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Open AccessArticle

Chemiluminescent Receptor Binding Assay for Ciguatoxins and Brevetoxins Using Acridinium Brevetoxin-B2

1
Faculty of Pharmacy, Kindai University, Higashiosaka 577-8502, Japan
2
Japan Food Research Laboratories, Tama Laboratory, Nagayama 6-11-10, Tama 206-0025, Japan
*
Author to whom correspondence should be addressed.
Toxins 2019, 11(10), 580; https://doi.org/10.3390/toxins11100580
Received: 5 August 2019 / Revised: 30 September 2019 / Accepted: 1 October 2019 / Published: 9 October 2019
(This article belongs to the Special Issue Marine Toxins Detection)
Ciguatera is the term for poisoning resulting from eating fish from tropical or subtropical regions. The causative toxins collectively named ciguatoxins (CTXs) widely differ in structures depending on their geographic origins, which range from the Pacific Ocean and the Indian Ocean to the Caribbean Sea. Neurotoxic shellfish poisoning (NSP) is caused by the ingestion of bivalve shellfish contaminated with brevetoxins (BTXs). Structurally, both CTXs and BTXs consist of fused ether rings aligned in a ladder shape. Pharmacologically, they bind at the same site (site-5) of voltage-gated sodium channels. However, the great structural diversity and the rare availability of reference toxins hinder LC-MS and ELISA methods, which operate on structure-based recognition. In this study, we prepared a chemiluminescent ligand, acridinium BTXB2 (ABTX), and tested its suitability for use in competitive binding assays to detect CTXs and BTXs. The affinity of ABTX to the rat brain synaptosome estimated by Ki (1.66 pM) was approximately two-fold higher than that of PbTx-3 (BTX3). In addition, the equilibrium dissociation constant (KD) was 0.84 nM, the maximum number of binding was 6.76 pmol toxin/mg protein, and the detection limit was 1.4 amol. The assays performed on samples spiked with CTX3C or BTXB4 (N-palmitoylBTXB2) at 0.2–1.0 ng CTX/g fish flesh, and 200–800 ng BTXB4/g shellfish showed a linear relationship between the theoretical and observed toxin amounts. View Full-Text
Keywords: ciguatera; ciguatoxins; neurotoxic shellfish poisoning; brevetoxins; acridinium ligand; chemiluminescent binding assay; synaptosome ciguatera; ciguatoxins; neurotoxic shellfish poisoning; brevetoxins; acridinium ligand; chemiluminescent binding assay; synaptosome
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MDPI and ACS Style

Murata, K.; Yasumoto, T. Chemiluminescent Receptor Binding Assay for Ciguatoxins and Brevetoxins Using Acridinium Brevetoxin-B2. Toxins 2019, 11, 580.

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