High-resolution mass spectrometry applied to the identification of transformation products of quinolones from stability studies and new metabolites of enrofloxacin in chicken muscle tissues

Assessment of Enrofloxacin Usage and Residue Levels of Enrofloxacin-Ciprofloxacin in Breast and Liver Tissues of Commercial Broilers Sold in Kampala-Uganda

Background

Human exposure to veterinary drugs like fluoroquinolones occurs due to the presence of their residues in foods from animal sources in varying concentrations. The existence of antibiotic residues in foodstuffs can pose great public health problems to consumers. This study aimed to assess enrofloxacin use patterns and assess residue levels of enrofloxacin/ciprofloxacin in breast muscle and liver tissues of broiler chickens sold for consumption in Kampala capital city.

Methods

This was a cross-sectional study that involved both field survey and laboratory-based methods. The field study involved the use of qualitative and semi-quantitative data collection tools to interview 34 broiler farmers and 10 veterinary drugs vendors. For the determination of enrofloxacin/ciprofloxacin levels, 68 chicken breast and liver tissue samples were collected from main markets in Kampala over one month and analyzed using HPLC-UV.

Results

Enrofloxacin was the most used antibiotic (100%) for the management of poultry diseases, majorly respiratory diseases (100%), salmonella infections (40%), and disease prevention (60%). Over 76% of the farmers knew the meat withdrawal time (WDT) for enrofloxacin, but none of them adhered to this. Over 70% of the farmers reported that the veterinary drugs vendors were not providing meat WDT information. Enrofloxacin/ciprofloxacin residues were identified in 35.3% (12/34) of the muscle and 38.2% (13/34) of the liver tissues analyzed. Of those muscle and liver tissue samples that tested positive, 25% (3/12) and 38.5% (5/13) respectively had drug concentrations higher than the recommended Maximum Residue Limits. The overall mean enrofloxacin/ciprofloxacin concentration in the chicken muscle and liver tissues was 83.6 (±34.5) µg/kg and 171.5 (±75.9) µg/kg.

Conclusion

This observed presence of enrofloxacin/ciprofloxacin levels above safety requirements is attributable to inadequate medicines use information provided by veterinary drugs vendors to farmers and also to the non-compliance of some farmers to meat WDT due to the economic implications.

Oxidation towards enrofloxacin degradation over nanoscale zero-valent copper: mechanism and products

Enrofloxacin (ENR) is a widely used veterinary fluoroquinolone antibiotic and is frequently detected in water environments. The degradation of ENR was examined utilizing molecular oxygen mediation using nanometer zero-valent copper (nZVC) as the catalyst in this work. The dosage of nZVC, initial pH, and reaction temperature were investigated as contributing factors to ENR degradation. The effects of Cl^-, NO^3-, SO4^2-, and humic acid on the degradation of ENR were investigated. The actual effects were evaluated using natural water. The reactive oxygen species (ROS) that participated in the reaction were identified, their generation mechanisms were elucidated, and the effects on ENR degradation were assessed. More emphasis was given to exploring ENR degradation and transformation pathways via analyses of HPLC-TOF-MS. Data showed that at 35 ℃, with an initial pH of 3 and exposed to air, an nZVC dose of 0.5 g·L^-1 degraded ENR by 99.51% dramatically. HO^• radicals were identified as the dominant ROS, and conversions among Cu⁰, Cu⁺, and Cu²⁺ played crucial roles in the generation of ROS. The destruction mechanism of ENR was speculated based on analyses of HPLC-TOF-MS results as the transformation of the piperazine ring into an oxidized state with a -COOH substitution with HO^•, which caused ENR to be mineralized and converted into CO₂, H₂O, and [Formula: see text]. The ECOSAR program has been used to evaluate the toxicity of ENR and its degradation products, and oxidative degradation of nZVC significantly reduced its toxicity and increased its biodegradability. This research proposes a capable and practical method for removing ENR from water.

Nontargeted screening of veterinary drugs and their metabolites in milk based on mass defect filtering using liquid chromatography-high-resolution mass spectrometry

The development of nontargeted screening strategy for veterinary drugs and their metabolites is very important for food safety. In this study, a nontargeted screening strategy was developed to find the potentially hazardous substances based on mass defect filtering (MDF) using liquid chromatography-high-resolution mass spectrometry. First, the drug metabolites of 112 veterinary drugs from seven classes of antimicrobials were predicted. Second, three MDF models were established, including the traditional rectangular MDF, the enhanced parallelogram MDF, and the polygonal MDF. Finally, the strategy was applied to nontargeted screening of veterinary drugs in 36 milk samples. The polygonal MDF model based on the distribution area of parent drugs and their metabolites showed a better filtering effect. After removing food components and performing MDF, about 10% of the substances remained, and four veterinary drugs and six drug metabolites were discovered and identified, showing the effectiveness of this strategy. The nontargeted screening strategy can rapidly remove interfering substances and find the suspected compounds. It can also be used for nontargeted screening of veterinary drugs and their metabolites in other food matrices.

Metabolites in Milk after Enrofloxacin Treatment and Their Persistence to Temperature

In this work, metabolomic profile changes in milk from cows affected by mastitis and treated with enrofloxacin (ENR) have been studied using LC-HRMS techniques. Principal component analysis was applied to the obtained results, and the interest was focused on changes affecting compounds without a structural relationship to ENR. Most of the compounds, whose concentrations were modified as a result of the pharmacological treatment and/or the pathological status, were related to amino acids and peptides. Compounds that may become possible biomarkers for either disease or treatment have been detected. Additionally, the alterations caused by thermal processes, such as those applied to milk before consumption, on the identified metabolites have also been considered.

Water-soluble manganese porphyrins as good catalysts for cipro- and levofloxacin degradation: Solvent effect, degradation products and DFT insights

Synthetic manganese porphyrins (MnPs), in the presence of oxidants, were employed for the degradation of fluoroquinolone antibiotics. Ciprofloxacin (CIP) and levofloxacin (LEV) degradation by iodosylbenzene, iodobenzene diacetate, H₂O₂ and meta-chloroperbenzoic acid using water-soluble MnP catalysts yielded thirteen and nine products, respectively, seven of which have been proposed for the first time. The MnP catalysts have demonstrated the ability to degrade these antibiotics to a high degree (up to 100% degradation). The structures of the degradation products were proposed based on mass spectrometry analysis, and density functional theory calculations could confirm how the substituent moieties attached to the basic chemical structure of the fluoroquinolones influence the degradation reactions. CIP has been shown to be a more reactive substrate towards the porphyrinic catalysts tested because of its three-membered ring. However, the catalysts could almost completely degrade LEV, highlighting the ability of these porphyrins to act as catalysts to degrade environmental pollutants.

Development of a new SLE-SPE-HPLC-MS/MS method for the determination of selected antibiotics and their transformation products in anthropogenically altered solid environmental matrices

The presence of antibiotic residues, their bioactive metabolites and other transformation products in the environment may adversely affect the organisms that live in the environment and may also contribute to increasing the antibiotic resistance of bacteria. It is particularly difficult to determine the types of contaminants in solid samples, in particular, those that are anthropogenically changed, e.g., as a result of controlled biochemical processes. Therefore, the aim of this research was to develop of a new method for the determination of twelve antibiotics belonging to different groups, such as penicillins, sulfonamides, tetracyclines, quinolones, imidazoles and cefalosporins, in digested manure and activated sludge samples, which were used as examples of anthropogenically altered environmental solid samples. The analyses were performed using high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The solid-liquid extraction (SLE) method to isolate analytes from digested manure and activated sludge was developed and optimized, the same as clean-up procedure followed by solid phase extraction (SPE). The recovery ranged from 45 to 85%. Finally, the validated method was applied to the determination of the selected antibiotics in manure and activated sludge samples after an anaerobic digestion process.. An additional aim of the study was to verify whether the developed method allows simultaneous detection of transformation products of the studied antibiotics in solid samples. The study showed that by optimizing the analysis conditions, it is possible to simultaneously determine the selected antibiotics and their transformation products (including their epimeric forms), which can significantly improve the ability to control the efficiency of the biological processes used in this area. In practice, this means that the developed methodology may be particularly useful in the context of research and other works related to the anaerobic digestion of activated sludge, manure or other solid substrates of environmental origin.

Ciprofloxacin by-products in seawater environment in the presence and absence of gilt-head bream

The widespread use of pharmaceuticals has caused a growing concern on the presence of pharmaceuticals such as the antibiotic ciprofloxacin (CIPRO) in the aquatic environment, since they may exert adverse effects on non-target organisms, including fish. In order to study the uptake, distribution in different tissues (liver, muscle, brain and gill) and biofluids (plasma and bile), metabolism and elimination of CIPRO in gilt-head bream (Sparus aurata), controlled dosing experiments for 8 days at 200 μg/L concentration were carried out. CIPRO was only observed in bile at concentration up to 315 ± 4 ng/mL, probably due to its low octanol-water partition coefficient (log P = -2.4 at pH 7.4) and the zwitterionic behavior (pKa₁ = 5.76 and pKa₂ = 8.68). CIPRO by-products (BPs) were also identified in seawater environment, both in presence and absence of fish. The analysis done by means of liquid chromatography-high resolution mass spectrometry (hybrid quadrupole-Orbitrap) permitted the annotation of up to 35 BPs of CIPRO in seawater and bile, from which 30 structures were reported for the first time. These results confirm that CIPRO is very susceptible to photolysis, and that it goes through various phase I and phase II metabolisms in the fish. All these results suggested that, for a complete characterization of CIPRO exposure, BPs should also be included in the biomonitoring campaigns since they might also be toxicologically relevant.

Metabolic profile modifications in milk after enrofloxacin administration studied by liquid chromatography coupled with high resolution mass spectrometry

High resolution accurate mass spectrometry (HRMS) operating in full scan MS mode was used in the search and identification of metabolites in raw milk from cows medicated with enrofloxacin. Data consisting of m/z features were taken throughout the entire chromatogram of milk samples from medicated animals and were compared with blank samples. Twenty six different compounds were identified. Some of them were attributed to structures related to enrofloxacin while others were dipeptides or tripeptides. Additionally, enrofloxacin was administered in a controlled treatment for three days. Milk was collected daily from the first day of treatment and until four days after in the search for the identified compounds. The obtained data were chemometrically treated by Principal Component Analysis. Samples were classified by this method into three different groups corresponding to days 1-2, day 3 and days 4-7 considering the different concentration profile evolution of metabolites during the days studied. Tentative metabolic pathways were designed to rationalize the presence of the newly identified compounds.