Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, School of Resources and Environment, Anhui Agricultural University, 130 Changjiang West Road, Hefei 230036, Anhui, China.
Anhui Province Key Laboratory of Farmland Ecological Conservation and Pollution Prevention, School of Resources and Environment, Anhui Agricultural University, 130 Changjiang West Road, Hefei 230036, Anhui, China.
J Hazard Mater. 2021 Jun 15;412:125197. doi: 10.1016/j.jhazmat.2021.125197. Epub 2021 Jan 27.
Naturally-occurring phenolic acids (PAs) act as humic precursors that participate in the conversion behaviors and coupling pathways of steroidal estrogens (SEs) during laccase-triggered humification processes (L-THPs). Herein, the influences and mechanisms of PAs on Trametes versicolor laccase-evoked 17β-estradiol (E2) conversion kinetics and humification routes were explored. Fungal laccase was fleet in converting > 99% of E2, and the calculated pseudo-first-order velocity constant and half-time values were respectively 0.039 min and 17.906 min. PAs containing an O-dihydroxy moiety such as gallic acid and caffeic acid evidently hampered E2 humification owning to the yielded highly reactive O-quinones reversed E2 radicals by hydrogen transfer mechanism, implying that the inhibition effect was enormously dependent upon the number and position of the phenolic -OH present in humic precursors. Oligomers and polymers with carbon-carbon/oxygen links were tentatively found as E2 main humified species resulting from laccase-evoked successive oxidative-coupling. Note that PAs participating in the humification also encountered oxydehydrogenation, self-polymerization, and cross-binding to E2. Interestingly, the -COOH and -OCH groups of PAs could be deprived in radical-caused self/co-polymerization. The generation of humified products not only circumvented the environmental risks of parent compounds but accelerated global carbon sequestration. To our knowledge, this is the first in-depth revelation of the humification pathways and related mechanisms of SEs with humic precursors in aquatic ecosystems by L-THPs.
天然存在的酚酸（PAs）作为腐殖质前体，在漆酶引发的腐殖化过程（L-THPs）中参与甾体雌激素（SEs）的转化行为和偶联途径。在此，探讨了 PAs 对糙皮侧耳漆酶引发的 17β-雌二醇（E2）转化动力学和腐殖化途径的影响和机制。真菌漆酶迅速将 >99%的 E2 转化，计算出的拟一级速度常数和半衰期值分别为 0.039 min 和 17.906 min。含有邻二羟基结构的 PAs，如没食子酸和咖啡酸，由于生成的高反应性 O-醌通过氢转移机制逆转了 E2 自由基，从而明显阻碍了 E2 的腐殖化，这表明抑制效应极大地取决于腐殖质前体中酚-OH 的数量和位置。通过漆酶引发的连续氧化偶联，推测发现具有碳-碳/氧键的低聚物和聚合物是 E2 的主要腐殖化产物。值得注意的是，参与腐殖化的 PAs 也经历了氧化脱氢、自聚合和与 E2 的交叉结合。有趣的是，PAs 的-COOH 和-OCH 基团可以在自由基引起的自/共聚中被剥夺。腐殖质产物的生成不仅避免了母体化合物的环境风险，而且加速了全球碳封存。据我们所知，这是通过 L-THPs 首次深入揭示水生生态系统中 SEs 与腐殖质前体的腐殖化途径和相关机制。
