Debrominated, hydroxylated and methoxylated metabolism in maize (Zea mays L.) exposed to lesser polybrominated diphenyl ethers (PBDEs)

Abstract

Debrominated, hydroxylated and methoxylated metabolism in maize (Zea mays L.) exposed to lesser polybrominated diphenyl ethers (PBDEs) Sen" Debromination, hydroxylation and methoxylation of PBDEs in plant occurred rapidly. " The introduction of a hydroxyl/methoxy group at the ortho-positions was easier. " PBDEs are more susceptible to metabolism in leaves and stems than in roots." P MeO-PBDEs concentration was significantly higher than P OH-PBDEs concentration. a r t i c l e i n f o a b s t r a c tA hydroponic experiment was conducted to investigate the debrominated, hydroxylated and methoxylated metabolism of polybrominated diphenyl ethers (PBDEs, BDE-15, -28 and -47) in maize. A total of six debrominated metabolites (de-PBDEs), seven hydroxylated PBDEs (OH-PBDEs, including two unidentified OH-di-PBDEs and one unidentified OH-tri-PBDE) and four methoxylated PBDEs (MeO-PBDEs) were determined in the exposed plants. The metabolic products were detected in maize only after 12 h of exposure to the PBDEs. However, the concentration of each type of the metabolites (de-PBDEs, OH-PBDEs or MeOPBDEs) decreased at the later exposure time, possibly due to further metabolism. The removal of a bromine atom or the introduction of a hydroxyl/methoxy group was easier at the ortho-positions on the biphenyl structure than at the para-positions. Concentration ratios of the total debrominated, hydroxylated or methoxylated metabolites to the parent congener (BDE-28 or -47) generally followed the order of leaves > stems ) roots, and MeO-PBDEs > de-PBDEs ) OH-PBDEs. These results suggest that metabolism occurred preferentially in leaves and stems than in roots. Less transformation and shorter elimination half-life of OH-PBDEs would contribute to the lower concentrations of OH-PBDEs than of de-PBDEs or MeO-PBDEs in maize.

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

“…Furthermore, the concentrations of the individual OH-PBDEs were also significantly correlated to their corresponding MeO-PBDE congeners (4 0 -OH-BDE17 and 4 0 -MeO-BDE17, 3 0 -OH-BDE28 and 3 0 -MeO-BDE28, 3-OH-BDE47 and 3-MeO-BDE47, 5-OH-BDE47 and 5-MeO-BDE47, 6-OH-BDE47 and 6-MeO-BDE47, 2 0 -OH-BDE68 and 2 0 -MeO-BDE68, 6-OH-BDE85 and 6-MeO-BDE85, respectively) in the soils (P < 0.05). Significant correlations were also obtained in our previous hydroponic experiment between 3-OH-BDE28 and 3-MeO-BDE28, OH-BDE47 and MeO-BDE47 in maize (P < 0.05, Wang et al, 2012). It was therefore speculated that OH-PBDEs and MeO-PBDEs may share to some extent a common source or similar bioaccumulation behavior in the soils and plants.…”

“…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).…”

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

“…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.…”

“…Despite their high importance, studies on the behavior of PBDEs in terrestrial plants are very limited, particularly regarding the biotransformation of PBDEs, OH-PBDEs and MeO-PBDEs in plants. In our previous work, transformation of PBDEs to lower brominated PBDEs, OH-PBDEs and MeO-PBDEs in plants was observed (Huang et al, 2010;Wang et al, 2012). Sun et al (2014) recently reported the reciprocal transformation between OH-PBDEs and the corresponding MeO-PBDEs in young whole pumpkin plants by a hydroponic experiment.…”