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Open AccessFeature PaperArticle

Maitotoxin-4, a Novel MTX Analog Produced by Gambierdiscus excentricus

Ifremer, Phycotoxins Laboratory, rue de l’Ile d’Yeu, BP 21105, F-44311 Nantes, France
Mer Molécules Santé (MMS) Laboratory EA2160, University of Nantes, LUNAM, Pharmacy Faculty, 9 rue Bias, F-44035 Nantes, France
Department of Life Science, University of Trieste, Via Giorgieri 5, 34127 Trieste, Italy
Toxicology of Contaminants Unit, ANSES Laboratory—French Agency for Food, Environmental and Occupational Health and Safety, Fougères, 10 B rue Claude Bourgelat, 35133 Javené, France
Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Vigo, Subida a Radio Faro 50, 36390 Vigo, Spain
Laboratório de Microalgas Marinhas, Departamento de Ecologia e Recursos Marinhos, Universidade Federal do Estado do Rio de Janeiro (UNIRIO), Rio de Janeiro 22290-240, Brazil
National Oceanic and Atmospheric Administration, National Ocean Service, National Centers for Coastal Ocean Science, Center for Coastal Fisheries and Habitat Research (CCFHR), 101 Pivers Island Road, Beaufort, NC 28516, USA
Author to whom correspondence should be addressed.
Mar. Drugs 2017, 15(7), 220;
Received: 13 June 2017 / Revised: 30 June 2017 / Accepted: 5 July 2017 / Published: 11 July 2017
Maitotoxins (MTXs) are among the most potent toxins known. These toxins are produced by epi-benthic dinoflagellates of the genera Gambierdiscus and Fukuyoa and may play a role in causing the symptoms associated with Ciguatera Fish Poisoning. A recent survey revealed that, of the species tested, the newly described species from the Canary Islands, G. excentricus, is one of the most maitotoxic. The goal of the present study was to characterize MTX-related compounds produced by this species. Initially, lysates of cells from two Canary Island G. excentricus strains VGO791 and VGO792 were partially purified by (i) liquid-liquid partitioning between dichloromethane and aqueous methanol followed by (ii) size-exclusion chromatography. Fractions from chromatographic separation were screened for MTX toxicity using both the neuroblastoma neuro-2a (N2a) cytotoxicity and Ca2+ flux functional assays. Fractions containing MTX activity were analyzed using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) to pinpoint potential MTX analogs. Subsequent non-targeted HRMS analysis permitted the identification of a novel MTX analog, maitotoxin-4 (MTX4, accurate mono-isotopic mass of 3292.4860 Da, as free acid form) in the most toxic fractions. HRMS/MS spectra of MTX4 as well as of MTX are presented. In addition, crude methanolic extracts of five other strains of G. excentricus and 37 other strains representing one Fukuyoa species and ten species, one ribotype and one undetermined strain/species of Gambierdiscus were screened for the presence of MTXs using low resolution tandem mass spectrometry (LRMS/MS). This targeted analysis indicated the original maitotoxin (MTX) was only present in one strain (G. australes S080911_1). Putative maitotoxin-2 (p-MTX2) and maitotoxin-3 (p-MTX3) were identified in several other species, but confirmation was not possible because of the lack of reference material. Maitotoxin-4 was detected in all seven strains of G. excentricus examined, independently of their origin (Brazil, Canary Islands and Caribbean), and not detected in any other species. MTX4 may therefore serve as a biomarker for the highly toxic G. excentricus in the Atlantic area. View Full-Text
Keywords: Gambierdiscus excentricus; maitotoxin-4; bioguided fractionation; size-exclusion chromatography (LH-20); neuro-2a (N2a) assay; LC-HRMS/MS (Q-Tof 6550); LC-LRMS/MS (API4000 QTrap) Gambierdiscus excentricus; maitotoxin-4; bioguided fractionation; size-exclusion chromatography (LH-20); neuro-2a (N2a) assay; LC-HRMS/MS (Q-Tof 6550); LC-LRMS/MS (API4000 QTrap)
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Pisapia, F.; Sibat, M.; Herrenknecht, C.; Lhaute, K.; Gaiani, G.; Ferron, P.-J.; Fessard, V.; Fraga, S.; Nascimento, S.M.; Litaker, R.W.; Holland, W.C.; Roullier, C.; Hess, P. Maitotoxin-4, a Novel MTX Analog Produced by Gambierdiscus excentricus. Mar. Drugs 2017, 15, 220.

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