Identification of a novel hydroxylated metabolite of 2,2′,3,5′,6-pentachlorobiphenyl formed in whole poplar plants

• Published in: Environmental science and pollution research international 2016-02, Vol.23 (3), p.2089-2098
• Main Authors: Ma, Cunxian, Zhai, Guangshu, Wu, Huimin, Kania-Korwel, Izabela, Lehmler, Hans-Joachim, Schnoor, Jerald L
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biotransformation; Chromatography; Chromatography, High Pressure Liquid; Cytochrome; Earth and Environmental Science; Ecotoxicology; Effects; enantiomers; Environment; Environmental Chemistry; Environmental Health; Enzymes; Gas chromatography; Gas Chromatography-Mass Spectrometry; Hydroxylation; Indicator organisms; Liquid chromatography; mammals; Mass spectrometry; Metabolites; Organic contaminants; Oxidation; Oxidation-Reduction; PCB; PCBs: Exposures; Persistent organic pollutants; Pollution studies; Polychlorinated biphenyls; Polychlorinated Biphenyls - chemistry; Polychlorinated Biphenyls - metabolism; Populus - chemistry; Populus - metabolism; Remediation and Regulation with special reference to PCBs in Schools; Roots; Scientific imaging; Stereoisomerism; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-015-5939-8

Polychlorinated biphenyls (PCBs) are a group of persistent organic pollutants consisting of 209 congeners. Oxidation of several PCB congeners to hydroxylated PCBs (OH-PCBs) in whole poplar plants has been reported before. Moreover, 2,2′,3,5′,6-pentachlorobiphenyl (PCB95), as a chiral congener, has been previously shown to be atropselectively taken up and transformed in whole poplar plants. The objective of this study was to determine if PCB95 is atropselectively metabolized to OH-PCBs in whole poplar plants. Two hydroxylated PCB95s were detected by high-performance liquid chromatography-mass spectrometry in the roots of whole poplar plants exposed to racemic PCB95 for 30 days. The major metabolite was confirmed to be 4′-hydroxy-2,2′,3,5′,6-pentachlorobiphenyl (4′-OH-PCB95) by gas chromatography-mass spectrometry (GC-MS) using an authentic reference standard. Enantioselective analysis showed that 4′-OH-PCB95 was formed atropselectively, with the atropisomer eluting second on the Nucleodex β-PM column (E2-4′-OH-PCB95) being slightly more abundant in the roots of whole poplar plants. Therefore, PCB95 can at least be metabolized into 4′-OH-PCB95 and another unknown hydroxylated PCB95 (as a minor metabolite) in whole poplar plants. Both atropisomers of 4′-OH-PCB95 are formed, but E2-4′-OH-PCB95 has greater atropisomeric enrichment in the roots of whole poplar plants. A comparison with mammalian biotransformation studies indicates a distinctively different metabolite profile of OH-PCB95 metabolites in whole poplar plants. Our observations suggest that biotransformation of chiral PCBs to OH-PCBs by plants may represent an important source of enantiomerically enriched OH-PCBs in the environment.