Confirmation of extensive natural distribution of azaspiracids in the tissue compartments of mussels (Mytilus edulis)

Liquid chromatography multiple tandem mass spectrometry (LC-MS/MS) has been applied to demonstrate that azaspiracid (AZA1), its isomer, AZA6, and its methyl- and demethyl-analogues, AZA2 and AZA3 respectively, are distributed throughout mussel (Mytilus edulis) tissue compartments. Large differences in both the toxin content and the toxin profiles were observed in 20 individual mussels from the same batch. The toxin levels found in the hepatopancreas of mussels were, AZA1 (0.02-5.0 μg/g); AZA2 (0.12-1.9 μg/g), AZA3 (0.06-0.88 μg/g) and AZA6 (0.05-2.0 μg/g). This study also examined the toxin content in mussel tissue compartments and it was found that the gills contributed significantly to the overall level of toxins in mussels. Although polyether toxins are usually concentrated in the hepatopancreas of shellfish this is not always the situation with azaspiracids. The mean distribution of azaspiracids in mussels was; hepatopancreas (60.6%), gills (12.0%) and adductor muscle (27.4%).