Formation of Azaspiracids-3, -4, -6, and -9 via Decarboxylation of Carboxyazaspiracid Metabolites from Shellfish

Abstract

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Domoic Acid, Okadaic Acid and Spirolides: Inter-Species Variability in Contamination and Cooking Effects

“…Hess et al (2005) [13] reported that processing of fresh raw mussels resulted in a two-fold increase in AZA levels in both whole flesh and digestive gland tissue compared to uncooked flesh. This change was attributed to water loss during steaming and was confirmed by McCarron et al (2009) [14] who investigated the effect of heating on AZAs in the absence of water loss. In the same way, McCarron et al, (2008) [15] and Reboreda et al (2010) [16] concluded that a steaming, autoclaving or boiling treatment increased the level of OA toxins (OA and DTX2) in the whole mussel flesh.…”

Quantitative analysis of azaspiracids in Azadinium spinosum cultures

“…To test this hypothesis, samples containing AZA1 and -2, their methyl esters, and AZA30 and -32 were treated with periodate, which oxidatively cleaves the 20,21-diol in AZAs to form a lactone derivative (Fig. 7) under mild conditions [7,40]. LC-MS/MS analysis showed complete conversion of AZA1 and -2, and of their methyl esters, to the lactone, whereas no detectable reaction occurred with AZA30 and -32, indicating that the latter compounds have been modified in the 20,21-diol moiety (Fig.…”

Improved Isolation Procedure for Azaspiracids from Shellfish, Structural Elucidation of Azaspiracid-6, and Stability Studies

“…19,20 It is believed that most of the other azaspiracid analogues are produced as a result of metabolic processes in shellfish or as a result of storage. 6,21 This belief was corroborated by a study in which an Irish strain of A. spinosum was fed directly to shellfish resulting in the formation of the analogues 3, 6, 17, and 19.…”

“…4 The azaspiracid group now includes more than 20 analogues that are either produced by phytoplankton, through biotransformation in shellfish, or as a byproduct formed as a result of storage of the toxin. 5,6 However, only 1−3 are currently regulated by the European Union (EU). 7 The other analogues had initially been found at lower concentrations and were therefore not deemed to be significant, but little is known about these additional analogues, and to date, only 1−5 have been isolated and fully characterized.…”