High Levels of Tetrodotoxin (TTX) in Trumpet Shell Charonia lampas from the Portuguese Coast

Abstract

Tetrodotoxin (TTX) is a potent neurotoxin, considered an emerging toxin in Europe where recently a safety limit of 44 µg TTX kg−1 was recommended by authorities. In this study, three specimens of the large gastropod trumpet shell Charonia lampas bought in a market in south Portugal were analyzed using a neuroblastoma cell (N2a) based assay and by LC-MS/MS. N2a toxicity was observed in the viscera of two individuals analyzed and LC-MS/MS showed very high concentrations of TTX (42.1 mg kg−1) and 4,9-anhydroTTX (56.3 mg kg−1). A third compound with m/z 318 and structurally related with TTX was observed. In the edible portion, i.e., the muscle, toxin levels were below the EFSA recommended limit. This study shows that trumpet shell marine snails are seafood species that may reach the markets containing low TTX levels in the edible portion but containing very high levels of TTX in non-edible portion raising concerns regarding food safety if a proper evisceration is not carried out by consumers. These results highlight the need for better understanding TTX variability in this gastropod species, which is critical to developing a proper legal framework for resources management ensuring seafood safety, and the introduction of these gastropods in the markets.

Tetrodotoxins in French Bivalve Mollusks—Analytical Methodology, Environmental Dynamics and Screening of Bacterial Strain Collections

“…Hitherto, TTX and its more than 30 known analogs (TTXs) have been found in an impressive diversity of phylogenetically unrelated organisms (both terrestrial, e.g., amphibians, and aquatic, e.g., fish from the Tetraodontidae family, worms, cephalopods, gastropods, bivalves, see for example the review of Noguchi and Arakawa [3]). A new TTX-like analogue (m/z 318.1) was even recently reported in the gastropod Charonia lampas from the Portuguese coast [4]. However, these toxins are considered an emerging threat in Europe and in bivalves (see reviews [5][6][7]).…”

An Updated Review of Tetrodotoxin and Its Peculiarities

“…The specimen's digestive glands contained extremely high parent TTX and total TTXs levels, with reported concentrations of 315,000 and 1,319,000 µg/kg, respectively [25]. Further investigations in Portuguese and Moroccan gastropods revealed the presence of TTXs at quantifiable levels in three more species, Steromphala umbilicalis (formerly Gibbula umbilicalis), Phorcus lineatus (formerly Monodonta lineata), and Onchidella celtica, as well as in additional C. lampas specimens, some at high concentrations [7,73,84,85]. In general, it appears that higher TTXs contents are detected in the viscera of gastropods, potentially indicating a dietary route of accumulation; however, in some species, TTXs are exclusively detected in the flesh instead, which suggests the possible existence of alternative TTX binding mechanisms or sources [37].…”

“…Until recently, TTX was believed to be confined to East Asia, but recent studies have shown that fish containing the toxin have been found in other regions of the Pacific and the Indian Ocean, as well as the Mediterranean Sea [3]. There are also many poisoning cases reported from countries, such as Australia [85,167,168], Brazil [169,170], Mexico [171], Oman [172], Madagascar [173], Reunion Island [174], Egypt [175], and Morocco [176].…”

Tetrodotoxin in live bivalve mollusks from Europe: Is it to be considered an emerging concern for food safety?

“…Some marine gastropods are, in fact, carnivorous and may wellfeed by scavenging (Taniyama et al, 2009;Wang et al, 2008) on TTX-bearing species, such as pufferfish (Noguchi et al, 2011). Costa et al (2021) linked the high amount of TTXs found in the viscera of a C. lampas specimen (42.1 and 56.3 mg/kg of TTX and 4,9-anhydroTTX, respectively) to the dietary habits of this gastropod, which feeds on starfish.…”

“…Other records were mainly in various species from Asian countries , until 2007 when the toxins were discovered in a specimen of C. lampas lampas from Portugal, which was linked to a case of human intoxication following ingestion of the gastro-pod contaminated flesh (Rodriguez et al, 2008). Following a pattern of occurrence that can resemble that seen for bivalve mollusks, TTXs in gastropods are being reported more often in Europe, involving different species harvested from France, Morocco, Portugal, and Spain (Blanco et al, 2019;Costa et al, 2021;Hort et al, 2020;Silva et al, 2012Silva et al, , 2019; Table 2). Interestingly, the amounts of TTXs detected in marine gastropods are by far higher than those in bivalves (Table 1).…”