Myeloperoxidase-catalyzed formation of PCDD/F from chlorophenols

Chlorophenols (CP) are transformed in vitro to polychlorinated dibenzo-p-di oxins and dibenzofurans (PCDD/F) by a biochemical-catalyzed oxidation. This is shown for 2,4,5-tri-, 2,3,4,6-tetra-and pentachlorophenol with myeloper oxidase recovered from human leucocytes in the presence of hydrogen peroxid e. The yield, the reaction, and the PCDD/F-pattern found depend on the CP. The formation rates are in the mu mol-per-mol range for all substrates. The experiments confirm the suspicion that a biochemical formation of PCDD/ F from precursors such as CPs can take place in the human body and that thi s metabolic pathway may lead to a higher inner exposure with PCDD/F than is now assumed. (C) 2000 Elsevier Science Ltd. All rights reserved.