Biooxidation of Ciguatoxins Leads to Species-Specific Toxin Profiles

In the last decade, several outbreaks of ciguatera fish poisoning (CFP) have been reported in the Canary Islands (central northeast Atlantic Ocean), confirming ciguatera as an emerging alimentary risk in this region. Five Gambierdiscus species, G. australes, G. excentricus, G. silvae, G. carolinianus and G. caribaeus, have been detected in macrophytes from this area and are known to produce the ciguatoxins (CTXs) that cause CFP. A characterization of the toxicity of these species is the first step in identifying locations in the Canary Islands at risk of CFP. Therefore, in this study the toxicity of 63 strains of these five Gambierdiscus species were analysed using the erythrocyte lysis assay to evaluate their maitotoxin (MTX) content. In addition, 20 of the strains were also analysed in a neuroblastoma Neuro-2a (N2a) cytotoxicity assay to determine their CTX-like toxicity. The results allowed the different species to be grouped according to their ratios of CTX-like and MTX-like toxicity. MTX-like toxicity was especially high in G. excentricus and G. australes but much lower in the other species and lowest in G. silvae. CTX-like toxicity was highest in G. excentricus, which produced the toxin in amounts ranging between 128.2 ± 25.68 and 510.6 ± 134.2 fg CTX1B equivalents (eq) cell−1 (mean ± SD). In the other species, CTX concentrations were as follows: G. carolinianus (100.84 ± 18.05 fg CTX1B eq cell−1), G. australes (31.1 ± 0.56 to 107.16 ± 21.88 fg CTX1B eq cell−1), G. silvae (12.19 ± 0.62 to 76.79 ± 4.97 fg CTX1B eq cell−1) and G. caribaeus (<LOD to 90.37 ± 15.89 fg CTX1B eq cell−1). Unlike the similar CTX-like toxicity of G. australes and G. silvae strains from different locations, G. excentricus and G. caribaeus differed considerably according to the origin of the strain. These differences emphasise the importance of species identification to assess the regional risk of CFP.

Section: Introductionmentioning

confidence: 99%

Toxicity Characterisation of Gambierdiscus Species from the Canary Islands

Rossignoli

Tudó

Bravo

et al. 2020

“…CP is endemic in temperate waters of the Pacific Ocean and Caribbean Sea and was recently detected in the Northeast Atlantic [2][3][4][5][6]. A main difficulty in advancing CP research is the lack of reference materials of these toxins and the numerous toxic analogues present in the toxic samples [7,8]. This lack of reference materials limits progress in method development and identification of CTX analogues responsible for the CP.…”

Section: Introductionmentioning

confidence: 99%

Liquid Chromatography Coupled to High-Resolution Mass Spectrometry for the Confirmation of Caribbean Ciguatoxin-1 as the Main Toxin Responsible for Ciguatera Poisoning Caused by Fish from European Atlantic Coasts

Estevez

Sibat

Leão-Martins

et al. 2020

Ciguatera poisoning (CP) is a common seafood intoxication mainly caused by the consumption of fish contaminated by ciguatoxins. Recent studies showed that Caribbean ciguatoxin-1 (C-CTX1) is the main toxin causing CP through fish caught in the Northeast Atlantic, e.g., Canary Islands (Spain) and Madeira (Portugal). The use of liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) combined with neuroblastoma cell assay (N2a) allowed the initial confirmation of the presence of C-CTX1 in contaminated fish samples from the abovementioned areas, nevertheless the lack of commercially available reference materials for these particular ciguatoxin (CTX) analogues has been a major limitation to progress research. The EuroCigua project allowed the preparation of C-CTX1 laboratory reference material (LRM) from fish species (Seriola fasciata) from the Madeira archipelago (Portugal). This reference material was used to implement a liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) for the detection of C-CTX1, acquisition of full-scan as well as collision-induced mass spectra of this particular analogue. Fragmentation pathways were proposed based on fragments obtained. The optimized LC-HRMS method was then applied to confirm C-CTX1 in fish (Bodianus scrofa) caught in the Selvagens Islands (Portugal).Key Contribution: LC-Q-TOF-MS in full-scan MS and MS/MS mode permitted successful acquisition of C-CTX1 spectra. Fragmentation pathways are presented. C-CTX1 was confirmed in a barred hogfish (Bodianus scrofa) from the Selvagens Islands (Portugal).

“…Roeder et al (2010) [69] reported that 2,3-dihydroxy-P-CTX-3C was produced by G. australes, G. carpenteri, G. caribaeus, G. pacificus, and G. toxicus. It is noted that this analogue is considered a fish metabolite and not produced by the dinoflagellates [70].…”

Section: Ciguatera Fish Poisoning Related Toxins and Their Toxicitymentioning

confidence: 99%

Ciguatera Fish Poisoning: The Risk from an Aotearoa/New Zealand Perspective

Rhodes

Smith

Murray

et al. 2020

Gambierdiscus and Fukuyoa species have been identified in Aotearoa/New Zealand’s coastal waters and G. polynesiensis, a known producer of ciguatoxins, has been isolated from Rangitāhua/Kermadec Islands (a New Zealand territory). The warming of the Tasman Sea and the waters around New Zealand’s northern subtropical coastline heighten the risk of Gambierdiscus proliferating in New Zealand. If this occurs, the risk of ciguatera fish poisoning due to consumption of locally caught fish will increase. Research, including the development and testing of sampling methods, molecular assays, and chemical and toxicity tests, will continue. Reliable monitoring strategies are important to manage and mitigate the risk posed by this emerging threat. The research approaches that have been made, many of which will continue, are summarised in this review.