Structure of Caribbean Ciguatoxin Isolated from Caranx latus

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• 作者：Richard J. Lewis ; Jean-Paul Vernoux ; and Ian M. Brereton
• 刊名：Journal of the American Chemical Society
• 出版年：1998
• 出版时间：June 24, 1998
• 年：1998
• 卷：120
• 期：24
• 页码：5914 - 5920
• 全文大小：171K
• 年卷期：v.120,no.24(June 24, 1998)
• ISSN：1520-5126

文摘

Caribbean ciguatoxins (C-CTXs) are responsible for thewidespread occurrence of ciguatera in theCaribbean Sea. The structure and configuration of C-CTX-1(1), the major ciguatoxin isolated from thehorse-eye jack (Caranx latus), has been determined from DQF-COSY,E-COSY, TOCSY, NOESY, ROESY, ge-HSQC, and HMQC experiments performed at 750 MHz and 500 MHz on a 0.13mages/entities/mgr.gif">mol sample. C-CTX-1 ([M+ H]⁺ m/z 1141.6 Da, molecularformula C₆₂H₉₂O₁₉) has aciguatoxin/brevetoxin ladder structure comprising14 trans-fused, ether-linked rings (7/6/6/7/8/9/7/6/8/6/7/6/7/6)assembled from 6 protonated fragments. Therelative stereochemistry and ring configuration of 1 wasdetermined from an analysis of coupling constant andNOE data. Like ciguatoxins in the Pacific Ocean (P-CTX), C-CTX-1possesses a flexible nine-memberedring which may be a conserved feature among ciguatoxins. However,C-CTX-1 has a longer contiguous carbonbackbone (57 vs 55 carbons for P-CTX-1), one extra ring, and ahemiketal in ring N but no spiroketal asfound in P-CTX. C-CTX-1 possesses a primary hydroxyl which mayallow selective derivatization. A minoranalogue, C-CTX-2, was also isolated from fish and assigned thestructure 56 epi-C-CTX-1 (2), since it slowlyrearranged to C-CTX-1 in solution. Given the structuralsimilarities between Caribbean and Pacific ciguatoxins,we propose that C-CTX-1 and C-CTX-2 arise from a Caribbean strain ofthe benthic dinoflagellate,Gambierdiscus toxicus.