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At least 19 recordsLinked to original sources
PubMed2003

Comparison of different fluorimetric HPLC methods for analysis of acidic polyether toxins in marine phytoplankton.

The human toxic syndrome, diarrhetic shellfish poisoning (DSP), is caused by polyether toxins that are present in bivalve molluscs but originate from some species of marine phytoplankton. During the last few years different HPLC methods with fluorescence detection (FLD) have been proposed for analysis of marine toxins, including polyether toxins, in shellfish and phytoplankton. Several derivatization reagents have been proposed in the literature, with the aim of converting the acidic DSP toxins into their corresponding fluorescent derivatives. In this work we report results obtained from HPLC-FLD analysis of extracts from phytoplankton, including Dinophysis spp.,harvested off the south-west coast of Ireland. Three different reagents were used for fluorescent derivatization: 3-bromomethyl-6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone (BrDMEQ), 9-chloromethylanthracene (CA), and "in situ" 9-anthracenyldiazomethane (ADAM). Derivatization was performed under conditions previously optimised. The DSP derivatives were cleaned using different SPE procedures then analysed by HPLC-FLD. In this study, the use of BrDMEQ, CA, and "in situ" ADAM was compared in terms of sensitivity and selectivity. Evaluation of HPLC methods for analysis of DSP toxin derivatives was also conducted; the presence of okadaic acid (OA), dinophysistoxin-2 (DTX-2), and pectenotoxin-2 seco acids (PTX1SAs) was detected in the sample extracts studied.

Animals↗
PubMed1994

Ionspray mass spectrometry of ciguatoxin-1, maitotoxin-2 and -3, and related marine polyether toxins.

A range of marine polyether toxins from dinoflagellates were analysed by ionspray mass spectrometry. Ciguatoxin-1 ([M+H]+ m/z = 1,111.8) purified from several fish species yielded singly charged ions corresponding to the parent ion, sodium and H2O adducts and ions for the loss of up to five H2O molecules. Ciguatoxin-1 was detected to 1 ng; however, interference from fish lipids precluded direct detection of ciguatoxin-1 in crude extracts from fish flesh spiked with ciguatoxin-1 at a level equivalent to 1.5 ng ciguatoxin-1/g of extracted flesh. Maitotoxin-2 yielded doubly and triply charged ions for sodium and potassium salts and likely possessed only one sulphate ester (M(r) = 3,298 for the mono-sodium salt). Maitotoxin-3, a recently isolated small maitotoxin, yielded singly charged ions including ions for the loss of one sulphate and up to four H2O molecules. Maitotoxin-3 is proposed to be a polyether compound possessing two sulphate esters (M(r) = 1,060.5 for the disodium salt). Brevetoxin-A ([M+H]+ m/z = 867.5) and brevetoxin-B ([M+H]+ m/z = 895.5) yielded singly charged ions corresponding to the parent ion, Na+ adducts and the loss of up to four H2O molecules. Okadaic acid ([M+H]+ m/z = 805.5) yielded singly charged ions corresponding to the parent ion and ions for the loss of up to three H2O molecules. A signal for M + 18 Da species that may represent [M+NH4]+ was observed for ciguatoxin-1, brevetoxin-A and -B, and okadaic acid. For all polyethers examined, the orifice potential influenced the relative intensity of the ions detected in a predictable manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Studies of polyether toxins in the marine phytoplankton, Dinophysis acuta, in Ireland using multiple tandem mass spectrometry.

Diarretic shellfish poisoning (DSP) is a toxic syndrome associated with the consumption of bivalve molluscs. The DSP toxins are polyether compounds, which include okadaic acid (OA), dinophysistoxins (DTXs), pectenotoxins (PTXs) and pectenotoxin seco acids (PTX2SAs). These toxins originate in marine dinoflagellates, including Dinophysis spp. Phytoplankton samples were collected from the southwest coast of Ireland and D. acuta was the predominant species. Monocultures of D. acuta cells were prepared by hand picking from microscope slides in order to confirm their toxin profiles. There was a remarkable consistency in the toxin profiles in all of the phytoplankton samples collected during the summer months, irrespective of location, depth or mesh size. Analysis using liquid chromatography-multiple tandem mass spectrometry (LC-MS/MS) revealed that DTX2 and OA were the predominant toxins at a consistent ratio. The average toxin composition was: DTX2 (53+/-5%), OA (26.5+/-2.3%) and total pectenotoxins (20.8+/-4.7%). Toxin profiles in D. acuta from Europe were distinctly different from those found in New Zealand, where PTX2 was the predominant toxin and DTX2 was absent.

Animals↗
PubMedDate not supplied

Modified immunoassays for polyether toxins: implications of biological matrixes, metabolic states, and epitope recognition.

Polyether marine toxins are responsible for the seafood intoxication phenomena known as neurotoxic shellfish poisoning (due to brevetoxins), ciguatera (due to ciguatoxin), and diarrheic shellfish poisoning (due to okadaic acid). Using traditional techniques of hapten (pure toxin) conjugation to protein to create complete antigen, animal immunization and antibody isolation, and specific antibody subpopulation purification, discriminating antibodies have been isolated that detect brevetoxins and ciguatoxin, but not okadaic acid, in a dose-dependent fashion. Using microorganic chemistry and purified toxins, a unique set of tools has been created for the study of polyether ladder toxin accumulation; depuration; and specific site localization in tissues, food sources, and clinical samples. Developed test protocols can detect toxin in dinoflagellate cells, in extracts from food sources, in seawater and culture media, and in human serum samples. Enzyme-linked immunosorbent assay protocols developed for eventual collaborative testing have been successful in limited applications within the laboratory (correlation coefficient of 0.92 excluding 2 outliers), and alternative formats are being developed to optimize the basic test for use in research laboratories, regulatory laboratories, and field inspections.

Antibodies↗
PubMed1998

Simplified solid-phase membrane immunobead assay (MIA) with monoclonal anti-ciguatoxin antibody (MAb-CTX) for detection of ciguatoxin and related polyether toxins.

The development of a simplified and modified procedure for the assessment of ciguatoxin (CTX) and related polyethers from ciguateric contaminated fish tissues is presented in this study. The previous method, stick-enzyme immunoassay (S-EIA) used an organic correction fluid-coated bamboo paddle stick for the solid phase; this new procedure, membrane immunobead assay (MIA), uses a plastic stick with a synthetic membrane laminated onto one end. The membrane is hydrophobic and serves as the solid-phase receptor for the binding of methanol-extracted CTX or its related polyether lipids from fish tissues. Detection of the bound polyether toxin(s) on the membrane is carried out with colored polystyrene beads coated with monoclonal antibody to CTX (MAb-CTX). Intensity of the color on the membrane is proportional to the amount of toxic polyethers on the membrane. The MIA is compared with previous procedures developed for CTX detection (S-EIA and solid-phase immunobead assay, SPIA) using State of Hawaii Department of Health (DOH) implicated ciguateric fishes, and reef fishes from Hawaii and Kwajalein. The data presented show good correlation between the three test systems, especially with ciguatera implicated fish and toxic, routinely assessed fishes in the mouse toxicity (MT) bioassay. Variations between MT results and those of the S-EIA, SPIA, and MIA of routine fishes are generally attributable to diverse toxins present in the fish species examined. The MIA is a simple, rapid, sensitive, and specific detection method for CTX and its related polyethers, with no reported false negative results. The test is useful for field and personal use and can be adapted to the laboratory for large-scale screening of potentially ciguateric fishes.

Animals↗
PubMed2005

Tetrahydropyran formation by rearrangement of an epoxy ester: a model for the biosynthesis of marine polyether toxins.

Acid-catalyzed rearrangement of the (S)-epoxide derived from 2alpha-allyl cholestanyl acetate resulted in a 1:1 mixture of a steroidal tetrahydrofuran and a steroidal tetrahydropyran. Formation of a six-membered ring supports the hypothesis that epoxy ester-orthester-cyclic ether rearrangement may be involved in the biosynthesis of ladder-type marine polyether toxins. This reaction represents a new biomimetic preparation of medium ring cyclic ethers.

Animals↗
PubMed1992

Liquid chromatographic mass spectrometric methods for the determination of marine polyether toxins.

Experiments with novel nitrogenous coumarin-based reagents yielded moderately fluorescent derivatives of brevetoxin-3 and ciguatoxin-1. The diethylaminocoumarin-carbamic acid esters of brevetoxin-3 were resolved by high performance liquid chromatography into two derivative peaks that correspond to substitutions at the C-37 and C-41 hydroxyls. The derivatives produced intense molecular ions under fast atom bombardment ionization conditions, confirming derivative identity. Ciguatoxin-1 was also successfully derivatized, resolved, and identified by HPLC-fluorometry with an estimated lower limit of detection of 0.5 to 1.0 ng.

Chromatography, High Pressure Liquid↗
PubMed2003

Geographical, temporal, and species variation of the polyether toxins, azaspiracids, in shellfish.

Azaspiracid Poisoning (AZP) is a new toxic syndrome that has caused human intoxications throughout Europe following the consumption of mussels (Mytilus edulis), harvested in Ireland. Shellfish intoxication is a consequence of toxin-bearing microalgae in the shellfish food chain, and these studies demonstrated a wide geographic distribution of toxic mussels along the entire western coastal region of Ireland. The first identification of azaspiracids in other bivalve mollusks including oysters (Crassostrea gigas), scallops (Pecten maximus), clams (Tapes phillipinarium), and cockles (Cardium edule) is reported. Importantly, oysters were the only shellfish that accumulated azaspiracids at levels that were comparable with mussels. The highest levels of total azaspiracids (microg/g) recorded to-date were mussels (4.2), oysters (2.45), scallops (0.40), cockles (0.20), and clams (0.61). An examination of the temporal variation of azaspiracid contamination of mussels in a major shellfish production area revealed that, although maximum toxin levels were recorded during the late summer period, significant intoxications were observed at periods when marine dinoflagellate populations were low. Although human intoxications have so far only been associated with mussel consumption, the discovery of significant azaspiracid accumulation in other bivalve mollusks could pose a threat to human health.

Animals↗
PubMed1996

Simple Designs for the Construction of Complex Trans-Fused Polyether Toxin Frameworks. A Convergent Strategy Based on Hydroxy Ketone Cyclization of C-Linked Oxacycles.

A single, unified convergent strategy for the stereocontrolled synthesis of trans-fused polyethers was developed. It was demonstrated that the epimerization and reductive intramolecular coupling of hydroxy ketones in reactions with silane-Lewis acids (SI-LA) to generate ethers in C-linked oxacycles is affected by its conformational preference in a predictable manner. The obtained results make evident that the influence of hydrogen bonding between a hemiketal hydroxyl and a 1,3-diaxial C-O bond is regular and predictable and that convergent synthesis of trans-fused polyethers may confidently be conducted on driving ring closure to oxane rings under thermodynamic conditions

Journal Article↗
PubMed1989

Brevetoxins: unique polyether dinoflagellate toxins.

Brevetoxins are lipid-soluble polyether marine toxins of unique structure and pharmacological function. Toxins are active in vivo in the nanomolar to picomolar concentration range and in vitro in isolated neuromuscular or giant axon preparations and in single-cell or subcellular model systems. Their effect is excitatory, mediated by the enhancement of cellular Na+ influx. Brevetoxins bind at site 5 on the voltage-sensitive sodium channel, a specificity shared with ciguatoxin. This site is allosterically linked to other natural toxin binding sites on the channel.

Animals↗
PubMed1996

Microalgal metabolites: a new perspective.

Occurrence of secondary metabolites in microalgae (protoctista) is discussed with respect to the phylogenic or taxonomic relationships of organisms. Biosynthetic mechanisms of certain metabolites such as paralytic shellfish poisoning toxins and polyether toxins are also discussed, and genetic aspects of the secondary metabolite production as well.

Classification↗
PubMed2003

The type B brevetoxin (PbTx-3) adversely affects development, cardiovascular function, and survival in Medaka (Oryzias latipes) embryos.

Brevetoxins are produced by the red tide dinoflagellate Karenia brevis. The toxins are lipophilic polyether toxins that elicit a myriad of effects depending on the route of exposure and the target organism. Brevetoxins are therefore broadly toxic to marine and estuarine animals. By mimicking the maternal route of exposure to the oocytes in finfish, we characterized the adverse effects of the type B brevetoxin brevetoxin-3 (PbTx-3) on embryonic fish development and survival. The Japanese rice fish, medaka (Oryzias latipes), was used as the experimental model in which individual eggs were exposed via microinjection to various known concentrations of PbTx-3 dissolved in an oil vehicle. Embryos injected with doses exceeding 1.0 ng/egg displayed tachycardia, hyperkinetic twitches in the form of sustained convulsions, spinal curvature, clumping of the erythrocytes, and decreased hatching success. Furthermore, fish dosed with toxin were often unable to hatch in the classic tail-first fashion and emerged head first, which resulted in partial hatches and death. We determined that the LD(50) (dose that is lethal to 50% of the fish) for an injected dose of PbTx-3 is 4.0 ng/egg. The results of this study complement previous studies of the developmental toxicity of the type A brevetoxin brevetoxin-1 (PbTx-1), by illustrating in vivo the differing affinities of the two congeners for cardiac sodium channels. Consequently, we observed differing cardiovascular responses in the embryos, wherein embryos exposed to PbTx-3 exhibited persistent tachycardia, whereas embryos exposed to PbTx-1 displayed bradycardia, the onset of which was delayed.

Animals↗
PubMed2002

Azaspiracid shellfish poisoning: unusual toxin dynamics in shellfish and the increased risk of acute human intoxications.

A number of recent acute human intoxications in Europe from the consumption of Irish mussels have been attributed to the presence of a new class of toxins named azaspiracids. The study demonstrates that azaspiracids behave differently from other polyether toxins, and this accounts for most false-negative results in the mouse bioassay employed by regulatory agencies to detect azaspiracids. Typically, polyether toxins are concentrated in the digestive glands of shellfish, but this is not always the situation with azaspiracids. Liquid chromatography-mass spectrometry (LC-MS), especially multiple tandem MS methods, have been applied to demonstrate that azaspiracid (AZA1) and its methyl- and demethyl- analogues, AZA2 and AZA3 respectively, are distributed throughout shellfish tissues. Using conventional mouse bioassay protocols, only 0-40% of the total azaspiracid content of shellfish was used in the assay, which could directly account for false-negative results. It was also observed that the toxin profiles differed significantly in various mussel tissues with AZA1 as the predominant toxin in the digestive glands and AZA3 predominant in the remaining tissues.

Acute Disease↗
PubMed1985

A rapid, simplified enzyme immunoassay stick test for the detection of ciguatoxin and related polyethers from fish tissues.

A simplified and rapid enzyme immunoassay stick test is presented in this study. The salient feature of this test is the use of a coating (Liquid Paper) on the stick to adsorb the lipid ciguatoxin and its related polyether toxins onto the stick. This rapid solid phase stick test has been able to differentiate clinically implicated fishes (14 samples) from non-toxic (60 samples) with P less than 0.005. Comparison of the stick test with the enzyme immunoassay procedure with the positive fish samples demonstrated a good correlation. All samples were positive by both procedures. Further comparison of the stick test, enzyme immunoassay and the mouse bioassay with unknown fish samples showed good relationships between the three procedures. Examination of 71 Seriola dumerili, a fish generally implicated in ciguatera poisoning, with the stick test procedure showed that 89% of the fishes were non-toxic and thus consumed without any incidence of ciguatera poisoning. Analysis of graded concentrations of ciguatoxin, in ng/ml of methanol, showed a typical immunological precipitation pattern. The stick test as conceived is simple and rapid, while retaining its sensitivity and specificity to detect ng levels of ciguatoxin and its related polyether toxins. It is suggested that the stick test will be valuable in the screening of ciguatoxin and related polyether toxins in contaminated fish tissues.

Animals↗
PubMedDate not supplied

Antibodies to maitotoxin elicited by immunization with toxin-fragment conjugates.

Maitotoxin is a water-soluble polyether toxin produced by the benthic dinoflagellate, Gambierdiscus toxicus. Toxin fragments generated by periodate oxidation were conjugated to keyhole limpet hemocyanin, and the resulting immunogens were used to elicit maitotoxin-specific antibodies in mice. A competitive immunoassay developed with polyclonal IgG antibodies detected approximately 3 nM purified maitotoxin standard (IC50 approximately 13 nM; 45 ng/ml) but did not detect other polyether marine toxins. These are the first reported maitotoxin-specific antibodies.

Animals↗
PubMed2001

The red tide toxin, brevetoxin, induces embryo toxicity and developmental abnormalities.

Brevetoxins are lipophilic polyether toxins produced by the red tide dinoflagellate Gymnodinium breve, and their neurotoxic effects on adult animals have been documented. In this study, we characterized adverse developmental effects of brevetoxin-1 (PbTx-1) using an exposure paradigm that parallels the maternal oocyte transfer of toxin. Medaka fish (Oryzias latipes) embryos were exposed to PbTx-1 via microinjection of toxin reconstituted in a triolein oil droplet. Embryos microinjected with doses of 0.1-8.0 ng/egg (ppm) of brevetoxin-1 exhibited pronounced muscular activity (hyperkinesis) after embryonic day 4. Upon hatching, morphologic abnormalities were commonly found in embryos at the following lowest adverse effect levels: 1.0-3.0 ppm, lateral curvature of the spinal column; 3.1-3.4 ppm, herniation of brain meninges through defects in the skull; and 3.4-4.0 ppm, malpositioned eye. Hatching abnormalities were also commonly observed at brevetoxin doses of 2.0 ppm and higher with head-first, as opposed to the normal tail-first, hatching, and doses > 4.1 ng/egg produced embryos that developed but failed to hatch. Given the similarity of developmental processes found between higher and lower vertebrates, teratogenic effects of brevetoxins have the potential to occur among different phylogenetic classes. The observation of developmental abnormalities after PbTx-1 exposure identifies a new spectrum of adverse effects that may be expected to occur following exposure to G. breve red tide events.

Animals↗