研究报告
赵旭蕾,董佳玥,陆隽鹤.氧氟沙星敏化光解磺胺甲恶唑[J].环境科学学报,2022,42(11):85-93
氧氟沙星敏化光解磺胺甲恶唑
- Ofloxacin sensitized photodegradation of sulfamethoxazole
- 基金项目：国家自然科学基金项目（No.21876085）
- 作者
- 单位
- 赵旭蕾
- 南京农业大学资源与环境科学学院，南京 210095
- 董佳玥
- 南京农业大学资源与环境科学学院，南京 210095
- 陆隽鹤
- 南京农业大学资源与环境科学学院，南京 210095
- 摘要：抗生素是环境中广泛存在的一类新兴污染物，因其可诱导细菌抗药性及产生抗性基因而备受关注.本研究发现氟喹诺酮类抗生素具有的光化学活性，可能影响共存的磺胺类抗生素（SAs）的转化.系统考察了一种典型的氟喹诺酮类抗生素—氧氟沙星（OFLO）对磺胺甲恶唑（SMX）的光化学转化.结果表明，在365 nm紫外光照条件下，OFLO可以有效敏化光解SMX.激发三重态（3OFLO*）是促进SMX光解的主要活性物质.密度泛函理论（DFT）计算结合高分辨率质谱（HRMS）分析表明，3OFLO*将SMX分子中的氨基氮氧化成一个自由基阳离子（R-NH2?+）.该自由基阳离子可水解生成羟胺衍生物，并进一步氧化生成亚硝化和硝化产物.此外，它们也可以二聚生成偶氮产物.光反应过程中，敏化剂OFLO也发生了降解.但OFLO的光解产物均保留了核心喹诺酮结构，因此也保留了OFLO分子的光敏活性.该研究有助于进一步了解抗生素复合污染情况下的环境行为，具有重要的环境意义.
- Abstract：Antibiotics have been recognized as emerging pollutants because their presence in the environment can induce antibiotic-resistant bacteria and genes. In this study， the photoreactions in the co-presence of ofloxacin （OFLO） and sulfamethoxazole （SMX） was examined. The results showed that OFLO can effectively sensitize the photodegradation of SMX upon 365 nm UV irradiation. The degradation of SMX was due to the reaction with excited triplet OFLO（3OFLO*） generated upon UV irradiation. Density functional theory （DFT） calculation combined with high-resolution mass spectrometry （HRMS） analysis suggested that 3OFLO* oxidized the aniline-nitrogen on the SMX molecule to a radical cation （R-NH2?+）. The radical cation can be hydrolyzed to hydroxylamine derivatives， and further be oxidized to nitrosation and nitration products. Alternatively， they can dimerize to generate an azo product. During the photoreaction， OFLO as a sensitizer was also degraded. HRMS analysis results showed that the core quinolone structure of OFLO remained intact. Thus， the photolysis products of OFLO largely inherited the photochemical reactivity of the parent compound. The findings advance the understandings of the behavior of fluoroquinolone antibiotics in aquatic environment.
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