metabolites were provided to a Norwegian collaborator for quantitative evaluation with a protein phosphatase 2A (PP2A) assay (the molecular target of the microcystins). The structures of new fast-acting toxins, isolated by collaborators in New Zealand from Australian shellfish, were determined by NMR spectroscopic and mass spectrometric analysis. One known and five new pinnatoxin analogues were identified.

LC-MS/MS analysis of shellfish and sea water samples from around the coast of Norway was initiated using analytical standards of pinnatoxins available from this work. Although pinnatoxins had not previously been reported in Europe, we found pinnatoxins in nearly 70 % of shellfish samples from late 2009 (some of which contained high levels) and in 100 % of stored sea water extracts from an earlier trial in 2007.