First Identification of 5,11-Dideoxytetrodotoxin in Marine Animals, and Characterization of Major Fragment Ions of Tetrodotoxin and Its Analogs by High Resolution ESI-MS/MS

Yotsu‐Yamashita, Mari; Abe, Yuka; Kudo, Yuta; Ritson‐Williams, Raphael; Paul, Valerie J.; Konoki, Keiichi; Cho, Yuko; Adachi, Masaatsu; Imazu, Takuya; Nishikawa, Toshio; Isobe, Mitsuaki

doi:10.3390/md11082799

Cited by 99 publications

(137 citation statements)

References 48 publications

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“…6). The structure assignment of these analogs can be verified as well by the relative eluting sequence of Amide column as reported by Yotsu-Yamashita et al [27], Rodriguez et al [31], and Kudo et al [50]. Two peaks were found for the transitions m/z 290→162 and m/z 290→272.…”

Section: Detection Of Ttx and Its Analogs In Cooked Seafoodmentioning

confidence: 73%

“…The peak with the transitions m/z 336→162 and m/z 336→318 could be mono-oxoTTX. Although 11-oxoTTX was reported in marine animals [27,31,50], the eluting sequence of this peak was different. 11-oxoTTX was eluted after TTX while the peak in this study was eluted before TTX.…”

Section: Detection Of Ttx and Its Analogs In Cooked Seafoodmentioning

confidence: 89%

“…The peak with the transitions m/z 304→162 and m/z 304→286 may be the mono-deoxyTTX. Although three analogs with 5-deoxyTTX, 6-deoxyTTX, and 11-deoxyTTX were reported by Kudo et al [50], this peak could be 11-deoxyTTX because the retention time was near to those of 4,9-anhydroTTX and 11-norTTX-6(R)-ol [27,31]. Two peaks were found for the transitions m/z 320→162 and m/z 320→302.…”

Section: Detection Of Ttx and Its Analogs In Cooked Seafoodmentioning

confidence: 98%

“…Yotsu-Yamashita et al used a high-resolution MS/MS to identify 5,11-dideoxyTTX and characterize the major fragment ions of TTX analogs in marine animals [27]. Kudo et al applied the single transition of [M+H] + →162 to screen and 1 H NMR and 13 C NMR to identify 8-epi-5,6,11-trideoxyTTX, 4,9-anhydro-8-epi-5,6,11-trideoxyTTX, 1-hydroxy-8-epi-5,6,11-trideoxyTTX, and 1-hydroxy-4,4a-anhydro-8-epi-5,6,11-trideoxyTTX from the newt, Cynops ensicauda popei [16].…”

Section: Detection Of Ttx and Its Analogs In Cooked Seafoodmentioning

confidence: 99%

“…The experimental methods used for the analysis of TTX include LC with a fluorescent detector (FLD) and postcolumn derivatization [23][24][25][26], and LC-MS/MS [3,11,13,[27][28][29][30]. TTX analogs can also be simultaneously screened by both techniques [18,31].…”

Section: Introductionmentioning

confidence: 99%

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Study of the matrix effects of tetrodotoxin and its content in cooked seafood by liquid chromatography with triple quadrupole mass spectrometry

Yu²,

Lü³

et al. 2015

J. Sep. Science

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Tetrodotoxin is a marine biotoxin with high acute toxicity. The levels in cooked seafood will help us to assess its intake in humans and may help assess the risk of toxicity. However, heavy matrices hinder the direct quantitation of tetrodotoxin. A quantitative method of measuring tetrodotoxin in cooked seafood using liquid chromatography with triple quadrupole mass spectrometry was established in this study. Tetrodotoxin was extracted from the sample matrix using 2% formic acid in methanol and cleaned using a cation exchange cartridge. The cleanup conditions were optimized. The matrix effects were determined using the postextraction spiking method and by comparing the slope of the linear regression equation in sample matrix to that in solvent. The limit of detection in the sample matrix was 5 μg/kg and the limit of quantification was 10 μg/kg. The mean recoveries at three spiking levels were 66.9-89.2% with relative standard deviations of 5.0-10.8% (n = 6) in five different matrices. Tetrodotoxin was found at concentrations of 26.1-2462 μg/kg in nine of 83 cooked seafoods tested in this study. Eight analogs of Tetrodotoxin were detected in the samples studied.

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Section: Detection Of Ttx and Its Analogs In Cooked Seafoodmentioning

confidence: 73%

Section: Detection Of Ttx and Its Analogs In Cooked Seafoodmentioning

confidence: 89%

Section: Detection Of Ttx and Its Analogs In Cooked Seafoodmentioning

confidence: 98%

Section: Detection Of Ttx and Its Analogs In Cooked Seafoodmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Study of the matrix effects of tetrodotoxin and its content in cooked seafood by liquid chromatography with triple quadrupole mass spectrometry

Yu²,

Lü³

et al. 2015

J. Sep. Science

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C5–C10 Directly Bonded Tetrodotoxin Analogues: Possible Biosynthetic Precursors of Tetrodotoxin From Newts

Kudo¹,

Yamashita²,

Mebs³

et al. 2014

Angewandte Chemie

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The identification of novel tetrodotoxin (TTX, 1) analogues would significantly contribute to the elucidation of its biosynthetic pathway. In this study, the first C5–C10 directly bonded TTX analogues, 4,9‐anhydro‐10‐hemiketal‐5‐deoxyTTX (2) and 4,9‐anhydro‐8‐epi‐10‐hemiketal‐5,6,11‐trideoxyTTX (3), were found in the newt Cynops ensicauda popei by using a screening method involving HILIC‐LC–MS/MS focused on the fragment ions of TTX analogues, and their structures were elucidated by spectroscopic methods. Compound 2 was detected in a wide range of newt species, and the 2 and TTX contents of 22 newt specimens were correlated (rs=0.88). Based on these results and its structural features, 2 was predicted to serve as a precursor of TTX that would be directly converted into 4,9‐anhydroTTX (4) by Baeyer–Villiger‐like oxidation or via 4,9‐anhydro‐5‐deoxyTTX formed by cleavage of the C5–C10 bond. The bicyclic carbon skeletons of 2 and 3 suggested a possible monoterpene origin for TTX.

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Cyclic Guanidine Compounds from Toxic Newts Support the Hypothesis that Tetrodotoxin is Derived from a Monoterpene

et al. 2016

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The biosynthesis of tetrodotoxin (TTX), a potent neurotoxin consisting of a 2,4-dioxaadamantane skeleton and a guanidine moiety, is an unsolved problem in natural product chemistry. Recently, the first C5-C10 directly bonded TTX analogue, 4,9-anhydro-10-hemiketal-5-deoxyTTX, was obtained from toxic newts and its carbon skeleton suggested a possible monoterpene origin. On the basis of this hypothesis, screening of predicted biosynthetic intermediates of TTX was performed using two MS-guided methods. Herein, five novel cyclic guanidine compounds from toxic newts are reported which commonly contain a cis-fused bicyclic structure including a six-membered cyclic guanidine. These structures could be biosynthetically derived from geranyl guanidine through oxidation, cyclization, and/or isomerization steps. LC-MS analysis confirmed the widespread distribution of the five novel compounds in toxic newt species. These results support the hypothesis that TTX is derived from a monoterpene.Tetrodotoxin (TTX; 1),[1] a potent and selective blocker of voltage-gated sodium ion channels, [2] causes fatal pufferfish poisoning. A recent study also advised caution with regards to low concentrations of TTX contamination in bivalve mollusks from some areas of Europe.[3] This molecule is still attracting the interest of pharmacologists and synthetic chemists.[4] TTX is distributed among various marine (such as pufferfish and snails) [5] and terrestrial (newts, frogs, and toads) [6] animals. In spite of the high interest in this unique toxin, its biosynthetic pathway is still unknown. Although toxic marine animals are considered to accumulate TTX produced by several species of bacteria, [7] bacterial gene clusters corresponding to TTX biosynthesis have not been elucidated thus far. In several studies, problems involving the isolation and cultivation of TTX-producing bacteria have been reported.[8] The debate on the internal or external origin of TTX in toxic terrestrial animals still continues, [9] but recently, no significant production of TTX or of its analogues have been observed in captivereared newts. [10] Feeding experiments performed in toxic newts by Shimizu and Kobayashi [11] resulted in no incorporation of potential TTX precursors. Although biosynthetic pathways of some natural toxins that contain guanidine group(s) have been elucidated, [12] the actual biosynthesis of TTX is still a matter of speculation.In an attempt to obtain clues for the biosynthesis of TTX, we [13] and Kotaki and Shimizu [14] identified several TTX analogues and predicted arginine and a C5 unit (isoprene or sugar) as precursors. However, we recently discovered the first C5-C10 directly bonded TTX analogue, named 4,9-anhydro-10-hemiketal-5-deoxyTTX (2), which is widely distributed among toxic newt species.[15] Based on its chemical structure (2), which consists of a guanidine and a C10 unit, we hypothesized that a monoterpene (geranyl pyrophosphate) is a precursor of TTX in terrestrial animals (Figure 1). [15] On the basis of this proposed pat...

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First Identification of 5,11-Dideoxytetrodotoxin in Marine Animals, and Characterization of Major Fragment Ions of Tetrodotoxin and Its Analogs by High Resolution ESI-MS/MS

Cited by 99 publications

References 48 publications

Study of the matrix effects of tetrodotoxin and its content in cooked seafood by liquid chromatography with triple quadrupole mass spectrometry

Study of the matrix effects of tetrodotoxin and its content in cooked seafood by liquid chromatography with triple quadrupole mass spectrometry

C5–C10 Directly Bonded Tetrodotoxin Analogues: Possible Biosynthetic Precursors of Tetrodotoxin From Newts

Cyclic Guanidine Compounds from Toxic Newts Support the Hypothesis that Tetrodotoxin is Derived from a Monoterpene

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