Sulfo-Gambierones, Two New Analogs of Gambierone Produced by Gambierdiscus excentricus.

Thomas Yon,Damien Réveillon,Korian Lhaute,R Wayne Litaker,William C Holland,Philipp Hess,Samuel Bertrand,Elise Robert,Manoëlla Sibat

doi:10.3390/md19120657

Abstract

Ciguatera poisoning is caused by the ingestion of fish or shellfish contaminated with ciguatoxins produced by dinoflagellate species belonging to the genera Gambierdiscus and Fukuyoa. Unlike in the Pacific region, the species producing ciguatoxins in the Atlantic Ocean have yet to be definitely identified, though some ciguatoxins responsible for ciguatera have been reported from fish. Previous studies investigating the ciguatoxin-like toxicity of Atlantic Gambierdiscus species using Neuro2a cell-based assay identified G. excentricus as a potential toxin producer. To more rigorously characterize the toxin profile produced by this species, a purified extract from 124 million cells was prepared and partial characterization by high-resolution mass spectrometry was performed. The analysis revealed two new analogs of the polyether gambierone: sulfo-gambierone and dihydro-sulfo-gambierone. Algal ciguatoxins were not identified. The very low ciguatoxin-like toxicity of the two new analogs obtained by the Neuro2a cell-based assay suggests they are not responsible for the relatively high toxicity previously observed when using fractionated G. excentricus extracts, and are unlikely the cause of ciguatera in the region. These compounds, however, can be useful as biomarkers of the presence of G. excentricus due to their sensitive detection by mass spectrometry.

Highlights

Species of benthic dinoflagellates in the genera Gambierdiscus and Fukuyoa have been widely studied because of their role in producing neurotoxins that can bioaccumulate in the food chain, in particular the potent group of ciguatoxins [1,2]
This study further investigated the metabolites of G. excentricus using low and highresolution mass spectrometry and provides new insights into the toxin profile of this species
The signals were first obtained using low-resolution mass spectrometry in negative ionization electrospray (ESI− ) (MRM mode focusing on maitotoxins, gambierones, gambieric acids and gambieroxide)

Summary

Introduction

Species of benthic dinoflagellates in the genera Gambierdiscus and Fukuyoa have been widely studied because of their role in producing neurotoxins that can bioaccumulate in the food chain, in particular the potent group of ciguatoxins [1,2]. Consumption of fish or shellfish contaminated with such toxins can cause ciguatera poisoning (CP), characterized by gastrointestinal, cardiological and mild to severe and long-lasting neurological symptoms [3,4]. This illness is widespread in tropical areas where these dinoflagellates occur, with an estimated 10,000 to 50,000 intoxications occurring annually [1]. Following a study published in 1999, a series of ever-increasing taxonomic investigations have resulted in the division of the original genus into two separate genera, “Gambierdiscus” and “Fukuyoa”, containing 18 and 3 described species, respectively [3,7,8,9]. Two major types of toxins potentially involved in ciguatera poisoning were discovered in fish flesh: maitotoxins (MTX), which are large non-polymeric amphiphilic polyethers, initially found in the viscera of the bristletooth surgeonfish Ctenochaetus striatus [10,11], and ciguatoxins (CTX), which are more apolar polyethers, firstly found in moray eel, Gymnothorax javanicus [12]

Methods

Results

Conclusion