Characterization of spirolides a, c, and 13-desmethyl c, new marine toxins isolated from toxic plankton and contaminated shellfish.
Three additional marine toxins, spirolides A (1), C (3), and 13-desmethyl-C (7), were isolated from contaminated scallops and phytoplankton collections obtained from a Nova Scotian aquaculture site, as well as from batch cultures of the dinoflagellate Alexandrium ostenfeldii obtained as a single-cell isolate from these phytoplankton assemblages. The structures of these new spirolide derivatives, characterized by mass spectrometry and NMR, indicate a close relationship with spirolides B (2) and D (4) isolated previously from contaminated shellfish in the same area. All of these compounds display "fast-acting" toxicity in the traditional bioassay used for monitoring shellfish, and this is related to the presence of a cyclic imine function in all these compounds. Those spirolides containing a vicinal dimethyl group in the seven-membered ring are resistant to oxalic acid hydrolysis, whereas those that do not are readily hydrolyzed. These observations suggest that the extra methyl group on the seven-membered imine ring of 3, 4, and 7 appears to block the process of imine hydrolysis perhaps by stereochemical interference.
Hu
T
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Institute for Marine Biosciences, National Research Council of Canada, 1411 Oxford Street, Halifax, Nova Scotia, Canada B3H 3Z1.
Burton
I W
IW
Cembella
A D
AD
Curtis
J M
JM
Quilliam
M A
MA
Walter
J A
JA
Wright
J L
JL
D000818:Animals; D004141:Dinoflagellida / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry* / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D008387:Marine Toxins / Q000737:chemistry* / Q000302:isolation & purification; D015394:Molecular Structure; D008974:Mollusca; D010933:Plankton / Q000737:chemistry*; D012758:Shellfish; D013141:Spiro Compounds
C429214:13-desmethyl-C; D007783:Lactones; D008387:Marine Toxins; D013141:Spiro Compounds; C429215:spirolide A; C429216:spirolide C