代谢
苯并三唑（BTs）是一种广泛分布在 aquatic environments 中的外源性污染物，由于它们的极性、顽固性和常见用途，因此越来越受到关注。在一些 water reclamation activities，如 stormwater bioretention 或用再生水灌溉作物时，BTs 会接触到植物，为消费者提供了潜在暴露途径。我们发现，在 hydroponic systems 中，BT 很快（大约每天 1-log）被拟南芥植物吸收并代谢成新的 BT 代谢物，其结构类似于色氨酸和植物激素吲哚乙酸；只有不到 1% 保持为母化合物。使用 LC-QTOF-MS 无靶向代谢组学，我们鉴定出两种主要的 BT 转化产物：糖基化和色氨酸生物合成途径的整合。BT 氨基酸代谢物在结构上类似于色氨酸和植物激素吲哚乙酸的储存形式。为了验证产物，合成了关键的中间体（通过 (1)H/(13)C NMR 验证）。在多重暴露时间质量平衡中，三种主要代谢物占 BT 的 60% 以上。糖基化的 BT 被植物排泄到水培介质中，这是一种以前未见过的现象。观察到的氨基酸代谢物可能是当色氨酸生物合成酶用合成 BT 替换本地吲哚分子时形成的，产生潜在的植物激素模拟物。这些结果表明，植物对 BT 的代谢可能会掩盖环境中 BT 污染的存在。此外，BT 衍生的代谢物在结构上与植物激素吲哚乙酸相关，因此应评估它们的不利生物效应。
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.
来源:Hazardous Substances Data Bank (HSDB)
