Detection and Spatio-Temporal Distribution of Pinnatoxins in Shellfish from the Atlantic and Cantabrian Coasts of Spain

Discovery of a series of portimine-A fatty acid esters in mussels

Vulcanodinium rugosum is a benthic dinoflagellate known for producing pinnatoxins, pteriatoxins, portimines and kabirimine. In this study, we aimed to identify unknown analogs of these emerging toxins in mussels collected in the Ingril lagoon, France. First, untargeted data acquisitions were conducted by means of liquid chromatography coupled to hybrid quadrupole-orbitrap mass spectrometry. Data processing involved a molecular networking approach, and a workflow dedicated to the identification of biotransformed metabolites. Additionally, targeted analyses by liquid chromatography coupled to triple quadrupole mass spectrometry were also implemented to further investigate and confirm the identification of new compounds. For the first time, a series of 13-O-acyl esters of portimine-A (n = 13) were identified, with fatty acid chains ranging between C12:0 and C22:6. The profile was dominated by the palmitic acid conjugation. This discovery was supported by fractionation experiments combined with the implementation of a hydrolysis reaction, providing further evidence of the metabolite identities. Furthermore, several analogs were semi-synthesized, definitively confirming the discovery of these metabolization products. A new analog of pinnatoxin, with a molecular formula of C42H65NO9, was also identified across the year 2018, with the highest concentration observed in August (4.5 μg/kg). The MS/MS data collected for this compound exhibited strong structural similarities with PnTX-A and PnTX-G, likely indicating a substituent C2H5O2 in the side chain at C33. The discovery of these new analogs will contribute to deeper knowledge of the chemodiversity of toxins produced by V. rugosum or resulting from shellfish metabolism, thereby improving our ability to characterize the risks associated with these emerging toxins.

The Temporal Distribution of Cyclic Imines in Shellfish in the Bays of Fangar and Alfacs, Northwestern Mediterranean Region

Spirolides (SPXs), gymnodimines (GYMs), and pinnatoxins (PnTXs) have been detected in shellfish from the northwestern Mediterranean coast of Spain. Several samples of bivalves were collected from Fangar Bay and Alfacs Bay in Catalonia over a period of over 7 years (from 2015 to 2021). Shellfish samples were analyzed for cyclic imines (CIs) on an LC1200 Agilent and 3200 QTrap triple-quadrupole mass spectrometer. In shellfish, SPX-1 was detected in two cases (of 26.5 µg/kg and 34 µg/kg), and GYM-A was only detected in trace levels in thirteen samples. Pinnatoxin G (PnTX-G) was detected in 44.6% of the samples, with its concentrations ranging from 2 µg/kg to 38.4 µg/kg. Statistical analyses revealed that seawater temperature influenced the presence or absence of these toxins. PnTX-G showed an extremely significant presence/temperature relationship in both bays in comparison to SPX-1 and GYM-A. The prevalence of these toxins in different bivalve mollusks was evaluated. A seasonal pattern was observed, in which the maximum concentrations were found in the winter months for SPX-1 and GYM-A but in the summer months for PnTX-G. The obtained results indicate that it is unlikely that CIs in the studied area pose a potential health risk through the consumption of a seafood diet. However, further toxicological information about CIs is necessary in order to perform a conclusive risk assessment.

Modelling spatiotemporal distributions of Vulcanodinium rugosum and pinnatoxin G in French Mediterranean lagoons: Application to human health risk characterisation

Consumption of seafood contaminated by phycotoxins produced by harmful algae is a major issue in human public health. Harmful algal blooms are driven by a multitude of environmental variables; therefore predicting human dietary exposure to phycotoxins based on these variables is a promising approach in health risk management. In this study, we attempted to predict the human health risks associated with Vulcanodinium rugosum and its neurotoxins, pinnatoxins (PnTXs), which have been regularly found in Mediterranean lagoons since their identification in 2011. Based on environmental variables collected over 1 year in four Mediterranean lagoons, we developed linear mixed models to predict the presence of V. rugosum and PnTX G contamination of mussels. We found that the occurrence of V. rugosum was significantly associated with seawater temperature. PnTX G contamination of mussels was highest in summer but persisted throughout the year. This contamination was significantly associated with seawater temperature and the presence of V. rugosum with a time lag, but not with dissolved PnTX G in seawater. By using the contamination model predictions and their potential variability/uncertainty, we calculated the human acute dietary exposures throughout the year and predicted that 25% of people who consume mussels could exceed the provisional acute benchmark value during the warmest periods. We suggest specific recommendations to monitor V. rugosum and PnTX G.

Lipophilic Shellfish Poisoning Toxins in Marine Invertebrates from the Galician Coast

For the purpose of assessing human health exposure, it is necessary to characterize the toxins present in a given area and their potential impact on commercial species. The goal of this research study was: (1) to screen the prevalence and concentrations of lipophilic toxins in nine groups of marine invertebrates in the northwest Iberian Peninsula; (2) to evaluate the validity of wild mussels (Mytilus galloprovincialis) as sentinel organisms for the toxicity in non-bivalve invertebrates from the same area. The screening of multiple lipophilic toxins in 1150 samples has allowed reporting for the first time the presence of 13-desmethyl spirolide C, pinnatoxin G, okadaic acid, and dinophysistoxins 2 in a variety of non-traditional vectors. In general, these two emerging toxins showed the highest prevalence (12.5-75%) in most of the groups studied. Maximum levels for 13-desmethyl spirolide C and pinnatoxin G were found in the bivalves Magallana gigas (21 µg kg-1) and Tellina donacina (63 µg kg-1), respectively. However, mean concentrations for the bivalve group were shallow (2-6 µg kg-1). Okadaic acid and dinophysistoxin 2 with lower prevalence (1.6-44.4%) showed, on the contrary, very high concentration values in specific species of crustaceans and polychaetes (334 and 235 µg kg--1, respectively), to which special attention should be paid. Statistical data analyses showed that mussels could be considered good biological indicators for the toxicities of certain groups in a particular area, with correlations between 0.710 (for echinoderms) and 0.838 (for crustaceans). Polychaetes could be an exception, but further extensive surveys would be needed to draw definitive conclusions.

Exploration of Vulcanodinium rugosum Toxins and their Metabolism Products in Mussels from the Ingril Lagoon Hotspot in France

Over the year 2018, we assessed toxin contamination of shellfish collected on a monthly basis in Ingril Lagoon, France, a site known as a hotspot for Vulcanodinium rugosum growth. This short time-series study gave an overview of the presence and seasonal variability of pinnatoxins, pteriatoxins, portimines and kabirimine, all associated with V. rugosum, in shellfish. Suspect screening and targeted analysis approaches were implemented by means of liquid chromatography coupled to both low- and high-resolution mass spectrometry. We detected pinnatoxin-A and pinnatoxin-G throughout the year, with maximum levels for each one observed in June (6.7 µg/kg for pinnatoxin-A; 467.5 µg/kg for pinnatoxin-G), whereas portimine-A was detected between May and September (maximum level = 75.6 µg/kg). One of the main findings was the identification of a series of fatty acid esters of pinnatoxin-G (n = 13) although the levels detected were low. The profile was dominated by the palmitic acid conjugation of pinnatoxin-G. The other 12 fatty acid esters had not been reported in European shellfish to date. In addition, after thorough investigations, two compounds were detected, with one being probably identified as portimine-B, and the other one putatively attributed to pteriatoxins. If available, reference materials would have ensured full identification. Monitoring of these V. rugosum emerging toxins and their biotransformation products will contribute towards filling the data gaps pointed out in risk assessments and in particular the need for more contamination data for shellfish.

Recent advancements in LC-MS based analysis of biotoxins: Present and future challenges

There has been a rising concern regarding the harmful impact of biotoxins, source of origin, and the determination of the specific type of toxin. With numerous reports on their extensive spread, biotoxins pose a critical challenge to figure out their parent groups, metabolites, and concentration. In that aspect, liquid chromatography-mass spectrometry (LC-MS) based analysis paves the way for its accurate identification and quantification. The biotoxins are ideally categorized as phytotoxins, mycotoxins, shellfish-toxins, ciguatoxins, cyanotoxins, and bacterial toxins such as tetrodotoxins. Considering the diverse nature of biotoxins, both low-resolution mass spectrometry (LRMS) and high-resolution mass spectrometry (HRMS) methods have been implemented for their detection. The sample preparation strategy for complex matrix usually includes "QuEChERS" extraction or solid-phase extraction coupled with homogenization and centrifugation. For targeted analysis of biotoxins, the LRMS consisting of a tandem mass spectrometer operating in multiple reaction monitoring mode has been widely implemented. With the help of the reference standard, most of the toxins were accurately quantified. At the same time, the suspect screening and nontarget screening approach are facilitated by the HRMS platforms during the absence of reference standards. Significant progress has also been made in sampling device employment, utilizing novel sample preparation strategies, synthesizing toxin standards, employing hybrid MS platforms, and the associated data interpretation. This critical review attempts to elucidate the progress in LC-MS based analysis in the determination of biotoxins while pointing out major challenges and suggestions for future development.

Emerging Marine Biotoxins in European Waters: Potential Risks and Analytical Challenges

Harmful algal blooms pose a challenge regarding food safety due to their erratic nature and forming circumstances which are yet to be disclosed. The best strategy to protect human consumers is through legislation and monitoring strategies. Global warming and anthropological intervention aided the migration and establishment of emerging toxin producers into Europe's temperate waters, creating a new threat to human public health. The lack of information, standards, and reference materials delay effective solutions, being a matter of urgent resolution. In this work, the recent findings of the presence of emerging azaspiracids, spirolildes, pinnatoxins, gymnodimines, palitoxins, ciguatoxins, brevetoxins, and tetrodotoxins on European Coasts are addressed. The information concerning emerging toxins such as new matrices, locations, and toxicity assays is paramount to set the risk assessment guidelines, regulatory levels, and analytical methodology that would protect the consumers.

Development of a Fast Liquid Chromatography Coupled to Mass Spectrometry Method (LC-MS/MS) to Determine Fourteen Lipophilic Shellfish Toxins Based on Fused-Core Technology: In-House Validation

Prevalence and incidence of the marine toxins (paralytic, amnesic, and lipophilic toxins) including the so-called emerging toxins (these are, gymnodimines, pinnatoxins, or spirolides among others) have increased in recent years all over the world. Climate change, which is affecting the distribution of their producing phytoplankton species, is probably one of the main causes. Early detection of the toxins present in a particular area, and linking the toxins to their causative phytoplankton species are key tools to minimize the risk they pose for human consumers. The development of both types of studies requires fast and highly sensitive analytical methods. In the present work, we have developed a highly sensitive liquid chromatography-mass spectrometry methodology (LC-MS/MS), using a column with fused-core particle technology, for the determination of fourteen lipophilic toxins in a single run of 3.6 min. The performance of the method was evaluated for specificity, linearity, precision (repeatability and reproducibility) and accuracy by analysing spiked and naturally contaminated samples. The in-house validation was successful, and the limit of detection (LOD) and quantification (LOQ) for all the toxins were far below their regulatory action limits. The method is suitable to be considered in monitoring systems of bivalves for food control.

First evidence that emerging pinnatoxin-G, a contaminant of shellfish, reaches the brain and crosses the placental barrier

Massive proliferation of some toxic marine dinoflagellates is responsible for the occurrence of harmful algal blooms and the contamination of fish and shellfish worldwide. Pinnatoxins (PnTx) (A-H) comprise an emerging phycotoxin family belonging to the cyclic imine toxin group. Interest has been focused on these lipophilic, fast-acting and highly potent toxins because they are widely found in contaminated shellfish, and can represent a risk for seafood consumers. PnTx display a potent antagonist effect on nicotinic acetylcholine receptors (nAChR), and in this study we assessed in vivo the ability of PnTx-G to cross physiological barriers to reach its molecular target. Radiolabeled [³H]-PnTx-G synthesized with good radiochemical purity and yield retained the high affinity of the natural toxin. Oral gavage or intravenous administration to adult rats and digital autoradiographic analyses revealed the biodistribution and toxicokinetics of [³H]-PnTx-G, which is rapidly cleared from blood, and accumulates in the liver and small intestine. The labeling of peripheral and brain adult/embryo rat tissues highlights its ability to cross the intestinal, blood-brain and placental barriers. High-resolution 3D-imaging and in vitro competition studies on rat embryo sections revealed the specificity of [³H]-PnTx-G binding and its selectivity for muscle and neuronal nAChR subtypes (such as α7 subtype). The use of a human perfused cotyledon model and mass spectrometry analyses disclosed that PnTx-G crosses the human placental barrier. The increasing worldwide occurrence of both the dinoflagellate Vulcanodinium rugosum and PnTx-contaminated shellfish, due to climate warming, raises concerns about the potential adverse impact that exposure to pinnatoxins may have for human health.

First examination of sterols in the marine dinoflagellate genus Vulcanodinium

Vulcanodinium is an ecologically relevant dinoflagellate genus due to its production of neurotoxins known as pinnatoxins. We present here the first examination of the sterols of a Vulcanodinium rugosum isolate. Sterols are ringed lipids that assist in maintaining rigidity of cellular membranes, and the Dinophyceae are well-studied for their ability to produce a diverse array of sterols, many of which have chemotaxonomic utility. We have determined that V. rugosum produces a set of major sterols, namely cholesterol, dinosterol, 4α,24-dimethyl-5α-cholest-22E-en-3β-ol, and 4α,24-dimethyl-5α-cholestan-3β-ol, common to the Dinophyceae. However, this displayed marked differences from those studied members of the genera Scrippsiella and Peridinium, the closest phylogenetic relatives. Included in these differences is production by V. rugosum of a much lower percentage of dinostanol, a saturated form of dinosterol.

Gymnodimine A in mollusks from the north Atlantic Coast of Spain: Prevalence, concentration, and relationship with spirolides

Gymnodimine A has been found in mollusks obtained along the whole northern coast of Spain from April 2017 to December 2019. This is the first time that this toxin is detected in mollusks from the Atlantic coast of Europe. The prevalence of the toxin was, in general, low, being detected on average in approximately 6% of the obtained samples (122 out of 1900). The concentrations recorded were also, in general, low, with a median of 1.3 μg kg^-1, and a maximum value of 23.93 μg kg^-1. The maxima of prevalence and concentration were not geographically coincident, taking place the first at the easternmost part of the sampled area and the second at the westernmost part. In most cases (>94%), gymnodimine A and 13-desmethyl spirolide C were concurrently detected, suggesting that Alexandrium ostenfeldii could be the responsible producer species. The existence of cases in which gymnodimine A was detected alone suggests also that a Karenia species could also be involved. The geographical heterogeneity of the distribution suggests that blooms of the producer species are mostly local. Not all bivalves are equally affected, clams being less affected than mussels, oysters, and razor clams. Due to their relatively low toxicity, and their low prevalence and concentration, it seems that these toxins do not pose an important risk for the mollusk consumers in the area.

In vitro investigation of the genotoxicity of portimine, a cyclic imine toxin produced by the dinoflagellate Vulcanodinium rugosum, on human hepatic HepaRG cells

Portimine, a recently identified cyclic imine produced by the dinoflagellate Vulcanodinium rugosum, has been described as a potent apoptotic agent in contrast to most of the cyclic imines that are well-known to be neurological toxins. As apoptosis can be a consequence of a high level of DNA lesions, we investigated the responses of portimine on several endpoints aimed at detecting DNA damage in the hepatic cell line HepaRG. Portimine induced phosphorylation of H2AX, which could possibly be consistent with the previously published induction of apoptosis with this toxin. In addition, detection of apoptosis through the activation of caspase-3, the induction of strand breaks detected by the comet assay as well as chromosome and genome mutations using the micronucleus assay were addressed. Surprisingly, portimine treatment resulted in increases in only γH2AX in differentiated HepaRG cells whereas no effects on the other endpoints were detected. These increases in γH2AX in the absence of genotoxic effects in the other tests could indicate that portimine could possibly induce a DNA replication stress and/or that the compound can be detoxified by the HepaRG cells.

Diversity and regional distribution of harmful algal events along the Atlantic margin of Europe

The IOC-ICES-PICES Harmful Algal Event Database (HAEDAT) was used to describe the diversity and spatiotemporal distribution of harmful algal events along the Atlantic margin of Europe from 1987 - 2018. The majority of events recorded are caused by Diarrhetic Shellfish Toxins (DSTs). These events are recorded annually over a wide geographic area from southern Spain to northern Scotland and Iceland, and are responsible for annual closures of many shellfish harvesting areas. The dominant causative dinoflagellates, members of the morphospecies 'Dinophysis acuminata complex' and D. acuta, are common in the waters of the majority of countries affected. There are regional differences in the causative species associated with PST events; the coasts of Spain and Portugal with the dinoflagellates Alexandrium minutum and Gymnodinium catenatum, north west France/south west England/south Ireland with A. minutum, and Scotland/Faroe Islands/Iceland with A. catenella. This can influence the duration and spatial scale of PST events as well as the toxicity of shellfish. The diatom Pseudo-nitzschia australis is the most widespread Domoic Acid (DA) producer, with records coming from Spain, Portugal, France, Ireland and the UK. Amnesic Shellfish Toxins (ASTs) have caused prolonged closures for the scallop fishing industry due to the slow depuration rate of DA. Amendments to EU shellfish hygiene regulations introduced between 2002 and 2005 facilitated end-product testing and sale of adductor muscle. This reduced the impact of ASTs on the scallop fishing industry and thus the number of recorded HAEDAT events. Azaspiracids (AZAs) are the most recent toxin group responsible for events to be characterised in the ICES area. Events associated with AZAs have a discrete distribution with the majority recorded along the west coast of Ireland. Ciguatera Poisoning (CP) has been an emerging issue in the Canary Islands and Madeira since 2004. The majority of aquaculture and wild fish mortality events are associated with blooms of the dinoflagellate Karenia mikimotoi and raphidophyte Heterosigma akashiwo. Such fish killing events occur infrequently yet can cause significant mortalities. Interannual variability was observed in the annual number of HAEDAT areas with events associated with individual shellfish toxin groups. HABs represent a continued risk for the aquaculture industry along the Atlantic margin of Europe and should be accounted for when considering expansion of the industry or operational shifts to offshore areas.

Cyclic imines in shellfish and ascidians in the northern Adriatic Sea

The aim of this study was to determine the occurrence of the most representative cyclic imines (CIs) gymnodimine (GYM), pinnatoxin G (PnTX-G), and 13-desmethyl SPX C (SPX1) in Mediterranean mussels (Mytilus galloprovincialis Lamarck, 1819) (n = 416), European oysters (Ostrea edulis Linnaeus, 1758) (n = 104), Queen scallops (Aequipecten opercularis Linnaeus, 1758) (n = 52) and edible ascidians of the Microcosmus spp. (n = 104) originating from nine harvesting and breeding areas in the northern part of the Adriatic Sea using ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). All CI concentrations were far below the guidance level of 400 μg SPXs/kg proposed by the EU Reference Laboratory for Marine Toxins. In contrast to Queen scallops and ascidians, in Mediterranean mussels and European oysters CIs were found throughout the year. Our data reveal the differences between species predisposed for CIs accumulation, as well as seasonal and locational variations in CIs occurrence.

Development of a data dependent acquisition-based approach for the identification of unknown fast-acting toxins and their ester metabolites

Phycotoxins in the marine food-web represent a serious threat to human health. Consumption of contaminated shellfish and/or finfish poses risk to consumer safety: several cases of toxins-related seafood poisoning have been recorded so far worldwide. Cyclic imines are emerging lipophilic toxins, which have been detected in shellfish from different European countries. Currently, they are not regulated due to the lack of toxicological comprehensive data and hence the European Food Safety Authority has required more scientific efforts before establishing a maximum permitted level in seafood. In this work, a novel data dependent liquid chromatography - high resolution mass spectrometry (LC-HRMS) approach has been successfully applied and combined with targeted studies for an in-depth investigation of the metabolic profile of shellfish samples. The proposed analytical methodology has allowed: i) to discover a plethora of unknown fatty acid esters of gymnodimines and ii) to conceive a brand new MS-based strategy, termed as backward analysis, for discovery and identification of new analogues. In particular, the implemented analytical workflow has broadened the structural diversity of cyclic imine family through the inclusion of five new congeners, namely gymnodimine -F, -G, -H, -I and -J. In addition, gymnodimine A (376.5 μg/kg), 13-desmethyl spirolide C (11.0-29.0 μg/kg) and pinnatoxin G (3.1-7.7 μg/kg) have been detected in shellfish from different sites of the Mediterranean basin (Tunisia and Italy) and the Atlantic coast of Spain, with the confirmation of the first finding of pinnatoxin G in mussels harvested in Sardinia (Tyrrhenian Sea, Italy).

Detection of Cyclic Imine Toxins in Dietary Supplements of Green Lipped Mussels (Perna canaliculus) and in Shellfish Mytilus chilensis

Seafood represents a significant part of the human staple diet. In the recent years, the identification of emerging lipophilic marine toxins has increased, leading to the potential for consumers to be intoxicated by these toxins. In the present work, we investigate the presence of lipophilic marine toxins (both regulated and emerging) in commercial seafood products from non-European locations, including mussels Mytilus chilensis from Chile, clams Tawerea gayi and Metetrix lyrate from the Southeast Pacific and Vietnam, and food supplements based on mussels formulations of Perna canaliculus from New Zealand. All these products were purchased from European Union markets and they were analyzed by UPLC-MS/MS. Results showed the presence of the emerging pinnatoxin-G in mussels Mytilus chilensis at levels up to 5.2 µg/kg and azaspiracid-2 and pectenotoxin-2 in clams Tawera gayi up to 4.33 µg/kg and 10.88 µg/kg, respectively. This study confirms the presence of pinnatoxins in Chile, one of the major mussel producers worldwide. Chromatograms showed the presence of 13-desmethyl spirolide C in dietary supplements in the range of 33.2-97.9 µg/kg after an extraction with water and methanol from 0.39 g of the green lipped mussels powder. As far as we know, this constitutes the first time that an emerging cyclic imine toxin in dietary supplements is reported. Identifying new matrix, locations, and understanding emerging toxin distribution area are important for preventing the risks of spreading and contamination linked to these compounds.

Acute Oral Toxicity of Pinnatoxin G in Mice

Pinnatoxin G (PnTx-G) is a marine cyclic imine toxin produced by the dinoflagellate Vulcanodinium rugosum, frequently detected in edible shellfish from Ingril Lagoon (France). As other pinnatoxins, to date, no human poisonings ascribed to consumption of PnTx-G contaminated seafood have been reported, despite its potent antagonism at nicotinic acetylcholine receptors and its high and fast-acting toxicity after intraperitoneal or oral administration in mice. The hazard characterization of PnTx-G by oral exposure is limited to a single acute toxicity study recording lethality and clinical signs in non-fasted mice treated by gavage or through voluntary food ingestion, which showed differences in PnTx-G toxic potency. Thus, an acute toxicity study was carried out using 3 h-fasted CD-1 female mice, administered by gavage with PnTx-G (8–450 µg kg⁻¹). At the dose of 220 µg kg⁻¹ and above, the toxin induced a rapid onset of clinical signs (piloerection, prostration, hypothermia, abdominal breathing, paralysis of the hind limbs, and cyanosis), leading to the death of mice within 30 min. Except for moderate mucosal degeneration in the small intestine recorded at doses of 300 µg kg⁻¹, the toxin did not induce significant morphological changes in the other main organs and tissues, or alterations in blood chemistry parameters. This acute oral toxicity study allowed to calculate an oral LD₅₀ for PnTx-G equal to 208 μg kg⁻¹ (95% confidence limits: 155–281 µg kg⁻¹) and to estimate a provisional NOEL of 120 µg kg⁻¹.

Analysis of Cyclic Imines in Mussels (Mytilus galloprovincialis) from Galicia (NW Spain) by LC-MS/MS

Cyclic imines (CIs) are being considered as emerging toxins in the European Union, and a scientific opinion has been published by the European Food Safety Authority (EFSA) in which an assessment of the risks to human health related to their consumption has been carried out. Recommendations on the EFSA opinion include the search for data occurrence of CIs in shellfish and using confirmatory methods by liquid chromatography-tandem mass spectrometry (LC-MS/MS), which need to be developed and optimized. The aim of this work is the application of LC-MS/MS to the analysis of gymnodimines (GYMs), spirolides (SPXs), pinnatoxins (PnTXs), and pteriatoxins (PtTXs) in mussels from Galician Rias, northwest Spain, the main production area in Europe, and therefore a representative emplacement for their evaluation. Conditions were adjusted using commercially available certified reference standards of GYM-A, SPX-1, and PnTX-G and evaluated through quality control studies. The EU-Harmonised Standard Operating Procedure for determination of lipophilic marine biotoxins in molluscs by LC-MS/MS was followed, and the results obtained from the analysis of eighteen samples from three different locations that showed the presence of PnTXs and SPXs are presented and discussed. Concentrations of PnTX-G and SPX-1 ranged from 1.8 to 3.1 µg/kg and 1.2 to 6.9 µg/kg, respectively, and PnTX-A was detected in the group of samples with higher levels of PnTX-G after a solid phase extraction (SPE) step used for the concentration of extracts.

Lipophilic Toxins in Galicia (NW Spain) between 2014 and 2017: Incidence on the Main Molluscan Species and Analysis of the Monitoring Efficiency

Galicia is an area with a strong mussel aquaculture industry in addition to other important bivalve mollusc fisheries. Between 2014 and 2017, 18,862 samples were analyzed for EU regulated marine lipophilic toxins. Okadaic acid (OA) was the most prevalent toxin and the only single toxin that produced harvesting closures. Toxin concentrations in raft mussels were generally higher than those recorded in other bivalves, justifying the use of this species as an indicator. The Rías of Pontevedra and Muros were the ones most affected by OA and DTX2 and the Ría of Ares by YTXs. In general, the outer areas of the Rías were more affected by OA and DTX2 than the inner ones. The OA level reached a maximum in spring, while DTX2 was almost entirely restricted to the fall-winter season. YTXs peaked in August-September. The toxins of the OA group were nearly completely esterified in all the bivalves studied except mussels and queen scallops. Risk of intoxication with the current monitoring system is low. In less than 2% of cases did the first detection of OA in an area exceed the regulatory limit. In no case, could any effect on humans be expected. The apparent intoxication and depuration rates were similar and directly related, suggesting that the rates are regulated mainly by oceanographic characteristics.

Pinnatoxins' Deleterious Effects on Cholinergic Networks: From Experimental Models to Human Health

Pinnatoxins (PnTXs) are emerging neurotoxins that were discovered about 30 years ago. They are solely produced by the marine dinoflagellate Vulcanodinium rugosum, and may be transferred into the food chain, as they have been found in various marine invertebrates, including bivalves. No human intoxication has been reported to date although acute toxicity was induced by PnTxs in rodents. LD₅₀ values have been estimated for the different PnTXs through the oral route. At sublethal doses, all symptoms are reversible, and no neurological sequelae are visible. These symptoms are consistent with impairment of central and peripheral cholinergic network functions. In fact, PnTXs are high-affinity competitive antagonists of nicotinic acetylcholine receptors (nAChRs). Moreover, their lethal effects are consistent with the inhibition of muscle nAChRs, inducing respiratory distress and paralysis. Human intoxication by ingestion of PnTXs could result in various symptoms observed in episodes of poisoning with natural nAChR antagonists. This review updates the available data on PnTX toxicity with a focus on their mode of action on cholinergic networks and suggests the effects that could be extrapolated on human physiology.