Funke Jan, Prasse Carsten, Dietrich Christian, Ternes Thomas A
Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068, Koblenz, Germany.
Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.
Water Res X. 2021 Jan 29;11:100090. doi: 10.1016/j.wroa.2021.100090. eCollection 2021 May 1.
Ozonation is an advanced treatment technology that is increasingly used for the removal of organic micropollutants from wastewater and drinking water. However, reaction of organic compounds with ozone can also result in the formation of toxic transformation products. In the present study, the degradation of the antiviral drug zidovudine during ozonation was investigated. To obtain further insights into the reaction mechanisms and pathways, results of zidovudine were compared with the transformation of the naturally occurring derivative thymidine. Kinetic experiments were accompanied by elucidation of formed transformation products using lab-scale batch experiments and subsequent liquid chromatography - high resolution mass spectrometry (LC-HRMS) analysis. Degradation rate constants for zidovudine with ozone in the presence of -BuOH as radical scavenger varied between 2.8 ∙ 10 M s (pH 7) and 3.2 ∙ 10 M s (pH 3). The structural difference of zidovudine to thymidine is the exchange of the OH-moiety by the azide function at position 3'. In contrast to inorganic azide, no reaction with ozone was observed for the organic bound azide. In total, nine transformation products (TPs) were identified for both zidovudine and thymidine. Their formation can be attributed to the attack of ozone at the C-C-double bond of the pyrimidine-base. As a result of rearrangements, the primary ozonide decomposed in three pathways forming two different TPs, including hydroperoxide TPs. Rearrangement reactions followed by hydrolysis and subsequent release of HO further revealed a cascade of TPs containing amide moieties. In addition, a formyl amide riboside and a urea riboside were identified as TPs indicating that oxidations of amide groups occur during ozonation processes.
臭氧化是一种先进的处理技术，越来越多地用于去除废水和饮用水中的有机微污染物。然而，有机化合物与臭氧的反应也可能导致有毒转化产物的形成。在本研究中，考察了臭氧化过程中抗逆转录病毒药物齐多夫定的降解情况。为了进一步深入了解反应机理和途径，将齐多夫定的结果与天然存在的衍生物胸苷的转化情况进行了比较。动力学实验通过实验室规模的间歇实验和随后的液相色谱-高分辨率质谱（LC-HRMS）分析来阐明形成的转化产物。在存在叔丁醇作为自由基清除剂的情况下，齐多夫定与臭氧的降解速率常数在2.8×10⁻⁴ M⁻¹ s⁻¹（pH 7）和3.2×10⁻³ M⁻¹ s⁻¹（pH 3）之间变化。齐多夫定与胸苷的结构差异在于3'位的羟基部分被叠氮基取代。与无机叠氮化物不同，未观察到有机结合叠氮化物与臭氧的反应。总共鉴定出齐多夫定和胸苷的九种转化产物（TPs）。它们的形成可归因于臭氧对嘧啶碱基碳-碳双键的攻击。由于重排，初级臭氧化物通过三条途径分解，形成两种不同的TPs，包括氢过氧化物TPs。重排反应后水解并随后释放出羟基，进一步揭示了一系列含有酰胺部分的TPs。此外，一种甲酰酰胺核糖苷和一种脲核糖苷被鉴定为TPs，表明在臭氧化过程中发生了酰胺基团的氧化。
