First toxin profile of ciguateric fish in Madeira Arquipelago (Europe)

Ciguatera fish poisoning (CFP) is a human foodborne intoxication caused by ingestion of tropical fishes contaminated with the potent polyether toxins known as ciguatoxins (CTXs). These toxins are issued from Gambierdiscus species of dinoflagellates. Herbivorous fish accumulate these toxins in their musculature and viscera after ingesting dinoflagellates. Epidemiological studies showed that CFP has been present in areas between 35 degrees North and 35 degrees South latitude, mainly, Indo-pacific and Caribbean areas, but not in waters closed to European and African continent. In the present paper, a specimen of Seriola dumerili weighing 70 kg and a smaller Seriola fasciata specimen, captured in waters belonging to Selvagens Islands (Madeira Arquipelago), were analyzed. Fishes from this genus were implicated in previous suspected ciguatera poisoning outbreaks in the Portuguese Madeira Arquipelago in the North Atlantic Ocean. Analysis was performed by two approaches, a functional method using cerebellar granule cells and by ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) method. The study was carried out in one portion of the tail muscle of Seriola fasciata and five parts of the body of Seriola dumerili (tail muscle, head, ventral muscle, mid muscle, and liver). The functional method consisted in the modification of the inward sodium current in cerebellar granule cells and the chemical method was a high resolution chromatography, which allowed elucidating the toxin profile in the samples. In addition, UPLC-MS technique was optimized and used for detecting and quantifying CTXs for the first time. After fish extraction and clean up, the chromatograms revealed the presence of CTX-1B at 1111.6 m/z, CTX-3C at 1023.5 m/z, a CTX analogue at 1040.6 m/z, and a CTX from the Caribbean or Indic waters at 1141.6 m/z. Therefore, the results obtained in the present paper for both methods confirm, for the first time, the presence of CTX in fish from Madeira Arquipelago.