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Darius HT, Revel T, Viallon J, Sibat M, Cruchet P, Longo S, Hardison DR, Holland WC, Tester PA, Litaker RW, McCall JR, Hess P, Chinain M. Comparative Study on the Performance of Three Detection Methods for the Quantification of Pacific Ciguatoxins in French Polynesian Strains of Gambierdiscus polynesiensis. Mar Drugs 2022; 20:md20060348. [PMID: 35736151 PMCID: PMC9229625 DOI: 10.3390/md20060348] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/14/2022] [Accepted: 05/19/2022] [Indexed: 02/04/2023] Open
Abstract
Gambierdiscus and Fukuyoa dinoflagellates produce a suite of secondary metabolites, including ciguatoxins (CTXs), which bioaccumulate and are further biotransformed in fish and marine invertebrates, causing ciguatera poisoning when consumed by humans. This study is the first to compare the performance of the fluorescent receptor binding assay (fRBA), neuroblastoma cell-based assay (CBA-N2a), and liquid chromatography tandem mass spectrometry (LC-MS/MS) for the quantitative estimation of CTX contents in 30 samples, obtained from four French Polynesian strains of Gambierdiscus polynesiensis. fRBA was applied to Gambierdiscus matrix for the first time, and several parameters of the fRBA protocol were refined. Following liquid/liquid partitioning to separate CTXs from other algal compounds, the variability of CTX contents was estimated using these three methods in three independent experiments. All three assays were significantly correlated with each other, with the highest correlation coefficient (r2 = 0.841) found between fRBA and LC-MS/MS. The CBA-N2a was more sensitive than LC-MS/MS and fRBA, with all assays showing good repeatability. The combined use of fRBA and/or CBA-N2a for screening purposes and LC-MS/MS for confirmation purposes allows for efficient CTX evaluation in Gambierdiscus. These findings, which support future collaborative studies for the inter-laboratory validation of CTX detection methods, will help improve ciguatera risk assessment and management.
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Affiliation(s)
- Hélène Taiana Darius
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
- Correspondence: ; Tel.: +689-40-416-484
| | - Taina Revel
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
| | - Jérôme Viallon
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
| | - Manoëlla Sibat
- IFREMER, PHYTOX, Laboratoire METALG, F-44000 Nantes, France; (M.S.); (P.H.)
| | - Philippe Cruchet
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
| | - Sébastien Longo
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
| | - Donnie Ransom Hardison
- National Oceanic and Atmospheric Administration, Center for Coastal Fisheries and Habitat Research, Beaufort, NC 28516, USA; (D.R.H.); (W.C.H.)
| | - William C. Holland
- National Oceanic and Atmospheric Administration, Center for Coastal Fisheries and Habitat Research, Beaufort, NC 28516, USA; (D.R.H.); (W.C.H.)
| | | | - R. Wayne Litaker
- CSS, Inc. Under Contract to National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science, National Ocean Service, Beaufort, NC 28516, USA;
| | - Jennifer R. McCall
- Center for Marine Science, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403, USA;
| | - Philipp Hess
- IFREMER, PHYTOX, Laboratoire METALG, F-44000 Nantes, France; (M.S.); (P.H.)
| | - Mireille Chinain
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
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Loeffler CR, Bodi D, Tartaglione L, Dell'Aversano C, Preiss-Weigert A. Improving in vitro ciguatoxin and brevetoxin detection: selecting neuroblastoma (Neuro-2a) cells with lower sensitivity to ouabain and veratridine (OV-LS). HARMFUL ALGAE 2021; 103:101994. [PMID: 33980434 DOI: 10.1016/j.hal.2021.101994] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 12/31/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
Marine biotoxins accumulating in seafood products pose a risk to human health. These toxins are often potent in minute amounts and contained within complex matrices; requiring sensitive, reliable, and robust methods for their detection. The mouse neuroblastoma (Neuro-2a) cytotoxicity assay (N2a-assay) is a sensitive, high-throughput, in vitro method effective for detecting sodium channel-specific marine biotoxins. The N2a-assay can be conducted to distinguish between specific effects on voltage-gated sodium (NaV) channels, caused by toxins that activate (e.g., ciguatoxins (CTXs), brevetoxins (PbTxs)) or block (e.g., tetrodotoxins, saxitoxins) the target NaV. The sensitivity and specificity of the assay to compounds activating the NaV are achieved through the addition of the pharmaceuticals ouabain (O) and veratridine (V). However, these compounds can be toxic to Neuro-2a cells and their application at insufficient or excessive concentrations can reduce the effectiveness of this assay for marine toxin detection. Therefore, during growth incubation, Neuro-2a cells were exposed to O and V, and surviving cells exhibiting a lower sensitivity to O and V (OV-LS) were propagated. OV-LS Neuro-2a cells were selected for 60-80% survival when exposed to 0.22/0.022 mM O/V during the cytotoxicity assay. At these conditions, OV-LS N2a cells demonstrated a 3.5-fold higher survival rate 71% ± 7.9 SD (n = 232), and lower sensitivity to O/V, compared to the original Neuro-2a cells 20% ± 9.0 SD (n = 16). Additionally, OV-LS N2a cells were 1.3-2.6-fold more sensitive for detecting CTX3C 1.35 pg/ml, CTX1B 2.06 pg/ml, and PbTx-3 3.04 ng/ml compared to Neuro-2a cells using 0.1/0.01 mM O/V. Detection of CTX3C in a complex fish matrix using OV-LS cells was 0.0048 pg CTX3C/mg fish tissue equivalent. This work shows the potential for a significant improvement in sensitivity for CTX3C, CTX1B, and PbTx-3 using the OV-LS N2a-assay.
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Affiliation(s)
- Christopher R Loeffler
- German Federal Institute for Risk Assessment, Department Safety in the Food Chain, National Reference Laboratory of Marine Biotoxins, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany - www.bfr.bund.de; Department of Pharmacy, School of Medicine and Surgery, University of Napoli Federico II, Via D. Montesano 49, 80131, Napoli, Italy.
| | - Dorina Bodi
- German Federal Institute for Risk Assessment, Department Safety in the Food Chain, National Reference Laboratory of Marine Biotoxins, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany - www.bfr.bund.de
| | - Luciana Tartaglione
- Department of Pharmacy, School of Medicine and Surgery, University of Napoli Federico II, Via D. Montesano 49, 80131, Napoli, Italy; CoNISMa - Italian Interuniversity Consortium on Marine Sciences, Piazzale Flaminio 9, 00196 Rome, Italy
| | - Carmela Dell'Aversano
- Department of Pharmacy, School of Medicine and Surgery, University of Napoli Federico II, Via D. Montesano 49, 80131, Napoli, Italy; CoNISMa - Italian Interuniversity Consortium on Marine Sciences, Piazzale Flaminio 9, 00196 Rome, Italy
| | - Angelika Preiss-Weigert
- German Federal Institute for Risk Assessment, Department Safety in the Food Chain, National Reference Laboratory of Marine Biotoxins, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany - www.bfr.bund.de
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Pierre O, Fouchard M, Buscaglia P, Le Goux N, Leschiera R, Mignen O, Fluhr JW, Misery L, Le Garrec R. Calcium Increase and Substance P Release Induced by the Neurotoxin Brevetoxin-1 in Sensory Neurons: Involvement of PAR2 Activation through Both Cathepsin S and Canonical Signaling. Cells 2020; 9:E2704. [PMID: 33348659 PMCID: PMC7767211 DOI: 10.3390/cells9122704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 12/17/2022] Open
Abstract
Red tides involving Karenia brevis expose humans to brevetoxins (PbTxs). Oral exposition triggers neurotoxic shellfish poisoning, whereas inhalation induces a respiratory syndrome and sensory disturbances. No curative treatment is available and the pathophysiology is not fully elucidated. Protease-activated receptor 2 (PAR2), cathepsin S (Cat-S) and substance P (SP) release are crucial mediators of the sensory effects of ciguatoxins (CTXs) which are PbTx analogs. This work explored the role of PAR2 and Cat-S in PbTx-1-induced sensory effects and deciphered the signaling pathway involved. We performed calcium imaging, PAR2 immunolocalization and SP release experiments in monocultured sensory neurons or co-cultured with keratinocytes treated with PbTx-1 or P-CTX-2. We demonstrated that PbTx-1-induced calcium increase and SP release involved Cat-S, PAR2 and transient receptor potential vanilloid 4 (TRPV4). The PbTx-1-induced signaling pathway included protein kinase A (PKA) and TRPV4, which are compatible with the PAR2 biased signaling induced by Cat-S. Internalization of PAR2 and protein kinase C (PKC), inositol triphosphate receptor and TRPV4 activation evoked by PbTx-1 are compatible with the PAR2 canonical signaling. Our results suggest that PbTx-1-induced sensory disturbances involve the PAR2-TRPV4 pathway. We identified PAR2, Cat-S, PKA, and PKC that are involved in TRPV4 sensitization induced by PbTx-1 in sensory neurons.
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Affiliation(s)
- Ophélie Pierre
- EA4685 Laboratory of Interactions Neurons-Keratinocytes (LIEN), Faculty of Medicine and Health Sciences, University Brest, F-29200 Brest, France; (M.F.); (R.L.); (J.W.F.); (L.M.); (R.L.G.)
| | - Maxime Fouchard
- EA4685 Laboratory of Interactions Neurons-Keratinocytes (LIEN), Faculty of Medicine and Health Sciences, University Brest, F-29200 Brest, France; (M.F.); (R.L.); (J.W.F.); (L.M.); (R.L.G.)
- Department of Dermatology, University Hospital of Brest, F-29200 Brest, France
| | - Paul Buscaglia
- InsermUMR1227, Lymphocytes B et Autoimmunity, University Brest, F-29200 Brest, France; (P.B.); (N.L.G.); (O.M.)
| | - Nelig Le Goux
- InsermUMR1227, Lymphocytes B et Autoimmunity, University Brest, F-29200 Brest, France; (P.B.); (N.L.G.); (O.M.)
| | - Raphaël Leschiera
- EA4685 Laboratory of Interactions Neurons-Keratinocytes (LIEN), Faculty of Medicine and Health Sciences, University Brest, F-29200 Brest, France; (M.F.); (R.L.); (J.W.F.); (L.M.); (R.L.G.)
| | - Olivier Mignen
- InsermUMR1227, Lymphocytes B et Autoimmunity, University Brest, F-29200 Brest, France; (P.B.); (N.L.G.); (O.M.)
| | - Joachim W. Fluhr
- EA4685 Laboratory of Interactions Neurons-Keratinocytes (LIEN), Faculty of Medicine and Health Sciences, University Brest, F-29200 Brest, France; (M.F.); (R.L.); (J.W.F.); (L.M.); (R.L.G.)
- Department of Dermatology, University Hospital of Brest, F-29200 Brest, France
- Department of Dermatology and Allergology, Universitaetsmedizin Charit Berlin, D-10117 Berlin, Germany
| | - Laurent Misery
- EA4685 Laboratory of Interactions Neurons-Keratinocytes (LIEN), Faculty of Medicine and Health Sciences, University Brest, F-29200 Brest, France; (M.F.); (R.L.); (J.W.F.); (L.M.); (R.L.G.)
- Department of Dermatology, University Hospital of Brest, F-29200 Brest, France
| | - Raphaële Le Garrec
- EA4685 Laboratory of Interactions Neurons-Keratinocytes (LIEN), Faculty of Medicine and Health Sciences, University Brest, F-29200 Brest, France; (M.F.); (R.L.); (J.W.F.); (L.M.); (R.L.G.)
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PAR2, Keratinocytes, and Cathepsin S Mediate the Sensory Effects of Ciguatoxins Responsible for Ciguatera Poisoning. J Invest Dermatol 2020; 141:648-658.e3. [PMID: 32800876 DOI: 10.1016/j.jid.2020.07.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 01/14/2023]
Abstract
Ciguatera fish poisoning is caused by the consumption of fish contaminated with ciguatoxins (CTXs). The most distressing symptoms are cutaneous sensory disturbances, including cold dysesthesia and itch. CTXs are neurotoxins known to activate voltage-gated sodium channels, but no specific treatment exists. Peptidergic neurons have been critically involved in ciguatera fish poisoning sensory disturbances. Protease-activated receptor-2 (PAR2) is an itch- and pain-related G protein‒coupled receptor whose activation leads to a calcium-dependent neuropeptide release. In this study, we studied the role of voltage-gated sodium channels, PAR2, and the PAR2 agonist cathepsin S in the cytosolic calcium increase and subsequent release of the neuropeptide substance P elicited by Pacific CTX-2 (P-CTX-2) in rat sensory neurons and human epidermal keratinocytes. In sensory neurons, the P-CTX-2‒evoked calcium response was driven by voltage-gated sodium channels and PAR2-dependent mechanisms. In keratinocytes, P-CTX-2 also induced voltage-gated sodium channels and PAR2-dependent marked calcium response. In the cocultured cells, P-CTX-2 significantly increased cathepsin S activity, and cathepsin S and PAR2 antagonists almost abolished P-CTX-2‒elicited substance P release. Keratinocytes synergistically favored the induced substance P release. Our results demonstrate that the sensory effects of CTXs involve the cathepsin S-PAR2 pathway and are potentiated by their direct action on nonexcitable keratinocytes through the same pathway.
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Oishi T. Design and Synthesis of Artificial Ladder-Shaped Polyethers for Exploring Biological Functions. HETEROCYCLES 2019. [DOI: 10.3987/rev-18-sr(f)1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Kitchen SA, Bourdelais AJ, Taylor AR. Interaction of a dinoflagellate neurotoxin with voltage-activated ion channels in a marine diatom. PeerJ 2018; 6:e4533. [PMID: 29632739 PMCID: PMC5888156 DOI: 10.7717/peerj.4533] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/05/2018] [Indexed: 01/04/2023] Open
Abstract
Background The potent neurotoxins produced by the harmful algal bloom species Karenia brevis are activators of sodium voltage-gated channels (VGC) in animals, resulting in altered channel kinetics and membrane hyperexcitability. Recent biophysical and genomic evidence supports widespread presence of homologous sodium (Na+) and calcium (Ca2+) permeable VGCs in unicellular algae, including marine phytoplankton. We therefore hypothesized that VGCs of these phytoplankton may be an allelopathic target for waterborne neurotoxins produced by K. brevis blooms that could lead to ion channel dysfunction and disruption of signaling in a similar manner to animal Na+ VGCs. Methods We examined the interaction of brevetoxin-3 (PbTx-3), a K. brevis neurotoxin, with the Na+/Ca2+ VGC of the non-toxic diatom Odontella sinensis using electrophysiology. Single electrode current- and voltage- clamp recordings from O. sinensis in the presence of PbTx-3 were used to examine the toxin’s effect on voltage gated Na+/Ca2+ currents. In silico analysis was used to identify the putative PbTx binding site in the diatoms. We identified Na+/Ca2+ VCG homologs from the transcriptomes and genomes of 12 diatoms, including three transcripts from O. sinensis and aligned them with site-5 of Na+ VGCs, previously identified as the PbTx binding site in animals. Results Up to 1 µM PbTx had no effect on diatom resting membrane potential or membrane excitability. The kinetics of fast inward Na+/Ca2+ currents that underlie diatom action potentials were also unaffected. However, the peak inward current was inhibited by 33%, delayed outward current was inhibited by 25%, and reversal potential of the currents shifted positive, indicating a change in permeability of the underlying channels. Sequence analysis showed a lack of conservation of the PbTx binding site in diatom VGC homologs, many of which share molecular features more similar to single-domain bacterial Na+/Ca2+ VGCs than the 4-domain eukaryote channels. Discussion Although membrane excitability and the kinetics of action potential currents were unaffected, the permeation of the channels underlying the diatom action potential was significantly altered in the presence of PbTx-3. However, at environmentally relevant concentrations the effects of PbTx- on diatom voltage activated currents and interference of cell signaling through this pathway may be limited. The relative insensitivity of phytoplankton VGCs may be due to divergence of site-5 (the putative PbTx binding site), and in some cases, such as O. sinensis, resistance to toxin effects may be because of evolutionary loss of the 4-domain eukaryote channel, while retaining a single domain bacterial-like VGC that can substitute in the generation of fast action potentials.
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Affiliation(s)
- Sheila A Kitchen
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, United States of America
| | - Andrea J Bourdelais
- Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC, United States of America
| | - Alison R Taylor
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, United States of America
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Álvarez-Méndez SJ, García C, Martín VS. The Evans Aldol–Prins cyclization: a general and stereoselective method for the synthesis of 2,3,4,5,6-pentasubstituted tetrahydropyrans. Chem Commun (Camb) 2016; 52:3380-3. [PMID: 26878814 DOI: 10.1039/c6cc00160b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A method for the synthesis of 2,3,4,5,6-pentasubstituted THPs with good yields and diastereoselectivities through an Evans Aldol–Prins strategy is described.
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Affiliation(s)
- Sergio J. Álvarez-Méndez
- Instituto Universitario de Bio-Orgánica “Antonio González” (IUBO-AG)
- Centro de Investigaciones Biomédicas de Canarias (CIBICAN)
- Departamento de Química Orgánica
- Universidad de La Laguna
- 38206 La Laguna
| | - Celina García
- Instituto Universitario de Bio-Orgánica “Antonio González” (IUBO-AG)
- Centro de Investigaciones Biomédicas de Canarias (CIBICAN)
- Departamento de Química Orgánica
- Universidad de La Laguna
- 38206 La Laguna
| | - Víctor S. Martín
- Instituto Universitario de Bio-Orgánica “Antonio González” (IUBO-AG)
- Centro de Investigaciones Biomédicas de Canarias (CIBICAN)
- Departamento de Química Orgánica
- Universidad de La Laguna
- 38206 La Laguna
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Yamada K, Kuriyama H, Hara T, Murata M, Irie R, Harntaweesup Y, Satake M, Fukuzawa S, Tachibana K. Interaction analysis of a ladder-shaped polycyclic ether and model transmembrane peptides in lipid bilayers by using Förster resonance energy transfer and polarized attenuated total reflection infrared spectroscopy. Bioorg Med Chem 2014; 22:3773-80. [DOI: 10.1016/j.bmc.2014.04.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/21/2014] [Accepted: 04/22/2014] [Indexed: 01/18/2023]
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Holland WC, Litaker RW, Tomas CR, Kibler SR, Place AR, Davenport ED, Tester PA. Differences in the toxicity of six Gambierdiscus (Dinophyceae) species measured using an in vitro human erythrocyte lysis assay. Toxicon 2013; 65:15-33. [PMID: 23313447 DOI: 10.1016/j.toxicon.2012.12.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 12/04/2012] [Accepted: 12/05/2012] [Indexed: 11/24/2022]
Abstract
This study examined the toxicity of six Gambierdiscus species (Gambierdiscus belizeanus, Gambierdiscus caribaeus, Gambierdiscus carolinianus, Gambierdiscus carpenteri, Gambierdiscus ribotype 2 and Gambierdiscus ruetzleri) using a human erythrocyte lysis assay. In all, 56 isolates were tested. The results showed certain species were significantly more toxic than others. Depending on the species, hemolytic activity consistently increased by ∼7-40% from log phase growth to late log - early stationary growth phase and then declined in mid-stationary growth phase. Increasing growth temperatures from 20 to 31 °C for clones of G. caribaeus showed only a slight increase in hemolytic activity between 20 and 27 °C. Hemolytic activity in the G. carolinianus isolates from different regions grown over the same 20-31 °C range remained constant. These data suggest that growth temperature is not a significant factor in modulating the inter-isolate and interspecific differences in hemolytic activity. The hemolytic activity of various isolates measured repeatedly over a 2 year period remained constant, consistent with the hemolytic compounds being constitutively produced and under strong genetic control. Depending on species, greater than 60-90% of the total hemolytic activity was initially associated with the cell membranes but diffused into solution over a 24 h assay incubation period at 4 °C. These findings suggest that hemolytic compounds produced by Gambierdiscus isolates were held in membrane bound vesicles as reported for brevetoxins produced by Karenia brevis. Gambierdiscus isolates obtained from other parts of the world exhibited hemolytic activities comparable to those found in the Caribbean and Gulf of Mexico confirming the range of toxicities is similar among Gambierdiscus species worldwide. Experiments using specific inhibitors of the MTX pathway and purified MTX, Gambierdiscus whole cell extracts, and hydrophilic cell extracts containing MTX, were consistent with MTX as the primary hemolytic compound produced by Gambierdiscus species. While the results from inhibition studies require validation by LC-MS analysis, the available data strongly suggest differences in hemolytic activity observed in this study reflect maitotoxicity.
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Affiliation(s)
- William C Holland
- National Oceanic and Atmospheric Administration, National Ocean Service, National Centers for Coastal Ocean Science, Center for Coastal Fisheries and Habitat Research, 101 Pivers Island Road, Beaufort, NC 28516, USA
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Kumar-Roiné S, Taiana Darius H, Matsui M, Fabre N, Haddad M, Chinain M, Pauillac S, Laurent D. A review of traditional remedies of ciguatera fish poisoning in the Pacific. Phytother Res 2012; 25:947-58. [PMID: 21287650 DOI: 10.1002/ptr.3396] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Ciguatera fish poisoning (CFP) is an illness caused by eating tropical coral fish contaminated with ciguatoxins (CTXs). The clinical management of patients with CFP is generally supportive and symptomatic in nature as no antidote exists. Of the many drugs prescribed, several have been claimed to be efficient in small, uncontrolled studies, but the outcomes of treatments with these medicines are often contradictory. In New Caledonia, traditional remedies are commonly employed in the treatment of CFP and of the 90 plant species catalogued as useful in CFP, the most popular herbal remedy by far is a decoction prepared from the leaves of Heliotropium foertherianum Diane & Hilger (Boraginaceae). Other important plants used in the treatment of CFP include Euphorbia hirta L. (Euphorbiaceae) and Vitex L. sp. (Lamiaceae). This review focuses on the evidence for efficacy of these species and pharmacological studies which support their use. Other plants used in CFP and the conventional treatment of CFP are also discussed briefly.
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Affiliation(s)
- Shilpa Kumar-Roiné
- UMR 152-Laboratoire de Pharmacochimie des Substances Naturelles et Pharmacophores Redox, Université de Toulouse, UPS, 118 Rte de Narbonne, F-31062 Toulouse Cedex 9, France
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Cagide E, Louzao MC, Espiña B, Ares IR, Vieytes MR, Sasaki M, Fuwa H, Tsukano C, Konno Y, Yotsu-Yamashita M, Paquette LA, Yasumoto T, Botana LM. Comparative cytotoxicity of gambierol versus other marine neurotoxins. Chem Res Toxicol 2011; 24:835-42. [PMID: 21517028 DOI: 10.1021/tx200038j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many microalgae produce compounds that exhibit potent biological activities. Ingestion of marine organisms contaminated with those toxins results in seafood poisonings. In many cases, the lack of toxic material turns out to be an obstacle to make the toxicological investigations needed. In this study, we evaluate the cytotoxicity of several marine toxins on neuroblastoma cells, focusing on gambierol and its effect on cytosolic calcium levels. In addition, we compared the effects of this toxin with ciguatoxin, brevetoxin, and gymnocin-A, with which gambierol shares a similar ladder-like backbone, as well as with polycavernoside A analogue 5, a glycosidic macrolide toxin. For this purpose, different fluorescent dyes were used: Fura-2 to monitor variations in cytosolic calcium levels, Alamar Blue to detect cytotoxicity, and Oregon Green 514 Phalloidin to quantify and visualize modifications in the actin cytoskeleton. Data showed that, while gambierol and ciguatoxin were successful in producing a calcium influx in neuroblastoma cells, gymnocin-A was unable to modify this parameter. Nevertheless, none of the toxins induced morphological changes or alterations in the actin assembly. Although polycavernoside A analogue 5 evoked a sharp reduction of the cellular metabolism of neuroblastoma cells, gambierol scarcely reduced it, and ciguatoxin, brevetoxin, and gymnocin-A failed to produce any signs of cytotoxicity. According to this, sharing a similar polycyclic ether backbone is not enough to produce the same effects on neuroblastoma cells; therefore, more studies should be carried out with these toxins, whose effects may be being underestimated.
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Affiliation(s)
- E Cagide
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo, Spain
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Abstract
This Article describes the total synthesis of the marine ladder toxin brevenal utilizing a convergent synthetic strategy. Critical to the success of this work was the use of olefinic-ester cyclization reactions and the utilization of glycal epoxides as precursors to C-C and C-H bonds.
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Affiliation(s)
- Yuan Zhang
- Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA
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13
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Szpilman AM, Carreira EM. Probing the Biology of Natural Products: Molecular Editing by Diverted Total Synthesis. Angew Chem Int Ed Engl 2010; 49:9592-628. [DOI: 10.1002/anie.200904761] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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14
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Szpilman AM, Carreira EM. Untersuchung der Biologie von Naturstoffen: systematische Strukturvariation durch umgelenkte Totalsynthese. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200904761] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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15
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Ciguatera: A public health perspective. Toxicon 2010; 56:123-36. [DOI: 10.1016/j.toxicon.2009.09.008] [Citation(s) in RCA: 213] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2009] [Revised: 09/15/2009] [Accepted: 09/18/2009] [Indexed: 11/19/2022]
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16
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Truxal LT, Bourdelais AJ, Jacocks H, Abraham WM, Baden DG. Characterization of tamulamides A and B, polyethers isolated from the marine dinoflagellate Karenia brevis. JOURNAL OF NATURAL PRODUCTS 2010; 73:536-40. [PMID: 20218657 PMCID: PMC2881462 DOI: 10.1021/np900541w] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Florida red tides occur as the result of blooms of the marine dinoflagellate Karenia brevis. K. brevis is known to produce several families of fused polyether ladder compounds. The most notable compounds are the brevetoxins, potent neurotoxins that activate mammalian sodium channels. Additional fused polyether ladder compounds produced by K. brevis include brevenal, brevisin, and hemibrevetoxin B, all with varying affinities for the same binding site on voltage-sensitive sodium channels. The structure elucidation and biological activity of two additional fused polyether ladder compounds containing seven fused ether rings will be described in this paper. Tamulamide A (MW = 638.30) and tamulamide B (MW = 624.29) were isolated from K. brevis cultures, and their structures elucidated using a combination of NMR spectroscopy and high-resolution mass spectrometry. Tamulamides A and B were both found to compete with tritiated brevetoxin-3 ([(3)H]-PbTx-3) for its binding site on rat brain synaptosomes. However, unlike the brevetoxins, tamulamides A and B showed no toxicity to fish at doses up to 200 nM and did not cause significant bronchoconstriction in sheep pulmonary assays.
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Affiliation(s)
| | - Andrea J. Bourdelais
- Author to whom correspondence should be addressed. Tel: 910-962-2365, Fax: 910-962-2410,
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17
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B. Wang E, Parish CA. Conformational Analysis of a Model for the trans-Fused FGH Ether Rings in Brevetoxin A. J Org Chem 2010; 75:1582-8. [DOI: 10.1021/jo902558h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Evan B. Wang
- Department of Chemistry, Gottwald Center for the Sciences, University of Richmond, Richmond, Virginia 23173
| | - Carol A. Parish
- Department of Chemistry, Gottwald Center for the Sciences, University of Richmond, Richmond, Virginia 23173
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18
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Khan U, Benabderrazik N, Bourdelais AJ, Baden DG, Rein K, Gardinali PR, Arroyo L, O'Shea KE. UV and solar TiO(2) photocatalysis of brevetoxins (PbTxs). Toxicon 2009; 55:1008-16. [PMID: 19931554 DOI: 10.1016/j.toxicon.2009.11.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 11/09/2009] [Accepted: 11/13/2009] [Indexed: 11/19/2022]
Abstract
Karenia brevis, the harmful alga associated with red tide, produces brevetoxins (PbTxs). Exposure to these toxins can have a negative impact on marine wildlife and serious human health consequences. The elimination of PbTxs is critical to protect the marine environment and human health. TiO(2) photocatalysis under 350 nm and solar irradiation leads to significant degradation of PbTxs via first order kinetics. ELISA results demonstrate TiO(2) photocatalysis leads to a significant decrease in the bioactivity of PbTxs as a function of treatment time. Experiments conducted in the presence of synthetic seawater, humic material and a hydroxyl scavenger showed decreased degradation. PbTxs are highly hydrophobic and partition to organic microlayer on the ocean surface. Acetonitrile was employed to probe the influence of an organic media on the TiO(2) photocatalysis of PbTxs. Our results indicate TiO(2) photocatalysis may be applicable for the degradation of PbTxs.
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Affiliation(s)
- Urooj Khan
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
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19
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Vilotijevic I, Jamison T. Epoxidöffnungskaskaden zur Synthese polycyclischer Polyether-Naturstoffe. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200900600] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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Llewellyn LE. Sodium channel inhibiting marine toxins. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2009; 46:67-97. [PMID: 19184585 DOI: 10.1007/978-3-540-87895-7_3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Saxitoxin (STX), tetrodotoxin (TTX) and their many chemical relatives are part of our daily lives. From killing people who eat seafood containing these toxins, to being valuable research tools unveiling the invisible structures of their pharmacological receptor, their global impact is beyond measure. The pharmacological receptor for these toxins is the voltage-gated sodium channel which transports Na ions between the exterior to the interior of cells. The two structurally divergent families of STX and TTX analogues bind at the same location on these Na channels to stop the flow of ions. This can affect nerves, muscles and biological senses of most animals. It is through these and other toxins that we have developed much of our fundamental understanding of the Na channel and its part in generating action potentials in excitable cells.
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Affiliation(s)
- Lyndon E Llewellyn
- Australian Institute of Marine Science, Townsville MC, QLD 4810, Australia.
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21
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Vilotijevic I, Jamison TF. Epoxide-opening cascades in the synthesis of polycyclic polyether natural products. Angew Chem Int Ed Engl 2009; 48:5250-81. [PMID: 19572302 PMCID: PMC2810545 DOI: 10.1002/anie.200900600] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The structural features of polycyclic polyether natural products can, in some cases, be traced to their biosynthetic origin. However in case that are less well understood, only biosynthetic pathways that feature dramatic, yet speculative, epoxide-opening cascades are proposed. We summarize how such epoxide-opening cascade reactions have been used in the synthesis of polycyclic polyethers (see scheme) and related natural products.The group of polycyclic polyether natural products is of special interest owing to the fascinating structure and biological effects displayed by its members. The latter includes potentially therapeutic antibiotic, antifungal, and anticancer properties, and extreme lethality. The polycyclic structural features of this class of compounds can, in some cases, be traced to their biosynthetic origin, but in others that are less well understood, only to proposed biosynthetic pathways that feature dramatic, yet speculative, epoxide-opening cascades. In this review we summarize how such epoxide-opening cascade reactions have been used in the synthesis of polycyclic polyethers and related natural products.
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Affiliation(s)
- Ivan Vilotijevic
- Department of Chemistry, Massachusettes Institute of Technology, Cambridge, MA 02139 (USA), Fax: (+1) 617-324-0253, , , Homepage: http://web.mit.edu/chemistry/jamison
| | - Timothy F. Jamison
- Department of Chemistry, Massachusettes Institute of Technology, Cambridge, MA 02139 (USA), Fax: (+1) 617-324-0253, , , Homepage: http://web.mit.edu/chemistry/jamison
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22
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Michelliza S, Abraham WM, Jacocks HM, Schuster T, Baden DG. Synthesis, modeling, and biological evaluation of analogues of the semisynthetic brevetoxin antagonist beta-naphthoyl-brevetoxin. Chembiochem 2008; 8:2233-9. [PMID: 18000915 DOI: 10.1002/cbic.200700317] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Brevetoxins are neurotoxic compounds produced by the dinoflagellate Karenia brevis. Extensive blooms induce neurotoxic shellfish poisoning (NSP) and asthma-like symptoms in humans. beta-naphthoyl-brevetoxin, the first semisynthetic brevetoxin antagonist, has been defined as the lead compound in the investigation of the mechanisms of bronchoconstriction induced by inhaled brevetoxins and relaxation or reversal of those effects by selected derivatives. In pursuit of more potent and effective brevetoxin antagonists, a series of beta-naphthoyl-brevetoxin analogues have been synthesized. Activities were determined by competitive displacement of tritiated brevetoxin-3 from rat brain synaptosomes and by lung resistance measurements in sheep. Additionally, preliminary computational structural studies have been performed. All analogues bound to rat brain synaptosomes with affinities similar to beta-naphthoyl-brevetoxin but exhibited very different responses in sheep. The biological evaluations along with computational studies suggest that the brevetoxin binding site in rat brain synaptosome might be different from the ones in lung tissue and both steric and electrostatic factors contribute to the efficacy of brevetoxin antagonism.
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Affiliation(s)
- Sophie Michelliza
- Center for Marine Science, University of North Carolina Wilmington, 5600 Marvin. K. Moss Lane, Wilmington, NC 28409, USA.
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23
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LePage KT, Rainier JD, Johnson HWB, Baden DG, Murray TF. Gambierol acts as a functional antagonist of neurotoxin site 5 on voltage-gated sodium channels in cerebellar granule neurons. J Pharmacol Exp Ther 2007; 323:174-9. [PMID: 17609421 DOI: 10.1124/jpet.107.124271] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The marine toxin gambierol, a polyether ladder toxin derived from the marine dinoflagellate Gambierdiscus toxicus, was evaluated for interaction with voltage-gated sodium channels (VGSCs) in cerebellar granule neuron (CGN) cultures. At concentrations ranging from 10 nM to 10 microM, gambierol alone had no effect on the intracellular Ca2+ concentration [Ca2+]i of exposed CGN cultures. Furthermore, there was no evidence of neurotoxicity in CGN cultures exposed for 2 h to gambierol (1 nM-10 microM). However, gambierol was a potent inhibitor (IC50 = 189 nM) of the elevation of [Ca2+]i that accompanies exposure of CGN cultures to the VGSC activator brevetoxin-2 (PbTx-2). To further explore the potential interaction of gambierol with VGSCs, the influence of gambierol on PbTx-2-induced neurotoxicity was assessed. Gambierol reduced the PbTx-2-induced efflux of lactate dehydrogenase in exposed CGN cultures in a concentration-dependent manner (IC50 = 471 nM). It is noteworthy that the potencies of gambierol as an inhibitor of both PbTx-2-induced Ca2+ influx and cytotoxicity were coincident. Finally, the inhibitory effects of gambierol on PbTx-2-induced elevation of [Ca2+]i were compared with those of brevenal, a natural inhibitor of the toxic effects of brevetoxin isolated from cultures of Karina brevis. Like gambierol, brevenal inhibited PbTx-2-induced elevation of [Ca2+]i in a concentration-dependent manner (IC50 = 108.6 nM). These results provide evidence for gambierol acting as a functional antagonist of neurotoxin site 5 on neuronal VGSCs.
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Affiliation(s)
- K T LePage
- Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, USA
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24
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Design and synthesis of simplified polycyclic ethers and evaluation of their interaction with an α-helical peptide as a model of target proteins. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.03.041] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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Ciminiello P, Fattorusso E. Bivalve Molluscs as Vectors of Marine Biotoxins Involved in Seafood Poisoning. MOLLUSCS 2006; 43:53-82. [PMID: 17153338 DOI: 10.1007/978-3-540-30880-5_3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Molluscs of many sorts, which are high in protein and trace minerals, have always been a substantial portion of the human diet. A great variety of mollusc species are therefore of commercial importance throughout the world. Episodes of poisoning occasionally happen to the consumers of molluscs, the main hazard being represented by bivalve molluscs. These organisms are filter-feeders, feeding mainly on a wide range of phytoplankton species. Among the thousands of species of microscopic algae at the base of the marine food chain, there are a few dozen which produce potent toxins. One major category of impact occurs when toxic phytoplankton are filtered from the water as food by shellfish, which then accumulate the algal toxins to levels which can be lethal to humans. Incidences of poisoning related to marine algal toxins come under the main categories of paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), diarrhetic shellfish poisoning (DSP), and amnesic shellfish poisoning (ASP), depending upon the toxins and the symptoms that they cause. Since the beginning of the 1990s, a research program has been initiated to examine the toxin profiles in mussels from the Adriatic Sea. Since then, a number of polyether toxins have been isolated and characterized, some of which represent new additions to the DSP class of biotoxins. During this investigation, new types of toxins have also been isolated. The recent application of LC-MS methods for the detection of Adriatic marine biotoxins made it possible to speed up the analysis of toxic samples.
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Affiliation(s)
- P Ciminiello
- Dipartimento di Chimica delle Sostanze Naturali, Università degli Studi di Napoli Federico II, Via D. Montesano 49, 80131 Naples, Italy
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26
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Dechraoui MYB, Tiedeken JA, Persad R, Wang Z, Granade HR, Dickey RW, Ramsdell JS. Use of two detection methods to discriminate ciguatoxins from brevetoxins: Application to great barracuda from Florida Keys. Toxicon 2005; 46:261-70. [PMID: 15982699 DOI: 10.1016/j.toxicon.2005.04.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Revised: 04/01/2005] [Accepted: 04/04/2005] [Indexed: 11/30/2022]
Abstract
In Florida (USA), numerous cases of human ciguatera fish poisoning, as well as neurotoxic shellfish poisoning following consumption of local seafood products, have been reported. By using in parallel, the sodium channel receptor binding assay (RBA), and the ouabain/veratridine-dependent cytotoxicity assay (N2A assay), we established criteria to identify, detect, and quantify ciguatoxins in fish extracts, with a brevetoxin as internal standard. Results showed that the Caribbean ciguatoxin C-CTX-1 exhibited an 8-fold higher potency in the RBA than brevetoxins and, a 440 and 2300-fold higher potency in the N2A assay than PbTx-1 and PbTx-3, respectively. Moreover, a sensitivity comparison between assays revealed that the N2A assay was more sensitive (12-fold) for ciguatoxin analysis, whereas the RBA was more sensitive (3-24-fold) for brevetoxins analysis. Based on the relative potency between toxins and the opposite sensitivity of both assays we have used the RBA and the N2A assay to screen great barracuda (Sphyraena barracuda) collected from the Florida Keys for ciguatoxins and brevetoxins. Fish extract analysis showed a sodium channel-dependent activity consistent with the presence of ciguatoxins, and not brevetoxins. Among 40 barracudas analyzed, 60% contained ciguatoxin levels in their liver measurable by the N2A assay with the most toxic fish containing 2.1ppb C-CTX-1 equivalents.
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Affiliation(s)
- M-Yasmine Bottein Dechraoui
- Marine Biotoxins Program, Center for Coastal Environmental Health and Biomolecular Research, NOAA-National Ocean Service, Charleston, SC 29412, USA
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27
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Cheng YS, McDonald JD, Kracko D, Irvin CM, Zhou Y, Pierce RH, Henry MS, Bourdelaisa A, Naar J, Baden DG. Concentration and particle size of airborne toxic algae (brevetoxin) derived from ocean red tide events. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2005; 39:3443-9. [PMID: 15954221 PMCID: PMC2652738 DOI: 10.1021/es048680j] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Red tides in the Gulf of Mexico are formed by blooms of the dinoflagellate Karenia brevis, which produces brevetoxins (PbTx). Brevetoxins can be transferred from water to air in the wind-powered whitecapped waves during red tide episodes. Inhalation exposure to marine aerosol containing PbTx causes respiratory problems. A liquid chromatograph/ tandem mass spectrometric method was developed for the detection and quantitation of several PbTxs in ambient samples collected during red tide events. This method was complemented by a previously developed antibody assay that analyzes the entire class of PbTx compounds. The method showed good linearity, accuracy, and reproducibility, allowing quantitation of PbTx compounds in the 10 pg/m3 range. Air concentrations of PbTxs and brevenal for individual samples ranged from 0.01 to 80 ng/m3. The particle size showed a single mode with a mass median diameter between 6 and 10 microm, which was consistent for all of the PbTx species that were measured. Our results imply that individual PbTxs were from the same marine aerosol or from marine aerosol that was produced from the same process. The particle size indicated the likelihood of high deposition efficiency in the respiratory tract with the majority of aerosol deposited in the upper airways and small but not insignificant deposition in the lower airways.
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Affiliation(s)
- Yung Sung Cheng
- Lovelace Respiratory Research Institute, 2425 Ridgecrest, SE, Albuquerque, New Mexico 87108, USA.
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Baden DG, Bourdelais AJ, Jacocks H, Michelliza S, Naar J. Natural and derivative brevetoxins: historical background, multiplicity, and effects. ENVIRONMENTAL HEALTH PERSPECTIVES 2005; 113:621-5. [PMID: 15866774 PMCID: PMC1257558 DOI: 10.1289/ehp.7499] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2004] [Accepted: 02/09/2005] [Indexed: 05/02/2023]
Abstract
Symptoms consistent with inhalation toxicity have long been associated with Florida red tides, and various causal agents have been proposed. Research since 1981 has centered on a group of naturally occurring trans-fused cyclic polyether compounds called brevetoxins that are produced by a marine dinoflagellate known as Karenia brevis. Numerous individual brevetoxins have been identified from cultures as well as from natural bloom events. A spectrum of brevetoxin derivatives produced by chemical modification of the natural toxins has been prepared to examine the effects of functional group modification on physiologic activity. Certain structural features of natural and synthetic derivatives of brevetoxin appear to ascribe specific physiologic consequences to each toxin. Differential physiologic effects have been documented with many of the natural toxins and derivatives, reinforcing the hypothesis that metabolism or modification of toxin structures modulates both the specific toxicity (lethality on a per milligram basis) and potentially the molecular mechanism(s) of action. A series of naturally occurring fused-ring polyether compounds with fewer rings than brevetoxin, known as brevenals, exhibit antagonistic properties and counteract the effects of the brevetoxins in neuronal and pulmonary model systems. Taken together, the inhalation toxicity of Florida red tides would appear to depend on the amount of each toxin present, as well as on the spectrum of molecular activities elicited by each toxin. Toxicity in a bloom is diminished by the amount brevenal present.
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Affiliation(s)
- Daniel G Baden
- University of North Carolina at Wilmington, Center for Marine Science, 5600 Marvin Moss Lane, Wilmington, NC 28409, USA.
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Choich J, Salierno JD, Silbergeld EK, Kane AS. Altered brain activity in brevetoxin-exposed bluegill, Lepomis macrochirus, visualized using in vivo 14C 2-deoxyglucose labeling. ENVIRONMENTAL RESEARCH 2004; 94:192-197. [PMID: 14757382 DOI: 10.1016/j.envres.2003.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This study investigated the neurological effects of sublethal brevetoxin (PbTx-2) exposure in bluegill (Lepomis macrochirus) by measuring alterations in 2-deoxyglucose (2-DG) uptake in the brains of exposed fish. Changes in regional brain activity were quantified using digitized autoradiographs from exposed and control fish. Brains of brevetoxin-exposed fish had significantly higher labeling of 2-DG than brains of control fish. Regional increases in labeling were observed in the optic lobes, telencephalon, and cerebrum of PbTx-2 exposed fish. From these observations, we conclude that sublethal brevetoxin exposure in vivo in bluegill increases neurological stimulation, measured through quantification of [14C]2-DG uptake in the brain. Increases in the uptake of [14C]2-DG from this study may be indicative of differences in neural activity in the PbTx-exposed fish and are likely associated with the action of PbTx-2 on voltage-gated sodium channels (VGSC), as well as neurological alterations in calcium and neurotransmitter release downstream resulting from VGSC activation. These techniques quantify physiological alterations in fish brain activity resulting from exposure to brevetoxin and possibly other harmful algal bloom toxins.
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Affiliation(s)
- J Choich
- University of Maryland, Baltimore, Program in Toxicology, 10 South Pine Street, MD 21201, USA
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30
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Bottein Dechraoui MY, Ramsdell JS. Type B brevetoxins show tissue selectivity for voltage-gated sodium channels: comparison of brain, skeletal muscle and cardiac sodium channels. Toxicon 2003; 41:919-27. [PMID: 12782093 DOI: 10.1016/s0041-0101(03)00088-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Brevetoxins and ciguatoxins are two classes of phycotoxins which exert their toxic effect by binding to site-5 of voltage-gated sodium channels. Sodium channels, a family of at least 10 structurally different proteins, are responsible for the rising phase of the action potential in membranes of neuronal, cardiac and muscular excitable cells. This work is a comparative study of the binding properties and the cytotoxic effects of ciguatoxins and brevetoxins on human embryonic cells (HEK) stably expressing either the skeletal muscle (Na(v)1.4), or the cardiac (Na(v)1.5) sodium channel alpha-subunit isoforms. We report that type A (PbTx-1) and type B (PbTx-3 and PbTx-2) brevetoxins as well as ciguatoxins target both cardiac and muscle channels; type B brevetoxins show isoform selectivity, presenting a lower affinity for the heart than the skeletal muscle channel. The lower selectivity of type B brevetoxins for heart sodium channels may result from a more rigid backbone structure than is found in type A brevetoxins and ciguatoxins.
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Affiliation(s)
- Marie-Yasmine Bottein Dechraoui
- Marine Biotoxins Program, Center for Coastal Environmental Health and Biomolecular Research, NOAA-National Ocean Service, 219 Fort Johnson Road, Charleston, SC 29412, USA
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31
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Berry JP, Reece KS, Rein KS, Baden DG, Haas LW, Ribeiro WL, Shields JD, Snyder RV, Vogelbein WK, Gawley RE. Are Pfiesteria species toxicogenic? Evidence against production of ichthyotoxins by Pfiesteria shumwayae. Proc Natl Acad Sci U S A 2002; 99:10970-5. [PMID: 12163648 PMCID: PMC123194 DOI: 10.1073/pnas.172221699] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2002] [Indexed: 11/18/2022] Open
Abstract
The estuarine genus Pfiesteria has received considerable attention since it was first identified and proposed to be the causative agent of fish kills along the mid-Atlantic coast in 1992. The presumption has been that the mechanism of fish death is by release of one or more toxins by the dinoflagellate. In this report, we challenge the notion that Pfiesteria species produce ichthyotoxins. Specifically, we show that (i) simple centrifugation, with and without ultrasonication, is sufficient to "detoxify" water of actively fish-killing cultures of Pfiesteria shumwayae, (ii) organic extracts of lyophilized cultures are not toxic to fish, (iii) degenerate primers that amplify PKS genes from several polyketide-producing dinoflagellates failed to yield a product with P. shumwayae DNA or cDNA, and (iv) degenerate primers for NRPS genes failed to amplify any NRPS genes but (unexpectedly) yielded a band (among several) that corresponded to known or putative PKSs and fatty acid synthases. We conclude that P. shumwayae is able to kill fish by means other than releasing a toxin into bulk water. Alternative explanations of the effects attributed to Pfiesteria are suggested.
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Affiliation(s)
- J P Berry
- Department of Chemistry/National Institute of Environmental Health Sciences, Marine and Freshwater Biomedical Science Center, University of Miami, P.O. Box 249118, Coral Gables, FL 33124, USA
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32
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Sasaki M, Noguchi T, Tachibana K. Intramolecular radical cyclization-ring-closing metathesis approach to fused polycyclic ethers. Convergent synthesis and conformational analysis of the (E)FGH ring system of ciguatoxin. J Org Chem 2002; 67:3301-10. [PMID: 12003539 DOI: 10.1021/jo010974p] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A convergent synthetic route to the (E)FGH ring system 4 of ciguatoxins, the causative toxins for ciguatera fish poisoning, has been developed. The synthesis features convergent coupling to form dioxane acetal, regioselective acetal cleavage by diethylaluminum phenylthiolate or diisobutylaluminum phenylselenolate followed by intramolecular radical cyclization to construct the oxepane ring G, and a ring-closing metathesis reaction to form the hexahydrooxonine ring F. The hexahydrooxonine ring F of tetracyclic model system 4 existed as a 5:1 equilibrium mixture of two conformers (UP and DOWN conformers), with the UP one predominating. This is the first illustration that reproduces the preference for the UP conformer over the DOWN one, which preference was observed for natural ciguatoxins.
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Affiliation(s)
- Makoto Sasaki
- Department of Chemistry, Graduate School of Science, The University of Tokyo, and CREST, Japan Science and Technology Corporation (JST), Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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Candenas M, Pinto FM, Cintado CG, Morales EQ, Brouard I, Dı́az M, Rico M, Rodrı́guez E, Rodrı́guez RM, Pérez R, Pérez RL, Martı́n JD. Synthesis and biological studies of flexible brevetoxin/ciguatoxin models with marked conformational preference. Tetrahedron 2002. [DOI: 10.1016/s0040-4020(02)00047-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Mattei C, Dechraoui MY, Molgó J, Meunier FA, Legrand AM, Benoit E. Neurotoxins targetting receptor site 5 of voltage-dependent sodium channels increase the nodal volume of myelinated axons. J Neurosci Res 1999; 55:666-73. [PMID: 10220108 DOI: 10.1002/(sici)1097-4547(19990315)55:6<666::aid-jnr2>3.0.co;2-h] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The effects of a C57 type ciguatoxin (CTX-3C) and two types of brevetoxins (PbTx-1 and PbTx-3), known to bind to receptor site 5 of the neuronal voltage-dependent Na+ channel-protein, were studied on the morphology of living frog myelinated axons using confocal laser scanning microscopy. During the action of CTX-3C, PbTx-1, and PbTx-3 (10-50 nM), a marked swelling of nodes of Ranvier was observed without apparent modification of internodal parts of axons. In all cases, toxin-induced nodal swelling attained a steady-state within 75-100 min that was well maintained during an additional 90-115 min. The nodal swelling was reversed by an external hyperosmotic solution containing 100 mM D-mannitol and could be completely prevented by blocking voltage-dependent Na+ channels with 1 microM tetrodotoxin. It is suggested that CTX-3C, PbTx-1, and PbTx-3 by activating Na+ channels cause a continuous Na+ entry into axons, increasing internal Na+ concentration. Such an increase directly or indirectly disturbs the osmotic equilibrium between intra- and extra-axonal media, resulting in an influx of water, which is responsible for the long-lasting nodal swelling. Similar results were previously reported with two C60 type ciguatoxins (CTX-1B and CTX-4B). Thus, it is concluded that the four types of toxins targetting receptor site 5 of neuronal voltage-dependent Na+ channels, not only enhance nerve membrane excitability but also, on a long-term basis, cause a marked increase in the axonal volume.
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Affiliation(s)
- C Mattei
- Laboratoire de Neurobiologie Cellulaire et Moléculaire, CNRS, Gif sur Yvette, France
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Dechraoui MY, Naar J, Pauillac S, Legrand AM. Ciguatoxins and brevetoxins, neurotoxic polyether compounds active on sodium channels. Toxicon 1999; 37:125-43. [PMID: 9920485 DOI: 10.1016/s0041-0101(98)00169-x] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Ciguatoxins (CTXs) and brevetoxins (PbTxs) modify the activation and inactivation processes of voltage-sensitive sodium channels (VSSC). In this study, the specific binding to rat brain synaptosomes of two commercial PbTxs, five purified CTXs and their derivatives was evaluated in competition with various concentrations of radiolabelled brevetoxin ([3H]PbTx-3). The results indicate that all CTXs bind specifically and with high affinity to sodium channels. Statistical analysis of the calculated inhibition constants identified two classes of toxins: the PbTxs and the less polar CTXs, and a group of CTXs of very high affinity. Relatively small chemical differences between the CTXs gave rise to significant differences in their affinity to the rat brain sodium channels. Cytotoxic effects associated with sodium channel activation were evaluated for the two classes of toxins on murine neuroblastoma cells, and their acute toxicity was determined in mice. CTXs have shown high affinities to VSSC of rat brain membranes and strong cytotoxic effects on neuroblastoma cells which correlate with their very low LD50 in mice. For PbTxs, it is different. Although binding with high affinity to VSSC and giving rise to significant cytotoxic effects, they are known to be poorly toxic intraperitoneally to mice. Furthermore, within the CTXs family, even though the most toxic compound (CTX-1B) has the highest affinity and the less toxic one (CTX-4B) the lowest affinity, a detailed analysis of the data pointed out a complex situation: (i) high affinity and toxicity seem to be related to the hydroxylation of the molecule on the A-ring rather than to the backbone type, (ii) acute toxicity in mice does not follow exactly the sodium-dependent cytotoxicity on neuroblastoma cells. These data suggest that the high toxicity of CTXs is related to sodium-dependent disturbances of the excitable membranes but might also involve other cellular mechanisms.
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Affiliation(s)
- M Y Dechraoui
- Institut de Recherches Médicales Louis Malardé, Papeete, Tahiti, French Polynesia
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36
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Meunier FA, Colasante C, Molgo J. Sodium-dependent increase in quantal secretion induced by brevetoxin-3 in Ca2+-free medium is associated with depletion of synaptic vesicles and swelling of motor nerve terminals in situ. Neuroscience 1997; 78:883-93. [PMID: 9153666 DOI: 10.1016/s0306-4522(96)00568-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Brevetoxin-3 at nanomolar concentrations markedly enhanced spontaneous quantal transmitter release from neuromuscular junctions equilibrated in a Ca2+-free EGTA medium. After about 3 h, the sustained increase in miniature endplate potential frequency led to an exhaustion of transmitter release. This increase still occurred after loading the nerve terminals with the Ca2+ chelator bis-(aminophenoxy)ethanetetra-acetate or after pretreatment with various pharmacological agents known to prevent Ca2+ release from intracellular pools, but was completely prevented by the Na+ channel blocker tetrodotoxin. Brevetoxin-3 also increased miniature endplate potential frequency from junctions treated with botulinum type-A toxin, but to a smaller extent than at normal junctions. At normal junctions, brevetoxin-3 exposure for 2 h increased the three-dimensional projected area of living motor nerve terminals in situ by about 74% while at botulinum type-A poisoned junctions a similar toxin exposure caused only a 29% increase. Tetrodotoxin prevented such effects, indicating that they are related to both Na+ entry into the terminals and increased quantal transmitter release. Ultrastructural examination of nerve terminals from junctions exposed for 3 h to brevetoxin-3 revealed profound depletions of clear and large dense core synaptic vesicles and an increase in coated vesicles and axolemma infoldings. These results indicate that brevetoxin-3 impairs the recycling of clear synaptic vesicles and are consistent with our immunofluorescent observations showing that synaptophysin epitopes can be revealed without nerve terminal permeabilization. In contrast, no such changes were detected in nerve terminals poisoned with botulinum type-A toxin which, after 3 h exposure to brevetoxin-3, retained their synaptic vesicles and had a normal appearance. We conclude that tetrodotoxin-sensitive Na+ entry into motor nerve terminals induced by brevetoxin-3 triggers external Ca2+-independent asynchronous quantal transmitter release, blocks synaptic vesicle recycling and induces swelling of the terminals. We suggest that an excess of cytoplasmic Na+ per se can activate the asynchronous neurotransmitter release process.
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Affiliation(s)
- F A Meunier
- Laboratoire de Neurobiologie Cellulaire et Moléculaire, Centre National de la Recherche Scientifique, Gif sur Yvette, France
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37
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Ciminiello P, Fattorusso E, Forino M, Magno S, Poletti R, Satake M, Viviani R, Yasumoto T. Yessotoxin in mussels of the northern Adriatic Sea. Toxicon 1997; 35:177-83. [PMID: 9080574 DOI: 10.1016/s0041-0101(96)00130-4] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This study investigated the composition of diarrhoetic shellfish toxins in the hepatopancreas of mussels from the northern Adriatic Sea. The major toxins were shown to be yessotoxin, identified by its chromatographic properties and spectral data, and okadaic acid, detected both by fluorometric high-performance liquid chromatography and by comparison of its spectral properties with those of an authentic sample.
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Affiliation(s)
- P Ciminiello
- Dipartimento di Chimica dell Sostanze Naturali, Università degli studi di Napoli, Federico II, Italy
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Cestèle S, Sampieri F, Rochat H, Gordon D. Tetrodotoxin reverses brevetoxin allosteric inhibition of scorpion alpha-toxin binding on rat brain sodium channels. J Biol Chem 1996; 271:18329-32. [PMID: 8702472 DOI: 10.1074/jbc.271.31.18329] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Voltage-sensitive sodium channels are responsible for the initiation of action potentials in many excitable cells. Several neurotoxins bind to distinct receptor sites on sodium channels and reveal strong allosteric interactions among them. Scorpion alpha toxins, which inhibit sodium channel inactivation by binding to receptor site 3, have been very important tools to study sodium channel structure and function. Recently, we have shown that brevetoxin induce a strong negative allosteric modulation on scorpion alpha-toxin binding on rat brain sodium channels, in contrast to previously published studies. In this report we have examined the reasons for this discrepancy and found new, unexpected allosteric interactions between the tetrodotoxin and brevetoxin receptor sites, using scorpion alpha-toxin as sensitive probe for subtle conformational changes on sodium channels. Tetrodotoxin reverses the negative modulation induced by brevetoxin on scorpion alpha-toxin binding, revealing new dynamic interactions in sodium channel structure.
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Affiliation(s)
- S Cestèle
- Laboratory of Biochemistry, CNRS URA 1455, Faculty of Medicine Nord, Jean Roche Institute, Boulevard Pierre Dramard, 13916 Marseille Cedex 20, France
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Benoit E, Juzans P, Legrand AM, Molgo J. Nodal swelling produced by ciguatoxin-induced selective activation of sodium channels in myelinated nerve fibers. Neuroscience 1996; 71:1121-31. [PMID: 8684616 DOI: 10.1016/0306-4522(95)00506-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Ciguatoxin-1b, the major toxin involved in ciguatera fish poisoning, and D-mannitol were examined on frog nodes of Ranvier using confocal laser scanning microscopy and conventional current- and voltage-clamp techniques. During the action of 10 nM ciguatoxin-1b, an increase in nodal volume was observed as determined by digital image processing and three-dimensional reconstruction of axons. The increase was prevented by blocking Na+ channels with tetrodotoxin. Ciguatoxin-1b (10 nM) induced high frequency action potential discharges up to 70-100 Hz. Analysis of Na+ current revealed that the toxin modified a current fraction which was activated at resting membrane potential and failed to inactivate. Increasing the osmolality of the external solution by about 50% with D-mannitol restored the nodal volume to its control value and suppressed spontaneous action potentials. In addition, D-mannitol affected unmodified and ciguatoxin-1b-treated Na+ currents in a similar manner causing a reduction of maximum conductance, negative shifts of current reversal potential and modification of the voltage-dependence of current activation and inactivation. In conclusion, ciguatoxin-1b induced a tetrodotoxin-sensitive swelling of nodes of Ranvier and selectively affected the Na+ current of myelinated axons. It is proposed that ciguatoxin-1b, by modifying Na+ current, increased intracellular Na+ concentration which caused water influx and nodal swelling. This may explain some of the reported symptoms of ciguatera fish poisoning. D-mannitol, an agent used for ciguatera treatment, was found to reverse the effects of ciguatoxin-1b by reducing Na+ entry and increasing the efflux of water through its osmotic action. It is the first time that osmotic changes produced by the selective activation of ionic channels, i.e. Na+ channels, are reported.
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Affiliation(s)
- E Benoit
- Laboratoire de Physiologie Cellulaire, E.R.S. C.N.R.S., Université de Paris Sud, Orsay, France
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Gawley RE, Rein KS, Jeglitsch G, Adams DJ, Theodorakis EA, Tiebes J, Nicolaou KC, Baden DG. The relationship of brevetoxin 'length' and A-ring functionality to binding and activity in neuronal sodium channels. CHEMISTRY & BIOLOGY 1995; 2:533-41. [PMID: 9383457 DOI: 10.1016/1074-5521(95)90187-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Brevetoxins are polyether ladder toxins that are ichthyotoxic at nanomolar concentrations. They bind to voltage-gated sodium channels, causing four distinct electrophysiological effects: (i) a shift of activation potential; (ii) occurrence of subconductance states; (iii) induction of longer mean open times of the channel; and (iv) inhibition of channel inactivation. We set out to determine whether these functions all require the same structural elements within the brevetoxin molecules. RESULTS Several synthetically prepared structural analogs of brevetoxin B were examined in synaptosome receptor binding assays and by functional electrophysiological measurements. A truncated analog is not ichthyotoxic at micromolar concentrations, shows decreased receptor-binding affinity, and causes only a shift of activation potential without affecting mean open times or channel inactivation. An analog with the A-ring carbonyl removed binds to the receptor with nanomolar affinity, produces a shift of activation potential and inhibits inactivation, but does not induce longer mean open times. An analog in which the A-ring diol is reduced shows low binding affinity, yet populates five subconductance states. CONCLUSIONS Our data are consistent with the hypothesis that binding to sodium channels requires an elongated cigar-shaped molecule, approximately 30 A long. The four electrophysiological effects of the brevetoxins are not produced by a single structural feature, however, since they can be decoupled by using modified ligands, which are shown here to be partial sodium channel agonists. We propose a detailed model for the binding of brevetoxins to the channel which explains the differences in the effects of the brevetoxin analogs. These studies also offer the potential for developing brevetoxin antagonists.
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Affiliation(s)
- R E Gawley
- Department of Chemistry, University of Miami, Coral Gables, FL 33124, USA
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Cestèle S, Ben Khalifa RB, Pelhate M, Rochat H, Gordon D. Alpha-scorpion toxins binding on rat brain and insect sodium channels reveal divergent allosteric modulations by brevetoxin and veratridine. J Biol Chem 1995; 270:15153-61. [PMID: 7797499 DOI: 10.1074/jbc.270.25.15153] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
At least six topologically separated neurotoxin receptor sites have been identified on sodium channels that reveal strong allosteric interactions among them. We have studied the allosteric modulation induced by veratridine, binding to receptor site 2, and brevetoxin PbTx-1, occupying receptor site 5, on the binding of alpha-scorpion toxins at receptor site 3, on three different neuronal sodium channels: rat brain, locust, and cockroach synaptosomes. We used 125I-AaH II, the most active alpha-scorpion toxin on vertebrates, and 125I-Lqh alpha IT, shown to have high activity on insects, as specific probes for receptor site 3 in rat brain and insect sodium channels. Our results reveal that brevetoxin PbTx-1 generates three types of effects at receptor site 3:1) negative allosteric modulation in rat brain sodium channels, 2) positive modulation in locust sodium channels, and 3) no effect on cockroach sodium channel. However, PbTx-1 activates sodium channels in cockroach axon similarly to its activity in other preparation. Veratridine positively modulates both rat brain and locust sodium channels but had no effect on alpha-toxin binding in cockroach. The dramatic differences in allosteric modulations in each sodium channel subtype suggest structural differences in receptor sites for PbTx-1 and/or at the coupling regions with alpha-scorpion toxin receptor sites in the different sodium channels, which can be detected by combined application of specific channel modifiers and may elucidate the dynamic gating activity and the mechanism of allosteric interactions among various neurotoxin receptors.
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Affiliation(s)
- S Cestèle
- Faculty of Medicine Nord, Institut Féderatif de Recherche Jean Roche, Laboratory of Biochemistry, URA CNRS 1455, Marseille, France
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Melinek R, Rein KS, Schultz DR, Baden DG. Brevetoxin PbTx-2 immunology: differential epitope recognition by antibodies from two goats. Toxicon 1994; 32:883-90. [PMID: 7527163 DOI: 10.1016/0041-0101(94)90367-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The epitopic regions of the brevetoxin PbTx-3 molecule, produced by the marine dinoflagellate Ptychodiscus brevis, have been identified by structural modification at three distinct regions of the toxin. These are: the A-ring lactone region of the molecule, the K-ring side-chain and the H-ring. The modified PbTx-3 derivatives were tested for their ability to bind brevetoxin goat antisera directed against the PbTx-3 molecule, by radioimmunoassay. The results showed that at least two major epitopes and one minor epitope are recognized: the A-ring lactone region of the molecule and the K-ring side-chain, and the H-ring. The results illustrate the variety of antibodies which may be produced, even within a species, and suggests that epitope characterization is important in the development of assays which are to be employed in seafood safety issues.
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Affiliation(s)
- R Melinek
- Marine and Freshwater Biomedical Sciences Center, University of Miami, FL 33149
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Baden DG, Rein KS, Gawley RE, Jeglitsch G, Adams DJ. Is the A-ring lactone of brevetoxin PbTx-3 required for sodium channel orphan receptor binding and activity? NATURAL TOXINS 1994; 2:212-21. [PMID: 7952946 DOI: 10.1002/nt.2620020410] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Brevetoxin PbTx-3 and non-toxic derivative 4 were investigated for their abilities to bind to the specific brevetoxin receptor site on rat brain synaptosomes and to modulate the normal function of voltage-gated sodium channels as determined by patch clamping of cultured neurons. Compounds 4 and 5 are produced from PbTx-3 by opening of the A-ring lactone to the saturated and unsaturated diols using sodium borohydride in ethanol. Natural PbTx-3 exhibited tighter binding to rat brain synaptosomes by at least 3 orders of magnitude as determined by competitive radioligand binding experiments, and was also more effective at activating voltage-gated channels. Patch clamping revealed the 3 orders of magnitude greater potency of PbTx-3 toxin over 5, although each produced delayed sodium channel opening and a pronounced delay in inactivation. Conformational modeling of the Brevetoxin B backbone indicates that the two molecules are identical except for the region of the A-Ring lactone. Thus, we conclude that the brevetoxin PbTx-3 backbone requires electrophilic functionality in the region of the lactone in PbTx-3, and that opening of the ring in 5 is sufficient to substantially reduce both binding and activity.
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Affiliation(s)
- D G Baden
- Marine and Freshwater Biomedical Sciences Center, RSMAS University of Miami, Florida
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Sasaki M, Hasegawa A, Tachibana K. Stereoselective synthesis of a KLM ring model of ciguatoxin: Confirmation of the C54 stereochemistry. Tetrahedron Lett 1993. [DOI: 10.1016/s0040-4039(00)61366-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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