Toxicity and toxin profile of La Réunion (Indian Ocean) fish containing CTX-like compounds

Several outbreaks of ciguatera poisoning have been recorded in La Réunion (SW Indian Ocean) since 1986. Toxicities and toxin profiles of fish from the Indian Ocean are poorly documented. In this work, a multidisciplinary study on the toxicity of fish from the Indian Ocean by neuro-2a cell-based assay was assessed, and the CTX-like compounds were evaluated by a magnetic bead-based immunoassay. The toxin profile is described by liquid chromatography coupled to tandem mass spectrometry and high-resolution mass spectrometry. The liver, muscle, and viscera of four fish specimens of three different species (one Lutjanus bohar, two Variola louti and one Carcharinus leucas) caught in the waters of La Réunion were analysed. One of the V. louti specimens was obtained after a CP incident. Their toxicity values ranged between 0.01 and 2.69 μg CTX1B equiv.·kg^-1 in flesh, 1.60 and 6.50 μg CTX1B equiv.·kg^-1 in liver and 0.07 and 4.77 μg CTX1B equiv.·kg^-1 in viscera. In general, liver and viscera showed higher concentrations of CTX-like compounds than flesh. Several potential CTX congeners were identified. LC-MS/MS confirmed the presence of CTX1B, 52-epi-54-deoxyCTX1B and 54-deoxyCTX1B in the flesh of the V. louti specimen involved in the CP incident. CTX1B was identified in the three tissues of the other V. louti individual and in the L. bohar. The C. leucas samples revealed the presence of a complex CTXs profile showing congeners of the CTX3C-group. The strategy used within this research work could be a valuable tool for future food safety monitoring in the Indian Ocean area.