In Vivo Metabolism of 2,2′,4,4′-Tetrabromodiphenyl Ether (BDE-47) in Young Whole Pumpkin Plant

Abstract

Polybrominated diphenyl ethers (PBDEs) are widely distributed persistent organic pollutants. In vitro and in vivo research using various animal models have shown that PBDEs might be transformed to hydroxylated PBDEs, but there are few studies on in vivo metabolism of PBDEs by intact whole plants. In this research, pumpkin plants (Cucurbita maxima × C. moschata) were hydroponically exposed to 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). A debromination product (BDE-28) and four hydroxylated metabolites (5-OH-BDE-47, 6-OH-BDE-47, 4'-OH-BDE-49, and 4-OH-BDE-42) were detected in different parts of the whole plant. In addition, 4-methoxylated-2,2',3,4'-tetraBDE (4-MeO-BDE-42) was observed as a methoxylation product. Root exudates in solution were found to play an important role in metabolizing BDE-47 to a specific OH-PBDE: 4'-OH-BDE-49. BDE-28 was found to translocate more easily and accumulate in shoots than BDE-47 due to the lower hydrophobicity and molecular weight. The concentration ratio between metabolites and parent compound BDE-47 was lower for OH-PBDEs than that for both BDE-28 and 4-MeO-BDE-42. The metabolism pathway of BDE-47 in young whole plants was proposed in this study.

Uptake, translocation and biotransformation kinetics of BDE-47, 6-OH-BDE-47 and 6-MeO-BDE-47 in maize (Zea mays L.)

“…BDE-28 was found to be the dominant product in maize after exposure for 3 h, while the lower debrominated metabolites, BDE-15, BDE-3, and bromine atom rearrangement metabolites, BDE-12/13, BDE-10, BDE-2, were detected after exposure for 6 h. These suggested that debromination of BDE-47 took place step-by-step and preferentially occurred at ortho-positions. Wang et al (2012) and Sun et al (2013a) have also detected OH-PBDEs and MeO-PBDEs as biotransformation products of BDE-47 in maize and pumpkin, respectively, but both failed to answer the question whether the MeO-PBDEs were formed by methylation of the OH-PBDE metabolites or direct methoxylation of the parent PBDEs. In this study, the hydroxylated metabolites in maize were found after exposure for 3 h ( Fig.…”

“…Hydroxylated PBDEs (OH-PBDEs) and methoxylated PBDEs (MeO-PBDEs) have also been identified in various environmental media (Ueno et al, 2008;Wang et al, 2014) and biological samples (Kelly et al, 2008;Teuten et al, 2005). Their origin is far from clear, and increasing evidence has shown the existence of transformation of PBDEs to OH-PBDEs and MeO-PBDEs (Stapleton et al, 2009;Sun et al, 2013a;Wang et al, 2012). Debrominated PBDEs, OH-PBDEs and MeO-PBDEs have greater potencies for some adverse effects such as embryo developmental toxicity (Boxtel et al, 2008), genotoxicity (Ji et al, 2011) and endocrine disrupting effects (He et al, 2008;Meerts et al, 2001;Wiseman et al, 2011) than their precursor PBDEs, and may bring additional adverse influences to bear on the environment and human health; therefore their formations and behaviors in the environment have received increasing attention.…”

Characterization of polybrominated diphenyl ethers (PBDEs) and hydroxylated and methoxylated PBDEs in soils and plants from an e-waste area, China

“…However, ortho-substituted OH-PBDEs and MeO-PBDEs have also been detected in PBDE exposure plants and animals (Qiu et al, 2007; Wang et al, 2012;Sun et al, 2013b), and meta-and parasubstituted compounds have also been found in environmental matrices Qiu et al, 2009;Sun et al, 2013a;Zhang et al, 2012). In the present study the ortho-, meta-and para-substituted OH-PBDEs and MeO-PBDEs were all detected in the soil and plant samples with 6-OH-BDE47, 6-OH-BDE85, 2 0 -OH-BDE3, 6 0 -OH-BDE99, 3 0 -OH-BDE7, 6-MeO-BDE85 and 2 0 -MeO-BDE3 as the major congeners (Figs.…”

“…OH-PBDEs and MeO-PBDEs have been found in marine organisms (algae, mussel and fish), human blood, plants and abiotic samples such as surface water, snow, rain, soils and marine sediments (Bradley et al, 2011;Malmvärn et al, 2005;Sinkkonen et al, 2004;Sun et al, 2013a;Ueno et al, 2008;Verreault et al, 2005;Zhang et al, 2012). Recent studies also detected OH-PBDEs and MeO-PBDEs in organisms and plants after in vivo PBDE exposures (Marsh et al, 2006;Qiu et al, 2007;Sun et al, 2013b;Wan et al, 2010;Wang et al, 2012).…”

Structure prediction of methyoxy-polybrominated diphenyl ethers (MeO-PBDEs) through GC–MS analysis of their corresponding PBDEs

“…As a kind of important bio-transformation products of polybrominated diphenyl ethers (PBDEs) or natural products [1][2][3][4], methoxylated PBDEs (MeO-PBDEs) are found in various environmental matrices [5][6][7] and have drawn considerable attention due to their relatively higher toxicity when compared to the corresponding parent compounds of PBDEs [8][9][10]. According to the theoretical speculation, there could be 837 MeO-PBDE congeners with one methoxyl substitution on the diphenyl rings ( Fig.…”