Dereplication of Gambierdiscusbalechii extract by LC-HRMS and in vitro assay: First description of a putative ciguatoxin and confirmation of 44-methylgambierone

Detection of Extremely Low Level Ciguatoxins through Monitoring of Lithium Adduct Ions by Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry

Ciguatera poisoning (CP) is the most common type of marine biotoxin food poisoning worldwide, and it is caused by ciguatoxins (CTXs), thermostable polyether toxins produced by dinoflagellate Gambierdiscus and Fukuyoa spp. It is typically caused by the consumption of large fish high on the food chain that have accumulated CTXs in their flesh. CTXs in trace amounts are found in natural samples, and they mainly induce neurotoxic effects in consumers at concentrations as low as 0.2 µg/kg. The U.S. Food and Drug Administration has established CTX maximum permitted levels of 0.01 µg/kg for CTX1B and 0.1 µg/kg for C-CTX1 based on toxicological data. More than 20 variants of the CTX1B and CTX3C series have been identified, and the simultaneous detection of trace amounts of CTX analogs has recently been required. Previously published works using LC-MS/MS achieved the safety levels by monitoring the sodium adduct ions of CTXs ([M+Na]+ > [M+Na]+). In this study, we optimized a highly sensitive method for the detection of CTXs using the sodium or lithium adducts, [M+Na]+ or [M+Li]+, by adding alkali metals such as Na+ or Li+ to the mobile phase. This work demonstrates that CTXs can be successfully detected at the low concentrations recommended by the FDA with good chromatographic separation using LC-MS/MS. It also reports on the method's new analytical conditions and accuracy using [M+Li]+.

Ciguatera poisoning in French Polynesia: A review of the distribution and toxicity of Gambierdiscus spp., and related impacts on food web components and human health

Ciguatera Poisoning (CP) is a seafood poisoning highly prevalent in French Polynesia. This illness results from the consumption of seafood contaminated with ciguatoxins (CTXs) produced by Gambierdiscus, a benthic dinoflagellate. Ciguatera significantly degrades the health and economic well-being of local communities largely dependent on reef fisheries for their subsistence. French Polynesia has been the site of rich and active CP research since the 1960's. The environmental, toxicological, and epidemiological data obtained in the frame of large-scale field surveys and a country-wide CP case reporting program conducted over the past three decades in the five island groups of French Polynesia are reviewed. Results show toxin production in Gambierdiscus in the natural environment may vary considerably at a temporal and spatial scale, and that several locales clearly represent Gambierdiscus spp. "biodiversity hotspots". Current data also suggest the "hot" species G. polynesiensis could be the primary source of CTXs in local ciguateric biotopes, pending formal confirmation. The prevalence of ciguatoxic fish and the CTX levels observed in several locales were remarkably high, with herbivores and omnivores often as toxic as carnivores. Results also confirm the strong local influence of Gambierdiscus spp. on the CTX toxin profiles characterized across multiple food web components including in CP-prone marine invertebrates. The statistics, obtained in the frame of a long-term epidemiological surveillance program established in 2007, point towards an apparent decline in the number of CP cases in French Polynesia as a whole; however, incidence rates remain dangerously high in some islands. Several of the challenges and opportunities, most notably those linked to the strong cultural ramifications of CP among local communities, that need to be considered to define effective risk management strategies are addressed.

Algal ciguatoxin identified as source of ciguatera poisoning in the Caribbean

Ciguatera poisoning (CP) is a severe seafood-borne disease, caused by the consumption of reef fish contaminated with Caribbean ciguatoxins (C-CTXs) in the Caribbean and tropical Atlantic. However, C-CTXs have not been identified from their presumed algal source, so the relationship to the CTXs in fish causing illness remains unknown. This has hindered the development of detection methods, diagnostics, monitoring programs, and limited fundamental knowledge on the environmental factors that regulate C-CTX production. In this study, in vitro and chemical techniques were applied to unambiguously identify a novel C-CTX analogue, C-CTX5, from Gambierdiscus silvae and Gambierdiscus caribaeus strains from the Caribbean. Metabolism in vitro by fish liver microsomes converted algal C-CTX5 into C-CTX1/2, the dominant CTX in ciguatoxic fish from the Caribbean. Furthermore, C-CTX5 from G. silvae was confirmed to have voltage-gated sodium-channel-specific activity. This finding is crucial for risk assessment, understanding the fate of C-CTXs in food webs, and is a prerequisite for development of effective analytical methods and monitoring programs. The identification of an algal precursor produced by two Gambierdiscus species is a major breakthrough for ciguatera research that will foster major advances in this important seafood safety issue.