Abstract
Tetrodotoxin (TTX) is a potent marine neurotoxin with bacterial origin. To date, around 28 analogs of TTX are known, but only 12 were detected in marine organisms, namely TTX, 11-oxoTTX, 11-deoxyTTX, 11-norTTX-6(R)-ol, 11-norTTX-6(S)-ol, 4-epiTTX, 4,9-anhydroTTX, 5,6,11-trideoxyTTX, 4-CysTTX, 5-deoxyTTX, 5,11-dideoxyTTX, and 6,11-dideoxyTTX. TTX and its derivatives are involved in many cases of seafood poisoning in many parts of the world due to their occurrence in different marine species of human consumption such as fish, gastropods, and bivalves. Currently, this neurotoxin group is not monitored in many parts of the world including in the Indian Ocean area, even with reported outbreaks of seafood poisoning involving puffer fish, which is one of the principal TTX vectors know since Egyptian times. Thus, the main objective of this review was to assess the incidence of TTXs in seafood and associated seafood poisonings in the Indian Ocean and the Red Sea. Most reported data in this geographical area are associated with seafood poisoning caused by different species of puffer fish through the recognition of TTX poisoning symptoms and not by TTX detection techniques. This scenario shows the need of data regarding TTX prevalence, geographical distribution, and its vectors in this area to better assess human health risk and build effective monitoring programs to protect the health of consumers in Indian Ocean area.
Highlights
The tropical and subtropical climates predominant in the Indian Ocean zone, accompanied by industrialization and population increase, are pointed to as the main factors that, together with eutrophication, contribute to the development of toxic phytoplankton blooms—harmful algal blooms (HABs) and bacteria [1]
Around 28 analogs of TTX were described (Figure 1 and Table 1) and some of them were detected in marine organisms [53], with their relative toxicity well known [45]: TTX, 11-oxoTTX, 11-deoxyTTX, 11-norTTX-6(R)-ol, 11-norTTX-6(S)-ol, 4-epiTTX, 4,9-anhydroTTX, 5,6,11-trideoxyTTX [45], 4-CysTTX, 5-deoxyTTX, 5,11-dideoxyTTX, and 6,11-dideoxyTTX [54,55,56,57] (Table 1)
Methods for TTX analysis and their respective limits of quantification (LOQs) and detection (LODs) are described in Table 4 and include the mouse bioassay [12,36,52,89], receptor-based assay [90], immunoassay [31,36,52,73,77,82,89,91,92,93], thin-layer chromatography [13,72], high-performance liquid chromatography [84,94,95], gas chromatography–mass spectrometry [76,84,95], liquid chromatography coupled to mass spectrometry [33,40,96,97,98], surface plasmon resonance [30], and liquid chromatography with fluorescence detection (FLD) [15,32,89]
Summary
The tropical and subtropical climates predominant in the Indian Ocean zone, accompanied by industrialization and population increase, are pointed to as the main factors that, together with eutrophication, contribute to the development of toxic phytoplankton blooms—harmful algal blooms (HABs) and bacteria [1]. Due to the lack of TTX monitoring programs, the episodes of human seafood poisoning are still common in the Indian Ocean area, since seafood is the most common food for many people living along coastal zones [16,17,18,19,20,21,22,24,26,28,29,30,31,32,33,34,35,36,37,38]. 28 incidence of TTX in the Indian Ocean and the Red Sea zones and associated was to review human seafood poisoning incidents. Incidence of TTX in the Indian Ocean and the Red Sea zones and associated human seafood poisoning incidents. The monitoring of TTXs in this geographic zone is recommended
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