title: Rapid Phytotransformation of Benzotriazole Generates Synthetic Tryptophan and Auxin Analogs in Arabidopsis.
abstract: Benzotriazoles (BTs) are xenobiotic contaminants widely distributed in aquatic environments and of emerging concern due to their polarity, recalcitrance, and common use. During some water reclamation activities, such as stormwater bioretention or crop irrigation with recycled water, BTs come in contact with vegetation, presenting a potential exposure route to consumers. We discovered that BT in hydroponic systems was rapidly (approximately 1-log per day) assimilated by Arabidopsis plants and metabolized to novel BT metabolites structurally resembling tryptophan and auxin plant hormones; <1% remained as parent compound. Using LC-QTOF-MS untargeted metabolomics, we identified two major types of BT transformation products: glycosylation and incorporation into the tryptophan biosynthetic pathway. BT amino acid metabolites are structurally analogous to tryptophan and the storage forms of auxin plant hormones. Critical intermediates were synthesized (authenticated by (1)H/(13)C NMR) for product verification. In a multiple-exposure temporal mass balance, three major metabolites accounted for >60% of BT. Glycosylated BT was excreted by the plants into the hydroponic medium, a phenomenon not observed previously. The observed amino acid metabolites are likely formed when tryptophan biosynthetic enzymes substitute synthetic BT for native indolic molecules, generating potential phytohormone mimics. These results suggest that BT metabolism by plants could mask the presence of BT contamination in the environment. Furthermore, BT-derived metabolites are structurally related to plant auxin hormones and should be evaluated for undesirable biological effects.
authors: ReNUWIt Engineering Research Center, ‡Department of Civil & Environmental Engineering, §Department of Chemistry, ∥Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Gregory H
authors: GH
authors: LeFevre
authors: ReNUWIt Engineering Research Center, ‡Department of Civil & Environmental Engineering, §Department of Chemistry, ∥Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Claudia E
authors: CE
authors: Müller
authors: ReNUWIt Engineering Research Center, ‡Department of Civil & Environmental Engineering, §Department of Chemistry, ∥Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Russell Jingxian
authors: RJ
authors: Li
authors: ReNUWIt Engineering Research Center, ‡Department of Civil & Environmental Engineering, §Department of Chemistry, ∥Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Richard G
authors: RG
authors: Luthy
authors: ReNUWIt Engineering Research Center, ‡Department of Civil & Environmental Engineering, §Department of Chemistry, ∥Department of Chemical Engineering, Stanford University , Stanford, California 94305, United States.
authors: Elizabeth S
authors: ES
authors: Sattely
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D001673:Biodegradation, Environmental; D006031:Glycosylation; D018527:Hydroponics; D007210:Indoleacetic Acids / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D055442:Metabolome; D013997:Time Factors; D014230:Triazoles / Q000737:chemistry / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D007210:Indoleacetic Acids; D014230:Triazoles; C012771:benzotriazole; D014364:Tryptophan