Alkali Metal- and Acid-Catalyzed Interconversion of Goniodomin A with Congeners B and C


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Bernd.Krock [ at ] awi.de

Abstract

Goniodomin A (GDA, 1) is a phycotoxin produced by at least four species of Alexandrium dinoflagellates that are found globally in brackish estuaries and lagoons. It is a linear polyketide with six oxygen heterocyclic rings that is cyclized into a macrocyclic structure via lactone formation. Two of the oxygen heterocycles in 1 comprise a spiro-bis-pyran, whereas goniodomin B (GDB) contains a 2,7-dioxabicyclo[3.3.1]nonane ring system fused to a pyran. When H2O is present, 1 undergoes facile conversion to isomer GDB and to an α,β-unsaturated ketone, goniodomin C (GDC, 7). GDB and GDC can be formed from GDA by cleavage of the spiro-bis-pyran ring system. GDA, but not GDB or GDC, forms a crown ether-type complex with K+. Equilibration of GDA with GDB and GDC is observed in the presence of H+ and of Na+, but the equilibrated mixtures revert to GDA upon addition of K+. Structural differences have been found between the K+ and Na+ complexes. The association of GDA with K+ is strong, while that with Na+ is weak. The K+ complex has a compact, well-defined structure, whereas Na+ complexes are an ill-defined mixture of species. Analyses of in vitro A. monilatum and A. hiranoi cultures indicate that only GDA is present in the cells; GDB and GDC appear to be postharvest transformation products.



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Helmholtz Cross Cutting Activity (2021-2027)
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Peer-reviewed, Web of Science / Scopus
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Published
Eprint ID
55219
DOI 10.1021/acs.jnatprod.1c00586

Cite as
Harris, C. M. , Krock, B. , Tillmann, U. , Tainter, C. J. , Stec, D. F. , Andersen, A. J. C. , Larsen, T. O. , Reece, K. S. and Harris, T. M. (2021): Alkali Metal- and Acid-Catalyzed Interconversion of Goniodomin A with Congeners B and C , Journal of Natural Products, 84 (9), pp. 2554-2567 . doi: 10.1021/acs.jnatprod.1c00586


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