Interlaboratory Evaluation of Multiple LC-MS/MS Methods and a Commercial ELISA Method for Determination of Tetrodotoxin in Oysters and Mussels.

Background: Given the recent detection of tetrodotoxin (TTX) in bivalve molluscs but the absence of a full collaborative validation study for TTX determination in a large number of shellfish samples, interlaboratory assessment of method performance was required to better understand current capabilities for accurate and reproducible TTX quantitation using chemical and immunoassay methods.

Objective: The aim was to conduct an interlaboratory study with multiple laboratories, using results to assess method performance and acceptability of different TTX testing methods.

Methods: Homogenous and stable mussel and oyster materials were assessed by participants using a range of published and in-house detection methods to determine mean TTX concentrations.

Structure Elucidation and Biological Evaluation of Maitotoxin-3, a Homologue of Gambierone, from .

species are the producers of the marine toxins ciguatoxins and maitotoxins which cause worldwide human intoxications recognized as Ciguatera Fish Poisoning. A deep chemical investigation of a cultured strain of , collected in the Caribbean Sea, led to the identification of a structural homologue of the recently described gambierone isolated from the same strain. The structure was elucidated mainly by comparison of NMR and MS data with those of gambierone and ascertained by 2D NMR data analyses.

Rapid analysis of paralytic shellfish toxins and tetrodotoxins by liquid chromatography-tandem mass spectrometry using a porous graphitic carbon column.

Although paralytic shellfish toxins (PSTs) have traditionally been analyzed by liquid chromatography with either pre- or post-column derivatization, and these methods have been validated successfully through inter-laboratory studies, mass spectrometry methods have also been described in literature for use in monitoring programs. However, methods using liquid chromatography coupled with mass spectrometry (LC-MS) need to be improved in terms of sensitivity, analyte recovery and retention time stability because of undesirable matrix effects. Furthermore, tetrodotoxin (TTX) has been found in northern European bivalves, so it is important to analyze TTX compounds alongside PSTs because characteristics of their toxicity are similar.

Acute Oral Toxicity of Tetrodotoxin in Mice: Determination of Lethal Dose 50 (LD50) and No Observed Adverse Effect Level (NOAEL).

Tetrodotoxin (TTX) is starting to appear in molluscs from the European waters and is a hazard to seafood consumers. This toxin blocks sodium channels resulting in neuromuscular paralysis and even death. As a part of the risk assessment process leading to a safe seafood level for TTX, oral toxicity data are required.

Liquid Chromatography with a Fluorimetric Detection Method for Analysis of Paralytic Shellfish Toxins and Tetrodotoxin Based on a Porous Graphitic Carbon Column.

Paralytic shellfish toxins (PST) traditionally have been analyzed by liquid chromatography with either pre- or post-column derivatization and always with a silica-based stationary phase. This technique resulted in different methods that need more than one run to analyze the toxins. Furthermore, tetrodotoxin (TTX) was recently found in bivalves of northward locations in Europe due to climate change, so it is important to analyze it along with PST because their signs of toxicity are similar in the bioassay.

Evaluation of the Impact of Mild Steaming and Heat Treatment on the Concentration of Okadaic Acid, Dinophysistoxin-2 and Dinophysistoxin-3 in Mussels.

This study explores the effect of laboratory and industrial steaming on mussels with toxin concentrations above and below the legal limit. We used mild conditions for steaming, 100 °C for 5 min in industrial processing, and up to 20 min in small-scale laboratory steaming. Also, we studied the effect of heat on the toxin concentration of mussels obtained from two different locations and the effect of heat on the levels of dinophysistoxins 3 (DTX3) in both the mussel matrix and in pure form (7-O-palmitoyl okadaic ester and 7-O-palmytoleyl okadaic ester).

Differential effects of ciguatoxin and maitotoxin in primary cultures of cortical neurons.

Ciguatoxins (CTXs) and maitotoxins (MTXs) are polyether ladder shaped toxins derived from the dinoflagellate Gambierdiscus toxicus. Despite the fact that MTXs are 3 times larger than CTXs, part of the structure of MTXs resembles that of CTXs. To date, the synthetic ciguatoxin, CTX 3C has been reported to activate voltage-gated sodium channels, whereas the main effect of MTX is inducing calcium influx into the cell leading to cell death.

Benefit of 13-desmethyl spirolide C treatment in triple transgenic mouse model of Alzheimer disease: beta-amyloid and neuronal markers improvement.

Spirolides are marine toxins that are not currently in the routine monitoring assays. Nicotinic receptors seem to be the target of these compounds making them a promising pharmacological tool for related diseases as dementias as previously shown in vitro. In the present work, the bioavailability of 13-desMethyl spirolide C (13-desMeC) in the brain and in vivo effects were tested.

Ice-like encapsulated water by two cholic acid moieties.

Starting from the structure of ice (in which each water molecule is surrounded by other four water molecules forming a tetrahedron with a value of 4.51Å for the edge O-O distance), and the knowledge that this value also corresponds to the O7-O12 distance of the skeleton of cholic acid, it is hypothesized that two steroid cholic acid moieties, with an appropriate steroid-steroid distance and a belly-to-belly orientation, could encapsulate a single water molecule between them. To check this hypothesis two succinyl derivatives of cholic acid (a monomer and the related head-head dimer in which the succinyl group is the linking bridge) were designed.

Solid-phase receptor-based assay for the detection of cyclic imines by chemiluminescence, fluorescence, or colorimetry.

The spirolides and gymnodimines are marine phycotoxins included in the group of cyclic imines. The toxicity of these compounds to humans is still unknown, although their toxicity by intraperitoneal injection in rodents is very high. A receptor-based method was developed using the competition of the 13-desmethyl spirolide C with biotin-labeled α-bungarotoxin for binding to nicotinic acetylcholine receptors and the immobilization of the α-bungarotoxin-receptor complex on streptavidin-coated surfaces.

Supramolecular structures generated by a p-tert-butylphenylamide derivative of deoxycholic acid. From planar sheets to tubular structures through helical ribbons.

The formation of supramolecular structures initiated by a p-tert-butylphenylamide derivative of deoxycholic acid (Na-t-butPhDC) is investigated. At 1.18 mM concentration of Na-t-butPhDC and 37 degrees C, initial flat ribbons are observed which self-transform into helical ribbons (with a mean pitch angle of 47 +/- 6 degrees) which finally originate molecular tubes with an external diameter of 241 +/- 28 nm.

Aggregation behavior of tetracarboxylic surfactants derived from cholic and deoxycholic acids and ethylenediaminetetraacetic acid.

The reaction of 3beta-aminoderivatives of cholic and deoxycholic acids (steroid residues) with dimethyl ester of ethylenediaminetetraacetic acid (bridge) leads to the formation of dimers carrying four carboxylic organic functions, two of them located on the side chain of each steroid residue and the other two on the bridge. As tetrasodium salts, these new compounds behave as surfactants and have been characterized by surface tension, fluorescence intensity of pyrene (as a probe), and static and dynamic light scattering measurements. Thermodynamic parameters for micellization were obtained from the dependence of the critical micelle concentration (cmc) with temperature.

Bile acids: chemistry, physiology, and pathophysiology.

The family of bile acids includes a group of molecular species of acidic steroids with very peculiar physical-chemical and biological characteristics. They are synthesized by the liver from cholesterol through several complementary pathways that are controlled by mechanisms involving fine-tuning by the levels of certain bile acid species. Although their best-known role is their participation in the digestion and absorption of fat, they also play an important role in several other physiological processes.

Synthesis and characterization of a new gemini surfactant derived from 3alpha,12alpha-dihydroxy-5beta-cholan-24-amine (steroid residue) and ethylenediamintetraacetic acid (spacer).

A new gemini steroid surfactant derived from 3alpha,12alpha-dihydroxy-5beta-cholan-24-amine (steroid residue) and ethylenediamintetraacetic acid (spacer) was synthesized and characterized in aqueous solution by surface tension, fluorescence intensity of pyrene, and light scattering (static and dynamic) measurements. These techniques evidence the existence of a threshold concentration (cac), below which a three layers film is formed at the air-water interface. Above the cac, two types of aggregates--micelles and vesicle-like aggregates--coexist in a metastable state.