title: Interconversion between Methoxylated and Hydroxylated Polychlorinated Biphenyls in Rice Plants: An Important but Overlooked Metabolic Pathway.
abstract: To date, there is limited knowledge on the methoxylation of polychlorinated biphenyls (PCBs) and the relationship between hydroxylated polychlorinated biphenyls (OH-PCBs) and methoxylated polychlorinated biphenyls (MeO-PCBs) in organisms. In this study, rice (Oryza sativa L.) was chosen as the model organism to determine the metabolism of PCBs in plants. Limited para-substituted 4'-OH-CB-61 (major metabolite) and 4'-MeO-CB-61 (minor metabolite) were found after a 5-day exposure to CB-61, while ortho- and meta-substituted products were not detected. Interconversion between OH-PCBs and MeO-PCBs in organisms was observed for the first time. The demethylation ratio of 4'-MeO-CB-61 was 18 times higher than the methylation ratio of 4'-OH-CB-61, indicating that formation of OH-PCBs was easier than formation of MeO-PCBs. The transformation products were generated in the roots after 24 h of exposure. The results of in vivo and in vitro exposure studies show that the rice itself played a key role in the whole transformation processes, while endophytes were jointly responsible for hydroxylation of PCBs and demethylation of MeO-PCBs. Metabolic pathways of PCBs, OH-PCBs, and MeO-PCBs in intact rice plants are proposed. The findings are important in understanding the fate of PCBs and the source of OH-PCBs in the environment.
authors.affiliation: Department of Environmental Science, Zhejiang University , Hangzhou, Zhejiang 310058, China.
authors.forename: Jianteng
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Environmental Science, Zhejiang University , Hangzhou, Zhejiang 310058, China.|Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control , Hangzhou, Zhejiang 310058, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Pan
authors.affiliation: State Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University , Hangzhou, Zhejiang 310058, China.
authors.forename: Zhenzhu
authors.initials: Z
authors.lastname: Su
authors.affiliation: Department of Environmental Science, Zhejiang University , Hangzhou, Zhejiang 310058, China.|Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control , Hangzhou, Zhejiang 310058, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhan
authors.affiliation: Department of Environmental Science, Zhejiang University , Hangzhou, Zhejiang 310058, China.|Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control , Hangzhou, Zhejiang 310058, China.
authors.forename: Lizhong
authors.initials: L
authors.lastname: Zhu
mesh_terms: D060026:Endophytes / Q000187:drug effects / Q000378:metabolism; D006900:Hydroxylation; D053858:Metabolic Networks and Pathways; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D011078:Polychlorinated Biphenyls / Q000378:metabolism / Q000493:pharmacokinetics*
chemical_list: D011078:Polychlorinated Biphenyls