title: Trophic dynamics of hexabromocyclododecane diastereomers and enantiomers in fish in a laboratory feeding study.
abstract: The laboratory trophic transfer of hexabromocyclododecanes (HBCDs) was studied using predatory (oscar) fish and a prey species (tiger barb) exposed to a technical HBCD. Gut absorption, dynamic changes of diastereomer pattern and enantiomer fractions, and potential metabolism of HBCDs were examined. Compared with β- or γ-HBCD, α-HBCD showed lower absorption efficiency in the gut of oscar fish. A predominance of γ-HBCD was observed in the tiger barb after 5 d HBCD-exposed and oscar feeding on the tiger barb for 16 d. After 20 d of depuration, 41.1% γ-HBCD and 42.7% β-HBCD disappeared, and α-HBCD exceeded the initial amount. The transformation from γ-HBCD predominance in the food to α-HBCD predominance in the oscar was attributed mainly to the isomerization of γ-HBCD (at least 3% and up to 22.7%) to α-HBCD. Selective enrichment of the (+) α- and (-) β-enantiomers and no enantioselective enrichment of γ-HBCD were observed in the tiger barbs. No enantioselective uptake of the 3 diasteromers was found in the oscar gut. The enantiomer fractions of α- and γ-diastereomers were significantly higher, but that of β-diastereomer were significantly lower in the oscars than in the tiger barbs, indicating enantioselective metabolism of the 3 diastereomers. Two HBCD monohydroxylated metabolites were detected in the 2 fish species, but their composition patterns differed, indicating a species-specific metabolism of HBCD in the studied fish species.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Luo
authors.forename: Wei
authors.initials: W
authors.lastname: Ruan
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Zeng
authors.forename: Hong-Ying
authors.initials: HY
authors.lastname: Liu
authors.forename: She-Jun
authors.initials: SJ
authors.lastname: Chen
authors.forename: Jiang-Ping
authors.initials: JP
authors.lastname: Wu
authors.forename: Bi-Xian
authors.initials: BX
authors.lastname: Mai
mesh_terms: D000818:Animals; D023681:Cichlids / Q000378:metabolism*; D003530:Cyprinidae / Q000378:metabolism*; D005243:Feces / Q000737:chemistry; D020387:Food Chain; D006842:Hydrocarbons, Brominated / Q000737:chemistry / Q000378:metabolism*; D013045:Species Specificity; D013237:Stereoisomerism; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*
chemical_list: D006842:Hydrocarbons, Brominated; D014874:Water Pollutants, Chemical; C089796:hexabromocyclododecane
keywords: Diastereomer pattern; Enantiomer fractions; Gastrointestinal absorption; Hexabromocyclododecanes; Species-specific metabolism