Identification of Novel Gymnodimines and Spirolides from the Marine Dinoflagellate Alexandrium ostenfeldii


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tilmann.harder [ at ] awi.de

Abstract

Cyclic imine toxins are neurotoxic, macrocyclic compounds produced by marine dinoflagellates. Mass spectrometric screenings of extracts from natural plankton assemblages revealed a high chemical diversity among this toxin class, yet only few toxins are structurally known. Here we report the structural characterization of four novel cyclic-imine toxins (two gymnodimines (GYMs) and two spirolides (SPXs)) from cultures of Alexandrium ostenfeldii. A GYM with m/z 510 (1) was identified as 16-desmethylGYM D. A GYM with m/z 526 was identified as the hydroxylated degradation product of (1) with an exocyclic methylene at C-17 and an allylic hydroxyl group at C-18. This compound was named GYM E (2). We further identified a SPX with m/z 694 as 20-hydroxy-13,19-didesmethylSPX C (10) and a SPX with m/z 696 as 20-hydroxy-13,19-didesmethylSPX D (11). This is the first report of GYMs without a methyl group at ring D and SPXs with hydroxyl groups at position C-20. These compounds can be conceived as derivatives of the same nascent polyketide chain, supporting the hypothesis that GYMs and SPXs are produced through common biosynthetic genes. Both novel GYMs 1 and 2 were detected in significant amounts in extracts from natural plankton assemblages (1: 447 pg; 2: 1250 pg; 11: 40 pg per mL filtered seawater respectively).



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ISI/Scopus peer-reviewed
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Published
Eprint ID
48532
DOI 10.3390/md16110446

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Zurhelle, C. , Nieva, J. , Tillmann, U. , Harder, T. , Krock, B. and Tebben, J. (2018): Identification of Novel Gymnodimines and Spirolides from the Marine Dinoflagellate Alexandrium ostenfeldii , Marine Drugs, 16 (11), p. 446 . doi: 10.3390/md16110446


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