Structural elucidation of ciguatoxin congeners by fast-atom bombardment tandem mass spectroscopy
Structural elucidation of ciguatoxin congeners by fast-atom bombardment tandem mass spectroscopy
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DOI：
10.1021/ja9944204
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发表时间：
2000-05-24
影响因子：
15
通讯作者：
Naoki, H
中科院分区：
文献类型：
--
作者：
Yasumoto, T;Igarashi, T;Naoki, H
许多热带鱼种在摄入后可能会引起一种被称为雪卡特拉的中毒。1致病毒素来源于一种附生甲藻冈比亚毒素，通过食草性鱼类进入食物链。从毒藻中分离得到CTX4A、2 CTX4B、3和CTX3C4毒素，并对其结构进行了鉴定。这些甲藻毒素在鱼类中发生变化，产生主要毒素雪卡毒素(CTX)、1、3、5和一些同系物。由于很难获得足够的材料进行核磁共振研究，许多同系物仍未确定。最近，从毒藻和法属波利尼西亚采集的三种鱼中分离出了50个有毒组分。6尽管我们尽了最大努力，许多馏分仍然是微克级的混合物。多年来，我们利用快原子轰击串联质谱仪(FAB/MS/MS)，结合核磁共振技术，对聚醚类化合物进行了结构研究：如：玉米毒素、8a毒素、8b短杆菌毒素B2至B4、8c、d、e和阿司匹酸。位于分子末端附近的离子电荷促进了高能(8千伏)碰撞激活引起的电荷远程碎裂。9虽然CTX同系物没有电荷基团，但我们发现它们的Na-加合离子可以提供类似的信息。当需要进一步支持结构分配时，我们制备了2-磺基苯甲酸酯。为了确定螺环碳的构型，我们采用了酸催化
Many tropical species of fish when ingested may cause an intoxication known as ciguatera. 1 The causative toxins originate in an epiphytic dinoflagellate Gambierdiscus toxicus and enter the food chain via herbivorous to carnivorous fish. Toxins labeled as CTX4A, 2 CTX4B, 3 and CTX3C4 were isolated from G. toxicus and their structures elucidated. These dinoflagellate toxins undergo changes in the fish, yielding the principal toxin, ciguatoxin (CTX), 1, 3, 5 and a number of congeners. Many of the congeners remained unidentified because of the extreme difficulty in obtaining enough material for NMR studies. Recently, 50 toxic fractions were isolated from G. toxicus and from three species of fish collected in French Polynesia. 6 Despite our best effort, many of the fractions remained mixtures in microgram amounts. We undertook structural elucidation with these small and impure samples by new strategies.For years we have used fast-atom bombardment tandem mass spectrometry (FAB/MS/MS), 7 in combination with NMR, for structural studies of polyether compounds: eg, yessotoxin, 8a maitotoxin, 8b brevetoxins B2 through B4, 8c, d, e and azaspiracid. 8f An ionic charge located near the termini of the molecules facilitated charge-remote fragmentations induced by high-energy (8 kV) collision activation. 9 Though CTX congeners possess no charge group, we found that their Na-adduct ions could provide comparable information. When further support for structural assignment was needed, we prepared 2-sulfobenzoates. 10 To assign the configuration of spiro carbons, we followed acid-catalyzed