Enantiomeric Specificity of Methylsulfonyl-PCBs and Distribution of Bis(4-chlorophenyl) Sulfone, PCB, and DDE Methyl Sulfones in Grey Seal Tissues

Abstract

PCB methyl sulfones (MeSO2-PCBs) are lipophilic PCB metabolites of which five of the environmentally relevant meta/para pairs are chiral (i.e., exist as atropisomeric pairs). Methylsulfonyl-DDE (MeSO2-DDE) is a DDE metabolite, while bis(4-chlorophenyl) sulfone (BCPS) is a commercial monomer used for thermoplastic production. All these sulfones are well-known environmental contaminants. In this study, liver, lung, and adipose tissue in grey seals (Halichoerus grypus) from the Baltic Sea, naturally exposed to organochlorines via their food, were analyzed for the compounds mentioned. MeSO2-PCBs, 3-MeSO2-DDE, and BCPS were all found in significantly higher concentrations in the liver than in lung and blubber. Their strong liver retention, represented by a median of 42 microg/g l.w. of sigmaMeSO2-PCBs, has previously been mainly neglected in assessments of exposure. The highest concentrations of PCBs and DDE were still found in the grey seal blubber. The atropisomeric composition of MeSO2-PCB congeners was determined, and their enantiomeric fractions were calculated and compared in blubber, liver, and lung tissues. The enantiomeric specificity was equal in all tissues. A notably high abundance (>94%) was observed for one atropisomer in each chiral MeSO2-PCB pair. The first eluting atropisomer (A1) was dominating for all para-substituted MeSO2-PCBs studied, while the second eluting atropisomers (A2) were as dominant in all meta-substituted MeSO2-PCBs in all samples analyzed. In the liver, as much as 50% of sigmaMeSO2-PCBs consisted of the second eluting atropisomer (A2) of 5-MeSO2-CB149. The results imply that the sulfone group is crucial for the specific liver retention of MeSO2-PCBs, 3-MeSO2-DDE, and BCPS.

Methylsulfonyl polychlorinated biphenyls in fish from an electronic waste‐recycling site in South China: Levels, congener profiles, and chiral signatures

“…2), suggesting no tissuespecific enantioselective retention of the enantiomers in the fish. No tissue-specific enantiomer enrichment of MeSO 2 -PCBs was reported in higher organisms, for example, 4-91, 5 0 -and 4 0 -132, 5-and 4-149, and 5 0 -and 4 0 -174 in the blubber, liver, and lung tissues of grey seals from the Baltic Sea [17], and 4 0 -132 in the liver, adipose, and lung tissues of rats dosed with pure CB 132 or technical PCB mixture [16,18]. However, distinct EFs were found in the lung compared with the adipose and liver for 5-and 4-149 in the rats exposed to technical PCB mixture due to the enantioselective transformation of these congeners in the liver and adipose other than the lung [18].…”

“…Analogous to their parent compounds, these chiral congeners can undergo enantiomeric enrichment in biological tissues and display enantioselective toxicity [15]. However, the tissue-specific retention of chiral MeSO 2 -PCBs has not been adequately investigated, and all of the investigations have been performed only in mammals [16][17][18]. Little information is available about these chiral MeSO 2 -PCBs in fish species.…”

Metabolism and metabolites of polychlorinated biphenyls

“…These atropisomers may or may not be generated in a 1:1 ratio, but the metabolites, like PCB atropisomers, seem to have different half-lives in animal tissues and in biota (Püttmann et al, 1989, Larsson et al, 2004, Larsson et al, 2002, Chu et al, 2003a). The atropselective formation of chiral OH-PCBs has been shown both in vivo (Kania-Korwel et al, 2008b, Kania-Korwel et al, 2012) and in vitro (Kania-Korwel et al, 2011, Wu et al, 2011, Lu et al, 2013, Wu et al, 2013a, Wu et al, 2014, Wu et al, 2013b, Zhai et al, 2013b).…”

Chirality as an Environmental Forensics Tool

“…Changing the location of the methyl sulfone moiety results in preferential accumulation of 5-and 5 0 -MeSO 2 -PCBs in liver tissue and 4-MeSO 2 -PCBs in lung tissue, most likely from selective protein binding [7]. It is likely that such binding is probably enantioselective as well, as suggested by the highly enantioselective residues of MeSO 2 -PCBs in seal tissues [261].…”