Advantages of LC–MS–MS compared to LC–MS for the determination of nitrofuran residues in honey

Detection of nitrofurazone with metal-organic frameworks and reduced graphene oxide composites: insights from molecular dynamics simulations

Two-dimensional metal-organic framework (MOF) composites were produced by incorporating Fe-MOFs into reduced graphene oxide (rGO) nanosheets to form Fe-MOF/rGO composites by hydrothermal synthesis. SEM, TEM, XRD, XPS, and measurements of contact angles were used to characterize the composites. TEM studies revealed that the rod-like-shaped Fe-MOFs were extensively dispersed on the rGO sheets. Incorporating Fe-MOF into rGO significantly improves performance due to the large surface area, chemical stability, and high electrical conductivity. The response signals for the electrochemical sensing performance of Fe-MOF/rGO-modified electrodes to nitrofurazone (NFZ) were significantly enhanced. Differential pulse voltammetry was used to detect the NFZ, and the MOF/rGO sensor possesses a lower detection limit (0.77μM) with two dynamic ranges from 0.6-60 to 128-499.3 μM and high sensitivity (1.909 μA·mM^-1·cm^-2). Moreover, the anti-interference properties of the sensor were quite reproducible and stable. To understand the mechanism responsible for the enhanced sensing performance of the composite, grand canonical Monte Carlo calculations were performed for Fe-MOF/rGO composites with five unit cells of Fe-MOF and four layers of rGO. We attributed the improvement to the fact that the interface between the Fe-MOF and rGO absorbed increased NFZ molecules. The findings reported herein confirm that such Fe-MOF/rGO composites have significantly improved electrochemical performance and practical applicability of sensing nitrofurazone.

Simultaneous Screening of Nitrofuran Metabolites in Honey Using Biochip Array Technology: Validation Study According to the Decision 2002/657/EC of the European Union

Background

Although no authorization is available for antibiotics to treat bee diseases, some veterinary compounds are used by beekeepers, and each country sets its own thresholds. Inappropriate and excessive use of these drugs can cause allergic reactions and antibiotic resistance in humans who consume the remaining antibiotic residues in honey and its products. It is, therefore, relevant to monitor the presence of antibiotic residues in this matrix.

Objectives

A rapid method for the simultaneous screening of nitrofuran metabolite residues in honey was validated according to Commission Decision 2002/657/EC (C.D 657) and the European guideline for the validation of screening methods for veterinary medicines.

Methods

This multi-analytical screening method enables the simultaneous determination of four nitrofuran metabolites [3-amino-2-oxazolidone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), 1-Aminohydantoin HCl (ADH), and semicarbazide (SEC)] from a single honey sample. Thirty-five honey samples were collected randomly as real samples for screening from Tehran, IR Iran, Germany, and the Netherlands in 2018.

Results

For all four antibiotic residues, the positivity threshold T was higher than the cut-off value Fm, and no false-positive results were obtained for three antibiotics (AOZ, AMOZ, and SEC). Detection capabilities (CCβ) of all compounds were under the minimum required performance limit (MRPL) authorized by the European Commission (currently 1 μg/kg). The screening results of 15 domestic and 20 imported honey samples showed that the levels of AOZ in 6.66% and 10% of the samples, the level of AMOZ in 13.33% and 0% of the samples, and the level of SEC in 33.33% and 40% of the samples were less than the cut-off ([in relative light units (RLUs)], respectively.

Conclusions

This study found that this technique is valid for detecting and quantifying three antibiotic residues in honey samples at the measured validation levels. This method was simple, rapid, and capable of simultaneously screening three nitrofuran metabolites from a single honey sample.

Unrevealing the Potential of Sansevieria trifasciata Prain Fraction for the Treatment of Androgenetic Alopecia by Inhibiting Androgen Receptors Based on LC-MS/MS Analysis, and In-Silico Studies

Androgenetic Alopecia (AGA) occurs due to over-response to androgens causing severe hair loss on the scalp, and requires the development of new and efficient drugs to treat this condition. This study explores and identifies secondary metabolites from Sansevieriatrifasciata Prain using the LC-MS/MS and in-silico method. The inhibitory activity of bioactive compounds from S. trifasciata Prain against androgen receptors (PDB ID: 4K7A) was evaluated molecularly using docking and dynamics studies by comparing their binding energies, interactions, and stability with minoxidil. The results of the LC-MS/MS analysis identified Methyl pyrophaeophorbide A (1), Oliveramine (2), (2S)-3′, 4′-Methylenedioxy-5, 7-dimethoxyflavane (3), 1-Acetyl-β-carboline (4), Digiprolactone (5), Trichosanic acid (6) and Methyl gallate (7) from the leaves subfraction of this plant. Three alkaloid compounds (compounds 1, 3, and 4), and one flavonoid (compound 2), had lower docking scores of −7.0, −5.8, −5.2, and −6.3 kcal/mol, respectively. The prediction of binding energy using the MM-PBSA approach ensured that the potency of the four compounds was better than minoxidil, with energies of −66.13, −59.36, −40.39, and −40.25 kJ/mol for compounds 1, 3, 2, and 4, respectively. The dynamics simulation shows the stability of compound 1 based on the trajectory analysis for the 100 ns simulation. This research succeeded in identifying the compound and assessing the anti-alopecia activity of Sansevieria trifasciata Prain. Seven compounds were identified as new compounds never reported in Sansevieria trifasciata Prain. Four compounds were predicted to have better anti-alopecia activity than minoxidil in inhibiting androgen receptors through an in silico approach.

Determination of Nitrofuran Metabolites in Complex Food Matrices Using a Rough, Cheap, Easy-Made Wooden-Tip-Based Solid-Phase Microextraction Probe and LC-MS/MS

In this study, a rough, cheap, easy-made wooden-tip-based solid-phase microextraction (SPME) probe was first developed for simultaneous determination of 4 nitrofuran metabolite derivatives in complex food matrices via LC-MS/MS. A simple dip-coating method was used to coat wooden tips with biocompatible polyacrylonitrile (PAN) and N-vinylpyrrolidone-co-divinylbenzene, also known as HLB particles, which served as the extractive substrate in the proposed device. Compared with the traditional solid-phase extraction (SPE) method, the proposed device shortens sample clean-up time, reduces solvent consumption, and decreases testing costs. In addition, the main parameters affecting the SPME procedure efficiency were investigated in detail and the optimal conditions were found. The method was validated using three different food matrixes (pork, croaker, and honey) by spiking with the four metabolites at 0.5, 1.0, and 5.0 μg/kg, as well as their internal standards. The average recovery of all nitrofuran metabolite derivatives ranges from 97.4–109.5% (pork), 87.5–112.7% (croaker), and 98.6–109.0% (honey). Relative standard deviations were all <10% for intraday and interday precision. The values of limit of detection and limit of quantification were, respectively, ranging from 0.011 to 0.123 and 0.033 to 0.369 μg/kg (pork), 0.009 to 0.112 and 0.027 to 0.339 μg/kg (croaker), and 0.010 to 0.131 and 0.030 to 0.293 μg/kg (honey). The presented method was applied to the analysis of real positive samples.

Artificial Intelligence in Functional Food Ingredient Discovery and Characterisation: A Focus on Bioactive Plant and Food Peptides

Scientific research consistently demonstrates that diseases may be delayed, treated, or even prevented and, thereby, health may be maintained with health-promoting functional food ingredients (FFIs). Consumers are increasingly demanding sound information about food, nutrition, nutrients, and their associated health benefits. Consequently, a nutrition industry is being formed around natural foods and FFIs, the economic growth of which is increasingly driven by consumer decisions. Information technology, in particular artificial intelligence (AI), is primed to vastly expand the pool of characterised and annotated FFIs available to consumers, by systematically discovering and characterising natural, efficacious, and safe bioactive ingredients (bioactives) that address specific health needs. However, FFI-producing companies are lagging in adopting AI technology for their ingredient development pipelines for several reasons, resulting in a lack of efficient means for large-scale and high-throughput molecular and functional ingredient characterisation. The arrival of the AI-led technological revolution allows for the comprehensive characterisation and understanding of the universe of FFI molecules, enabling the mining of the food and natural product space in an unprecedented manner. In turn, this expansion of bioactives dramatically increases the repertoire of FFIs available to the consumer, ultimately resulting in bioactives being specifically developed to target unmet health needs.

Highly sensitive SERS detection of residual nitrofurantoin and 1-amino-hydantoin in aquatic products and feeds

Nitrofurantoin (NFT), a typical highly effective nitrofuran antibiotic drug, has been prohibited but still widely found in animal food products. It can be metabolized in animals to form 1-amino-hydantoin (AHD) that can then form stable and toxic metabolite-protein adducts. Hence, the detection of NFT and AHD in aquatic products and feeds is very important. However, there are limited reports concerning NFT detection and none about AHD by using surface-enhanced Raman spectroscopy (SERS) method. Herein, potassium bromide (KBr) decorated silver (Ag) nanoparticles (Ag-BrNPs)-based SERS approach was proposed for NFT and AHD detection. The limit of detection (LOD) for NFT was 1 μg/L. The detection of NFT residues in sea cucumber and fish feeds was also realized with the LOD of 1 and 50 ng/g, respectively. More importantly, the sensing of AHD was easily realized with the SERS approach for the first time. After the derivatization with 2-nitrobenzaldehyde (2-NBA), Ag-BrNPs were also successfully utilized for AHD detection in sea cucumber with the LOD of 5 ng/g.

Presence of nitrofurans and their metabolites in gelatine

Following the detection of semicarbazide (SEM) in gelatine by Italian Authorities, at levels exceeding by three times the reference point for action (RPA) of 1 μg/kg, set out by Commission Regulation (EU) 2019/1871 for nitrofurans and their metabolites, the European Commission mandated EFSA to investigate the available sources of nitrofurans and their metabolites in gelatine. European Commission also asked EFSA to provide approaches that would distinguish SEM occurring due to illegal treatment with nitrofurazone from SEM produced during food processing. The literature indicates that SEM, both free and bound to macromolecules, could occur also in food products such as gelatine, during food processing, arising from the use of disinfecting agents and/or from reactions of various food components and, therefore, SEM cannot be considered as an unequivocal marker of the abuse of nitrofurazone in animal production. It is recommended to investigate in more detail which processing conditions lead to the formation of SEM in gelatine during its production and what levels can be found. One potential approach to distinguishing between SEM from nitrofurazone and SEM from other sources in food products, such as gelatine, might be based on determining the ratio of bound:free SEM in a sample of gelatine. However, whether the ratio of bound:free SEM would unequivocally distinguish between SEM arising from nitrofurazone abuse or from other sources still needs to be demonstrated.

Determination of nitrofuran metabolites in honey using a new derivatization reagent, magnetic solid-phase extraction and LC-MS/MS

In this study, 5-nitro-2-furaldehyde (5-NFA) was proposed as a new derivatizing agent for nitrofuran metabolites. It reacts with nitrofuran metabolites producing the parent nitrofurans (furazolidone, furaltadone, nitrofurantoin, and nitrofurazone). Magnetic hypercrosslinked polystyrene (HCP/Fe₃O₄) was first used for magnetic solid phase extraction (MSPE) clean-up before the determination of nitrofuran metabolite derivatives in honey via LC-MS/MS. Main parameters affecting the derivatization and MSPE efficiency were investigated in detail and the optimal conditions were found. The method was validated using honey spiked with the four metabolites at 1, 2 and 200 μg kg^-1. Recoveries of >85% were achieved for the all analytes. The matrix calibration curve was fitted with the correlation coefficient (R²) > 0.99 in the range of 1-200 μg kg^-1. Precision values expressed as relative standard deviation (RSD) were <12% and <15% for intra-day and inter-day precision, respectively. The limits of detection (LODs) for the nitrofuran metabolites were of 0.1-0.3 μg kg^-1 and the limits of quantitation (LOQs) were of 0.3-1.0 μg kg^-1. The proposed LC-MS/MS method was applied to the analysis of real honey samples.

Honey and its nutritional and anti-inflammatory value

Inflammation is the main key role in developing chronic diseases including cancer, cardiovascular diseases, diabetes, arthritis, and neurodegenerative diseases which possess a huge challenge for treatment. With massively compelling evidence of the role played by nutritional modulation in preventing inflammation-related diseases, there is a growing interest into the search for natural functional foods with therapeutic and preventive actions. Honey, a nutritional healthy product, is produced mainly by two types of bees: honeybee and stingless bee. Since both types of honey possess distinctive phenolic and flavonoid compounds, there is recently an intensive interest in their biological and clinical actions against inflammation-mediated chronic diseases. This review shed the light specifically on the bioavailability and bioaccessibility of honey polyphenols and highlight their roles in targeting inflammatory pathways in gastrointestinal tract disorders, edema, cancer, metabolic and cardiovascular diseases and gut microbiota.

Determination of Nitrofuran Metabolites in Fish by Ultraperformance Liquid Chromatography-Photodiode Array Detection with Thermostatic Ultrasound-Assisted Derivatization

Nitrofuran (NF) is a class of broad-spectrum antibiotics that are used illegally in animal feeding. NF and its metabolites have proven to pose potential risk to human health. To address the current analytical needs to quantify low levels of NF metabolites in animal foods, a sensitive method was developed for simultaneous detection of four NF metabolites in fish products by an ultraperformance liquid chromatography-diode array detector (UPLC-DAD). With 2-nitrobenzaldehyde (2-NBA) as the derivatizing reagent, the metabolites were hydrolyzed and derivatized under the assistance of thermostatic ultrasound. Compared with the current detection methods, the time of the derivatization reaction has been shortened from 16 to 2 h. The relative coefficient of four NF metabolite derivatives reached more than 0.998, with excellent linear relationship. The limits of detection (LODs) and limits of quantification (LOQs) of six repeated determinations reached 0.25-0.33 and 0.80-1.10 μg/kg, respectively. For all four NF metabolites, the limit of detection of the method was below the minimum required performance limit (MRPL) of 1.0 μg/kg, which makes it compatible with the EU requirements. The recoveries ranging from 89.8 to 101.9% with relative standard deviation below 6.5% were obtained for all of the NF metabolites. What's more, this method was successfully applied for the determination of four NF metabolites in the fish products. As a promising approach, this method could also be extended for the quantitation of NF metabolites in aquaculture and poultry products.

A mechanical stability enhanced luminescence lanthanide MOF test strip encapsulated with polymer net for detecting picric acid and macrodantin

The improper use of organic explosives and antibiotics have brought serious threats to the public health and the environmental safety, exploiting cost-effective and handy luminescent sensors with water stability and high selectivity in monitoring and detecting these hazardous substances are of utmost importance. Herein, we developed a simple yet powerful luminescent test strip sensor in a facile way. As for fabricating this test strip, the filter paper used for filtering lanthanide MOF (Ln-MOF) of [Tb(HIP)(H₂O)₅]·(H₂O)·(HIP)_1/2 (Tb-HIP, where HIP is 5-hydroxyisophthalate) powders was firstly recycled, and encapsulated with poly(methyl methacrylate) (PMMA) polymer net. The as-fabricated Tb-HIP test strips exhibit enhanced mechanical stability than the un-encapsulated ones, and show characteristic green emission of Tb³⁺. These test strips can behave as promising highly selective luminescent probes for picric acid (PA) and macrodantin (MDT) even existence of relevant potentially competing analytes. The detection limit for PA is 0.26 μM, and for MDT is 0.21 μM. In addition, the sensors can be successfully applied to detect PA in the river water samples as well as MDT in serum samples with satisfactory results. More importantly, the Tb-HIP test strips are highly efficient, recyclable luminescence sensors to detect PA and MDT.

Feasibility of a novel multispot nanoarray for antibiotic screening in honey

Practical solutions for multiple antibiotic determination in food are required by the food industry and regulators for cost-effective screening purposes. This study describes the feasibility in development and preliminary performance of a novel multispot nanoarray for antibiotic screening in honey. Using a multiplex approach, the metabolites of the four main nitrofuran antibiotics, including morpholinomethyl-2-oxazolidone (AMOZ), 3-amino-2-oxazolidinone (AOZ), semicarbazide (SEM), 1-aminohydantoin (AHD) and chloramphenicol (CAP), were simultaneously detected. Antibodies specific to the five antibiotics were nano-spotted onto microtitre plate wells and a direct competitive assay format was employed. The assay characteristics and performance were evaluated for feasibility as a screening tool for antibiotic determination in honey to replace traditional ELISAs. Optimisation of the spotting and assay parameters was undertaken with both individual and multiplex calibration curves generated in PBS and a honey matrix. The limits of detection as determined by the 20% inhibitory concentrations (IC₂₀) were determined as 0.19, 0.83, 0.09, 15.2 and 35.9 ng ml^-1 in PBS, 0.34, 0.87, 0.17, 42.1 and 90.7 ng ml^-1 in honey (fortified at the start of the extraction), and 0.23, 0.98, 0.24, 24.8 and 58.9 ng ml^-1 in honey (fortified at the end of the extraction) for AMOZ, AOZ, CAP, SEM and AHD respectively. This work has demonstrated the potential of multiplex analysis for antibiotics with results available for 40 samples within a 90-min period for antibiotics sharing a common sample preparation. Although both the SEM and AHD assay do not show the required sensitivity with the antibodies available for use to meet regulatory limits, with further improvements in these particular antibodies this multiplex format has the potential to show a reduction in cost with reduced labour time in combination with the high-throughput screening of samples. This is the first 96-well spotted microtitre plate nanoarray for the semi-quantitative and simultaneous analysis of antibiotics.

Enhancement of the capabilities of liquid chromatography-mass spectrometry with derivatization: general principles and applications

The integration of liquid chromatography-mass spectrometry (LC-MS) with derivatization is a relatively new and unique strategy that could add value and could enhance the capabilities of LC-MS-based technologies. The derivatization process could be carried out in various analytical steps, for example, sampling, storage, sample preparation, HPLC separation, and MS detection. This review presents an overview of derivatization-based LC-MS strategy over the past 10 years and covers both the general principles and applications in the fields of pharmaceutical and biomedical analysis, biomarker and metabolomic research, environmental analysis, and food-safety evaluation. The underlying mechanisms and theories for derivative reagent selection are summarized and highlighted to guide future studies.

Nitroreductive metabolic activation of some carcinogenic nitro heterocyclic food contaminants in rat mammary tissue cellular fractions

Several nitrofurans and nitroimidazoles have been widely used in veterinary medicine. Some of these compounds are breast carcinogens in rodents and their mechanism of action is hypothesized to be related to reactive metabolites generated by nitroreduction and/or via oxygen-dependent redox cycling. The present work describes the nitroreductive metabolism of nitrofurazone, nitrofurantoin, furazolidone, and metronidazole by the cytosolic and microsomal fractions of mammary tissue from female Sprague-Dawley rats. The data obtained were compared with those obtained with nifurtimox and benznidazole, two well-known rodent carcinogen/mutagens nitroheterocycles. The nitroreductase activity of pure milk xanthine-oxidoreductase (XOR) was evaluated for screening purposes. All the nitrofurans were nitroreduced either by the pure XOR or the cytosolic fraction in the presence of hypoxanthine, and these activities were inhibited by allopurinol. Furthermore, they were nitroreduced by the microsomal fraction in the presence of NADPH, except for the nitrofurazone, suggesting the participation of cytochrome P450 reductase. Nitrofurans metabolism was significantly more intense than that of NFX. No equivalent nitroreductase activity was observed in either subcellular fraction using nitroimidazolic compounds as substrates. These results suggest that the nitroreductive metabolism of nitrofurans and the subsequent redox cycling might be involved in the associated mammary tissue carcinogenic effects.