Synthesis of typical sulfonamide antibiotics with [14C]- and [13C]-labelling on phenyl ring for environmental studies

Background As a kind of widely used antibiotics, sulfonamide antibiotics (SAs) has become ubiquitous environmental contaminants that caused public concerns. The behavior of SAs in complex environmental system need to be elucidated, which is hampered by unavailability or high cost of isotope-labelled SAs. Results Using commercially available uniformly [l4C]- and [l3C]-labelled aniline as starting material, we synthesized [phenyl-ring-14C]- and [phenyl-ring-l3C]-labelled sulfamethoxazole (SMX), sulfamonomethoxine (SMM), and sulfadiazine (SDZ) using four-step (via condensation of labelled N-acetylsulfanilyl chloride and aminoheterocycles) or five-step (via condensation of labelled N-acetylsulfonamide and chloroheterocycles) reactions in good yields (5.0−22.5% and 28.1−54.1% for [14C]- and [13C]-labelled SAs, respectively) and high purities (> 98.0%). Conclusion The synthesis of [l4C]-labelled SAs could be completed on milligram-level, being feasible for preparation of labelled SAs with high specific radioactivity. This study provides efficient and maneuverable methods to obtain a variety of [14C]- or [13C]-labelled SAs for studies on their environmental behavior, such as fate, transformation, and bioaccumulation.

Distribution of Sulfonamide Antibiotics and Resistance Genes and Their Correlation with Water Quality in Urban Rivers(Changchun City), China in Autumn and Winter

With the extensive use of antibiotics, antibiotics contamination and antibiotic resistance genes (ARGs) in the water environment is becoming severe. In this study, the distribution characteristics of sulfonamide antibiotics and resistance genes in the urban section of the Yitong River in autumn and winter were studied. The correlation between them and water quality parameters was analyzed using liquid chromatography/mass spectrometry (LC/MS/MS) and polymerase chain reaction (PCR) fluorescence quantitative technology. The results showed that the concentration of seven sulfonamide antibiotics in surface water and sediment of the river was generally at the level of ng/L and ng/g; the total concentration range was 11.08-160.60ng/L and ND-85.68ng/g, respectively. The total concentrations of antibiotics were similar in autumn and winter, where SMX was the primary type of antibiotics. The results of Risk Quotients (RQs) showed that SMX and SDZ had moderate acute risk to the corresponding sensitive species in river water, SPD and SIZ had low acute risk, while the rest had no risk. The total bacterial abundance in surface water and sediment was in the range of 10 5 -10 6 and 10 8 -10 11 , respectively. The detection rates of three sulfonamide resistance genes were 100%; the relative abundance was in the range of 10 -3 -10 -1 , and sul1 was the primary resistance gene. The correlation analysis showed that most antibiotics were significantly related. The three resistance genes had a positive correlation, negative correlation, and non-correlation, and most antibiotics had a weak correlation with resistance genes. Nutrients had a more significant impact on antibiotics, and other water quality indicators had a more negligible effect on antibiotics and resistance genes.