Identification of Novel Gymnodimines and Spirolides from the Marine Dinoflagellate Alexandrium ostenfeldii
AbstractCyclic 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). View Full-Text
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Description: The following are available online at www.mdpi.com/xxx/s1, Figure S1: Structures of known and novel gymnodimines; Figure S2: Structures of known and novel spirolides; Figure S4-S22 NMR-spectra of 1; Figure S23: CD-spectra of 1 and 4 and simulated CD spectra of 1, S24-S31 NMR-spectra of 2; Figure S32-S53 NMR-spectra of 10; Figure S54-S62 NMR-spectra of 11; Table S1: Mass transitions of spiroimines included in LC-MS/MS analysis; Figure S63: LC-MS/MS chromatogram of station SL92-2. Raw NMR data (Topspin) and annotated Mestre files are available in the data repository PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.895116 .
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Zurhelle, C.; Nieva, J.; Tillmann, U.; Harder, T.; Krock, B.; Tebben, J. Identification of Novel Gymnodimines and Spirolides from the Marine Dinoflagellate Alexandrium ostenfeldii. Mar. Drugs 2018, 16, 446.
Zurhelle C, Nieva J, Tillmann U, Harder T, Krock B, Tebben J. Identification of Novel Gymnodimines and Spirolides from the Marine Dinoflagellate Alexandrium ostenfeldii. Marine Drugs. 2018; 16(11):446.Chicago/Turabian Style
Zurhelle, Christian; Nieva, Joyce; Tillmann, Urban; Harder, Tilmann; Krock, Bernd; Tebben, Jan. 2018. "Identification of Novel Gymnodimines and Spirolides from the Marine Dinoflagellate Alexandrium ostenfeldii." Mar. Drugs 16, no. 11: 446.
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