Classen Nicola, Lin Xin, Schmidt Burkhard
a Institute of Biology V , RWTH Aachen University , Aachen , Germany.
J Environ Sci Health B. 2015;50(2):69-80. doi: 10.1080/03601234.2015.975579.
The metabolism of [UL-(14)C]-2,2',5,5'-tetrachlorobiphenyl ((14)C-PCB-52), [UL-(14)C]-2,2',4,4',5,5'-hexachlorobiphenyl ((14)C-PCB-153, and a congeneric mixture of [UL-(14)C]-labeled polychlorinated biphenyls ((14)C-PCB-Mix) was studied in cell suspension cultures of wheat (Triticum aestivum L. cv. 'Heines Koga II'). About 50% of applied (14)C-PCB-52 (20 μg/assay) was transformed during 96 h of incubation. While 7.6% on non-extractable residues emerged, turnover of (14)C-PCB-52 was mainly due to soluble polar metabolites. These were subjected to chemical glycoside cleavage. In the resulting hydrolysate, four aglycons were identified by GC-EIMS, namely four tetrachloro-hydroxy-biphenyl isomers (C6H6Cl4O, M(+·) at m/z = 306, 308, 310 and 312), and one trichloro-hydroxy-biphenyl (C6H7Cl3O, M(+·) at m/z = 272, 274 and 276). Number and character of hydroxylated products pointed to cytochromes P450 as enzymatic catalysts of hydroxylation. (14)C-PCB-153 was metabolized by wheat to minor degree if at all. Due to GC-EIMS analysis, of (14)C-PCB-Mix consisted of biphenyl, one mono-, four di-, seven tri-, eleven tetra-, and four pentachlorobiphenyls besides traces of further mono- and hexachlorobiphenyls. Among these were PCB-28, PCB-52, PCB 101, and PCB-118 (identified by seven key congeners standard). The mixture resembled industrial products Clophen A30 or Aroclor 1016. Metabolic turnover of applied (14)C-PCB-Mix (15 μg/assay) was 30% after 96 h; 8.4% of non-extractable residues emerged. Using DDE (p,p'-dichlorodiphenyl-dichloroethylene) as internal standard it was demonstrated that biphenyl, one monochloro-, two dichloro-, and one trichlorobiphenyl were completely metabolized to polar products. Partial metabolization occurred with one di-, five tri-, and four tetrachlorobiphenyls. Two tri-, four tetra-, and all pentachlorbiphenyls proved to be stable. Due to strong interference by matrix, evaluation of three congeners was not possible. In addition to wheat, results of similar experiments with cell cultures of other species are briefly mentioned.
在小麦（普通小麦品种“Heines Koga II”）的细胞悬浮培养物中研究了[UL-(14)C]-2,2',5,5'-四氯联苯（(14)C-PCB-52）、[UL-(14)C]-2,2',4,4',5,5'-六氯联苯（(14)C-PCB-153）以及[UL-(14)C]标记的多氯联苯同系物混合物（(14)C-PCB-Mix）的代谢情况。在96小时的孵育过程中，约50%施加的(14)C-PCB-52（20μg/测定）发生了转化。虽然7.6%出现在不可提取的残留物中，但(14)C-PCB-52的周转主要归因于可溶性极性代谢物。对这些代谢物进行了化学糖苷裂解。在所得水解产物中，通过气相色谱-电子轰击离子质谱法（GC-EIMS）鉴定出四种苷元，即四种四氯羟基联苯异构体（C6H6Cl4O，质荷比m/z = 306、308、310和312处的M(+·)）以及一种三氯羟基联苯（C6H7Cl3O，质荷比m/z = 272、274和276处的M(+·)）。羟基化产物的数量和特征表明细胞色素P450是羟基化的酶促催化剂。(14)C-PCB-153在小麦中即使有代谢也是程度较小。通过GC-EIMS分析，(14)C-PCB-Mix除了痕量的其他单氯和六氯联苯外，还由联苯、一种单氯、四种二氯、七种三氯、十一种四氯和四种五氯联苯组成。其中包括PCB-28、PCB-52、PCB 101和PCB-118（通过七种关键同系物标准鉴定）。该混合物类似于工业产品Clophen A30或Aroclor 1016。施加的(14)C-PCB-Mix（15μg/测定）在96小时后的代谢周转为30%；8.4%出现在不可提取的残留物中。使用p,p'-二氯二苯二氯乙烯（DDE）作为内标表明，联苯、一种单氯、两种二氯和一种三氯联苯完全代谢为极性产物。一种二氯、五种三氯和四种四氯联苯发生了部分代谢。两种三氯、四种四氯和所有五氯联苯被证明是稳定的。由于基质的强烈干扰，无法对三种同系物进行评估。除了小麦外，还简要提及了其他物种细胞培养的类似实验结果。
