Department of Civil and Environmental Engineering and IIHR Hydroscience and Engineering, The University of Iowa, Iowa City, IA 52242, United States.
Department of Civil and Environmental Engineering and IIHR Hydroscience and Engineering, The University of Iowa, Iowa City, IA 52242, United States.
Sci Total Environ. 2021 Sep 1;785:147341. doi: 10.1016/j.scitotenv.2021.147341. Epub 2021 Apr 27.
Methoxylated polychlorinated biphenyls (MeO-PCBs) are overlooked metabolites of PCBs. In general, they are more toxic to plants than their parent congeners. However, information on the fate of MeO-PCBs and the relationship between methoxylated, hydroxylated and sulfated metabolites of PCBs in plants is scarce. In this work, poplar plants (Populus deltoides × nigra, DN34) were hydroponically and separately exposed to 4'-methoxy-4-monochlorobiphenyl (4'-MeO-PCB 3) and 4'-PCB 3 sulfate for 10 days to investigate the uptake, translocation and metabolism of MeO-PCBs and the relationship between methoxy-PCBs, hydroxyl-PCBs and PCB sulfates within plants. Results showed that 4'-MeO-PCB 3 and 4'-PCB 3 sulfate were taken up by the roots of poplar plants and translocated from roots to shoots and leaves. 4'-OH-PCB 3 and 4'-PCB 3 sulfate were identified as the hydroxylated metabolite and sulfate metabolite of 4'-MeO-PCB 3 in poplar, respectively. In the backward reaction, 4'-OH-PCB 3 and 4'-MeO-PCB 3 were found as metabolites of 4'-PCB 3 sulfate. For exposure groups, the yields of 4'-OH-PCB 3 produced from 4'-MeO-PCB 3 and 4'-PCB 3 sulfate were 1.29% and 0.13% respectively. The yield of 4'-PCB 3 sulfate which originated from 4'-MeO-PCB 3 in wood and root samples of exposure groups was only 0.02%. Only 0.04% of the initial mass of 4'-PCB 3 sulfate was transformed to 4'-MeO-PCB 3 in the exposure groups. The sulfation yield of 4'-OH-PCB 3 was higher than hydrolysis yield of 4'-PCB 3 sulfate, indicating that formation of PCB sulfates was predominant over the reverse reaction, the formation of hydroxy-PCBs. These results provide new perspective on the transport, metabolism, and fate of MeO-PCBs, and also help to better understand sources of OH-PCBs and PCB sulfates in the environment. This study provides the first evidence of interconversion of sulfate metabolites from methoxy-PCBs and methoxy-PCBs from PCB sulfates.
甲氧基多氯联苯（MeO-PCBs）是多氯联苯（PCBs）被忽视的代谢物。一般来说，它们对植物的毒性比其母体同系物更强。然而，关于 MeO-PCBs 的命运以及植物中 PCBs 的甲氧基、羟基和硫酸化代谢物之间关系的信息却很少。在这项工作中，采用水培法分别将 4'-甲氧基-4-单氯联苯（4'-MeO-PCB 3）和 4'-PCB 3 硫酸盐暴露于 34 株黑杨（Populus deltoides × nigra，DN34）植物，以研究 MeO-PCBs 的吸收、转运和代谢，以及植物内甲氧基-PCBs、羟基-PCBs 和 PCB 硫酸盐之间的关系。结果表明，4'-MeO-PCB 3 和 4'-PCB 3 硫酸盐被杨树植物的根部吸收，并从根部转运到茎和叶。4'-OH-PCB 3 和 4'-PCB 3 硫酸盐分别被鉴定为杨树中 4'-MeO-PCB 3 的羟基化代谢物和硫酸盐代谢物。在逆向反应中，4'-OH-PCB 3 和 4'-MeO-PCB 3 被发现为 4'-PCB 3 硫酸盐的代谢物。对于暴露组，4'-MeO-PCB 3 和 4'-PCB 3 硫酸盐分别产生 4'-OH-PCB 3 的产率为 1.29%和 0.13%。暴露组木材和根样本中 4'-MeO-PCB 3 衍生的 4'-PCB 3 硫酸盐的产率仅为 0.02%。暴露组中，4'-PCB 3 硫酸盐的初始质量只有 0.04%转化为 4'-MeO-PCB 3。4'-OH-PCB 3 的硫酸化产率高于 4'-PCB 3 硫酸盐的水解产率，这表明 PCB 硫酸盐的形成优先于逆反应，即羟基-PCBs 的形成。这些结果为 MeO-PCBs 的运输、代谢和命运提供了新的视角，也有助于更好地了解环境中 OH-PCBs 和 PCB 硫酸盐的来源。本研究首次提供了甲氧基-PCBs 的硫酸盐代谢物与 PCB 硫酸盐中甲氧基-PCBs 相互转化的证据。
