Terajima Takehito, Uchida Hideaki, Abe Naoki, Yasumoto Takeshi
a Department of Food and Nutrition Science, Graduate School of Agriculture , Tokyo University of Agriculture , Setagaya , Tokyo , Japan.
b Japan Customer Service Operation , Agilent Technologies Japan, Ltd , Hachioji, Tokyo , Japan.
Biosci Biotechnol Biochem. 2019 Mar;83(3):381-390. doi: 10.1080/09168451.2018.1550356. Epub 2018 Nov 26.
Palytoxin analogs are marine toxins with large complex polyol structures. A benthic dinoflagellate Ostreopsis siamensis produces more than ten palytoxins (ostreocins, OSTs). The limited sample availability of minor OSTs restricts the definition of their chemical structures. The present investigation characterizes structures of two minor OSTs, i.e., ostreocin-A (OSTA) and ostreocin-E1 (OSTE1), using ostreocin-D (OSTD) as a reference compound, by liquid chromatography/quadrupole-time-of-flight mass spectrometry. The molecular formulas of OSTA and OSTE1 were CHNO and CHNO, respectively. Compared to OSTD, OSTA has an extra oxygen atom whereas OSTE1 lacks one oxygen atom and two hydrogen atoms. The MS/MS experiments (precursor ions: [M + H] and [M-H]) suggested a hydroxyl substitution at C82 in OSTA and alteration(s) between C53 and C100 in OSTE1. Further analysis of structural details in OSTE1 was performed through a pseudo-MS experiment (precursor ion: m/z 1432.748). Accordingly, the planar structures of OSTA and OSTE1 were assigned to 42,82-dihydroxy-3,26-didemethyl-19,44-dideoxypalytoxin and 42-hydroxy-3,26-didemethyl-19,44,73-trideoxypalytoxin-72-ene, respectively. Abbreviations:CID: collision induced dissociation; HR-LC/MS/MS: high-resolution liquid chromatography/tandem mass spectrometry; LC/ESI/Q-TOF MS: liquid chromatography/quadrupole time-of-flight mass spectrometry equipped with an electrospray ionization source; NMR: nuclear magnetic resonance; OSTs: ostreocins; OSTA: ostreocin-A; OSTB: ostreocin-B; OSTD: ostreocin-D; OSTE1: ostreocin-E1; OVTX-a: ovatoxin-a; OVTXs: ovatoxins; PLTX: palytoxin.
岩沙海葵毒素类似物是具有大型复杂多元醇结构的海洋毒素。一种底栖甲藻——暹罗裸甲藻能产生十多种岩沙海葵毒素（ostreocins，OSTs）。次要OSTs的样本可用性有限，限制了其化学结构的确定。本研究以岩沙海葵毒素-D（OSTD）作为参考化合物，通过液相色谱/四极杆-飞行时间质谱法对两种次要OSTs，即岩沙海葵毒素-A（OSTA）和岩沙海葵毒素-E1（OSTE1）的结构进行了表征。OSTA和OSTE1的分子式分别为C₁₂₉H₂₀₃N₃O₅₄和C₁₂₉H₂₀₁N₃O₅₂。与OSTD相比，OSTA多一个氧原子，而OSTE1少一个氧原子和两个氢原子。MS/MS实验（前体离子：[M + H]⁺和[M - H]⁻）表明，OSTA中C82处有羟基取代，OSTE1中C53和C100之间有变化。通过伪MS实验（前体离子：m/z 1432.748）对OSTE1的结构细节进行了进一步分析。据此，OSTA和OSTE1的平面结构分别被确定为42,82-二羟基-3,26-二去甲基-19,44-二脱氧岩沙海葵毒素和42-羟基-3,26-二去甲基-19,44,73-三脱氧岩沙海葵毒素-72-烯。缩写：CID：碰撞诱导解离；HR-LC/MS/MS：高分辨率液相色谱/串联质谱；LC/ESI/Q-TOF MS：配备电喷雾电离源的液相色谱/四极杆飞行时间质谱；NMR：核磁共振；OSTs：岩沙海葵毒素；OSTA：岩沙海葵毒素-A；OSTB：岩沙海葵毒素-B；OSTD：岩沙海葵毒素-D；OSTE1：岩沙海葵毒素-E1；OVTX-a：卵毒素-a；OVTXs：卵毒素；PLTX：岩沙海葵毒素
