Assessing the Toxicity of Lagocephalus sceleratus Pufferfish from the Southeastern Aegean Sea and the Relationship of Tetrodotoxin with Gonadal Hormones

Aptamer-antibody sandwich lateral flow test for rapid visual detection of tetrodotoxin in pufferfish

Tetrodotoxin (TTX) is a highly potent marine toxin which can cause severe poisoning following consumption of contaminated fish and seafood. Thus, a sensitive, reliable and simple test is required for rapid screening of samples and prevention of intoxication. Herein, we translated a previously reported microtiter plate hybrid aptamer-antibody assay into a rapid lateral flow assay (LFA) test. The test relies on an aptamer immobilized on the membrane and an antibody conjugated with gold nanoparticles to provide a visual result when TTX is present in the sample. The optimized test is simple (one-step), rapid (<20 min), highly sensitive (visual limit of detection of 0.3 ng/mL TTX in buffer corresponding to 0.78 mg TTX/kg tissue), specific, reproducible and with long storage life. It was validated by analyzing contaminated pufferfish tissue extracts and it successfully detected TTX below the current limits set by official bodies. The analysis performed with this device in combination with a simple LFA reader for quantification was in excellent agreement with other established methods, further demonstrating the value of this test as a simple, low-cost and reliable analytical tool to ensure food safety, protect human health, and broaden the knowledge on the correlation between biological parameters and environmental data.

Marine natural products

Covering: January to the end of December 2023This review covers the literature published in 2023 for marine natural products (MNPs), with 582 citations (541 for the period January to December 2023) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, the submerged parts of mangroves and other intertidal plants. The emphasis is on new compounds (1220 in 340 papers for 2023), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of the progress in the study of prokaryote involvement in macro-invertebrate MNP production is discussed.

Toxicity Equivalency Factors for Tetrodotoxin Analogues Determined with Automated Patch Clamp on Voltage-Gated Sodium Channels in Neuro-2a Cells

Tetrodotoxin (TTX) is a potent marine neurotoxin, responsible for numerous poisoning incidents and some human fatalities. To date, more than 30 TTX analogues have been identified, but their individual toxicities and roles in poisoning remain largely unknown. In this work, the toxicity equivalency factors (TEFs) of five TTX analogues were determined by assessing the blockade of voltage-gated sodium channels in Neuro-2a cells using automated patch clamp (APC). All TTX analogues were less toxic than TTX. The derived TEFs were applied to the individual TTX analogues concentrations measured in pufferfish samples, using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). A comparison of these results with those obtained from APC analysis demonstrated that TEFs can be effectively used to translate LC-MS/MS analytical data into meaningful toxicological information. This is the first study to utilize APC device for the toxicological assessment of TTX analogues, highlighting its potential as a bioanalytical tool for seafood safety management and human health protection.

Automated Patch Clamp for the Detection of Tetrodotoxin in Pufferfish Samples

Tetrodotoxin (TTX) is a marine toxin responsible for many intoxications around the world. Its presence in some pufferfish species and, as recently reported, in shellfish, poses a serious health concern. Although TTX is not routinely monitored, there is a need for fast, sensitive, reliable, and simple methods for its detection and quantification. In this work, we describe the use of an automated patch clamp (APC) system with Neuro-2a cells for the determination of TTX contents in pufferfish samples. The cells showed an IC50 of 6.4 nM for TTX and were not affected by the presence of muscle, skin, liver, and gonad tissues of a Sphoeroides pachygaster specimen (TTX-free) when analysed at 10 mg/mL. The LOD achieved with this technique was 0.05 mg TTX equiv./kg, which is far below the Japanese regulatory limit of 2 mg TTX equiv./kg. The APC system was applied to the analysis of extracts of a Lagocephalus sceleratus specimen, showing TTX contents that followed the trend of gonads > liver > skin > muscle. The APC system, providing an in vitro toxicological approach, offers the advantages of being sensitive, rapid, and reliable for the detection of TTX-like compounds in seafood.

Assessment of Human Health Impacts from Invasive Pufferfish (Attacks, Poisonings and Fatalities) across the Eastern Mediterranean

The silver-cheeked toadfish Lagocephalus sceleratus (Gmelin 1789), and to a lesser degree the orange spotted toadfish Torquigener hypselogeneion (Bleeker, 1852), pose threats to human health from physical attacks and poisonings in the Eastern Mediterranean Sea. This study reviewed human health-related impacts resulting from these pufferfish, compiling and assessing records from online sources, the peer-reviewed literature, medical records, personal interviews, and observations across the Eastern Mediterranean in the years 2004 to 2023. A total of 198 events impacting human health were documented: 28 records of physical attacks, at least 144 non-lethal poisoning episodes, and 27 human fatalities resulting from consumption. The majority of the reported incidences occurred in Syria, Türkiye, and Lebanon. Most physical attacks occurred in summer, while most poisoning events occurred during winter. The number of recorded incidents greatly increased after 2019, especially with regard to poisonings, yet whether this is related to greater media attention, or to increased fish abundance is unclear. This is the first comprehensive study to collate findings on attacks, poisonings and fatalities caused by these pufferfish in the Mediterranean Sea, and may help in improving national health policies. We urge the continuation of national campaigns to caution residents and tourists of these species' high toxicities and potential aggressiveness.