- Antibacterial activity of sulfamethoxazole transformation products (TPs): General relevance for sulfonamide TPs modified at the para position
-
Sulfonamide antibiotics undergo transformation in the aquatic environment through biodegradation, photolysis, or hydrolysis. In this study, the residual antibacterial activity of 11 transformation products (TPs) of sulfamethoxazole (SMX) was investigated with regard to their in vitro growth and luminescence inhibition on Vibrio fischeri (30 min and 24 h exposure). Two transformation products, 4-hydroxy-SMX and N4-hydroxy-acetyl-SMX, were synthesized in-house and confirmed by nuclear magnetic resonance and high-resolution mass spectrometry. Results of individual compound experiments showed that TPs modified at the para amino group still exhibit clear antibacterial effects, whereas TPs resulting from breakdown of the SMX structure lost this mechanism of action. 4-NO2- and 4-OH-SMX were found to inhibit growth to a clearly greater extent than the parent compound, SMX. In contrast, the N4-acetyl- and N4-hydroxy-acetyl-derivatives retain less than 10 and 5% of the effect of SMX on growth and luminescence inhibition, respectively. The effect of a mixture of para-modified TPs was observed to be additive. Considering the homologous series of sulfa drugs widely prescribed and their common mechanism of action, the potential environmental impact must consider the total amount of sulfonamide antibiotics and their derivative TPs, which might end up in a water body. Extrapolating the results obtained here for the para TPs of SMX to other sulfa drugs and determining the persistence and occurrence of these compounds in the aquatic environment is required for improved risk assessment. (Chemical Equation Presented).
- Majewsky, Marius,Wagner, Danny,Delay, Markus,Br?se, Stefan,Yargeau, Viviane,Horn, Harald
-
-
Read Online
- 0D/1D AgI/MoO3 Z-scheme heterojunction photocatalyst: Highly efficient visible-light-driven photocatalyst for sulfamethoxazole degradation
-
Low dimension nano photocatalysts show great potential in the field of treating contaminated water for their large surface area and size effect. In this study, a 0D/1D AgI/MoO3 Z-scheme photocatalyst with striking photocatalytic performance was constructed successfully. The one-dimensional MoO3 nanobelts were prepared by a simple hydrothermal method, and then it was modified by AgI nanoparticles in a handy deposition approach. When choosing sulfamethoxazole (SMZ) as the target contaminant, the rate constant value of the optimal 0D/1D AgI/MoO3 composite could hit up to 0.13 min?1, which is nearly 22.4 times and 32.5 times as that of pure MoO3 (0.0058 min?1) and AgI (0.0040 min?1), respectively. A series of detailed characterizations give evidences that the charge transfer in the composite followed Z scheme mechanism. Therefore, efficient separation/transfer and the remained high redox activity of photogenerated carriers played a vital role in the sharply enhanced photocatalytic properties. The possible degradation pathways of SMZ were proposed based on the intermediates detected by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Meanwhile, the magnificent cyclic stability makes the material a promising material in the practical application.
- Xu, Jing,Chen, Juan,Ao, Yanhui,Wang, Peifang
-
supporting information
p. 3226 - 3230
(2021/05/29)
-
- A convenient synthesis of phenols
-
Anilines are rapidly, often within 60 minutes, converted into the corresponding phenols in up to 87% isolated yield. The presented experimentally simple protocol display broad compatibility with a variety of functional groups, and in particular, well suited for the preparation of methyl-substituted phenols. Such phenols are not easily available by other synthetic approaches. The formation of phenolic radical coupling products was not observed even for activated anilines using this open flask method.
- Kristianslund, Renate,Vik, Anders,Hansen, Trond V.
-
supporting information
p. 2809 - 2814
(2018/12/04)
-
- Insight into sulfamethoxazole degradation, mechanism, and pathways by AgBr-BaMoO4 composite photocatalyst
-
A composite photocatalyst, AgBr-BaMoO4 was fabricated by two step method; microwave hydrothermal and precipitation-deposition. The as prepared photocatalyst samples were characterized by various techniques. The facet coupling was seen between the (204) plane of BaMoO4 and (200)/(222) planes of AgBr on the basis of XRD/HRTEM analysis. The pharmaceutical pollutant, sulfamethoxazole was adopted to investigate the photocatalytic performances of samples under UV–vis irradiation. The AgBr-BaMoO4 composite degraded the aqueous sulfamethoxazole drug in UV–vis light about 64% within 75 min, which was attributed to efficient separation of photogenerated electron–hole pairs across the interface between Ag/AgBr and BaMoO4. The multi-electron induced oxygen reduced reaction (ORR) was observed. The radical trapping experiment indicates that OH? has major role for sulfamethoxazole degradation. The four successive photodegradation of sulfamethoxazole in UV–vis light indicates the stability of composite photocatalyst. Furthermore, the three different degradation pathways were designed on the basis of retention time and molecular masses of 18 degraded organic fragments that was confirmed by high-performance liquid chromatography photodiode array (HPLC-PDA) and high resolution-quadruple time of flight electrospray ionization mass spectroscopy (HR-QTOF ESI/MS) techniques. The total organic carbon (TOC) analysis suggested the mineralization of SMZ by composite photocatalyst. This study not only demonstrates the enhancement of photocatalytic performance of wide band gap semiconductor by making composite with narrow band gap semiconductor but also detail degradation pathways and mechanisms of sulfamethoxazole.
- Ray, Schindra Kumar,Dhakal, Dipesh,Lee, Soo Wohn
-
p. 686 - 695
(2018/07/14)
-