Electrochemical oxidation of fluoroquinolone antibiotics: Mechanism, residual antibacterial activity and toxicity change.
Electrochemical oxidation of fluoroquinolone antibiotics: Mechanism, residual antibacterial activity and toxicity change.
复制标题
DOI：
10.1016/j.watres.2016.06.005
复制
发表时间：
2016-10
期刊：
影响因子：
12.8
通讯作者：
Linyan Zhu;B. Santiago-Schübel;Hongxia Xiao;H. Hollert;S. Kueppers
中科院分区：
文献类型：
--
作者：
Linyan Zhu;B. Santiago-Schübel;Hongxia Xiao;H. Hollert;S. Kueppers
本文研究了三种典型氟喹诺酮类抗生素(FQS)的电化学氧化机理，并考察了氧化过程中残留抗菌活性和毒性的变化。采用电化学质谱联用技术研究了环丙沙星(CIP)、诺氟沙星(NOR)和氧氟沙星(OFL)的氧化过程。鉴定了每个母体化合物的8个氧化产物，并确定了它们的化学结构。通过在线EC-MS记录了各产品在0~3000 mV电压范围内的变化趋势。根据氧化产物的结构信息和转化趋势，提出了氧化途径。我们发现FQS的氧化机理是通过与羟基自由基的反应使哌嗪环发生羟基化和裂解，而氟喹诺酮核心保持不变。通过对革兰氏阴性菌鼠伤寒沙门氏菌的区带抑制试验，评价了母体化合物及其氧化混合物的抗菌活性。结果表明，CIP和NOR的氧化混合物保持了较低的抗菌活性，而OFL的抗菌活性在氧化后几乎消失。此外，通过藻类生长抑制试验(Desmodesmus Subspicatus)对三种FQS及其氧化混合物的毒性进行了评价。计算生长速率终点的藻类抑制试验的中位有效浓度(EC50)值。电化学氧化后，CIP和NOR对绿藻的毒性不变，而OFL的毒性显著增加。本文的结果有助于理解FQS的电化学氧化机理，并突出了FQS在电化学氧化过程中的潜在环境风险。
In this paper, we studied the electrochemical oxidation mechanisms of three typical fluoroquinolone antibiotics (FQs), and investigated residual antibacterial activity and toxicity changes after oxidation processes. Electrochemistry coupled to mass spectrometry (EC-MS) was used to study the oxidation processes of ciprofloxacin (CIP), norfloxacin (NOR) and ofloxacin (OFL). Eight oxidation products for each parent compound were identified and their chemical structures were elucidated. The transformation trend of each product, with the continuous increase of voltage from 0 to 3000 mV, was recorded by online EC-MS. The oxidation pathways were proposed based on the structural information and transformation trends of oxidation products. We found the oxidation mechanisms of FQs consisted of the hydroxylation and cleavage of piperazinyl ring via reactions with hydroxyl radicals, while the fluoroquinolone core remained intact. The antibacterial activity of the parent compounds and their oxidation mixtures was estimated using zone inhibition tests for gram-negative bacteria Salmonella typhimurium. It was found that the oxidation mixtures of CIP and NOR retained the antibacterial properties with lower activity compared to their parent compounds, while the antibacterial activity of OFL was almost eliminated after oxidation. Furthermore, the toxicity of the three FQs and their oxidation mixtures were evaluated using algal growth inhibition test (Desmodesmus subspicatus). The median effective concentration (EC50) values for the algal inhibition tests were calculated for the end point of growth rate. The toxicity of CIP and NOR to green algae after electrochemical oxidation, remained unchanged, while that of OFL significantly increased. The results presented in this paper contribute to an understanding of the electrochemical oxidation mechanisms of FQs, and highlight the potential environmental risks of FQs after electrochemical oxidation processes.