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An untargeted metabolomics approach was used to investigate a cultured strain of Microcystis aeruginosa (UTEX LB2386) known to be a prolific producer of a diverse class of cyanopeptides. Identification of a putative new compound with a molecular weight of 996 led to the purification and structure elucidation of this new member of the micropeptin class of cyanopeptides. Micropeptin 996 displayed potent inhibition of the serine protease enzyme chymotrypisin relative to structurally related members of this class.

Chemical investigation of a cultured strain of Microcystis aeruginosa revealed the presence of three new microginin analogs, microginins 680, 646, and 612. While nearly all other previously reported microginins possess the unusual 3-amino-2-hydroxydecanoic (Ahda) acyl moiety, these new compounds are members of an extremely rare sub-class containing the β-amino acid residue 3-amino-2-hydroxy-octanoic acid (Ahoa). Additionally, microginins 680 and 646 (di-chloro and mono-chloro, respectively) represent the first halogenated examples of the Ahoa group in a natural product.

The novel gymnodimine congener 12-methylgymnodimine was isolated from the dinoflagellate Alexandrium peruvianum from the New River in North Carolina. In addition, the presence of 13-desmethylspirolide C was confirmed by NMR characterization. This marks the first time these two classes of cyclic imines have been found in the same organism, providing further evidence for a direct genetic relationship between the biosynthetic pathways for gymnodimines and spirolides suggested by comparison of their structures.

Synthesis of the BC/DE ring model of brevisin, a polycyclic ether isolated from the red tide dinoflagellate Karenia brevis, is reported. Comparison of the NMR data of the BC/DE ring model with those corresponding to the same region of brevisin led to the confirmation of its structure around the acyclic juncture.

A monocyclic ether alkaloid, brevisamide ( 1 ) was isolated from the dinoflagellate Karenia brevis that produces a variety of ladder-frame polyethers. Its proposed biosynthetic intermediate ( 2 ) comprising a linear backbone with an E -olefin functionality was synthesized for biosynthetic studies on the marine ladder-frame polyethers.

Hoffmaniolide, a novel macrolide, was isolated and identified from the marine dinoflagellate Prorocentrum hoffmannianum .

Two new spirolide derivatives, E and F, have been isolated in low yield from shellfish extracts. Absence of activity in the mouse bioassay of these derivatives, and of the secondary amine reduction product of spirolide B, identifies the spirolide pharmacophore as the cyclic imine moiety.

Two novel water-soluble sulfated DSP toxin derivatives 4 and 5, are reported from the benthic dinoflagellate Prorocentrum maculosum. Their occurrence supports the idea that all DSP toxin-producing Prorocentrum species biosynthesize such compounds as a means of toxin storage, and perhaps as a means of eventually exporting them from the cell.

The opiathobranch, Elysia chlorotica , contains two major polypropionate-derived metabolites. The leaat polar component is ( 1 ), the enantiomer of a previously reported molluscan metabollte. The second component, elysone ( 2 ), possesses the same relative stereochemistry as ( 1 ) but contains an additional propionate unit.

13C NMR studies (with simultaneous 1H, 2H-decoupling) of 13C, 2H-labelled methyl palmitate showed a gradation of 2H-retention along the acyl chain. The results are rationalized within the known steps of fatty acid biosynthesis.

The effect of intramolecular H-bonding and solvent acidity on the magnitude of one-bond 13C-15N spin-spin coupling constants has been examined using specifically 15N-labeled cyclo -(Gly-L-Pro-Gly)2 and related linear peptides.