title: Production of hydroxylated polybrominated diphenyl ethers from bromophenols by bromoperoxidase-catalyzed dimerization.
abstract: Hydroxylated polybrominated diphenyl ethers (HO-PBDEs) are emerging endocrine-disrupting compounds that are widely present in the marine environment. The origin of HO-PBDEs is generally attributed to metabolism of PBDEs and natural production in the environment. However, it is unclear how HO-PBDEs are produced naturally. Here we report the formation of HO-PBDEs from simple bromophenols (BPs) [e.g., 2,4-dibromophenol (2,4-DBP) and 2,4,6-tribromophenol (2,4,6-TBP)] under the catalysis of bromoperoxidase (BPO) isolated from the common marine red alga Corallina officinalis. Experiments at room temperature showed that BPO readily catalyzes the conversion of 2,4-DBP and 2,4,6-TBP to HO-PBDEs in the presence of Br(-) and H2O2. From analysis of the original forms and their corresponding methylated derivatives, the reaction products were tentatively identified as 2'-HO-BDE-121 and 4'-HO-BDE-121. The formation of HO-PBDEs was likely resulted from the coupling of bromophenoxy radicals generated by the oxidation of BPs via BPO-mediated processes. The presence of Br(-) in the reaction favored the conversion. The production of HO-PBDEs was found to be pH-dependent, and a higher yield was obtained at pH 6.5. In view of the abundance of BPs and C. officinalis in the marine environment, bioconversion of BPs mediated by BPO may be a potential route for the natural production of HO-PBDEs.
authors.affiliation: College of Biological and Environmental Engineering, Zhejiang University of Technology , Hangzhou 310032, China.
authors.forename: Kunde
authors.initials: K
authors.lastname: Lin
authors.forename: Jay
authors.initials: J
authors.lastname: Gan
authors.forename: Weiping
authors.initials: W
authors.lastname: Liu
mesh_terms: D001965:Bromides / Q000737:chemistry; D002384:Catalysis; D019281:Dimerization; D052244:Endocrine Disruptors / Q000737:chemistry / Q000378:metabolism; D055768:Halogenated Diphenyl Ethers / Q000737:chemistry* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D010544:Peroxidases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D010636:Phenols / Q000737:chemistry* / Q000378:metabolism; D000461:Rhodophyta / Q000201:enzymology; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism
chemical_list: D001965:Bromides; D052244:Endocrine Disruptors; D055768:Halogenated Diphenyl Ethers; D010636:Phenols; D014874:Water Pollutants, Chemical; D006861:Hydrogen Peroxide; D010544:Peroxidases; C026195:bromide peroxidase; C013930:2,4-dibromophenol; C004554:2,4,6-tribromophenol