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Xiao JX, Li FX, Ren SJ, Qu J. Studies on the Biomimetic Synthesis of Marine Ladder Polyethers via Endo-Selective Epoxide-to-Epoxonium Ring-Opening Cascades. Angew Chem Int Ed Engl 2024; 63:e202403597. [PMID: 38752455 DOI: 10.1002/anie.202403597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Indexed: 07/16/2024]
Abstract
Marine ladder polyethers have attracted the attention of chemists and biologists because of their potent biological activities. Synthetic chemists have attempted to construct their polyether frameworks by epoxide ring-opening cascades, as Nakanishi hypothesis describes. However, Baldwin's rules of ring closure state that exo-selective intramolecular cyclization of epoxy alcohols is preferred over endo-selective cyclization. Herein, we investigated epoxide ring-opening cascades of polyepoxy alcohols in [EMIM]BF4/PFTB (1-ethyl-3-methylimidazolium tetrafluoroborate /perfluoro-tert-butyl alcohol) and found that all-endo products were formed via epoxide-to-epoxonium ring-opening cyclizations (not restricted by Baldwin's rules, which only apply to intramolecular hydroxyl-to-epoxide cyclizations). We determined that the key factor enabling polyepoxy alcohols to undergo a high proportion of all-endo-selective cyclization was inhibition of exo-selective hydroxyl-to-epoxide cyclization starting from the terminal hydroxyl group of a polyepoxy alcohol. By introducing a slow-release protecting group to the terminal hydroxyl group, we could markedly increase the cyclization yields of polyether fragments with hydrogen atoms at the ring junctions. For the first time, we constructed consecutively fused six-membered-ring and fused seven-, eight-, and nine-membered-ring polyether fragments by epoxide-to-epoxonium ring-opening cyclizations through the addition of a suitable Lewis acid. We also suggest that the biosynthesis of marine ladder polyethers may proceed via epoxide-to-epoxonium ring-opening cyclization of polyepoxide.
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Affiliation(s)
- Jia-Xi Xiao
- College of Chemistry, Nankai University, The State Key Laboratory and Institute of Elemento-Organic Chemistry, Tianjin, 300071, China
| | - Feng-Xing Li
- College of Chemistry, Nankai University, The State Key Laboratory and Institute of Elemento-Organic Chemistry, Tianjin, 300071, China
| | - Shu-Jian Ren
- College of Chemistry, Nankai University, The State Key Laboratory and Institute of Elemento-Organic Chemistry, Tianjin, 300071, China
| | - Jin Qu
- College of Chemistry, Nankai University, The State Key Laboratory and Institute of Elemento-Organic Chemistry, Tianjin, 300071, China
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2
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Finol-Urdaneta RK, Zhorov BS, Baden DG, Adams DJ. Brevetoxin versus Brevenal Modulation of Human Nav1 Channels. Mar Drugs 2023; 21:396. [PMID: 37504927 PMCID: PMC10382042 DOI: 10.3390/md21070396] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/04/2023] [Accepted: 07/05/2023] [Indexed: 07/29/2023] Open
Abstract
Brevetoxins (PbTx) and brevenal are marine ladder-frame polyethers. PbTx binds to and activates voltage-gated sodium (Nav) channels in native tissues, whereas brevenal antagonizes these actions. However, the effects of PbTx and brevenal on recombinant Nav channel function have not been systematically analyzed. In this study, the PbTx-3 and brevenal modulation of tissue-representative Nav channel subtypes Nav1.2, Nav1.4, Nav1.5, and Nav1.7 were examined using automated patch-clamp. While PbTx-3 and brevenal elicit concentration-dependent and subtype-specific modulatory effects, PbTx-3 is >1000-fold more potent than brevenal. Consistent with effects observed in native tissues, Nav1.2 and Nav1.4 channels were PbTx-3- and brevenal-sensitive, whereas Nav1.5 and Nav1.7 appeared resistant. Interestingly, the incorporation of brevenal in the intracellular solution caused Nav channels to become less sensitive to PbTx-3 actions. Furthermore, we generated a computational model of PbTx-2 bound to the lipid-exposed side of the interface between domains I and IV of Nav1.2. Our results are consistent with competitive antagonism between brevetoxins and brevenal, setting a basis for future mutational analyses of Nav channels' interaction with brevetoxins and brevenal. Our findings provide valuable insights into the functional modulation of Nav channels by brevetoxins and brevenal, which may have implications for the development of new Nav channel modulators with potential therapeutic applications.
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Affiliation(s)
- Rocio K Finol-Urdaneta
- Illawarra Health & Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Boris S Zhorov
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223 Saint Petersburg, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
| | - Daniel G Baden
- Center for Marine Science, University of North Carolina Wilmington MARBIONC, Wilmington, NC 28409, USA
| | - David J Adams
- Illawarra Health & Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia
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3
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Fuwa H. Synthesis-Driven Stereochemical Assignment of Marine Polycyclic Ether Natural Products. Mar Drugs 2021; 19:257. [PMID: 33947080 PMCID: PMC8145320 DOI: 10.3390/md19050257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 01/11/2023] Open
Abstract
Marine polycyclic ether natural products have gained significant interest from the chemical community due to their impressively huge molecular architecture and diverse biological functions. The structure assignment of this class of extraordinarily complex natural products has mainly relied on NMR spectroscopic analysis. However, NMR spectroscopic analysis has its own limitations, including configurational assignment of stereogenic centers within conformationally flexible systems. Chemical shift deviation analysis of synthetic model compounds is a reliable means to assign the relative configuration of "difficult" stereogenic centers. The complete configurational assignment must be ultimately established through total synthesis. The aim of this review is to summarize the indispensable role of organic synthesis in stereochemical assignment of marine polycyclic ethers.
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Affiliation(s)
- Haruhiko Fuwa
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan
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L’Herondelle K, Talagas M, Mignen O, Misery L, Le Garrec R. Neurological Disturbances of Ciguatera Poisoning: Clinical Features and Pathophysiological Basis. Cells 2020; 9:E2291. [PMID: 33066435 PMCID: PMC7602189 DOI: 10.3390/cells9102291] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/07/2020] [Accepted: 10/12/2020] [Indexed: 12/12/2022] Open
Abstract
Ciguatera fish poisoning (CFP), the most prevalent seafood poisoning worldwide, is caused by the consumption of tropical and subtropical fish contaminated with potent neurotoxins called ciguatoxins (CTXs). Ciguatera is a complex clinical syndrome in which peripheral neurological signs predominate in the acute phase of the intoxication but also persist or reoccur long afterward. Their recognition is of particular importance in establishing the diagnosis, which is clinically-based and can be a challenge for physicians unfamiliar with CFP. To date, no specific treatment exists. Physiopathologically, the primary targets of CTXs are well identified, as are the secondary events that may contribute to CFP symptomatology. This review describes the clinical features, focusing on the sensory disturbances, and then reports on the neuronal targets and effects of CTXs, as well as the neurophysiological and histological studies that have contributed to existing knowledge of CFP neuropathophysiology at the molecular, neurocellular and nerve levels.
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Affiliation(s)
- Killian L’Herondelle
- University of Brest, School of Medicine, Laboratoire Interactions Epithéliums-Neurones (Univ Brest, LIEN), F-29200 Brest, France; (K.L.); (M.T.); (L.M.)
| | - Matthieu Talagas
- University of Brest, School of Medicine, Laboratoire Interactions Epithéliums-Neurones (Univ Brest, LIEN), F-29200 Brest, France; (K.L.); (M.T.); (L.M.)
- Department of Dermatology, University Hospital of Brest, F-29200 Brest, France
| | - Olivier Mignen
- University of Brest, School of Medicine, INSERM U1227, Lymphocytes B et auto-immunité, F-29200 Brest, France;
| | - Laurent Misery
- University of Brest, School of Medicine, Laboratoire Interactions Epithéliums-Neurones (Univ Brest, LIEN), F-29200 Brest, France; (K.L.); (M.T.); (L.M.)
- Department of Dermatology, University Hospital of Brest, F-29200 Brest, France
| | - Raphaele Le Garrec
- University of Brest, School of Medicine, Laboratoire Interactions Epithéliums-Neurones (Univ Brest, LIEN), F-29200 Brest, France; (K.L.); (M.T.); (L.M.)
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Li FX, Ren SJ, Li PF, Yang P, Qu J. An Endo-Selective Epoxide-Opening Cascade for the Fast Assembly of the Polycyclic Core Structure of Marine Ladder Polyethers. Angew Chem Int Ed Engl 2020; 59:18473-18478. [PMID: 32666578 DOI: 10.1002/anie.202007980] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Indexed: 12/13/2022]
Abstract
The rapid synthesis of marine ladder polyethers from polyepoxide precursors (in analogy with the biosynthetic pathway hypothesized by Nakanishi) is hampered by the fact that the exo-selective epoxide-opening cyclization cascade that gives THF-type polyethers is preferred over the endo-selective cascade that gives the desired products. We found that perfluoro-tert-butanol (PFTB) cooperating with 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF4 ) can promote endo-selective epoxide-opening cyclization reactions of trisubstituted epoxy alcohols. Starting from readily accessible homochiral polyepoxy alcohols with a methyl group at all the endo-cyclization sites, we were able to construct polyethers up to five consecutive fused 6-, 7-, and/or 8-membered rings in one step. Notably, molecules with the 7/7/6/6 and 7/7/6/7/6 polyether frameworks of hemibrevetoxin B and brevenal, respectively, could be synthesized in 40 % and 17 % chemical yields.
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Affiliation(s)
- Feng-Xing Li
- The State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Shu-Jian Ren
- The State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Pei-Fang Li
- The State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Peng Yang
- The State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
| | - Jin Qu
- The State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin, 300071, China
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6
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Li F, Ren S, Li P, Yang P, Qu J. An
Endo
‐Selective Epoxide‐Opening Cascade for the Fast Assembly of the Polycyclic Core Structure of Marine Ladder Polyethers. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202007980] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Feng‐Xing Li
- The State Key Laboratory and Institute of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Shu‐Jian Ren
- The State Key Laboratory and Institute of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Pei‐Fang Li
- The State Key Laboratory and Institute of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Peng Yang
- The State Key Laboratory and Institute of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
| | - Jin Qu
- The State Key Laboratory and Institute of Elemento-Organic Chemistry College of Chemistry Nankai University Tianjin 300071 China
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Assunção J, Guedes AC, Malcata FX. Biotechnological and Pharmacological Applications of Biotoxins and Other Bioactive Molecules from Dinoflagellates. Mar Drugs 2017; 15:E393. [PMID: 29261163 PMCID: PMC5742853 DOI: 10.3390/md15120393] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/12/2017] [Accepted: 12/15/2017] [Indexed: 12/26/2022] Open
Abstract
The long-lasting interest in bioactive molecules (namely toxins) produced by (microalga) dinoflagellates has risen in recent years. Exhibiting wide diversity and complexity, said compounds are well-recognized for their biological features, with great potential for use as pharmaceutical therapies and biological research probes. Unfortunately, provision of those compounds is still far from sufficient, especially in view of an increasing demand for preclinical testing. Despite the difficulties to establish dinoflagellate cultures and obtain reasonable productivities of such compounds, intensive research has permitted a number of advances in the field. This paper accordingly reviews the characteristics of some of the most important biotoxins (and other bioactive substances) produced by dinoflagellates. It also presents and discusses (to some length) the main advances pertaining to dinoflagellate production, from bench to large scale-with an emphasis on material published since the latest review available on the subject. Such advances encompass improvements in nutrient formulation and light supply as major operational conditions; they have permitted adaptation of classical designs, and aided the development of novel configurations for dinoflagellate growth-even though shearing-related issues remain a major challenge.
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Affiliation(s)
- Joana Assunção
- LEPABE-Laboratory of Process Engineering, Environment, Biotechnology and Energy, Rua Dr. Roberto Frias, s/n, P-4200-465 Porto, Portugal.
| | - A Catarina Guedes
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, Terminal de Cruzeiros do Porto de Leixões, Avenida General Norton de Matos, s/n, P-4450-208 Matosinhos, Portugal.
| | - F Xavier Malcata
- LEPABE-Laboratory of Process Engineering, Environment, Biotechnology and Energy, Rua Dr. Roberto Frias, s/n, P-4200-465 Porto, Portugal.
- Department of Chemical Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, P-4200-465 Porto, Portugal.
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Ciguatoxins Evoke Potent CGRP Release by Activation of Voltage-Gated Sodium Channel Subtypes Na V1.9, Na V1.7 and Na V1.1. Mar Drugs 2017; 15:md15090269. [PMID: 28867800 PMCID: PMC5618408 DOI: 10.3390/md15090269] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/04/2017] [Accepted: 08/16/2017] [Indexed: 02/03/2023] Open
Abstract
Ciguatoxins (CTXs) are marine toxins that cause ciguatera fish poisoning, a debilitating disease dominated by sensory and neurological disturbances that include cold allodynia and various painful symptoms as well as long-lasting pruritus. Although CTXs are known as the most potent mammalian sodium channel activator toxins, the etiology of many of its neurosensory symptoms remains unresolved. We recently described that local application of 1 nM Pacific Ciguatoxin-1 (P-CTX-1) into the skin of human subjects induces a long-lasting, painful axon reflex flare and that CTXs are particularly effective in releasing calcitonin-gene related peptide (CGRP) from nerve terminals. In this study, we used mouse and rat skin preparations and enzyme-linked immunosorbent assays (ELISA) to study the molecular mechanism by which P-CTX-1 induces CGRP release. We show that P-CTX-1 induces CGRP release more effectively in mouse as compared to rat skin, exhibiting EC50 concentrations in the low nanomolar range. P-CTX-1-induced CGRP release from skin is dependent on extracellular calcium and sodium, but independent from the activation of various thermosensory transient receptor potential (TRP) ion channels. In contrast, lidocaine and tetrodotoxin (TTX) reduce CGRP release by 53–75%, with the remaining fraction involving L-type and T-type voltage-gated calcium channels (VGCC). Using transgenic mice, we revealed that the TTX-resistant voltage-gated sodium channel (VGSC) NaV1.9, but not NaV1.8 or NaV1.7 alone and the combined activation of the TTX-sensitive VGSC subtypes NaV1.7 and NaV1.1 carry the largest part of the P-CTX-1-caused CGRP release of 42% and 34%, respectively. Given the contribution of CGRP to nociceptive and itch sensing pathways, our findings contribute to a better understanding of sensory symptoms of acute and chronic ciguatera that may help in the identification of potential therapeutics.
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9
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Shmukler YB, Nikishin DA. Ladder-Shaped Ion Channel Ligands: Current State of Knowledge. Mar Drugs 2017; 15:E232. [PMID: 28726749 PMCID: PMC5532674 DOI: 10.3390/md15070232] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 07/07/2017] [Accepted: 07/14/2017] [Indexed: 12/20/2022] Open
Abstract
Ciguatoxins (CTX) and brevetoxins (BTX) are polycyclic ethereal compounds biosynthesized by the worldwide distributed planktonic and epibenthic dinoflagellates of Gambierdiscus and Karenia genera, correspondingly. Ciguatera, evoked by CTXs, is a type of ichthyosarcotoxism, which involves a variety of gastrointestinal and neurological symptoms, while BTXs cause so-called neurotoxic shellfish poisoning. Both types of toxins are reviewed together because of similar mechanisms of their action. These are the only molecules known to activate voltage-sensitive Na⁺-channels in mammals through a specific interaction with site 5 of its α-subunit and may compete for it, which results in an increase in neuronal excitability, neurotransmitter release and impairment of synaptic vesicle recycling. Most marine ciguatoxins potentiate Nav channels, but a considerable number of them, such as gambierol and maitotoxin, have been shown to affect another ion channel. Although the extrinsic function of these toxins is probably associated with the function of a feeding deterrent, it was suggested that their intrinsic function is coupled with the regulation of photosynthesis via light-harvesting complex II and thioredoxin. Antagonistic effects of BTXs and brevenal may provide evidence of their participation as positive and negative regulators of this mechanism.
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Affiliation(s)
- Yuri B Shmukler
- Group of Embryophysiology, N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26, Vavilov st, 119334 Moscow, Russia.
| | - Denis A Nikishin
- Group of Embryophysiology, N.K. Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 26, Vavilov st, 119334 Moscow, Russia.
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10
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Le Garrec R, L'herondelle K, Le Gall-Ianotto C, Lebonvallet N, Leschiera R, Buhe V, Talagas M, Vetter I, Lewis RJ, Misery L. Release of neuropeptides from a neuro-cutaneous co-culture model: A novel in vitro model for studying sensory effects of ciguatoxins. Toxicon 2016; 116:4-10. [DOI: 10.1016/j.toxicon.2015.11.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 10/24/2015] [Accepted: 11/04/2015] [Indexed: 12/17/2022]
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The voltage-gated sodium channel: a major target of marine neurotoxins. Toxicon 2014; 91:84-95. [PMID: 25305552 DOI: 10.1016/j.toxicon.2014.09.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 09/18/2014] [Accepted: 09/30/2014] [Indexed: 12/16/2022]
Abstract
Voltage-gated sodium channels (Nav) are key components for nerve excitability. They initiate and propagate the action potential in excitable cells, throughout the central and peripheral nervous system, thus enabling a variety of physiological functions to be achieved. The rising phase of the action potential is driven by the opening of Nav channels which activate rapidly and carry Na(+) ions in the intracellular medium, and ends with the Na(+) current inactivation. The biophysical properties of these channels have been elucidated, through the use of pharmacological agents that disrupt the molecular mechanism of the channel functioning. Among them, marine toxins produced by venomous animals or microorganisms have been crucial to map the different allosteric binding sites of the channels, understand their mode of action and represent an emerging source of therapeutic agents to alleviate or cure Na(+) channels-linked human diseases. In this article, we review recent discoveries on the molecular and biophysical properties of the Na(+) channel as a target for marine neurotoxins, and present the ongoing developments of pharmacological agents as therapeutic tools.
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12
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Structure activity relationship of brevenal hydrazide derivatives. Mar Drugs 2014; 12:1839-58. [PMID: 24686558 PMCID: PMC4012454 DOI: 10.3390/md12041839] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 03/10/2014] [Accepted: 03/12/2014] [Indexed: 11/17/2022] Open
Abstract
Brevenal is a ladder frame polyether produced by the dinoflagellate Karenia brevis. This organism is also responsible for the production of the neurotoxic compounds known as brevetoxins. Ingestion or inhalation of the brevetoxins leads to adverse effects such as gastrointestinal maladies and bronchoconstriction. Brevenal shows antagonistic behavior to the brevetoxins and shows beneficial attributes when administered alone. For example, in an asthmatic sheep model, brevenal has been shown to increase tracheal mucosal velocity, an attribute which has led to its development as a potential treatment for Cystic Fibrosis. The mechanism of action of brevenal is poorly understood and the exact binding site has not been elucidated. In an attempt to further understand the mechanism of action of brevenal and potentially develop a second generation drug candidate, a series of brevenal derivatives were prepared through modification of the aldehyde moiety. These derivatives include aliphatic, aromatic and heteroaromatic hydrazide derivatives. The brevenal derivatives were tested using in vitro synaptosome binding assays to determine the ability of the compounds to displace brevetoxin and brevenal from their native receptors. A sheep inhalation model was used to determine if instillation of the brevenal derivatives resulted in bronchoconstriction. Only small modifications were tolerated, with larger moieties leading to loss of affinity for the brevenal receptor and bronchoconstriction in the sheep model.
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13
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Braidy N, Matin A, Rossi F, Chinain M, Laurent D, Guillemin GJ. Neuroprotective effects of rosmarinic acid on ciguatoxin in primary human neurons. Neurotox Res 2014; 25:226-34. [PMID: 24097334 DOI: 10.1007/s12640-013-9429-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/19/2013] [Accepted: 09/25/2013] [Indexed: 10/26/2022]
Abstract
Ciguatoxin (CTX), is a toxic compound produced by microalgae (dinoflagellate) Gambierdiscus spp., and is bio-accumulated and bio-transformed through the marine food chain causing neurological deficits. To determine the mechanism of CTX-mediated cytotoxicity in human neurons, we measured extracellular lactate dehydrogenase (LDH) activity, intracellular levels of nicotinamide adenine dinucleotide (NAD(+)) and H2AX phosphorylation at serine 139 as a measure for DNA damage in primary cultures of human neurons treated with Pacific (P)-CTX-1B and P-CTX-3C. We found these marine toxins can induce a time and dose-dependent increase in extracellular LDH activity, with a concomitant decline in intracellular NAD(+) levels and increased DNA damage at the concentration range of 5-200 nM. We also showed that pre- and post-treatment with rosmarinic acid (RA), the active constituent of the Heliotropium foertherianum (Boraginaceae) can attenuate CTX-mediated neurotoxicity. These results further highlight the potential of RA in the treatment of CTX-induced neurological deficits.
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Affiliation(s)
- N Braidy
- Centre for Healthy Brain Ageing, School of Psychiatry, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia,
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Stewart I, Lewis RJ, Eaglesham GK, Graham GC, Poole S, Craig SB. Emerging tropical diseases in Australia. Part 2. Ciguatera fish poisoning. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2013; 104:557-71. [DOI: 10.1179/136485910x12851868779902] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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15
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Gold EP, Jacocks HM, Bourdelais AJ, Baden DG. Brevenal, a brevetoxin antagonist from Karenia brevis, binds to a previously unreported site on mammalian sodium channels. HARMFUL ALGAE 2013; 26:12-19. [PMID: 23789024 PMCID: PMC3684244 DOI: 10.1016/j.hal.2013.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Brevetoxins are a family of ladder-frame polyether toxins produced by the marine dinoflagellate Karenia brevis. During blooms of K. brevis, inhalation of brevetoxins aerosolized by wind and wave action can lead to asthma-like symptoms in persons at the beach. Consumption of either shellfish or finfish contaminated by K. brevis blooms can lead to the development of neurotoxic shellfish poisoning. The toxic effects of brevetoxins are due to binding at a defined site on, and subsequent activation of, voltage-sensitive sodium channels (VSSCs) in cell membranes (site 5). In addition to brevetoxins, K. brevis produces several other ladder-frame compounds. One of these compounds, brevenal, has been shown to antagonize the effects of brevetoxin. In an effort to further characterize to effects of brevenal, a radioactive analog ([3H]-brevenol) was produced by reducing the side-chain terminal aldehyde moiety of brevenal to an alcohol using tritiated sodium borohydride. A KD of 67 nM and Bmax of 7.1 pmol/mg protein were obtained for [3H]-brevenol in rat brain synaptosomes, suggesting a 1:1 matching with VSSCs. Brevenal and brevenol competed for [3H]-brevenol binding with Ki values of 75 nM and 56 nM, respectively. However, although both brevenal and brevenol can inhibit brevetoxin binding, brevetoxin was completely ineffective at competition for [3H]-brevenol binding. After examining other site-specific compounds, it was determined that [3H]-brevenol binds to a site that is distinct from the other known sites including the brevetoxin site (site 5) although some interaction with site 5 is apparent.
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Affiliation(s)
- Elena P. Gold
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409
| | - Henry M. Jacocks
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409
| | - Andrea J. Bourdelais
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409
| | - Daniel G. Baden
- Center for Marine Science, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409
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16
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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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17
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Abstract
Chemical compounds participate in all the processes of life. Understanding the complex interactions of small molecules such as metabolites and drugs and the biological macromolecules that consume and produce them is key to gaining a wider understanding in a systemic context. Chemical property databases collect information on the biological effects and physicochemical properties of chemical entities. Accessing and using such databases is key to understanding the chemistry of toxic molecules. In this chapter, we present methods to search, understand, download, and manipulate the wealth of information available in public chemical property databases, with particular focus on the database of Chemical Entities of Biological Interest (ChEBI).
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PIETRA FRANCESCO. COMPUTER SIMULATIONS OF THE INTERACTION OF CIGUATOXIN 3C, BREVENAL AND ent-BREVENAL LADDER POLYETHERS WITH A HOMOLOGY MODEL OF THE VOLTAGE-GATED Kv1.5 POTASSIUM CHANNEL. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2011. [DOI: 10.1142/s021963360900526x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The interaction of ladder polyethers of marine origin, like ciguatoxin 3C and brevenal, as well as hypothetic ent-brevenal, with the human voltage-gated Kv1.5 potassium ion channel is investigated in this work using homology modeling, automated docking, and energy scoring from molecular dynamics (MD) simulations. A 3D homology model of the pore region of the Kv1.5 channel, previously developed from the 2.9 Å resolution crystal structure of the mammalian Kv1.2 channel — which has a very similar pore sequence — is used here. While ciguatoxin 3C did not enter the pore, both brevenal and ent-brevenal were found into the pore, the latter one with the best score. Binding is attended by notable strain in the ligands, and the corresponding energy increase was evaluated for ent-brevenal by self consistent field (SCF) and density functional theory (DFT) procedures. Egress of ent-brevenal from the pore, as a microscopical reversal of the ingress, was investigated by a smart form of biased MD simulations. While this study indicates ample room and attractive interactions for both brevenal and its enantiomer into the pore, whether these molecules will be found to inhibit voltage-gated potassium ion currents depends upon the barriers in the real system to access the pore, with their thermodynamic and kinetic requirements.
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Affiliation(s)
- FRANCESCO PIETRA
- Accademia Lucchese di Scienze, Lettere e Arti, Palazzo Ducale, 55100 Lucca, Italy
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Ebine M, Fuwa H, Sasaki M. Total synthesis of (-)-brevenal: a streamlined strategy for practical synthesis of polycyclic ethers. Chemistry 2011; 17:13754-61. [PMID: 22052481 DOI: 10.1002/chem.201101437] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 08/08/2011] [Indexed: 11/09/2022]
Abstract
We describe a streamlined strategy for the practical synthesis of trans-fused polycyclic ethers and its application to a concise total synthesis of (-)-brevenal, a new pentacyclic polyether natural product with intriguing biological activities. The B-, D-, and E-rings were constructed by TEMPO/PhI(OAc)(2)-mediated oxidative lactonization of the corresponding 1,6-diols, with minimal need for manipulation of oxygen functionalities. The B- and E-ring lactones were appropriately functionalized by Suzuki-Miyaura coupling of lactone-derived enol phosphates and subsequent stereoselective hydroboration. The A-ring was formed by our mixed thioacetalization methodology. The AB- and DE-ring fragments were assembled through Suzuki-Miyaura coupling, and the C-ring was forged in the same manner as that for the A-ring. More than two grams of the pentacyclic polyether core of (-)-brevenal have been synthesized by the synthetic route developed in this study.
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Affiliation(s)
- Makoto Ebine
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
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20
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Toxicokinetics of the ciguatoxin P-CTX-1 in rats after intraperitoneal or oral administration. Toxicology 2011; 284:1-6. [DOI: 10.1016/j.tox.2011.02.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 02/08/2011] [Accepted: 02/15/2011] [Indexed: 11/20/2022]
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21
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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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22
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Fleming LE, Kirkpatrick B, Backer LC, Walsh CJ, Nierenberg K, Clark J, Reich A, Hollenbeck J, Benson J, Cheng YS, Naar J, Pierce R, Bourdelais AJ, Abraham WM, Kirkpatrick G, Zaias J, Wanner A, Mendes E, Shalat S, Hoagland P, Stephan W, Bean J, Watkins S, Clarke T, Byrne M, Baden DG. Review of Florida Red Tide and Human Health Effects. HARMFUL ALGAE 2011; 10:224-233. [PMID: 21218152 PMCID: PMC3014608 DOI: 10.1016/j.hal.2010.08.006] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This paper reviews the literature describing research performed over the past decade on the known and possible exposures and human health effects associated with Florida red tides. These harmful algal blooms are caused by the dinoflagellate, Karenia brevis, and similar organisms, all of which produce a suite of natural toxins known as brevetoxins. Florida red tide research has benefited from a consistently funded, long term research program, that has allowed an interdisciplinary team of researchers to focus their attention on this specific environmental issue-one that is critically important to Gulf of Mexico and other coastal communities. This long-term interdisciplinary approach has allowed the team to engage the local community, identify measures to protect public health, take emerging technologies into the field, forge advances in natural products chemistry, and develop a valuable pharmaceutical product. The Review includes a brief discussion of the Florida red tide organisms and their toxins, and then focuses on the effects of these toxins on animals and humans, including how these effects predict what we might expect to see in exposed people.
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Affiliation(s)
- Lora E Fleming
- NSF NIEHS Oceans and Human Health Center, University of Miami, 4600 Rickenbacker Causeway, Miami, FL, 33149
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23
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Fuwa H, Ebine M, Sasaki M. Recent Applications of the Suzuki-Miyaura Cross-coupling to Complex Polycyclic Ether Synthesis. J SYN ORG CHEM JPN 2011. [DOI: 10.5059/yukigoseikyokaishi.69.1251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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24
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Fuwa H. Total Synthesis of Structurally Complex Marine Oxacyclic Natural Products. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2010. [DOI: 10.1246/bcsj.20100209] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Dual action of a dinoflagellate-derived precursor of Pacific ciguatoxins (P-CTX-4B) on voltage-dependent K+ and Na+ channels of single myelinated axons. Toxicon 2010; 56:768-75. [DOI: 10.1016/j.toxicon.2009.06.035] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2009] [Revised: 06/28/2009] [Accepted: 06/29/2009] [Indexed: 11/21/2022]
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Nguyen-Huu TD, Mattei C, Wen PJ, Bourdelais AJ, Lewis RJ, Benoit E, Baden DG, Molgó J, Meunier FA. Ciguatoxin-induced catecholamine secretion in bovine chromaffin cells: Mechanism of action and reversible inhibition by brevenal. Toxicon 2010; 56:792-6. [DOI: 10.1016/j.toxicon.2009.08.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2009] [Revised: 08/05/2009] [Accepted: 08/05/2009] [Indexed: 11/24/2022]
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Ryan JC, Morey JS, Bottein MYD, Ramsdell JS, Van Dolah FM. Gene expression profiling in brain of mice exposed to the marine neurotoxin ciguatoxin reveals an acute anti-inflammatory, neuroprotective response. BMC Neurosci 2010; 11:107. [PMID: 20796285 PMCID: PMC2939656 DOI: 10.1186/1471-2202-11-107] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Accepted: 08/26/2010] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Ciguatoxins (CTXs) are polyether marine neurotoxins and potent activators of voltage-gated sodium channels. This toxin is carried by multiple reef-fish species and human consumption of ciguatoxins can result in an explosive gastrointestinal/neurologic illness. This study characterizes the global transcriptional response in mouse brain to a symptomatic dose of the highly toxic Pacific ciguatoxin P-CTX-1 and additionally compares this data to transcriptional profiles from liver and whole blood examined previously. Adult male C57/BL6 mice were injected with 0.26 ng/g P-CTX-1 while controls received only vehicle. Animals were sacrificed at 1, 4 and 24 hrs and transcriptional profiling was performed on brain RNA with Agilent whole genome microarrays. RT-PCR was used to independently validate gene expression and the web tool DAVID was used to analyze gene ontology (GO) and molecular pathway enrichment of the gene expression data. RESULTS A pronounced 4°C hypothermic response was recorded in these mice, reaching a minimum at 1 hr and lasting for 8 hrs post toxin exposure. Ratio expression data were filtered by intensity, fold change and p-value, with the resulting data used for time course analysis, K-means clustering, ontology classification and KEGG pathway enrichment. Top GO hits for this gene set included acute phase response and mono-oxygenase activity. Molecular pathway analysis showed enrichment for complement/coagulation cascades and metabolism of xenobiotics. Many immediate early genes such as Fos, Jun and Early Growth Response isoforms were down-regulated although others associated with stress such as glucocorticoid responsive genes were up-regulated. Real time PCR confirmation was performed on 22 differentially expressed genes with a correlation of 0.9 (Spearman's Rho, p < 0.0001) with microarray results. CONCLUSIONS Many of the genes differentially expressed in this study, in parallel with the hypothermia, figure prominently in protection against neuroinflammation. Pathologic activity of the complement/coagulation cascade has been shown in patients suffering from a chronic form of ciguatera poisoning and is of particular interest in this model. Anti-inflammatory processes were at work not only in the brain but were also seen in whole blood and liver of these animals, creating a systemic anti-inflammatory environment to protect against the initial cellular damage caused by the toxin.
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Affiliation(s)
- James C Ryan
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC, USA
| | - Jeanine S Morey
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC, USA
| | | | - John S Ramsdell
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC, USA
| | - Frances M Van Dolah
- Marine Biotoxins Program, NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC, USA
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Caillaud A, de la Iglesia P, Darius HT, Pauillac S, Aligizaki K, Fraga S, Chinain M, Diogène J. Update on methodologies available for ciguatoxin determination: perspectives to confront the onset of ciguatera fish poisoning in Europe. Mar Drugs 2010; 8:1838-907. [PMID: 20631873 PMCID: PMC2901828 DOI: 10.3390/md8061838] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 05/18/2010] [Accepted: 06/10/2010] [Indexed: 11/29/2022] Open
Abstract
Ciguatera fish poisoning (CFP) occurs mainly when humans ingest finfish contaminated with ciguatoxins (CTXs). The complexity and variability of such toxins have made it difficult to develop reliable methods to routinely monitor CFP with specificity and sensitivity. This review aims to describe the methodologies available for CTX detection, including those based on the toxicological, biochemical, chemical, and pharmaceutical properties of CTXs. Selecting any of these methodological approaches for routine monitoring of ciguatera may be dependent upon the applicability of the method. However, identifying a reference validation method for CTXs is a critical and urgent issue, and is dependent upon the availability of certified CTX standards and the coordinated action of laboratories. Reports of CFP cases in European hospitals have been described in several countries, and are mostly due to travel to CFP endemic areas. Additionally, the recent detection of the CTX-producing tropical genus Gambierdiscus in the eastern Atlantic Ocean of the northern hemisphere and in the Mediterranean Sea, as well as the confirmation of CFP in the Canary Islands and possibly in Madeira, constitute other reasons to study the onset of CFP in Europe [1]. The question of the possible contribution of climate change to the distribution of toxin-producing microalgae and ciguateric fish is raised. The impact of ciguatera onset on European Union (EU) policies will be discussed with respect to EU regulations on marine toxins in seafood. Critical analysis and availability of methodologies for CTX determination is required for a rapid response to suspected CFP cases and to conduct sound CFP risk analysis.
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Affiliation(s)
- Amandine Caillaud
- IRTA, Ctra. Poble Nou, Km 5,5. 43540 Sant Carles de la Ràpita, Spain; E-Mails: (A.C.); (P.I.)
| | - Pablo de la Iglesia
- IRTA, Ctra. Poble Nou, Km 5,5. 43540 Sant Carles de la Ràpita, Spain; E-Mails: (A.C.); (P.I.)
| | - H. Taiana Darius
- Laboratoire des micro-algues toxiques, Institut Louis Malardé, BP30, 98713 Papeete Tahiti, French Polynesia; E-Mails: (H.T.D.); (M.C.)
| | - Serge Pauillac
- Institut Pasteur, 25-28 rue du docteur Roux, 75 015 Paris, France; E-Mail: (S.P.)
| | - Katerina Aligizaki
- Department of Botany, School of Biology, Faculty of Sciences, Aristotle University, 54 124 Thessaloniki, Greece; E-Mail: (K.A.)
| | - Santiago Fraga
- Instituto Español de Oceanografía, Subida a Radio Faro, 50, 36390 Vigo, Spain; E-Mail: (S.F.)
| | - Mireille Chinain
- Laboratoire des micro-algues toxiques, Institut Louis Malardé, BP30, 98713 Papeete Tahiti, French Polynesia; E-Mails: (H.T.D.); (M.C.)
| | - Jorge Diogène
- IRTA, Ctra. Poble Nou, Km 5,5. 43540 Sant Carles de la Ràpita, Spain; E-Mails: (A.C.); (P.I.)
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Phycotoxins: chemistry, mechanisms of action and shellfish poisoning. EXPERIENTIA SUPPLEMENTUM 2010; 100:65-122. [PMID: 20358682 DOI: 10.1007/978-3-7643-8338-1_3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Mattei C, Marquais M, Schlumberger S, Molgó J, Vernoux JP, Lewis RJ, Benoit E. Analysis of Caribbean ciguatoxin-1 effects on frog myelinated axons and the neuromuscular junction. Toxicon 2009; 56:759-67. [PMID: 19646468 DOI: 10.1016/j.toxicon.2009.07.026] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 07/22/2009] [Accepted: 07/23/2009] [Indexed: 10/20/2022]
Abstract
Caribbean ciguatoxin-1 (C-CTX-1) induced, after about 1h exposure, muscle membrane depolarisation and repetitive post-synaptic action potentials (APs) in frog neuromuscular preparations. This depolarising effect was also observed in a Ca(2+)-free medium with a strong enhancement of spontaneous quantal transmitter release, compared with control conditions. The ciguatoxin-induced increase in release could be accelerated when Ca(2+) was present in the extracellular medium. C-CTX-1 also enhanced nerve-evoked quantal acetylcholine (ACh) release. At normal neuromuscular junctions loaded with the fluorescent dye FM1-43, C-CTX-1 induced swelling of nerve terminals, an effect that was reversed by hyperosmotic d-mannitol. In myelinated axons, C-CTX-1 increased nodal membrane excitability, inducing spontaneous and repetitive APs. Also, the toxin enlarged the repolarising phase of APs in control and tetraethylammonium-treated axons. Overall, our data suggest that C-CTX-1 affects nerve excitability and neurotransmitter release at nerve terminals. We conclude that C-CTX-1-induced up-regulation of Na(+) channels and the inhibition of K(+) channels, at low nanomolar concentrations, produce a variety of functional dysfunctions that are in part responsible for the human muscle skeletal symptoms observed in ciguatera. All these dysfunctions seem to result from the subtle balance between ionic currents, intracellular Na(+) and Ca(2+) concentrations, and engaged second messengers.
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Affiliation(s)
- César Mattei
- CNRS, Institut de Neurobiologie Alfred Fessard - FRC2118, Laboratoire de Neurobiologie Cellulaire et Moléculaire - UPR9040, bât. 32-33, F-91198 Gif sur Yvette, France
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Marine Toxins Potently Affecting Neurotransmitter Release. MARINE TOXINS AS RESEARCH TOOLS 2009; 46:159-86. [DOI: 10.1007/978-3-540-87895-7_6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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