LC/MS analysis of brevetoxin metabolites in the Eastern oyster (Crassostrea virginica).
Brevetoxin (PbTx) metabolism was examined in the Eastern oyster (Crassostrea virginica) following exposure to a Karenia brevis red tide, by using LC/MS(/MS) and cytotoxicity assay. Metabolites observed in field-exposed oysters were confirmed in oysters exposed to K. brevis cultures in the laboratory. Previously, we identified a cysteine conjugate and its sulfoxide (MH(+): m/z 1018 and 1034) as metabolites of the brevetoxin congener PbTx-2. In the present study, we found a cysteine conjugate and its sulfoxide with A-type brevetoxin backbone structure (MH(+): m/z 990 and 1006), as probable derivatives of PbTx-1. We also found glycine-cysteine-PbTx (m/z 1047 and 1075), gamma-glutamyl-cysteine-PbTx (m/z 1147), and glutathione-PbTx (m/z 1176 and 1204) conjugates with A- and B-type backbone structures. Amino acid-PbTx conjugates react with fatty acids through amide linkage to form a series of fatty acid-amino acid-PbTx conjugates. These fatty acid conjugates are major contributors to the composite cytototoxic responses obtained in extracts of brevetoxin-contaminated oysters. Other brevetoxin derivatives found in oysters are consistent with hydrolytic ring-opening and oxidation/reduction reactions.
Wang
Zhihong
Z
Gulf Coast Seafood Laboratory, U.S. Food and Drug Administration, P.O. Box 158, 1 Iberville Drive, Dauphin Island, AL 36528-0158, USA.
Plakas
Steven M
SM
El Said
Kathleen R
KR
Jester
Edward L E
EL
Granade
H Ray
HR
Dickey
Robert W
RW
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001681:Biological Assay; D002853:Chromatography, Liquid; D003601:Cytotoxicity Tests, Immunologic; D004141:Dinoflagellida; D005227:Fatty Acids / Q000378:metabolism*; D005431:Florida; D006868:Hydrolysis; D008387:Marine Toxins / Q000737:chemistry* / Q000378:metabolism*; D013058:Mass Spectrometry; D010125:Ostreidae / Q000378:metabolism*; D010084:Oxidation-Reduction; D035964:Oxocins / Q000737:chemistry* / Q000378:metabolism*; D013781:Texas; D000095702:Polyether Toxins
D000596:Amino Acids; D005227:Fatty Acids; D008387:Marine Toxins; D035964:Oxocins; C053342:brevetoxin; D000095702:Polyether Toxins