Typical Sulfonamides Research Articles

Facile Room‐Temperature Synthesis of Novel Porous Three‐Component Hybrid Covalent Organic Polymers and Their Applications towards Sulfadiazine Adsorption

AbstractSince the environmental pollution posed by widely used sulfonamide antibiotics has been reported in natural aquatic system, designing novel adsorbents with excellent behaviors for adsorptive removal of sulfonamide antibiotics becomes a critical challenge in remediation management. Herein, two three‐component hybrid covalent organic polymers were successfully developed through a facile room‐temperature solution‐suspension method based on dynamic covalent Schiff‐base chemistry and used to remove a typical sulfonamide antibiotic [sulfadiazine (SDZ)] from aqueous solution. The 1,3,5‐triformylphloroglucinol (TFP) and benzene‐1,3,5‐tricarbohydrazide (BTCH) reacted with benzidine (BD) (JLUE‐COP‐26) and exhibited a good adsorption capacity for SDZ, followed by the reaction of TFP, BTCH and p‐phenylenediamine (PDA) (JLUE‐COP‐25). Moreover, the adsorption data of SDZ by two JLUE‐COPs were analyzed to be pseudo‐second‐order kinetic representable and Langmuir adsorption model fitted. In addition, the possible underlying mechanisms were proposed as a combination of porous feature, electrostatic force, hydrophobic interaction, π‐π stacking and hydrogen bonding interaction.

Removal of Sulfamethoxazole, Sulfathiazole and Sulfamethazine in their Mixed Solution by UV/H2O2 Process.

Sulfamethoxazole (SMZ), sulfathiazole (STZ) and sulfamethazine (SMT) are typical sulfonamides, which are widespread in aqueous environments and have aroused great concern in recent years. In this study, the photochemical oxidation of SMZ, STZ and SMT in their mixed solution using UV/H2O2 process was innovatively investigated. The result showed that the sulfonamides could be completely decomposed in the UV/H2O2 system, and each contaminant in the co-existence system fitted the pseudo-first-order kinetic model. The removal of sulfonamides was influenced by the initial concentration of the mixed solution, the intensity of UV light irradiation, the dosage of H2O2 and the initial pH of the solution. The increase of UV light intensity and H2O2 dosage substantially enhanced the decomposition efficiency, while a higher initial concentration of mixed solution heavily suppressed the decomposition rate. The decomposition of SMZ and SMT during the UV/H2O2 process was favorable under neutral and acidic conditions. Moreover, the generated intermediates of SMZ, STZ and SMT during the UV/H2O2 process were identified in depth, and a corresponding degradation pathway was proposed.

Enhanced sulfamethoxazole degradation by peroxymonosulfate activation with sulfide-modified microscale zero-valent iron (S-mFe0): Performance, mechanisms, and the role of sulfur species

Sulfide-modified microscale zero-valent iron (S-mFe0) was applied to activate peroxymonosulfate (PMS) to degrade sulfamethoxazole (SMX), a typical sulfonamide bacteriostatic antibiotic. In this work, the effects of S/Fe molar ratio, S-mFe0 dosage, PMS dosage, different initial pH value, dissolved oxygen, SMX concentration and inorganic ions on SMX removal by S-mFe0/PMS system were investigated, respectively. Besides, the role of sulfur species (including the FeS, SO32−, S2−) was studied. In contrast to mFe0/PMS system, the removal efficiency of SMX obtained by S-mFe0 /PMS system was increased by 29.4%. Radical quenching and Electron Paramagnetic Resonance spectroscope (EPR) tests identified that both OH and SO4− were committed to degrading SMX, and SO4− was proven to be the dominant one. The electrochemical analysis of S-mFe0 and bare mFe0, implying a better electron transfer ability of S-mFe0 due to the formation of FeS. Furthermore, the activation of S2− for PMS could be ruled out by EPR tests results. Conversely, SO32− could effectively activate PMS to generate reactive oxygen species (ROS). The catalytic mechanisms of S-mFe0/PMS system were clarified by SEM-EDS, XRD, XPS, radical quenching and EPR tests. Based on the detected intermediates via LC-TOF-MS/MS, the degradation pathways of SMX by S-mFe0/PMS system were proposed. Overall, the work suggests that S-mFe0/PMS system has a good potential for the elimination of micropollutants in the aquatic environment.

Effect of cation type in mixed Ca-Na systems on transport of sulfonamide antibiotics in saturated limestone porous media.

Retention and transport of sulfonamides (SAs) in subsurface can strongly affect groundwater quality. In this work, a range of laboratory batch sorption and column transport experiments were conducted to determine the effect of cation type in mixed Ca-Na systems on the retention and transport of two typical SAs, sulfadimethoxine (SDM) and sulfacetamide (SCA), in saturated limestone porous media. Column experimental data showed divalent cation Ca2+ played a more important role than monovalent cation Na+ in decreasing the transport of only SDM in co-cation systems in the saturated limestone media. Further, in the single-cation (i.e., including either Ca2+ or Na+) system, increasing ionic strength (IS) of either NaCl or CaCl2 had little effect on SCA transport; however, increasing of IS of CaCl2 promoted the retention of SDM in the saturated limestone porous media. This is mainly due to the cation bridging effect of Ca2+ on SDM and limestone. Overall, SDM showed much higher retention in the limestone columns than SCA, which can be attributed to the two SAs' different physicochemical properties. Moreover, limestone showed stronger ability to retain the two SAs than quartz sand. Findings in this study suggest that cation type and the concentration of certain electrolyte (e.g., CaCl2) as well as medium type play an important role in controlling the environmental fate and transport of antibiotics.

Dihydropteroate synthase based sensor for screening multi-sulfonamides residue and its comparison with broad-specific antibody based immunoassay by molecular modeling analysis

A biosensor that could simultaneously detect multi-analyte as many as in a single test is more favored when facing lots of samples for screening purpose. In such a biosensor, the recognition element with broad specificity and highly affinity is a key reagent for detection spectrum. Here we report a dihydropteroate synthase (DHPS) based biosensor for detecting 29 sulfonamides (SAs) in milk. The biosensor was established in a competitive format where HRP-labeled tracer and free SAs competitively binding to the limited amount of DHPS-DHPPP (6-hydroxymethyl-7,8-dihydropterin diphosphate) binary complex. Compared to other biosensors based on antibodies with the same objective, the current sensor employing DHPS provided not only highly sensitivity but also preponderant uniform affinities for all individual sulfonamide, which has never been achieved before in any immunosensor. However, the difference of recognition mechanism between DHPS and antibody remains unknown. To address this question, we deconstructed the variable region of two monoclonal antibodies produced by our group and then compared the intermolecular forces and key contacting amino acid residues of both DHPS and antibodies to several typical SAs with help of molecular modeling analysis. Results showed the orientation of the ligands in the binding site played a significant role during the recognition with proteins. The optimized assay provided a limit of detection (LOD) of 1.15–14.91 ng mL−1 and dynamic range was ranging from 1.54 to 126.85 ng mL−1 for 29 SAs. The developed biosensor finally was validated for five SAs in spiked milk with recovery values ranging from 72.7 to 129.3% and coefficients of variation less than 16.0%. The study showed that the biosensor based on DHPS make it a suitable screening method for the simultaneous determination of total SAs residues in food matrices.

Molecular iodine enhancing sulfadiazine photodegradation in water under UVA irradiation

Photodegradation of sulfadiazine (SD), a typical sulfonamide antibiotic (SA) frequently detected in the aquatic environment, under UVA irradiation enhanced by molecular iodine was investigated. Herein, molecular iodine I2 and coexisting I3− were provided by hydrogen peroxide and potassium iodide in acidic solution. During the treatment, highly reactive iodine radicals (I·, I2−), produced by UVA photolytic activation of both I2 and I3−, were verified as the dominated oxidant species against the decomposition of SD in aqueous solution. Besides, SD removal was found to be affected by the initial pH value, KI and H2O2 added concentrations.

Interaction between typical sulfonamides and bacterial diversity in drinking water.

The abuse of antibiotics is becoming more serious as antibiotic use has increased. The sulfa antibiotics, sulfamerazine (SM1) and sulfamethoxazole (SMZ), are frequently detected in a wide range of environments. The interaction between SM1/SMZ and bacterial diversity in drinking water was investigated in this study. The results showed that after treatment with SM1 or SMZ at four different concentrations, the microbial community structure of the drinking water changed statistically significantly compared to the blank sample. At the genus level, the proportions of the different bacteria in drinking water may affect the degradation of the SM1/SMZ. The growth of bacteria in drinking water can be inhibited after the addition of SM1/SMZ, and bacterial community diversity in drinking water declined in this study. Furthermore, the resistance gene sul2 was induced by SM1 in the drinking water.

New insights into the chlorination of sulfonamide: Smiles-type rearrangement, desulfation, and product toxicity

Sulfamethazine (SMZ) is a typical sulfonamide antibiotic that has been frequently detected in municipal sewage, surface waters and drinking water. In this study, the oxidation of SMZ by free chlorine (HOCl/OCl−) was investigated in detail, including the reaction kinetics, transformation products (TPs), reaction pathway, and toxicity change. Free available chlorine (FAC) was effective to eliminate SMZ, with a half-life of 0.98min in the presence of 3mg/L FAC and 10μg/L SMZ at pH 7. The removal favoured neutral pH ranging from 6.08 to 7.98. Twelve oxidation products were identified using HPLC-QTOF-MS and HPLC-MS/MS. The Smiles-type rearrangement and the following desulfation process were speculated as the major pathway, via which approximate 40% of SMZ were transformed. Quantum chemistry calculation indicated that the substitution of chlorine to the amino group increased the electrophilicity of the aniline carbon, and thus facilitated the rearrangement. The rearrangement and desulfation product, N-(4,6-dimethylpyrimidin-2-yl)benzene-1,4-diamine (DMPBDA), was identified using the corresponding standard substance. Most of the other TPs were originated from DMPBDA through further chlorination and coupling reaction. Toxicity assays employing the photobacterium V. fischeri indicate the generation of more toxic TPs compared to SMZ. As the reaction progressed, toxicity continued to increase, and the percentage inhibition reached 97% and 99% on the 7th day and 14th day, respectively. This study presented a new possible reaction pathway for the chlorination of sulfonamide antibiotics and provided useful information for better evaluation of the effectiveness and safety of chlorination.

Oxidation of sulfamethoxazole (SMX) by chlorine, ozone and permanganate—A comparative study

Sulfamethoxazole (SMX), a typical sulfonamide antibiotic, has been widely detected in secondary wastewater effluents and surface waters. In this work we investigated the oxidative degradation of SMX by commonly used oxidants of chlorine, ozone and permanganate. Chlorine and ozone were shown to be more effective for the removal of SMX (0.05–5.0mg/L), as compared with permanganate. Higher pH enhanced the oxidation of SMX by ozone and permanganate, but decreased the removal by chlorine. Moreover, the ozonation of SMX was significantly influenced by the presence of humic acid (HA), which exhibited negligible influence on the oxidation by chlorine and permanganate. Fairly lower mineralization of SMX occurred during the oxidation reactions, with the highest dissolved organic carbon (DOC) removal of 13% (for ozone). By using LC–MS/MS, 7, 5 and 5 oxidation products were identified for chlorine, ozone and permanganate and possible transformation pathways were proposed. It was shown that different oxidants shared some common pathways, such as the cleavage of SN bond, the hydroxylation of the benzene ring, etc. On the other hand, each of the oxidants also exhibited exclusive degradation mechanisms, leading to the formation of different transformation products (TPs). This work may provide useful information for the selection of oxidants in water treatment processes.

Fragmentation of typical sulfonamide drugs via heterolytic bond cleavage and stepwise rearrangement

Although many experiments have been carried out to elucidate the fragmentation of typical sulfonamide drugs, little effort has been devoted to understanding the reaction process theoretically.

Inhibition of α-class cytosolic human carbonic anhydrases I, II, IX and XII, and β-class fungal enzymes by carboxylic acids and their derivatives: New isoform-I selective nanomolar inhibitors

The members of a focused series of carboxylic acids and of their derivatives (esters, amides and metal complexes) have been investigated as inhibitors of the main cytosolic/transmembrane carbonic anhydrase isoforms, CA I, II, IX and XII, belonging to the mammalian α-class of CAs. These enzymes are present in red blood cells in submillimolar concentration, and typical sulfonamide CA inhibitors do not selectively inhibit any of them. Among such isozymes, the isoform-I is an ‘orphan’ target that mediates hemorrhagic retinal and cerebral vascular permeability, involved in retinal and cerebral disease. In the present study, we identified the first selective CA I nanomolar inhibitors, that displayed activity against other isozymes in micromolar/millimolar concentration range. Selective CA II over CA I inhibition has also been observed with some diketo acids/metal complexes. Few diketo acid derivatives showed inhibition activities against the fungal β-class enzymes from Candida albicans and Cryptococcus neoformans in low micromolar concentration range. Prediction of drug-like properties for the most interesting compounds suggests a favorable bioavailability.

Kinetics of Ozonation of Typical Sulfonamides in Water

Objective To investigate the kinetic rate constants ozone and hydroxyl radicals towards two groups of antimicrobials —sulfadiazine (SD) and sulfamethoxazole (SMX). Methods The solute consumption method was used to detect the rate constants of ozone alone with sulfadiazine and sulfamethoxazole, and tertiary butanol was selected as a scavenging agent and pH was adjusted to 2.5 by adding orthophosphate buffers (OB); and the competition kinetics studying methodwith nitrobenzene as a reference was applied to measure the rate constants of hydroxyl radicals towards sulfadiazine and sulfamethoxazole, and pH was adjusted to 7.0 by adding OB. Results The rate constants of SD and SMX with ozone alone were 261 mol −1 · dm 3 · s −1 and 303 mol −1 · dm3 · s −1 by calculating in low reaction system. The rate constants of hydroxyl radicals with SD and SMX were 2.2×1010 mol −1 · dm 3 · s −1 and 2.7×1010 mol −1 · dm 3 · s −1, respectively. Moreover, the rate constants of hydroxyl radicals with SMX were found to have increased from 3.6×109 mol −1 · dm 3 · s −1 to 2.8×1010 mol −1 · dm 3 · s −1 with pH value rising from 5.0 to 7.8. Conclusion SMX and SD are both refractory to ozone oxidation alone, and are liable to be degraded by hydroxyl radicals, and the rate constants of SMX with the hydroxyl radical slightly increases with pH rise.

Comparison of separation conditions and ionization methods for the liquid chromatography–mass spectrometric determination of sulfonamides

The effects of the type and concentration of buffer, composition of the mobile phase and the ionization mode, used for the separation and detection of sulfonamides with LC–MS, were studied. Five typical sulfonamides were selected as target compounds and beef meat was selected as a matrix sample. For the separation of sulfonamides, 0.05 M NH 4Ac in 13–15% aqueous acetonitrile, APCI ionization was more effective than ESI with regard to separation efficiency and the detection sensitivity.

Determination of Sulfonamides in Meat by Liquid Chromatography Coupled with Atmospheric Pressure Chemical Ionization Mass Spectrometry

Liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) has been used for the determination of sulfonamides in meat. Five typical sulfonamides were selected as target compounds, and beef meat was selected as a matrix sample. As internal standards, sulfapyridine and isotope labeled sulfamethazine ( 1 3 C 6 -SMZ) were used. Compared to the results of recent reports, our result have shown improved precision to a RSD of 1.8% for the determination of sulfamethazine spiked with 75 ng/g level in meat.