Biotransformation of tetrabromobisphenol A dimethyl ether back to tetrabromobisphenol A in whole pumpkin plants

Abstract

As the metabolites of tetrabromobisphenol A (TBBPA), tetrabromobisphenol A mono- and di-methyl ethers (TBBPA MME and TBBPA DME) have been detected in various environmental media. However, knowledge of the contribution of plants to their environmental fates, especially to the interactions between TBBPA DME and TBBPA, is quite limited. In this study, the metabolism and behaviors of TBBPA DME was studied with pumpkin plants through 15-day hydroponic exposure. The TBBPA were also studied separately using in-lab hydroponic exposure for comparison. The results showed that more TBBPA DME accumulated in pumpkin roots and translocated up to stems and leaves compared with TBBPA. Transformation of TBBPA DME occurred later and more slowly than that of TBBPA. Interconversion between TBBPA DME and TBBPA was verified in intact plants for the first time. Namely, TBBPA DME can be biotransformed to TBBPA MME (transformation ratio in mole mass, TRMM 0.50%) and to TBBPA (TRMM 0.53%) within pumpkin; and TBBPA can be biotransformed to TBBPA MME (TRMM 0.58%) and to TBBPA DME (TRMM 0.62%). In addition, two single benzene-ring metabolites, 2,6-dibromo-4-(2-(2-hydroxyl)-propyl)-anisole (DBHPA, TRMM 3.4%) with an O-methyl group and 2,6-dibromo-4-(2-(2-hydroxyl)-propyl)-phenetole (DBHPP, TRMM 0.57%) with an O-ethyl group, were identified as the transformation products in the TBBPA exposure experiments. The transformation and interconversion from TBBPA DME back to TBBPA is reported as a new pathway and potential source for TBBPA in the environment.

Two Typical Glycosylated Metabolites of Tetrabromobisphenol A Formed in Plants: Excretion and Deglycosylation in Plant Root Zones

“…However, TBBPA was only detected in roots and stems but not in the leaves of pumpkin seedlings, resembling the results of the TBBPA exposure experiment at a low concentration (0.18 μM). 8 The observed increases followed by decreases in roots and stems indicated rapid uptake, translocation, and transformation of TBBPA in pumpkin plants, consistent with previous observations in carrots exposed to 2,4dibromophenol. 17 Occurrence and Distribution of Glycosylated TBBPA in Pumpkin Seedlings after Hydroponic Exposure.…”

“…Plants can adsorb/absorb TBBPA from water, soil, and air . At the primary producer trophic level, plants can deliver TBBPA to animals and humans through the food chain .…”

Microbial transformation of widely used pharmaceutical and personal care product compounds

“…The interconversion between O-methylated and O-demethylated forms thus presents a mechanism by which a PPCP compound can be transformed in one environment and the original parent compound regenerated by microbes that are active in another environment. This is similar to reports of flame-retardant and antimicrobial compound transformations that have been described in plants 53,54 .…”

Uptake, phytovolatilization, and interconversion of 2,4-dibromophenol and 2,4-dibromoanisole in rice plants

“…Bromophenols can undergo O-methylation to form brominated anisoles in some marine algaes and mussels ( Lofstrand et al, 2010 ; Vetter et al, 2007 ), and several branches of bacteria in the natural environment ( Allard et al, 1987 ). Correspondingly, methylated phenol contaminants (i.e., methyl triclosan, methoxylated polychlorinated biphenyls, 6-methoxy-2,2′,4,4′-tetrabromodiphenyl ether (6-MeO-BDE-47), as well as tetrabromobisphenol A mono- and di-methyl ethers) can be biologically demethylated back to their parent compounds in high plants ( Fu et al, 2018 ; Hou et al, 2018 ; Sun et al, 2016 ; Xu et al, 2016 ). For instance, a significant amount (more than 15.0%) of methyl triclosan could be back converted to triclosan in A. thalina cells ( Fu et al, 2018 ).…”

“…Methylation and demethylation of organic and inorganic compounds are pervasive biotransformation processes in various plants ( Fu et al, 2018 ; Hou et al, 2018 ; Li et al, 2018 ; Sun et al, 2016 ; Xu et al, 2016 ; Zhang et al, 2019 ). Plant uptake, accumulation as well as volatilization of the contaminants can be significantly altered when methylation and demethylation processes occurred.…”