A sensitive and specific determination method for azaspiracids by liquid chromatography mass spectrometry

Current Research Status of Azaspiracids

The presence and impact of toxins have been detected in various regions worldwide ever since the discovery of azaspiracids (AZAs) in 1995. These toxins have had detrimental effects on marine resource utilization, marine environmental protection, and fishery production. Over the course of more than two decades of research and development, scientists from all over the world have conducted comprehensive studies on the in vivo metabolism, in vitro synthesis methods, pathogenic mechanisms, and toxicology of these toxins. This paper aims to provide a systematic introduction to the discovery, distribution, pathogenic mechanism, in vivo biosynthesis, and in vitro artificial synthesis of AZA toxins. Additionally, it will summarize various detection methods employed over the past 20 years, along with their advantages and disadvantages. This effort will contribute to the future development of rapid detection technologies and the invention of detection devices for AZAs in marine environmental samples.

Preparation and characterization of an immunoaffinity column for the selective extraction of azaspiracids

The presence of azaspiracids (AZAs) in shellfish may cause food poisoning in humans. AZAs can accumulate in shellfish filtering seawater that contains marine dinoflagellates such as Azadinium and Amphidoma spp. More than 60 AZA analogues have been identified, of which AZA1, AZA2 and AZA3 are regulated in Europe. Shellfish matrices may complicate quantitation by ELISA and LC-MS methods. Polyclonal antibodies have been developed that bind specifically to the C-26-C-40 domain of the AZA structure and could potentially be used for selectively extracting compounds containing this substructure. This includes almost all known analogues of AZAs, including AZA1, AZA2 and AZA3. Here we report preparation of immunoaffinity chromatography (IAC) columns for clean-up and concentration of AZAs. The IAC columns were prepared by coupling polyclonal anti-AZA IgG to CNBr-activated sepharose. The columns were evaluated using shellfish extracts, and the resulting fractions were analyzed by ELISA and LC-MS. The columns selectively bound over 300 ng AZAs per mL of gel without significant leakage, and did not retain the okadaic acid, cyclic imine, pectenotoxin and yessotoxin analogues that were present in the applied samples. Furthermore, 90-92% of the AZAs were recovered by elution with 90% MeOH, and the columns could be re-used without significant loss of performance.

Variability and profiles of lipophilic toxins in bivalves from Great Britain during five and a half years of monitoring: azaspiracids and yessotoxins

Cefas has been responsible for the delivery of official control biotoxin testing of bivalve molluscs from Great Britain for just over a decade. Liquid chromatography tandem mass spectrometric (LC-MS/MS) methodology has been used for the quantitation of lipophilic toxins (LTs) since 2011. The temporal and spatial distribution of okadaic acid group toxins and profiles in bivalves between 2011 and 2016 have been recently reported. Here we present data on the two other groups of regulated lipophilic toxins, azaspiracids (AZAs) and yessotoxins (YTXs), over the same period. The latter group has also been investigated for a potential link with Protoceratium reticulatum and Lingulodinium polyedra, both previously recognised as YTXs producing phytoplankton. On average, AZAs were quantified in 3.2% of all tested samples but notable inter-annual variation in abundance was observed. The majority of all AZA contaminated samples were found between July 2011 and August 2013 in Scotland, while only two, three-month long, AZA events were observed in 2015 and 2016 in the south-west of England. Maximum concentrations were generally reached in late summer or early autumn. Reasons for AZAs persistence during the 2011/2012 and 2012/2013 winters are discussed. Only one toxin profile was identified, represented by both AZA1 and AZA2 toxins at an approximate ratio of 2 : 1, suggesting a single microalgal species was the source of AZAs in British bivalves. Although AZA1 was always the most dominant toxin, its proportion varied between mussels, Pacific oysters and surf clams. The YTXs were the least represented group among regulated LTs. YTXs were found almost exclusively on the south-west coast of Scotland, with the exception of 2013, when the majority of contaminated samples originated from the Shetland Islands. The highest levels were recorded in the summer months and followed a spike in Protoceratium reticulatum cell densities. YTX was the most dominant toxin in shellfish, further strengthening the link to P. reticulatum as the YTX source. Neither homo-YTX, nor 45-OH homo-YTX were detected throughout the monitored period. 45-OH YTX, thought to be a shellfish metabolite associated with YTX elimination, contributed on average 26% in mussels. Although the correlation between 45-OH YTX abundance and the speed of YTX depuration could not be confirmed, we noted the half-life of YTX was more than two-times longer in queen scallops, which contained 100% YTX, than in mussels. No other bivalve species were affected by YTXs. This is the first detailed evaluation of AZAs and YTXs occurrences and their profiles in shellfish from Great Britain over a period of multiple years.

Toxic marine microalgae and shellfish poisoning in the British isles: history, review of epidemiology, and future implications

The relationship between toxic marine microalgae species and climate change has become a high profile and well discussed topic in recent years, with research focusing on the possible future impacts of changing hydrological conditions on Harmful Algal Bloom (HAB) species around the world. However, there is very little literature concerning the epidemiology of these species on marine organisms and human health. Here, we examine the current state of toxic microalgae species around the UK, in two ways: first we describe the key toxic syndromes and gather together the disparate reported data on their epidemiology from UK records and monitoring procedures. Secondly, using NHS hospital admissions and GP records from Wales, we attempt to quantify the incidence of shellfish poisoning from an independent source. We show that within the UK, outbreaks of shellfish poisoning are rare but occurring on a yearly basis in different regions and affecting a diverse range of molluscan shellfish and other marine organisms. We also show that the abundance of a species does not necessarily correlate to the rate of toxic events. Based on routine hospital records, the numbers of shellfish poisonings in the UK are very low, but the identification of the toxin involved, or even a confirmation of a poisoning event is extremely difficult to diagnose. An effective shellfish monitoring system, which shuts down aquaculture sites when toxins exceed regularity limits, has clearly prevented serious impact to human health, and remains the only viable means of monitoring the potential threat to human health. However, the closure of these sites has an adverse economic impact, and the monitoring system does not include all toxic plankton. The possible geographic spreading of toxic microalgae species is therefore a concern, as warmer waters in the Atlantic could suit several species with southern biogeographical affinities enabling them to occupy the coastal regions of the UK, but which are not yet monitored or considered to be detrimental.

A mussel tissue certified reference material for multiple phycotoxins. Part 1: design and preparation

The development of multi-analyte methods for lipophilic shellfish toxins based on liquid chromatography-mass spectrometry permits rapid screening and analysis of samples for a wide variety of toxins in a single run. Validated methods and appropriate certified reference materials (CRMs) are required to ensure accuracy of results. CRMs are essential for accurate instrument calibration, for assessing the complete analytical method from sample extraction to data analysis and for verifying trueness. However, CRMs have hitherto only been available for single toxin groups. Production of a CRM containing six major toxin groups was achieved through an international collaboration. Preparation of this material, CRM-FDMT1, drew on information from earlier studies as well as improved methods for isolation of toxins, handling bulk tissues and production of reference materials. Previous investigations of stabilisation techniques indicated freeze-drying to be a suitable procedure for preparation of shellfish toxin reference materials and applicable to a wide range of toxins. CRM-FDMT1 was initially prepared as a bulk wet tissue homogenate containing domoic acid, okadaic acid, dinophysistoxins, azaspiracids, pectenotoxin-2, yessotoxin and 13-desmethylspirolide C. The homogenate was then freeze-dried, milled and bottled in aliquots suitable for distribution and analysis. The moisture content and particle size distribution were measured, and determined to be appropriate. A preliminary toxin analysis of the final material showed a comprehensive toxin profile.

Cell volume decrease as a link between azaspiracid-induced cytotoxicity and c-Jun-N-terminal kinase activation in cultured neurons

Azaspiracids (AZAs) are a group of marine toxins recently described that currently includes 20 members. Not much is known about their mechanism of action, although the predominant analog in nature, AZA-1 targets several organs in vivo, including the central nervous system, and exhibits high neurotoxicity in vitro. AZA distribution is increasing globally with mussels being most widely implicated in AZA-related food poisoning events, with human poisoning by AZAs emerging as an increasing worldwide problem in recent years. We used pharmacological tools to inhibit the cytotoxic effect of the toxin in primary cultured neurons. Several targets for AZA-induced neurotoxicity were evaluated. AZA-1 elicited a concentration-dependent hyperpolarization in cerebellar granule cells of 2-3 days in vitro; however, it did not modify membrane potential in mature neurons. Furthermore, in immature cells, AZA-1 decreased the membrane depolarization evoked by exposure of the neurons to 50mM K(+). Preincubation of the neurons with 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), 4-acetamido-4'-isothiocyanato-2,2'-stilbenedisulfonic acid (SITS), 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), amiloride, or ouabain before addition of AZA-1 decreased the AZA-1-induced neurotoxicity and the increase in phosphorylated c-Jun-N-terminal kinase (JNK) caused by the toxin, indicating that disruption in ion fluxes was involved in the neurotoxic effect of AZA-1. Furthermore, short exposures of cultured neurons to AZA-1 caused a significant decrease in neuronal volume that was reverted by preincubation of the neurons with DIDS or amiloride before addition of the toxin. The results presented here indicate that the JNK activation induced by AZA-1 is secondary to the decrease in cellular volume elicited by the toxin.

Detection of diarrheic shellfish poisoning and azaspiracid toxins in Moroccan mussels: comparison of the LC-MS method with the commercial immunoassay kit

Diarrheic shellfish poisoning (DSP) is a recurrent gastrointestinal illness in Morocco, resulting from consumption of contaminated shellfish. In order to develop a rapid and reliable technique for toxins detection, we have compared the results obtained by a commercial immunoassay-“DSP-Check” kit” with those obtained by LC-MS. Both techniques are capable of detecting the toxins in the whole flesh extract which was subjected to prior alkaline hydrolysis in order to detect simultaneously the esterified and non esterified toxin forms. The LC-MS method was found to be able to detect a high level of okadaic acid (OA), low level of dinophysistoxin-2 (DTX2), and surprisingly, traces of azaspiracids 2 (AZA2) in mussels. This is the first report of a survey carried out for azaspiracid (AZP) contamination of shellfish harvested in the coastal areas of Morocco. The “DSP-Check” kit was found to detect quantitatively DSP toxins in all contaminated samples containing only OA, provided that the parent toxins were within the range of detection and was not in an ester form. A good correlation was observed between the two methods when appropriate dilutions were performed. The immunoassay kit appeared to be more sensitive, specific and faster than LC-MS for determination of DSP in total shellfish extract.

Formation of Azaspiracids-3, -4, -6, and -9 via decarboxylation of carboxyazaspiracid metabolites from shellfish

The azaspiracid (AZA) class of phycotoxins has been responsible for extended closures of shellfisheries in various locations around Europe, where levels of AZA1-3 are regulated in shellfish. Since their discovery in 1995, AZAs have been the focus of much research, resulting in the discovery of numerous analogues. During studies of procedures for processing of AZA-contaminated mussels ( Mytilus edulis ), an unusual phenomenon was observed involving AZA3. In uncooked tissues, AZA3 levels would increase significantly when heated for short periods of time in the absence of water loss. A similar increase in AZA3 concentrations occurred during storage of shellfish tissue reference materials for several months at temperatures as low as 4 degrees C. Concentrations of AZA1 and AZA2 did not change during these experiments. Several possible explanations were investigated, including an AZA3-specific matrix effect upon heating of tissues, release of AZA3 from the matrix, and formation of AZA3 from a precursor. Preliminary experiments indicated that toxin conversion was responsible, and more detailed studies focused on this possibility. LC-MS analysis of heating trials, deuterium labeling experiments, and kinetic studies demonstrated that a carboxylated AZA analogue, AZA17, undergoes rapid decarboxylation when heated to produce AZA3. Heat-induced decarboxylation of AZA19, AZA21, and AZA23 to form AZA6, AZA4, and AZA9, respectively, was also demonstrated. This finding is of great significance in terms of procedures used in the processing of shellfish for regulatory analysis, and it exemplifies the role that chemical analysis can play in understanding the contribution of metabolic processes to the toxin profiles observed in shellfish samples.

Azaspiracid shellfish poisoning: a review on the chemistry, ecology, and toxicology with an emphasis on human health impacts

Azaspiracids (AZA) are polyether marine toxins that accumulate in various shellfish species and have been associated with severe gastrointestinal human intoxications since 1995. This toxin class has since been reported from several countries, including Morocco and much of western Europe. A regulatory limit of 160 μg AZA/kg whole shellfish flesh was established by the EU in order to protect human health; however, in some cases, AZA concentrations far exceed the action level. Herein we discuss recent advances on the chemistry of various AZA analogs, review the ecology of AZAs, including the putative progenitor algal species, collectively interpret the in vitro and in vivo data on the toxicology of AZAs relating to human health issues, and outline the European legislature associated with AZAs.

Confirmation by LC-MS/MS of azaspiracids in shellfish from the Portuguese north-western coast

The search for azaspiracids (AZAs) in shellfish on the Portuguese coast started in 2002, but the presence of these toxins could not be demonstrated until the summer of 2006. Analysis by liquid-chromatography-tandem mass spectrometry (LC-MS/MS) allowed the confirmation of AZA2 as a dominant compound, followed by AZA1, in blue mussel (Mytilus galloprovincialis), common cockle (Cerastoderma edule), clams (Venerupis senegalensis, Ruditapes decussatus), razor clam (Solen marginatus) and oyster (Crassostrea spp). Traces of AZA3 were found only in blue mussel. Total levels of AZA1-3 determined in the whole flesh by LC-MS/MS ranged from 1.6 to 6.1 microg/kg. The finding of low levels of AZAs since 2002 suggests a low risk level when compared with the highest risks posed by diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP) toxins. However, the limited number of years studied might generate a misleading conclusion. The contamination with PSP is an example, as no contamination occurred for an extended period of time between 1996 and 2004, despite high levels having occurred outside this period. Thus, there appears overall a moderate likelihood of occurrence of AZAs in the range that may be relevant to consumers.

Azaspiracid: first evidence of protein binding in shellfish

The occurrence of azaspiracid (AZA) toxins in contaminated shellfish has been the focus of much research. The present study investigated the binding properties of these toxins in mussels of the species Mytilus edulis. The work involved extraction of proteins and AZAs from contaminated mussel hepatopancreas and examination of the extracts by isoelectric focusing (IEF), size exclusion chromatography (SEC) and sodium docecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Liquid chromatography coupled with tandem mass spectrometry analysis (LC-MS/MS) was also performed in this study to identify AZAs. Blank mussels were subjected to the same purification and analytical procedures. AZAs were found to be weakly bound to a protein with a molecular weight of 45 kDa, in samples of contaminated mussels. This protein, which was abundant in contaminated mussels, was also present in blank mussels, albeit at much lower concentrations. It was further noted that a 22 kDa protein was also present only in contaminated mussel samples.

The c-Jun-N-terminal kinase is involved in the neurotoxic effect of azaspiracid-1

AIMS

Azaspiracids (AZAs) are marine phycotoxins with an unknown mechanism of action, recently implicated in human intoxications. The predominant analog in nature, AZA-1 targets several organs in vivo, including the central nervous system and exhibits high neurotoxicity in vitro.

METHODS

We used pharmacological tools to inhibit the cytotoxic effect of the toxin in primary cultured neurons. Immunocytochemical techniques in combination with confocal microscopy were employed to examine the cellular mechanisms involved in the neurotoxic effect of AZA-1.

RESULTS

Several targets for azaspiracid-induced neurotoxicity, specifically the cAMP pathway, or protein kinase C and phosphatidylinositol 3-kinase activation were excluded. Interestingly, the specific c-Jun-N-terminal protein kinase (JNK) inhibitor SP 600125 protected cultured neurons against AZA-induced cytotoxicity. Immunocytochemistry experiments showed that AZA-1 increased the amount of phosphorylated JNK and caused nuclear translocation of the active protein that was prevented by SP 600125.

CONCLUSION

Our data constitute the relationship between azaspiracid-induced cytotoxicity and specific modifications in cellular transduction signals, specifically we found that JNK activation is associated with the cytotoxic effect of the toxin. These results should provide the basis to identify the mechanism of action of this group of toxins.

Effects of Azaspiracid-1, A Potent Cytotoxic Agent, on Primary Neuronal Cultures. A Structure−Activity Relationship Study

Azaspiracids (AZAs) are marine phycotoxins with an unknown mechanism of action, implicated in human intoxications. We investigated the effect of azaspiracid-1 (AZA-1) on the cytosolic calcium concentration ([Ca2+]c), intracellular pH (pHi), and neuron viability in neuronal cultures. AZA-1 increased [Ca2+]c and decreased neuronal viability. The effects of several fragments of the AZA-1 molecule (13 different chemical structures) were examined. The ent-ABCD-azaspiracid-1 (2) showed similar potency to AZA-1 (1) in increasing [Ca2+]c but higher cytotoxity than AZA-1. The chemical structures containing only the ABCD or the ABCDE ring domains (3-8) caused a [Ca2+]c increase but did not alter cell viability. The compounds containing only the FGHI ring domain of AZA-1 (9-14) did not modify the [Ca2+]c or the cell viability. Therefore, the effect of AZA-1 on [Ca2+]c depends on the presence of the ABCD or the ABCDE-ring structure, but the complete chemical structure is needed to produce neurotoxic effects.

Pectenotoxin-2 in single-cell isolates of Dinophysis caudata and Dinophysis acuta from the Galician Rías (NW Spain)

Dinophysis acuta and Dinophysis caudata are seasonal components of the dinoflagellate community in the Galician Rías Bajas (NW Spain). These species can be the main contributors to the occurrence of Lipophilic Shellfish Toxins (LST) in September-October, leading to prohibition of harvesting in an area of intensive mariculture (250 x 10(3)t of cultured mussels, 60 x 10(3)t of other shellfish in natural banks, per year). Previous analyses of okadaic acid (OA) and related toxins in these two species by HPLC revealed significant amounts of OA and DTX2 in D. acuta, but only trace amounts of OA in D. caudata cells, and led to the erroneous conclusion that the contribution of the latter species to autumn LST events was negligible. Recent analyses by LC-MS/MS of individually picked cells of D. acuta and D. caudata have shown that both species may have high levels of PTX2 (up to 30 pg and 130 pg cell(-1), respectively) and that this toxin can be the dominant toxin during toxic outbreaks associated with Dinophysis spp. Although the quick conversion of PTX2 to PTX-2SA in mussels may reduce the risks for human health, these results have important implications for monitoring programmes. The complex toxin profile of shellfish exposed to Dinophysis spp. populations should be taken into account when making decisions on the toxin control methods to be used as the basis of the programme. Conclusive toxicological studies are required to elucidate the public health relevance of the different PTXs derivatives and to provide the scientific basis for regulations.

Tissue distribution, effects of cooking and parameters affecting the extraction of azaspiracids from mussels, Mytilus edulis, prior to analysis by liquid chromatography coupled to mass spectrometry

This study used liquid chromatography coupled to mass spectrometry to identify some parameters important in the analysis of azaspiracids. The first aspect was the distribution of azaspiracids within mussels, in particular the content in the digestive gland as compared to the remaining tissues. In our study, azaspiracids accumulated in the digestive gland, similar to other lipophilic toxins. The ratio of toxin in the digestive gland compared to the whole mussel was on average circa 5, both for a bulk sample collected in Norway in 2004 and for 28 samples from Ireland collected over 3 years (2001-2003). These results may justify the practise to only analyse the digestive gland, a step considered necessary to achieve adequate detection limits for azaspiracids both in the mouse bioassay and other analytical techniques. Steaming of mussels as a sample pre-treatment was found to be another parameter affecting the result. Azaspiracids concentrated indirectly, i.e. through the loss of water or juice from the matrix. The cooked shellfish tissues had a concentration of azaspiracids 2-fold higher than the uncooked shellfish, both for whole flesh and for digestive gland tissue. This finding is of particular importance since it may affect the maximum guidance level at which shellfish may be allowed for human consumption. Finally, parameters affecting the extraction efficiency were studied, including the nature of the extraction solvent, the sample-to-solvent ratio and replicate extraction. The largest differences were observed between different solvents and between different sample-to-solvent ratios, while the effect of replicate extraction was minimal if large sample-to-solvent ratios were used. Duplicate extraction using 100% methanol was found to be the best combination of parameters.

Is there a risk of human poisoning by azaspiracids from shellfish harvested at the Portuguese coast?

Azaspiracid poisoning (AZP), the most recently discovered human gastrointestinal illness resulting from consumption of contaminated shellfish, so far has been found in coastal areas of northern Europe. This is the first report of a survey carried out for contamination of shellfish harvested in costal areas of Portugal for the presence of azaspiracids. The study design covered the commercial species usually more contaminated by toxins from dinoflagellates (blue mussel, common cockle, donax clam) in coastal areas representative of the NW, SW and south coasts. A method based on liquid chromatography-mass spectrometry was setup for the first time for this purpose. No azaspiracids were found on 300 samples tested between 2002 and 2003. On at least three samples a peak with a retention time matching that of AZA2 was found, never surpassing one tenth of the current EU limit. Unambiguous identification of any known AZA did not occur yet. The risk for human outbreaks of AZP seems to be very low, comparatively with amnesic shellfish poisoning (ASP), where levels close to the allowance level are found sparsely, or to diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP), where high levels and registered human outbreaks have been found in recent years.

Azaspiracid poisoning, the food-borne illness associated with shellfish consumption

Azaspiracid poisoning (AZP) is a recently discovered toxic syndrome that was identified following severe gastrointestinal illness from the consumption of contaminated mussels (Mytilus edulis). The implicated toxins, azaspiracids, are polyethers with unprecedented structural features. Studies toward total toxin synthesis revealed that the initial published structures were incorrect and they have now been revised. These toxins accumulate in bivalve molluscs that feed on toxic microalgae of the genus Protoperidinium, previously considered to be toxicologically benign. Although first identified in shellfish from Ireland, azaspiracid contamination of several types of bivalve shellfish species has now been confirmed throughout the western coastline of Europe. Toxicological studies have indicated that azaspiracids can induce widespread organ damage in mice and that they are probably more dangerous than previously known classes of shellfish toxins. The exclusive reliance on live animal bioassays to monitor azaspiracids in shellfish failed to prevent human intoxications. This was a consequence of poor sensitivity of the assay and the fact that azaspiracids are not exclusively found in the shellfish digestive glands used for toxin testing. The strict regulatory control of azaspiracids in shellfish now requires frequent testing of shellfish using highly specific and sensitive methods involving liquid chromatography-mass spectrometry.

The first identification of azaspiracids in shellfish from France and Spain

Incidents of human intoxications throughout Europe, following the consumption of mussels have been attributed to Azaspiracid Poisoning (AZP). Although first discovered in Ireland, the search for the causative toxins, named azaspiracids, in other European countries has now led to the first discovery of these toxins in shellfish from France and Spain. Separation of the toxins, azaspiracid (AZA1) and analogues, AZA2 and AZA3, was achieved using isocratic reversed-phase liquid chromatography coupled, via an electrospray ionisation source, to an ion-trap mass spectrometer. Azaspiracids were identified in mussels (Mytilus galloprovincialis), 0.24 microg/g, from Galicia, Spain, and scallops (Pecten maximus), 0.32 microg/g, from Brittany, France. Toxin profiles were similar to those found in the equivalent shellfish in Ireland in which AZA1 was the predominant toxin.

Detection of five new hydroxyl analogues of azaspiracids in shellfish using multiple tandem mass spectrometry

The polyether dinoflagellate toxins, azaspiracids, are responsible for azaspiracid poisoning (AZP), a new human toxic syndrome arising from the consumption of shellfish. To date, five azaspiracids have been isolated and fully structurally elucidated, including, AZA1, its 8-methyl and 22-demethyl analogues, AZA2 and AZA3, respectively, and two hydroxyl derivatives of AZA3, named AZA4 and AZA5. Using a recently developed method involving liquid chromatography with multiple tandem mass spectrometry (LC-MS(n)), five new azaspiracids, AZA7-AZA11, have been found in mussels (Mytilus edulis). AZA6 is a positional isomer of AZA1 and four of the new compounds are isomers with a mass of 857.5 amu. AZA7 and AZA8 are hydroxyl analogues of AZA1 while AZA9 and AZA10 are hydroxyl analogues of AZA6. AZA11 is a hydroxyl analogue of AZA2. The separation of all 11 azaspiracids was achieved using isocratic reversed phase liquid chromatography using a combination of eluent additives, trifluoroacetic acid and ammonium acetate. The ion-trap MS experiments, with electrospray ionisation, involved the fragmentation of the protonated molecule [M+H](+), trapping and fragmenting the product ions due to the loss of a water molecule [M+H-H(2)O](+), together with mass spectral data analysis that included the characteristic A-ring fragmentation for each compound.

Ubiquitous 'benign' alga emerges as the cause of shellfish contamination responsible for the human toxic syndrome, azaspiracid poisoning

A new human toxic syndrome, azaspiracid poisoning (AZP), was identified following illness from the consumption of contaminated mussels (Mytilus edulis). To discover the aetiology of AZP, sensitive analytical protocols involving liquid chromatography-mass spectrometry (LC-MS) were used to screen marine phytoplankton for azaspiracids. Collections of single species were prepared by manually separating phytoplankton for LC-MS analysis. A dinoflagellate species of the genus, Protoperidinium, has been identified as the progenitor of azaspiracids. Azaspiracid-1, and its analogues, AZA2 and AZA3, were identified in extracts of 200 cells using electrospray multiple tandem MS. This discovery has significant implications for both human health and the aquaculture industry since this phytoplankton genus was previously considered to be toxicologically benign. The average toxin content was 1.8 fmol of total AZA toxins per cell with AZA1 as the predominant toxin, accounting for 82% of the total.

Studies on azaspiracid biotoxins. III. Instrumental validation for rapid quantification of AZA 1 in complex biological matrices

Azaspiracids are neurotoxins produced by marine algae that have been detected in harvested mussels since 1995. They pose a significant threat to human health through the consumption of contaminated shellfish, and negatively impact the economy of areas where shellfish are harvested and processed. Regulatory agencies are beginning to advocate instrumental assays over traditional mouse bioassay methods. The development and validation of an assay method for AZA 1, the predominant azaspiracid toxin, and the production of a calibration standard and reference material will therefore be vital for quality control in monitoring laboratories worldwide. This report demonstrates a rapid and reproducible liquid chromatography/mass spectrometry (LC/MS) method for separation of all twelve known azaspiracids. Using a triple-quadrupole mass spectrometer, ultra-high sensitivity was obtained at the low-femtogram level injected on-column. At the same time, a linear response of three orders of magnitude was observed. We compared the results with those measured on an ion-trap mass spectrometer. The triple-quadrupole instrument was more sensitive, reliable and reproducible than the ion-trap instrument. The detection limit obtained on the ion-trap mass spectrometer was ten times higher than that obtained on the triple quadrupole. During the study, a new azaspiracid analog (AZA 7c) was discovered.

Comparison of solid-phase extraction methods for the determination of azaspiracids in shellfish by liquid chromatography-electrospray mass spectrometry

Azaspiracids have been identified as the cause of a new toxic syndrome called azaspiracid poisoning (AZP) that has led to incidents of human intoxications throughout Europe following the consumption of mussels. Although five AZP toxins have been structurally elucidated to-date, azaspiracid (AZA1), 8-methylazaspiracid (AZA2) and 22-demethylazaspiracid (AZA3) are the predominant toxins. Separation of the three main AZP toxins was achieved using reversed-phase liquid chromatography (LC) and coupled to an electrospray ionisation source of an ion-trap mass spectrometer. Five reversed-phase (C18) and three diol solid-phase extraction (SPE) cartridges were compared for their efficacy in the cleanup of shellfish matrix. The comparison was based on the optimum recoveries of AZA1, AZA2 and AZA3 from extracts of mussel tissues. LC-electrospray MS3 analysis was used to quantify the AZP toxins in wash and eluate fractions in the SPE studies. Good recovery and reproducibility data were obtained for one diol SPE cartridge and two C18 SPE cartridge types.

Azaspiracid shellfish poisoning: unusual toxin dynamics in shellfish and the increased risk of acute human intoxications

A number of recent acute human intoxications in Europe from the consumption of Irish mussels have been attributed to the presence of a new class of toxins named azaspiracids. The study demonstrates that azaspiracids behave differently from other polyether toxins, and this accounts for most false-negative results in the mouse bioassay employed by regulatory agencies to detect azaspiracids. Typically, polyether toxins are concentrated in the digestive glands of shellfish, but this is not always the situation with azaspiracids. Liquid chromatography-mass spectrometry (LC-MS), especially multiple tandem MS methods, have been applied to demonstrate that azaspiracid (AZA1) and its methyl- and demethyl- analogues, AZA2 and AZA3 respectively, are distributed throughout shellfish tissues. Using conventional mouse bioassay protocols, only 0-40% of the total azaspiracid content of shellfish was used in the assay, which could directly account for false-negative results. It was also observed that the toxin profiles differed significantly in various mussel tissues with AZA1 as the predominant toxin in the digestive glands and AZA3 predominant in the remaining tissues.

Pectenotoxins--an issue for public health: a review of their comparative toxicology and metabolism

Pectenotoxins (PTXs) are a group of toxins associated with diarrhetic shellfish poisoning (DSP) and isolated from DSP toxin-producing dinoflagellate algae. Consumption of shellfish contaminated with PTXs has been associated with incidences of severe diarrhetic illness resulting in hospitalisation. Concern has been raised for public health following the discovery that these toxins are not only hepatotoxic and can cause diarrhetic effects in mammals, but that they are potently cytotoxic to human cancer cell lines and have been found to be tumour promoters in animals. With advances in knowledge and technology, more PTXs are being identified, but little is known of their toxicology and the potential impact these toxins may have on public health in the long term. Without such information, adequate health-risk assessments for the consumption of shellfish contaminated with PTXs cannot be performed. This review gives a brief introduction to diarrhetic shellfish toxins, details the known toxicology and metabolism of PTXs in animals, and discusses known incidences of PTX poisoning in humans.