Transformation kinetics and pathways of tetracycline antibiotics with manganese oxide

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• 作者：Wan-Ru Chen¹ ; ^a ; Ching-Hua Huang ; ^a ; ^{ching-hua.huang@ce.gatech.edu}
• 关键词：Oxytetracycline ; Chlorotetracycline ; Oxidation ; Emerging contaminants ; Pharmaceuticals
• 刊名：Environmental Pollution
• 出版年：2011
• 出版时间：May 2011
• 年：2011
• 卷：159
• 期：5
• 页码：1092-1100
• 全文大小：629 K

文摘

Tetracycline antibiotics including tetracycline (TTC), oxytetracycline (OTC) and chlorotetracycline (CTC) undergo rapid transformation to yield various products in the presence of MnO₂ at mild conditions (pH 4–9 and 22 °C). Reaction rates follow the trend of CTC > TTC > OTC, and are affected by pH and complexation of TCs with Mg²⁺ or Ca²⁺. Experimental results of TTC indicate that MnO₂ promotes isomerization at the C ring to form iso-TTC and oxidizes the phenolic-diketone and tricarbonylamide groups, leading to insertion of up to 2 O most likely at the C9 and C2 positions. In contrast, reactions of OTC with MnO₂ generate little iso-OTC, but occur mainly at the A ring’s dimethylamine group to yield N-demethylated products. CTC yields the most complicated products upon reactions with MnO₂, encompassing transformation patterns observed with both TTC and OTC. The identified product structures suggest lower antibacterial activity than that of the parent tetracyclines.