Isolation and Characterization of [DLeu]microcystin-LY from CPCC-464.

[D-Leu]MC-LY () ([M + H]/ 1044.5673, Δ 2.0 ppm), a new microcystin, was isolated from strain CPCC464.

Sulfated diesters of okadaic acid and DTX-1: Self-protective precursors of diarrhetic shellfish poisoning (DSP) toxins.

Many toxic secondary metabolites used for defense are also toxic to the producing organism. One important way to circumvent toxicity is to store the toxin as an inactive precursor. Several sulfated diesters of the diarrhetic shellfish poisoning (DSP) toxin okadaic acid have been reported from cultures of various dinoflagellate species belonging to the genus Prorocentrum.

Development of Certified Reference Materials for Diarrhetic Shellfish Poisoning Toxins, Part 1: Calibration Solutions.

Okadaic acid (OA) and its analogs dinophysistoxins-1 (DTX1) and -2 (DTX2) are lipophilic polyethers produced by marine dinoflagellates. These toxins accumulate in shellfish and cause diarrhetic shellfish poisoning (DSP) in humans. Regulatory testing of shellfish is essential to safeguard public health and for international trade.

Investigations into the toxicology of spirolides, a group of marine phycotoxins.

Spirolides are marine phycotoxins produced by the dinoflagellates Alexandrium ostenfeldii and A. peruvianum. Here we report that 13-desmethyl spirolide C shows little cytotoxicity when incubated with various cultured mammalian cell lines.

Improved isolation procedure for azaspiracids from shellfish, structural elucidation of azaspiracid-6, and stability studies.

Azaspiracids are a group of lipophilic polyether toxins produced by the small dinoflagellate Azadinium spinosum. They may accumulate in shellfish and can result in illnesses when consumed by humans. Research into analytical methods, chemistry, metabolism, and toxicology of azaspiracids has been severely constrained by the scarcity of high-purity azaspiracids.

The preparation of certified calibration solutions for azaspiracid-1, -2, and -3, potent marine biotoxins found in shellfish.

The production and certification of a series of azaspiracid (AZA) calibration solution reference materials is described. Azaspiracids were isolated from contaminated mussels, purified by preparative liquid chromatography and dried under vacuum to the anhydrous form. The purity was assessed by liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy.

Characterization of a Dispiroketal Spirolide Subclass from Alexandrium ostenfeldii.

A new subclass of spirolide marine toxins, represented by spirolides H (1) and I (2), were isolated from the marine dinoflagellate Alexandrium ostenfeldii. Spirolides H and I are structurally distinct from other spirolides in that they contain a 5:6 dispiroketal ring system rather than the trispiroketal ring system characteristic of previously isolated spirolides. The structures were assigned using a combination of spectrometric and spectroscopic techniques.

Biosynthesis of 13-desmethyl spirolide C by the dinoflagellate Alexandrium ostenfeldii.

Biosynthetic origins of the cyclic imine toxin 13-desmethyl spirolide C were determined by supplementing cultures of the toxigenic dinoflagellate Alexandrium ostenfeldii with stable isotope-labeled precursors [1,2-13C2]acetate, [1-13C]acetate, [2-13CD3]acetate, and [1,2-13C2,15N]glycine and measuring the incorporation patterns by 13C NMR spectroscopy. Despite partial scrambling of the acetate labels, the results show that most carbons of the macrocycle are polyketide-derived and that glycine is incorporated as an intact unit into the cyclic imine moiety. This work represents the first conclusive evidence that such cyclic imine toxins are polyketides and provides support for biosynthetic pathways previously defined for other polyether dinoflagellate toxins.

Spirolides isolated from Danish strains of the toxigenic dinoflagellate Alexandrium ostenfeldii.

Using LC/MS methodology, spirolides were detected in two clonal isolates of Alexandrium ostenfeldii isolated from Limfjorden, Denmark. Examination of the LC/MS profiles of extracts from these Danish cultures revealed the presence of two dominant peaks representing two previously unidentified spirolide components and one minor peak identified as the previously reported desmethyl spirolide C (1). Culturing of these clonal strains, LF 37 and LF 38, of A.

Identification of pectenotoxin-11 as 34S-hydroxypectenotoxin-2, a new pectenotoxin analogue in the toxic dinoflagellate Dinophysis acuta from New Zealand.

A new pectenotoxin, which has been named pectenotoxin-11 (PTX11), was isolated from the dinoflagellate Dinophysis acuta collected from the west coast of New Zealand. The structure of PTX11 was determined as 34S-hydroxypectenotoxin-2 by tandem mass spectrometry and UV and NMR spectroscopy. PTX11 appears to be only the third pectenotoxin identified as a natural biosynthetic product from algae after pectenotoxin-2 and pectenotoxin-12.

Detection and identification of spirolides in norwegian shellfish and plankton.

Mussels sampled in the spring of 2002 and 2003 from Skjer, a location in Sognefjord, Norway, tested positive in the mouse bioassay for lipophilic toxins. The symptoms, which included cramps, jumping, and short survival times (as low as 4 min), were not characteristic of toxins previously observed in Norway. A survey of the algae present at the aquaculture sites showed that the toxicity correlated with blooms of Alexandrium ostenfeldii.

Studies of the biosynthesis of DTX-5a and DTX-5b by the dinoflagellate Prorocentrum maculosum: regiospecificity of the putative Baeyer-Villigerase and insertion of a single amino acid in a polyketide chain.

The biosynthetic origins of the diarrhetic shellfish poisoning toxins DTX-5a and DTX-5b have been elucidated by supplementing cultures of the producing organism Prorocentrum maculosum with stable isotope labeled precursors and determining the incorporation patterns by 13C NMR spectroscopy. The amino acid residue in the sulfated side chain is found to originate from glycine, and oxygen insertion in the chain is shown to occur after polyketide formation.