The reactions of glutathione (GSH) with polybrominated diphenyl ethers (PBDEs) quinones with different degrees of bromination on the PBDEs ring were studied. Liquid chromatography coupled with mass spectrometric (LC-MS) analysis showed that four types of adducts were formed from the reaction of each PBDEs quinone (PBDE-Q) with GSH. The proposed reaction pathway was confirmed using ion trap-MS/MS technique. Our results demonstrate that adduct-1 was formed following the Michael Addition, a reaction of the sulfhydryl group from GSH with electron deficient carbon from PBDEs-Q ring. Compared with other carbons on the quinone ring, carbon in position 6 has a smaller steric hindrance, thus the addition reaction is likely to occur in that position. Hydrated quinone-GSH adduct-1 is easily oxidized to generate an adduct-2 in an aqueous solution. Substitution reaction from bromine atom on adduct-2 quinone ring with sulfhydryl group from GSH further generates adduct-3 that is unstable and can be readily hydrolyzed to adduct-4 in aqueous solution. Both adduct-1 and adduct-4 were unstable as well, immediately oxidized to adduct-2 and adduct-3 in the air, respectively. The results reveal that brominated quinones undergo a rapid non-enzymatic debromination upon reaction with GSH, and open a new view for our understanding on mechanism of metabolism and the toxicity of this class of compounds.
Scopus Subject Areas
- Environmental Engineering
- Environmental Chemistry
- Health, Toxicology and Mutagenesis