Reciprocal Transformation between Hydroxylated and Methoxylated Polybrominated Diphenyl Ethers in Young Whole Pumpkin Plants

Abstract

Relationships among polybrominated diphenyl ethers (PBDEs), hydroxylated PBDEs (OH-PBDEs), and methoxylated PBDEs (MeO-PBDEs) have attracted considerable scientific interest. However, few studies have focused on the in vivo metabolism of these compounds by intact whole plants. In this work, interconversion between OH-tetraBDEs and MeO-tetraBDEs in young pumpkins was experimentally proven. Conversion ratios were higher for pumpkins exposed to OH-BDEs than for those exposed to MeO-BDEs. Twelve PBDE analogues showed different metabolic potential. The largest biotransformation ratio (12.4%) was observed for the transformation from 4-OH-BDE-42 to 4-MeO-BDE-42. The lowest interconversion ratios were found between 2′-OH-BDE-68 and 2′-MeO-BDE-68. Transformation products were mainly found in roots. Fewer metabolites were detected in stems, while no metabolites were detected in shoots. Root exudates were found to make only a small contribution to the conversion between OH- and MeO-PBDEs. This is the first study to demonstrate the reciprocal transformation of OH- and MeO-PBDEs in plants.