Plant Uptake and Metabolism of 2,4-dibromophenol in Carrot: In Vitro Enzymatic Direct Conjugation

Jianqiang Sun, Qiong Chen, Zhuxiu Qian, Yan Zheng, Shuai Yu, Anping Zhang

Index: 10.1021/acs.jafc.8b00543

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Abstract

Plants can extensively uptake organic contaminants from soil and subsequently transform them into various products. Those compounds containing hydroxyl may undergo direct conjugation with endogenous biomolecules in plants, and potentially be preserved as conjugates, thus enabling overlooked risk via consumptions of food crops. In this study, we evaluated the uptake and metabolism of 2,4-dibromophenol (DBP) by both carrot cells and whole plant. DBP was completely removed from cell cultures with a half-life of 10.8 h. Four saccharide conjugates, three amino acid conjugates and one phase I metabolite were identified via UPLC-QTOF-MS analysis. The dibromophenol glucopyranoside (glucose conjugate) was quantitated by synthesized standard and accounted for 9.3% of the initial spiked DBP at the end of incubation. The activity of glycosyltransferase was positively related to the production of DBP-glucopyranoside (p=0.02, R2=0.86), implying the role of enzymatic catalysis involved in phase II metabolism.