MOE Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, Wuhan 430074, PR China.
Chemosphere. 2011 Apr;83(3):340-8. doi: 10.1016/j.chemosphere.2010.12.025. Epub 2011 Jan 8.
This article describes the photolysis of azithromycin, a macrolide antibiotic with reported occurrence in environmental waters, under simulated solar radiation. The photodegradation followed first-order reaction kinetics in five matrices examined. In HPLC water, the degradation rate was the slowest (half-life: 20h), whereas in artificial freshwater supplemented with nitrate (5mgL(-1)) or humic acids (0.5mgL(-1)) the degradation of azithromycin was enhanced by factors of 5 and 16, respectively, which indicated the role of indirect photolysis involving the formation of highly reactive species. Following chromatographic separation on a UPLC system, the characterization of the transformation products was accomplished using high-resolution QqToF-MS analysis. The presence of seven photoproducts was observed and their formation was postulated to originate from (bis)-N-demethylation in the desosamine sugar, O-demethylation in the cladinose sugar, combinations thereof, as well as from hydrolytic cleavages of the desosamine and/or cladinose residue. Two of these photoproducts could also be detected in natural photodegradation process in river water which was spiked with azithromycin.
本文描述了阿奇霉素在模拟太阳光辐射下的光解情况，阿奇霉素是一种大环内酯类抗生素，有报道称其在环境水中出现过。在五种被检测的基质中，光降解遵循一级反应动力学。在 HPLC 水中，降解速度最慢（半衰期：20 小时），而在添加硝酸盐（5mg/L(-1))或腐殖酸（0.5mg/L(-1))的人工淡水中，阿奇霉素的降解速度分别提高了 5 倍和 16 倍，这表明间接光解涉及形成高反应性物质发挥了作用。在 UPLC 系统上进行色谱分离后，使用高分辨率 QqToF-MS 分析完成了转化产物的表征。观察到了七种光产物的存在，并提出了它们的形成源自于在去甲氨基糖中的（双）-N-去甲基化、在克拉定糖中的 O-去甲基化、它们的组合，以及来自去甲氨基糖和/或克拉定糖残基的水解裂解。其中两种光产物也可以在河水中的自然光降解过程中被检出，河水中被添加了阿奇霉素。
