LC-HRMS and Chemical Derivatization Strategies for the Structure Elucidation of Caribbean Ciguatoxins: Identification of C-CTX-3 and-4

Kryuchkov, Fedor; Robertson, Alison; Miles, Christopher O.; Mudge, Elizabeth M.; Uhlig, Silvio

doi:10.3390/md18040182

i

LC-HRMS and Chemical Derivatization Strategies for the Structure Elucidation of Caribbean Ciguatoxins: Identification of C-CTX-3 and-4

2020
By Kryuchkov, Fedor ; Robertson, Alison ; Miles, Christopher O. ; ...

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Journal Title:

Marine Drugs
Personal Author:

Kryuchkov, Fedor ; Robertson, Alison ; Miles, Christopher O. ; Mudge, Elizabeth M. ; Uhlig, Silvio
NOAA Program & Office:

NOS (National Ocean Service)
Description:

Ciguatera poisoning is linked to the ingestion of seafood that is contaminated with ciguatoxins (CTXs). The structural variability of these polyether toxins in nature remains poorly understood due to the low concentrations present even in highly toxic fish, which makes isolation and chemical characterization difficult. We studied the mass spectrometric fragmentation of Caribbean CTXs, i.e., the epimers C-CTX-1 and -2 (1 and 2), using a sensitive UHPLC–HRMS/MS approach in order to identify product ions of diagnostic value. We found that the fragmentation of the ladder-frame backbone follows a characteristic pattern and propose a generalized nomenclature for the ions formed. These data were applied to the structural characterization of a pair of so far poorly characterized isomers, C-CTX-3 and -4 (3 and 4), which we found to be reduced at C-56 relative to 1 and 2. Furthermore, we tested and applied reduction and oxidation reactions, monitored by LC–HRMS, in order to confirm the structures of 3 and 4. Reduction of 1 and 2 with NaBH4 afforded 3 and 4, thereby unambiguously confirming the identities of 3 and 4. In summary, this work provides a foundation for mass spectrometry-based characterization of new C-CTXs, including a suite of simple chemical reactions to assist the examination of structural modifications.
Keywords:

Coral Reef Fishes Fish Stock Assessment Native Fishes Coral Reef Fishes Fish Stock Assessment Native Fishes ciguatera; ciguatoxin; HRMS; Gambierdiscus; polyether toxin; LC–MS; fragmentation pathways; ladder-frame molecule; Scomberomorus cavalla; Sphyraena barracuda
Source:

Marine Drugs, 18(4) 1-14
DOI:

https://doi.org/10.3390/md18040182
Pubmed Central ID:

PMC7230550
Document Type:

Journal Article
Funding:

Grant no. NA11NOS4780028 ; Grant no. ECO17-35
Place as Subject:

Hawaii ; Pacific Ocean
Rights Information:

CC BY
Compliance:

Submitted
Main Document Checksum:

urn:sha256:d61b52477812d5ee3dca0f8de2c85ef9b1eb6ee56e355bb26833acaa6bdd51b8
Download URL:

https://repository.library.noaa.gov/view/noaa/28818/noaa_28818_DS1.pdf
File Type:

[PDF - 2.41 MB ]

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