Comparison of ELISA and HPLC for the determination of histamine in cheese

Visual detection of biogenic monoamines based on amine oxidase-peroxidase coupling reaction using ascorbic acid as H2O2 scavenger

This study represents a visual detection for total biogenic monoamines with naked eye as a simple and rapid semi-quantitative method for biogenic amine monitoring. The equivalent reaction of H2O2 with ascorbic acid resulted in color development by an amine oxidase-peroxidase coupling reaction in the samples containing the biogenic monoamines higher than the subjected ascorbic acid by 10 μM. Upon employing the commercial doenjang extracts as a model food, an additional heating step was requested, and the expected ranges for the biogenic monoamines from 360 to 480 μM covered the real contents of the samples (360.2-407.3 μM). Therefore, this visual detection method makes it possible to decide with naked eye whether the sample contains the biogenic monoamines higher than the ascorbic acid supplemented as much as a control level on manufacturing sites without instrumental analysis.

Histamine-Responsive Hydrogel Biosensors Based on Aptamer Recognition and DNA-Driven Swelling Hydrogels

Detection of chemical substances is essential for living a healthy and cultural life in the modern world. One type of chemical sensing technology, biosensing, uses biological components with molecular recognition abilities, enabling a broad spectrum of sensing targets. Short single-stranded nucleic acids called aptamers are one of the biological molecules used in biosensing, and sensing methods combining aptamers and hydrogels have been researched for simple sensing applications. In this research, we propose a hydrogel-based biosensor that uses aptamer recognition and DNA-driven swelling hydrogels for the rapid detection of histamine. Aptamer recognition and DNA-driven swelling hydrogels are directly linked via DNA molecular reactions, enabling rapid sensing. We selected histamine, a major food poisoning toxin, as our sensing target and detected the existence of histamine within 10 min with significance. Because this sensing foundation uses aptamers, which have a vast library of targets, we believe this system can be expanded to various targets, broadening the application of hydrogel-based biosensors.

A novel method for evaluating pseudoallergy based on β-hexosaminidase and its application for traditional Chinese medicine injections

Pseudoallergy is a typical and common adverse drug reaction to injections, especially in traditional Chinese medicine injections (TCMIs). At present, the evaluation methods for pseudoallergy include cell methods in vitro and animal methods in vivo. The mast cell evaluation method based on the β-hexosaminidase (β-Hex)-catalyzed substrate, 4-nitrophenyl-β-N-acetyl-D-glucosaminide (4-NPG), is an important method for the evaluation of drug-induced pseudoallergy, but it is prone to false positive results and has insufficient sensitivity. In this study, a novel β-Hex evaluation system with rat basophilic leukemia-2H3 cells based on high-performance liquid chromatography-fluorescence detection (HPLC-FLD) was established, which effectively increased the sensitivity and avoided false positive results. Cell viabilities were measured by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide assay. In addition, a method for the determination of histamine, which is another indicator in the development of pseudoallergy, was established to validate the above method. The results of this novel method indicated that two TCMIs (Shuxuening injection and Shenqi Fuzheng injection), which were considered to be pseudoallergenic using 4-NPG, were not pseudoallergenic. Overall, the novel β-Hex/HPLC-FLD evaluation system using Rat basophilic leukemia-2H3 cells established was effective and precise. It could be used for the evaluation of pseudoallergic reactions caused by TCMIs and other injections.

Analytical strategies for the determination of biogenic amines in dairy products

Biogenic amines (BA) are mainly produced by the decarboxylation of amino acids by enzymes from microorganisms that emerge during food fermentation or due to incorrectly applied preservation processes. The presence of these compounds in food can lead to a series of negative effects on human health. To prevent the ingestion of high amounts of BA, their concentration in certain foods needs to be controlled. Although maximum legal levels have not yet been established for dairy products, potential adverse effects have given rise to a substantial number of analytical and microbiological studies: they report concentrations ranging from a few mg/kg to several g/kg. This article provides an overview of the analytical methods for the determination of biogenic amines in dairy products, with particular focus on the most recent and/or most promising advances in this field. We not only provide a summary of analytical techniques but also list the required sample pretreatments. Since high performance liquid chromatography with derivatization is the most widely used method, we describe it in greater detail, including a comparison of derivatizing agents. Further alternative techniques for the determination of BA are likewise described. The use of biosensors for BA in dairy products is emerging, and current results are promising; this paper thus also features a section on the subject. This review can serve as a helpful guideline for choosing the best option to determine BA in dairy products, especially for beginners in the field.

A simpler potentiometric method for histamine assessment in blood sera

Histamine intolerance results from a disequilibrium of accumulated histamine and the capacity for histamine degradation. An impaired histamine degradation based on reduced DAO activity and the resulting histamine excess may cause numerous symptoms mimicking an allergic reaction. For that, the determination of histamine in blood or in food products has great importance to identify risk factors. A new histamine-selective electrode is proposed using cucurbit[6]uril (CB[6]), as ionophore, in the analysis of biological samples. The selection of this smart supramolecular organic framework was based on its apparent stability constant of histamine-CB[6] (log β) of 4.33. The optimized electrode based on a polymeric membrane (PVC) combines the histamine-selective ionophore with 2-nitrophenyl octyl ether as solvent mediator and potassium tetrakis(4-chlorophenyl)borate as anionic additive. Furthermore, multi-walled carbon nanotubes particles were included in the membrane composition to partly lower the detection limit of the method, while improving stability and lowering the response drift (± 4 mV). The electrodes showed a rapid response (≃ 13 s) in the pH operational range of 2.7-5.4, with a Nernstian slope of 30.9 ± 1.2 mV/dec, a detection limit of (3.00 ± 0.61) × 10^-7 mol/L, and a lower limit of the linear range of (3.00 ± 0.00) × 10^-7 mol/L. After miniaturization, the electrode was used as a detector in a sequential-injection lab-on-valve flow setup. The optimized flow conditions were achieved for sample injection volumes of 197 μL propelled towards the cell under detection, at a flow rate of 30 μL/s during 100 s, making the analysis of 30 samples per hour possible. The developed system was used to analyze spiked blood serum samples previously cleaned by using solid-phase extraction. The sample pretreatment of the serum samples using Oasis MCX cartridges showed outstanding efficiency for histamine determination. The recovery values for three different levels of histamine concentration (1 × 10^-4 mol/L, 1 × 10^-5 mol/L, and 1 × 10^-6 mol/L) were (97 ± 6)%, (103 ± 1)%, and (118 ± 9)%, respectively, showing that this method was suitable for biological samples.

Towards a catheter-based impedimetric sensor for the assessment of intestinal histamine levels in IBS patients

In this work, we report on the development of a catheter-based sensor designed for measuring the concentration of histamine in the human duodenum. Certain gut disorders, such as the irritable bowel syndrome (IBS), are associated with elevated levels of intestinal histamine due to chronic immune activation. As it is still impossible to determine histamine concentrations in vivo, a nasointestinal catheter with histamine-sensing capabilities has the potential to become a valuable diagnostic instrument. Regarding the sensing principle, we selected impedance spectroscopy using voltages that are compatible with intra-body applications with molecularly imprinted polymers (MIPs) as recognition elements. MIPs are synthetic receptors that offer the advantages of robustness, high specificity and selectivity for histamine as a target. In this specific case, the MIPs were synthesized from acryclic acid monomers, which guarantees a uniform binding capacity within the pH range of intestinal fluid. We have validated the catheter sensor on human intestinal liquids spiked with histamine in a testing setup that mimics the environment inside the duodenum. The dose-response curves show an analytical range between 5 and 200 nM of histamine, corresponding to physiologically normal conditions while higher concentrations correlate with disease. The key output signal of the sensor is the resistive component of the MIP-functionalized titanium electrodes as derived from the equivalent-circuit modelling of full-range impedance spectra. Future applications could be catheters tailored to cardiovascular, urological, gastrointestinal, and neurovascular applications. This, in combination with the versatility of the MIPs, will make this sensor platform a versatile diagnostic tool.

Biogenic Amines in Traditional Fiore Sardo PDO Sheep Cheese: Assessment, Validation and Application of an RP-HPLC-DAD-UV Method

This contribution aimed to measure for the first time the amount of biogenic amines (BAs) in one of the most ancient and traditional sheep cheese produced in Sardinia, Italy: the Protected Designation of Origin (PDO) Fiore Sardo. To achieve this, an original RP-HPLC-DAD-UV method has been developed that was completely validated in terms of LoD, LoQ, linearity, precision and trueness, and tested on 36 real Fiore Sardo PDO cheese samples produced by four different cheesemakers and marketed by four stores. The average total concentration of the eight BAs (i.e., tyramine, tryptamine, histidine, putrescine, cadaverine, 2-phenylethylamine, spermine and spermidine) measured in Fiore Sardo cheese was 700 mg/kg, with a range between 170 mg/kg and 1,100 mg/kg. A great variability in the total amount of BAs has been evidenced among the Fiore Sardo marketed in the four stores as well as for the cheeses purchased in different times in the same store. Tyramine (350 mg/kg), putrescine (150 mg/kg), histamine (80 mg/kg) and cadaverine (30 mg/kg) are the most abundant BAs found in this matrix. Among the many factors concurring, the dominant microflora of Fiore Sardo PDO is likely the principal cause of the qualitative and quantitative distribution of BAs in this matrix. Finally, the total amount of BAs found in Fiore Sardo PDO is not able to cause any health alert situation for consumers.

Challenges in Developing a Biochip for Intact Histamine Using Commercial Antibodies

This study describes the development and the challenges in the development of an on-chip immunoassay for histamine using commercially available antibodies. Histamine can be used as an indicator of food freshness and quality, but it is also a relevant marker in clinical diagnostics. Due to its low molecular weight, simple structure and thus low immunogenicity production of high specificity and affinity antibodies is difficult. From six commercial anti-histamine antibodies tested, only two bound the histamine free in the solution. A fluorescent on-chip immunoassay for histamine was established with a dynamic range of 8–111 µg/mL using polyclonal anti-histamine antibody H7403 from Sigma (Mendota Heights, MN, USA). The anti-histamine antibodies described and used in published literature are thoroughly reviewed and the quality of commercial antibodies and their traceability and quality issues are highlighted and extensively discussed.

Optimizing the preparation conditions and characterization of cross-linked enzyme aggregates of a monoamine oxidase

Monoamine oxidases are useful in determination of biogenic monoamines, particularly histamine and tyramine. In this study, cross-linked enzyme aggregates (CLEAs) technique was applied to improve the stability of a monoamine oxidase from Arthrobacter aurescens (AMAO). Under the optimized condition (50% of saturated ammonium sulfate, 5 mM glutaraldehyde, 2.0 mg/mL AMAO, 4 h-cross-linking at 25°C, pH 8.0), CLEAs-AMAO was recovered with a yield of 82% based on the subjected total enzyme activity. Both pH activity and stability at alkaline pHs of CLEAs-AMAO were significantly improved compared to those of the free enzyme, resulting in the shift of optimum pH to pH 8.0 and a broader pH profile. The half-life of the CLEAs at 65°C was elongated by 1.7-fold compared to that of the free enzyme, suggesting the thermal stability of AMAO was also improved by the CLEAs formation.

A sensitivity-enhanced heterologous immunochromatographic assay based on a monoclonal antibody for the rapid detection of histamine in saury samples

An immunochromatograhic strip for rapid detection of histamine based on a sensitive monoclonal antibody against p-nitrobenzoylated histamine was firstly reported.

Construction of a bifunctional enzyme fusion for the combined determination of biogenic amines in foods

Biogenic amines (BAs) are a group of low-molecular-mass organic bases derived from free amino acids. Due to the undesirable effects of BAs on human health, amine oxidase-based detection methods for BAs in foods have been developed. Here, we developed a bifunctional enzyme fusion (MAPO) using a Cu(2+)-containing monoamine oxidase (AMAO2) and a flavin adenine dinucleotide-containing putrescine oxidase (APUO) from Arthrobacter aurescens. It was necessary to activate MAPO with supplementary Cu(2+) ions, leading to a 6- to 12-fold improvement in catalytic efficiency (kcat/KM) for monoamines. The optimal temperatures of Cu(2+)-activated MAPO (cMAPO) for both tyramine and putrescine were 50 °C, and the optimal pH values for tyramine and putrescine were pH 7.0 and pH 8.0, respectively, consistent with those of AMAO2 and APUO, respectively. The cMAPO showed relative specific activities of 100, 99, 32, and 32 for 2-phenylethylamine, tyramine, histamine, and putrescine, respectively. The tyramine-equivalent BA contents of fermented soybean pastes by cMAPO were more than 90% of the total BA determined by HPLC. In conclusion, cMAPO is fully bifunctional toward biogenic monoamines and putrescine, allowing the combined determination of multiple BAs in foods. This colorimetric determination method could be useful for point-of-care testing to screen safety-guaranteed products prior to instrumental analyses.

Preparation and Recognized Characteristic of Histamine Molecularly Imprinted Polymers

HA MIP was prepared in acetonitrile-ethylene glycol mixed solvent ( 20:1，v/v), HA was used as the template, methacrylic acid (MAA) as the functional monomer, azobisisobutyronitrile (AIBN) as the initiator and ethylene glycol dimethaerylate (EGDMA) as the cross-linker. The UV spectrophotometry was used to demonstrate the interaction between HA and MAA. The adsorption characteristics of MIP to HA have been studied by equilibrium binding experiment and Scatchard analysis. The data obtained show that MIP reached equilibrium within 6 h. It is found that within the studied concentration range one HA molecule is entrapped by two MAA molecules The Scatchard chart shows the apparent maximum binding capacity (Bmax) and the dissociation contents (KD) of MIP are 170.5 μmol/g and 0.18 mmol/L, respctively. The MIP synthesized by this method have better binding ability to histamine and can be applied on the separation and detection of histamine.

Enzyme immunoassay for mycophenolic acid in milk and cheese

Mycophenolic acid (MPA) was reacted with N-hydroxysuccinimide and conjugated to keyhole limpet hemocyanin (KLH), and to horseradish peroxidase (HRP), respectively. The MPA-KLH was used to produce anti-MPA antiserum in rabbits. A competitive direct enzyme immunoassay (EIA) for MPA was established with anti-MPA antiserum and MPA-HRP conjugate. The mean 50% inhibition and detection limit of MPA standard curves (n = 103) were 197 +/- 67 and 81 +/- 48 pg/mL, respectively. The EIA was specific for MPA and its synthetic 2-morpholinoethyl ester, mycophenolate mofetil (91% relative cross-reactivity). Raw bulk milk and pasteurized milk, with and without beta-glucuronidase pretreatment, were analyzed by EIA. No MPA was found in milk, at a detection limit of 100 pg/mL (recovery 58-66% at 0.125-2 ng/mL). Blue-veined cheese from the German market (n = 53) was analyzed by EIA, and the detection limit was at 0.5 ng/g (recovery 68-79% at 5-100 ng/g). All but two cheeses contained MPA, although mostly (66%) at levels of <10 ng/g. MPA at 400-1200 ng/g was found in Roquefort cheeses. Highest levels (4-11 microg/g) were found in a German soft cheese preparation. MPA levels in mycelium-rich parts of cheese were 3 times higher than in mycelium-free parts.

Identification of 4-methylspinaceamine, a pictet-spengler condensation reaction product of histamine with acetaldehyde, in fermented foods and its metabolite in human urine

Previous study demonstrated that 4-methylspinaceamine (4-methyl-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine), a Pictet-Spengler condensation reaction product of histamine with acetaldehyde, is present in human urine. The current study sought to determine whether 4-methylspinaceamine is present in fermented foods; its presence might be expected since both histamine and acetaldehyde are often present in these foods. Soy sauce, fish sauce, cheese, and shao hsing wine (Chinese wine) were found to contain 4-methylspinaceamine. The concentration of 4-methylspinaceamine excreted in human urine was greatly elevated after ingestion of a meal containing soy sauce as a dietary source of 4-methylspinaceamine, demonstrating that the level of 4-methylspinaceamine in human urine was affected by dietary foods. In addition, a metabolite of 4-methylspinaceamine in human urine was investigated. An enhanced peak in the HPLC chromatogram of human urine samples after ingestion of 4-methylspinaceamine-containing foods was observed. A peak at the same retention time was also observed from a human urine sample after administration of 4-methylspinaceamine, suggesting that the peak was due to a metabolite. By comparison with the newly synthesized authentic compound, the metabolite was identified as 1,4-dimethylspinaceamine.

High-performance liquid chromatographic determination of biogenic amines in wines with an experimental design optimization procedure

A novel and sensitive HPLC method for determining biogenic amines in wine samples is described. It involves pre-column labeling of the analytes with 1,2-naphthoquinone-4-sulfonate (NQS) and liquid-liquid extraction of derivatives with chloroform for analyte preconcentration and sample clean-up. A linear gradient elution consisting of a mixture of 2% of acetic acid aqueous solution and methanol is used to separate the amine derivatives in a C18 column. The eluted compounds are detected spectrophotometrically at 270 nm. The optimization of both derivatization and separation conditions is accomplished by means of factorial and central composite designs and multicriteria decision functions. The analytical parameters of the method are established using red wine samples. Detection limits range from 0.006 to 0.315 mg L(-1). The run-to-run repeatabilities of retention times and peak areas are around 0.6 and 5.6%, respectively. Recoveries ranging from 91.9 to 105% prove the accuracy of the method for determining histamine, putrescine, cadaverine, tryptamine, phenylethylamine and serotonin in red wines. The proposed method has been applied to the analysis of commercial wines from different Spanish regions.

Simple and rapid determination of histamine in food using a new histamine dehydrogenase from Rhizobium sp

A colorimetric enzyme assay for the quantitative analysis of histamine in food has been developed using a new histamine dehydrogenase (HDH) from Rhizobium sp. The HDH specifically catalyzes the oxidation of histamine but not other biogenic amines such as putrescine and cadaverine. The principle of our photometric assay is as follows. The HDH catalyzes the oxidative deamination of histamine in the presence of 1-methoxy PMS (electron carrier), which converts WST-8 (tetrazolium salt) to a formazan. This product is measured in the visible range at 460 nm. The correlation between the histamine level and absorbance was acceptable, ranging from 0 to 96 microM with histamine standard solutions, corresponding to 0 to 30 microM of the reaction solution (r = 1.000, CV = 1.0% or less). Assays of canned tuna (in oil and soup) and raw tuna with 45-675 micromol/kg histamine added showed good recoveries of 96-113, 98-108, and 100-106%. The histamine contents of a commercial canned tuna and fish meal containing histamine at high concentrations were determined using the new method and other reference methods (HPLC method, Association of Official Analytical Chemists official method, and two commercial enzyme immunoassay test kits). This simple and rapid enzymatic method is as reliable as the conventional methods.

Identification of 4-methylspinaceamine - a Pictet – Spengler condensation reaction product of histamine with acetaldehyde - in human urine

This study reports the first identification of 4-methylspinaceamine (4-MSPA)-a Pictet Spengler condensation reaction product of histamine with acetaldehyde-in human urine. 4-MSPA was identified and quantified as follows: the target compound was partially purified by solvent extraction from a urine sample spiked with N-methylpiperazine (N-MP) as an internal standard, then derivatized to a naphthylthiourea derivative with 1-naphthylisothiocyanate (NITC) and finally analyzed by HPLC. For verification, 4-MSPA was also analyzed by ion spray-mass spectrometry (IS-MS), using 4-MSPA-d4 as an internal standard. The amount of 4-MSPA in human urine varied between individuals and from day-to-day, ranging from undetectable to 0.80 nmol/mL.

Relative reactivities of histamine and indoleamines with acetaldehyde

Relative reactivities of histamine and indoleamines such as tryptamine, 5-hydroxytryptamine and 5-methoxytryptamine with acetaldehyde (AA) under physiological conditions were investigated. AA was found to have much higher reactivity towards histamine than towards indoleamines. For example, when a reaction mixture of AA (1 mM) and histamine or tryptamine (5 mM) in 0.1 M phosphate buffer (pH 7.4) was incubated at 37 degrees C for 24 h, AA decreased by 11% in the case of tryptamine, while in the case of histamine, it decreased 88%. In addition, the reaction product of AA with histamine was investigated. Mixtures of a fixed amount of histamine (5 mM) and various amounts of AA (1-20 mM) in phosphate buffer (pH 7.4) were incubated for 5 h at 37 degrees C. In all cases, only one product, 4-methylspinaceamine (4-MSPA), was observed. The yield of 4-MSPA was in approximate agreement with the losses of histamine and AA, indicating that the loss of histamine caused by the reaction of AA was quantatively converted to 4-MSPA. These results show that the reaction of AA with histamine easily takes place to produce 4-MSPA in an aqueous medium close to physiological conditions.

A sensitive and selective determination method of histamine by HPLC with intramolecular excimer-forming derivatization and ?uorescence detection

A highly sensitive, selective and simple method is described for the determination of histamine by high-performance liquid chromatography (HPLC) with fluorescence detection. The method is based on an intramolecular excimer-forming fluorescence derivatization of histamine with 4-(1-pyrene)butyric acid N-hydroxysuccinimide ester (PSE), followed by reversed-phase HPLC. Histamine, having two amino moieties in a molecule, was converted to the dipyrene-labeled derivative by reaction with PSE. The derivative afforded intramolecular excimer fluorescence (450-540 nm), which can clearly be discriminated from the monomer fluorescence (370-420 nm) emitted from PSE. Typically, a 10 micro L sample solution was mixed with 100 micro L of derivatization reagent solution, which was a mixture of 0.5 mm PSE in acetonitrile and 0.5 mm potassium carbonate in water (8:2, v/v). The derivatization was carried out at 100 degrees C for 90 min. The PSE derivative of histamine could be separated by reversed-phase ODS column with isocratic elution using acetonitrile:water (82:18, v/v) containing 0.03% triethylamine. The detection limit (singnal-to-noise ratio = 3) of histamine was 0.5 fmol for a 30 micro L injection. The method was successfully applied to the determination of histamine in human urine, and had enough selectivity and sensitivity for urinary histamine quantification.

Characterization of selected Spanish table wine samples according to their biogenic amine content from liquid chromatographic determination

Pattern recognition techniques, such as principal component analysis, cluster analysis, and linear discriminant analysis, have been applied to samples of red, white, and rosé wines to determine whether some biogenic amines could be considered as chemical descriptors. Eight amines (tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine) were determined by RP-HPLC, after derivatization with dabsyl chloride. However, only putrescine, cadaverine, histamine, tyramine, spermidine, and spermine were found in the wines analyzed. From the association between variables obtained by principal component analysis and clustering and from the relationship found by linear discriminant analysis, it can be deduced that the amines generated during malolactic fermentation (putrescine, histamine, and tyramine) could be used as chemical descriptors to characterize table wine samples.

Possibilities of replacing and reducing animal tests in the pharmacopoeias: an evaluation of unused methods and proposals for change

The animal tests currently carried out according to the German and European pharmacopoeias are evaluated. The routine testing of biological medicines, excluding vaccines and pyrogen tests, is examined. The opportunities for replacing obligatory bioassays and safety tests are assessed, taking into account both pharmaceutical quality and animal welfare aspects. The aim is to encourage institutions, public authorities, and the pharmaceutical industry to investigate the importance and the necessity of the remaining tests. In addition, all parties should be encouraged to initiate integrated projects to develop, validate and establish alternative methods.