title: Confirmation of brevetoxin metabolism in the Eastern oyster (Crassostrea virginica) by controlled exposures to pure toxins and to Karenia brevis cultures.
abstract: Previously, we analyzed Eastern oysters (Crassostrea virginica) naturally exposed to a Karenia brevis red tide and found that brevetoxins (PbTx) are rapidly accumulated and metabolized. Several metabolites were isolated and later identified, including a cysteine-PbTx conjugate (MH(+): m/z 1018) and its sulfoxide product (m/z 1034). In the present study, we confirm and extend those findings by examining PbTx metabolism and elimination in oysters exposed to pure toxins (PbTx-2 and -3) under controlled conditions. Waterborne PbTx-3 was rapidly accumulated, but not metabolized, in the oyster and was largely eliminated within 2 weeks after exposure. In contrast, PbTx-2 was accumulated and rapidly metabolized. Metabolites of PbTx-2 included the reduction product PbTx-3 (m/z 897), and the cysteine conjugates (m/z 1018 and 1034) isolated previously from the field samples. Levels of the metabolite PbTx-3 in PbTx-2-exposed oysters were highest immediately after exposure and declined at a rate similar to parent PbTx-3 in PbTx-3-exposed oysters. Cysteine-PbTx persisted for 8 weeks after exposure. The same metabolites were confirmed in oysters exposed to laboratory cultures of K. brevis. PbTx metabolites contribute to neurotoxic shellfish poisoning (NSP) and should be included in analytical protocols for monitoring shellfish toxicity after a K. brevis red tide event.
authors.affiliation: Gulf Coast Seafood Laboratory, US Food and Drug Administration, 1 Iberville Drive, P.O. Box 158, Dauphin Island, AL 36528-0158, USA. splakas@cfsan.fda.gov
authors.forename: Steven M
authors.initials: SM
authors.lastname: Plakas
authors.forename: Kathleen R
authors.initials: KR
authors.lastname: el-Said
authors.forename: Edward L E
authors.initials: EL
authors.lastname: Jester
authors.forename: H Ray
authors.initials: HR
authors.lastname: Granade
authors.forename: Steven M
authors.initials: SM
authors.lastname: Musser
authors.forename: Robert W
authors.initials: RW
authors.lastname: Dickey
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects; D002853:Chromatography, Liquid; D004141:Dinoflagellida / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D008387:Marine Toxins / Q000737:chemistry / Q000493:pharmacokinetics* / Q000633:toxicity; D051379:Mice; D009447:Neuroblastoma / Q000473:pathology; D010125:Ostreidae / Q000737:chemistry / Q000378:metabolism*; D035964:Oxocins; D021241:Spectrometry, Mass, Electrospray Ionization; D014407:Tumor Cells, Cultured / Q000187:drug effects; D000095702:Polyether Toxins
chemical_list: D008387:Marine Toxins; D035964:Oxocins; C053342:brevetoxin; D000095702:Polyether Toxins