Publication Date:
2021-05-19
Description:
Five new hydantoin alkaloids, named parazoanthines A-E (1-5), were isolated as the major constituents
of the Mediterranean sea anemone Parazoanthus axinellae. Their structural elucidation was achieved
through NMR spectroscopic and mass spectrometric analyses. The absolute configuration of the chiral
compounds 1 and 4 was determined by comparison between experimental and TDDFT calculated CD
spectra. The configuration of the trisubstituted double bond of 2, 3, and 5 was deduced from the 3JH6-C4
coupling constant value. This family of alkaloids represents the first example of natural 3,5-
disubstituted hydantoins which do not exhibit a methyl at N-3. All compounds were tested for their
natural toxicity (Microtox® assay) and parazoanthine C (3) exhibited the highest natural toxicity.
3
Relatively few chemical studies of zoanthids have been reported so far, despite evidence of their rich
natural products chemistry.1 Colonial sea anemones of the genus Parazoanthus have been identified in
almost all the oceans and they often have been described as epibionts of marine sponges belonging to
the Agelas or Axinella genera. As sponges are known to exude toxic compounds, these zoanthids must
have developed adaptative tools to minimize effects of such toxins. Two groups of compounds have
been described from Parazoanthus species: fluorescent guanidine alkaloids of the zoanthoxanthin
families,2-7 and ecdysteroids.8 As part of an ongoing research program to investigate the chemodiversity
of Mediterranean invertebrates,9 specimens of Parazoanthus axinellae were collected near Marseilles
(Plane island) as epibionts of the sponge Axinella damicornis. Because the LC–MS analyses of their
crude extracts evidenced brominated compounds as major constituents, we decided to undertake the full
chemical study of this species from which only zoanthoxanthins have been previously described.2,3 We
report herein the isolation and structural characterization of a new class of alkaloids named
parazoanthines A-E (1-5) with a rare 3,5-disubstituted hydantoin core.
Description:
Published
Description:
sea anemones, Parazoanthus, structure elucidation, stereochemistry
Keywords:
Alkaloids
;
Alkaloids
Repository Name:
AquaDocs
Type:
Journal Contribution
