Glycerophosphodiesterase 3 (GDE3) is a lysophosphatidylinositol-specific ectophospholipase C acting as an endocannabinoid signaling switch.

Endocannabinoid signaling plays a regulatory role in various (neuro)biological functions. 2-arachidonoylglycerol (2-AG) is the most abundant endocannabinoid, and although its canonical biosynthetic pathway involving phosphoinositide-specific phospholipase C and diacylglycerol lipase α is known, alternative pathways remain unsettled. Here, we characterize a noncanonical pathway implicating glycerophosphodiesterase 3 (GDE3, from GDPD2 gene). Human GDE3 expressed in HEK293T cell membranes catalyzed the conversion of lysophosphatidylinositol (LPI) into monoacylglycerol and inositol-1-phosphate. The enzyme was equally active against 1-acyl and 2-acyl LPI. When using 2-acyl LPI, where arachidonic acid is the predominant fatty acid, LC-MS analysis identified 2-AG as the main product of LPI hydrolysis by GDE3. Furthermore, inositol-1-phosphate release into the medium occurred upon addition of LPI to intact cells, suggesting that GDE3 is actually an ecto-lysophospholipase C. In cells expressing G-protein-coupled receptor GPR55, GDE3 abolished 1-acyl LPI-induced signaling. In contrast, upon simultaneous ex-pression of GDE3 and cannabinoid receptor CB2, 2-acyl LPI evoked the same signal as that induced by 2-AG. These data strongly suggest that, in addition to degrading the GPR55 LPI ligand, GDE3 can act as a switch between GPR55 and CB2 signaling. Coincident with a major expression of both GDE3 and CB2 in the spleen, spleens from transgenic mice lacking GDE3 displayed doubling of LPI content compared with WT mice. Decreased production of 2-AG in whole spleen was also observed, supporting the in vivo relevance of our findings. These data thus open a new research avenue in the field of endocannabinoid generation and reinforce the view of GPR55 and LPI being genuine actors of the endocannabinoid system.

Oxysterol levels and metabolism in the course of neuroinflammation: insights from in vitro and in vivo models.

BACKGROUND: Oxysterols are cholesterol derivatives that have been suggested to play a role in inflammatory diseases such as obesity, atherosclerosis, or neuroinflammatory diseases. However, the effect of neuroinflammation on oxysterol levels has only been partially studied so far. METHODS: We used an HPLC-MS method to quantify over ten oxysterols both in in vitro and in vivo models of neuroinflammation. In the same models, we used RT-qPCR to analyze the expression of the enzymes responsible for oxysterol metabolism. Using the BV2 microglial cell line, we explored the effect of lipopolysaccharide (LPS)-induced (M1-type) and IL-4-induced (M2-type) cell activation on oxysterol levels. We also used LPS-activated co-cultures of mouse primary microglia and astrocytes. In vivo, we induced a neuroinflammation by administering LPS to mice. Finally, we used a mouse model of multiple sclerosis, namely the experimental autoimmune encephalomyelitis (EAE) model, that is characterized by demyelination and neuroinflammation. RESULTS: In vitro, we found that LPS activation induces profound alterations in oxysterol levels. Interestingly, we could discriminate between control and LPS-activated cells based on the changes in oxysterol levels both in BV2 cells and in the primary co-culture of glial cells. In vivo, the changes in oxysterol levels were less marked than in vitro. However, we found in both models increased levels of the GPR183 agonist 7α,25-dihydroxycholesterol. Furthermore, we studied in vitro the effect of 14 oxysterols on the mRNA expression of inflammatory markers in LPS-activated co-culture of microglia and astrocytes. We found that several oxysterols decreased the LPS-induced expression of pro-inflammatory markers. CONCLUSIONS: These data demonstrate that inflammation profoundly affects oxysterol levels and that oxysterols can modulate glial cell activation. This further supports the interest of a large screening of oxysterol levels when studying the interplay between neuroinflammation and bioactive lipids.

Non-invasive in vivo imaging of early metabolic tumor response to therapies targeting choline metabolism.

The cholinic phenotype, characterized by elevated phosphocholine and a high production of total-choline (tCho)-containing metabolites, is a metabolic hallmark of cancer. It can be exploited for targeted therapy. Non-invasive imaging biomarkers are required to evaluate an individual's response to targeted anticancer agents that usually do not rapidly cause tumor shrinkage. Because metabolic changes can manifest at earlier stages of therapy than changes in tumor size, the aim of the current study was to evaluate (1)H-MRS and diffusion-weighted MRI (DW-MRI) as markers of tumor response to the modulation of the choline pathway in mammary tumor xenografts. Inhibition of choline kinase activity was achieved with the direct pharmacological inhibitor H-89, indirect inhibitor sorafenib and down-regulation of choline-kinase α (ChKA) expression using specific short-hairpin RNA (shRNA). While all three strategies significantly decreased tCho tumor content in vivo, only sorafenib and anti-ChKA shRNA significantly repressed tumor growth. The increase of apparent-diffusion-coefficient of water (ADCw) measured by DW-MRI, was predictive of the induced necrosis and inhibition of the tumor growth in sorafenib treated mice, while the absence of change in ADC values in H89 treated mice predicted the absence of effect in terms of tumor necrosis and tumor growth. In conclusion, (1)H-choline spectroscopy can be useful as a pharmacodynamic biomarker for choline targeted agents, while DW-MRI can be used as an early marker of effective tumor response to choline targeted therapies. DW-MRI combined to choline spectroscopy may provide a useful non-invasive marker for the early clinical assessment of tumor response to therapies targeting choline signaling.

High-fat diet feeding differentially affects the development of inflammation in the central nervous system.

BACKGROUND: Obesity and its associated disorders are becoming a major health issue in many countries. The resulting low-grade inflammation not only affects the periphery but also the central nervous system. We set out to study, in a time-dependent manner, the effects of a high-fat diet on different regions of the central nervous system with regard to the inflammatory tone. METHODS: We used a diet-induced obesity model and compared at several time-points (1, 2, 4, 6, 8, and 16 weeks) a group of mice fed a high-fat diet with its respective control group fed a standard diet. We also performed a large-scale analysis of lipids in the central nervous system using HPLC-MS, and we then tested the lipids of interest on a primary co-culture of astrocytes and microglial cells. RESULTS: We measured an increase in the inflammatory tone in the cerebellum at the different time-points. However, at week 16, we evidenced that the inflammatory tone displayed significant differences in two different regions of the central nervous system, specifically an increase in the cerebellum and no modification in the cortex for high-fat diet mice when compared with chow-fed mice. Our results clearly suggest region-dependent as well as time-dependent adaptations of the central nervous system to the high-fat diet. The differences in inflammatory tone between the two regions considered seem to involve astrocytes but not microglial cells. Furthermore, a large-scale lipid screening coupled to ex vivo testing enabled us to identify three classes of lipids-phosphatidylinositols, phosphatidylethanolamines, and lysophosphatidylcholines-as well as palmitoylethanolamide, as potentially responsible for the difference in inflammatory tone. CONCLUSIONS: This study demonstrates that the inflammatory tone induced by a high-fat diet does not similarly affect distinct regions of the central nervous system. Moreover, the lipids identified and tested ex vivo showed interesting anti-inflammatory properties and could be further studied to better characterize their activity and their role in controlling inflammation in the central nervous system.

Development and validation of an HPLC-MS method for the simultaneous quantification of key oxysterols, endocannabinoids, and ceramides: variations in metabolic syndrome.

Oxysterols, ceramides, and endocannabinoids are three families of bioactive lipids suggested to be involved in obesity and metabolic syndrome. To facilitate the quantification of these potentially interconnected lipids, we have developed and validated a liquid chromatography coupled to mass spectrometry method allowing for their simultaneous quantification from tissues. Sample purification is of great importance when quantifying oxysterols due to the potential artifactual conversion of cholesterol into oxysterols. Therefore, we developed a novel solid-phase extraction procedure and demonstrated that it allowed for good recoveries of the three families of analytes without artifactual oxidation of cholesterol. The oxysterols, ceramides, and endocannabinoids and their respective internal standards were chromatographically separated by HPLC and ionized using the atmospheric pressure chemical ionization (APCI) source of an LTQ-orbitrap mass spectrometer. The repeatability and bias were within the acceptance limits for all 23 lipids of interest. The sensitivity (limit of detection (LOD) and limit of quantification (LOQ)) and specificity of the method allowed us to quantify all the analytes in the liver and adipose tissue of control and high-fat diet-fed C57BL/6 mice. We found that 16 weeks of high-fat diet strongly impacted the hepatic levels of several oxysterols, ceramides, and endocannabinoids. A partial least-squares discriminant analysis (PLS-DA) based on the variations of the hepatic levels of these 23 bioactive lipids allowed differentiating the lean mice from the obese mice.

Implication of the anti-inflammatory bioactive lipid prostaglandin D2-glycerol ester in the control of macrophage activation and inflammation by ABHD6.

Proinflammatory macrophages are key mediators in several pathologies; thus, controlling their activation is necessary. The endocannabinoid system is implicated in various inflammatory processes. Here we show that in macrophages, the newly characterized enzyme α/ß-hydrolase domain 6 (ABHD6) controls 2-arachidonoylglycerol (2-AG) levels and thus its pharmacological effects. Furthermore, we characterize a unique pathway mediating the effects of 2-AG through its oxygenation by cyclooxygenase-2 to give rise to the anti-inflammatory prostaglandin D2-glycerol ester (PGD2-G). Pharmacological blockade of cyclooxygenase-2 or of prostaglandin D synthase prevented the effects of increasing 2-AG levels by ABHD6 inhibition in vitro, as well as the 2-AG-induced increase in PGD2-G levels. Together, our data demonstrate the physiological relevance of the interaction between the endocannabinoid and prostanoid systems. Moreover, we show that ABHD6 inhibition in vivo allows for fine-tuning of 2-AG levels in mice, therefore reducing lipopolysaccharide-induced inflammation, without the characteristic central side effects of strong increases in 2-AG levels obtained following monoacylglycerol lipase inhibition. In addition, administration of PGD2-G reduces lipopolysaccharide-induced inflammation in mice, thus confirming the biological relevance of this 2-AG metabolite. This points to ABHD6 as an interesting therapeutic target that should be relevant in treating inflammation-related conditions, and proposes PGD2-G as a bioactive lipid with potential anti-inflammatory properties in vivo.

Quality Control and Safety Assessment of Online-Purchased Food Supplements Containing Red Yeast Rice (RYR).

Dietary supplements containing red yeast rice (RYR), a fermentation product of the fungus Monascus purpureus grown on white rice, remain popular in Europe as proclaimed cholesterol-lowering aids. The cholesterol-lowering effects are due to the occurrence of monacolin K, which is often present as a mixture of monacolin K lactone (MK) and as monacolin K hydroxy acid (MKA). MK is structurally similar to the cholesterol-lowering medicine lovastatin. Recently, due to safety concerns linked to the use of statins, the European Commission prohibited RYR supplements with a maximum serving exceeding 3 mg of total monacolins per day. Moreover, the amount of the mycotoxin citrinin, potentially produced by M. purpureus, was also reduced to 100 µg/kg. Evidently, manufacturers that offer their products on the European market, including the online market, must also be compliant with these limits in order to guarantee the safety of their products. Therefore, thirty-five different RYR supplements, purchased from an EU-bound e-commerce platform or from registered online pharmacies, were screened for their compliance to the European legislation for citrinin content and the amount of total monacolin K. This was conducted by means of a newly developed LC-MS/MS methodology that was validated according to ISO 17025. Moreover, these supplements were also screened for possible adulteration and any contamination by micro-organisms and/or mycotoxins. It was found that at least four of the thirty-five RYR supplements (≈11%) might have reason for concern for the safety of the consumer either due to high total monacolin K concentrations exceeding the European predefined limits for total monacolins or severe bacterial contamination. Moreover, three samples (≈9%) were likely adulterated, and the labeling of six of the seventeen samples (≈35%) originating from an EU-based e-commerce platform was not compliant, as either the mandatory warning was missing or incomplete or the total amount of monacolins was not mentioned.

Potential (co-)contamination of dairy milk with AFM1 and MC-LR and their synergistic interaction in inducing mitochondrial dysfunction in HepG2 cells.

Several toxic metabolites, such as aflatoxin M1 (AFM1), are known to contaminate dairy milk. However, as mentioned in an external EFSA report, there is a knowledge gap regarding the carry-over of certain emerging toxins such as microcystin-LR (MC-LR). Therefore, this work aimed to develop an LC-MS/MS method for MC-LR quantification in dairy milk. Also, the method included AFM1 as a common fungal metabolite and applied to analyze 113 dairy milk samples collected directly after the end of the summer peak. Both toxins were below their LODs, keeping the question on MC-LR carry-over still unanswered. Moreover, an in silico analysis, using a 3D molecular modeling was performed, pointing to a possible interaction between MC-LR and milk proteins, especially ß-lactoglobulin. Since AFM1 and MC-LR are hepatotoxic, their interaction in inducing mitochondrial dysfunction in HepG2 cells was investigated at low (subcytotoxic) concentrations. Live cell imaging-based assays showed an inhibition in cell viability, without involvement of caspase-3/7, and a hyperpolarization in the mitochondrial membrane potential after the exposure to a mixture of 100 ng mL-1 AFM1 and 1000 ng mL-1 MC-LR for 48h. Extracellular flux analysis revealed inhibitions of several key parameters of mitochondrial function (basal respiration, ATP-linked respiration, and spare respiratory capacity).

Experimental accumulation and depuration kinetics and natural occurrence of microcystin-LR in basil (Ocimum basilicum L.).

Microcystin-LR (MC-LR) is a hepatotoxic metabolite that naturally occurs during some cyanobacterial blooms in eutrophic waterbodies, and irrigation of edible plants with MC-LR-contaminated water causes bioaccumulation of the toxin. However, sufficient information about accumulation and depuration mechanics in hydroculture-grown herb plants is still lacking. This work aimed at 1) investigating bioaccumulation and depuration of MC-LR in basil, 2) verifying the possible MC-LR detoxification mechanisms in the plant, and 3) detecting the natural occurrence of MC-LR in basil (n = 50) collected from the Belgian market. Basil plants grown in a hydroculture were exposed to MC-LR (5, 20, and 50 µg L-1) spiked in a Hoagland solution for seven days. MC-LR depuration was also studied by transferring the plants to a non-contaminated Hoagland solution after exposure to MC-LR for another seven days. MC-LR concentrations in Hoagland solution, basil leaves, and roots were quantified using a validated UHPLC-MS/MS method. In addition, ELISA and LC-HRMS (only basil leaves) were used for confirmation. The results showed an increase in the accumulated levels of MC-LR at higher exposure doses, with higher MC-LR levels in roots than in leaves for all the treatment conditions. For MC-LR depuration, significant reductions were observed in all the treatment conditions for roots only. No MC-LR conjugates, potentially related to metabolism, were detected by LC-HRMS. Finally, MC-LR was detected in one store-bought basil sample, representing the first occurrence of cyanotoxins in an edible crop from Belgium.

Analysis of Patulin in Apple Products Marketed in Belgium: Intra-Laboratory Validation Study and Occurrence.

Apple and apple derivatives (e.g., juices, puree) are the most important foodstuffs contaminated with patulin (PAT) in the human diet. To routinely monitor these foodstuffs and ensure that the PAT levels are below the maximum permitted levels, a method using liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) has been developed. Afterwards, the method was successfully validated, reaching quantification limits of 1.2 µg/L for apple juice and cider, and 2.1 µg/kg for puree. Recovery experiments were performed with samples fortified with PAT in the range of 25-75 µg/L for juice/cider and 25-75 µg/kg for puree. The results show overall average recovery rates of 85% (RSDr = 13.1%) and 86% (RSDr = 2.6%) with maximum extended uncertainty (Umax, k = 2) of 34 and 35% for apple juice/cider and puree, respectively. Next, the validated method was applied to 103 juices, 42 purees and 10 ciders purchased on the Belgian market in 2021. PAT was not found in the cider samples, but it was present in 54.4% of the tested apple juices (up to 191.1 µg/L) and 7.1% of the puree samples (up to 35.9 µg/kg). When comparing the results to the maximum levels set by Regulation EC n° 1881/2006 (i.e., 50 µg/L for juices and 25 µg/kg for puree for adults, and 10 µg/kg for infants and young children), exceedances were observed in five apple juices and one puree sample, for infants and young children. Using these data, a potential risk assessment for consumers can be suggested, and it is found that the quality of apple juices and purees sold in Belgium needs further regular surveillance.

Development, validation, and application of a multimatrix UHPLC-MS/MS method for quantification of Datura-type alkaloids in food.

A quantitative ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the determination of tropane alkaloids (TAs), atropine and scopolamine, in a variety of food products. The sample preparation of cereal-based food, oilseeds, honey, and pulses consisted of a solid-liquid extraction with an acidified mixture of methanol and water, while an additional step of solid-phase extraction on a cation-exchange sorbent was introduced in the treatment of teas and herbal infusions, aromatic herbs, spices and food supplements. The limits of quantification of the method varied from 0.5 to 2.5 µg kg-1. Apparent recovery was in the range of 70-120%, and repeatability and intermediate precision were below 20%. The method was successfully applied in a proficiency testing exercise as well as in the analysis of various commercial foods. Only 26% of the analysed food samples contained one or both TAs. The mean concentrations for atropine and scopolamine amounted to 21.9 and 6.5 µg kg-1, respectively, while the maximum concentrations were 523.3 and 131.4 µg kg-1, respectively. Overall, the highest levels of TA sum were found in an herbal infusion of fennel and a spice mix containing fennel and anise seeds.

Validation of a Targeted LC-MS/MS Method for Cereulide and Application in Food and Faeces.

Cereulide is an emetic toxin produced by some strains of Bacillus cereus. This bacterial toxin, a cyclic 1.2 kDa dodecadepsipeptide, is stable to heat and acids and causes nausea and vomiting when ingested via contaminated food. This work aimed to develop and validate a targeted analytical method applying liquid chromatography-tandem mass spectrometry (LC-MS/MS) to quantify this toxin in food and human faeces. Samples were extracted with acetonitrile in the presence of 13C6-cereulide, a labelled internal standard, and purified by centrifugation and filtration. The limits of quantification were 0.5 and 0.3 µg kg-1 for food and faeces, respectively. The linearity of the method was very good, with calculated R2 values above 0.995. The mean recovery of the method was within the acceptable range of 70.0%-120.0%, the repeatability was not higher than 7.3%, and the highest intra-laboratory reproducibility was 8.9%. The estimated range for the expanded measurement uncertainty was between 5.1% and 18.0%. The LC-MS/MS method was used to analyse one food sample (rice) from a Belgian foodborne outbreak and five faecal samples from patients with clinical symptoms after consumption of the contaminated rice. The levels of cereulide were 12.22 µg g-1 for food and between 6.32 and 773.37 ng g-1 for faecal samples.

The association of N-palmitoylethanolamine with the FAAH inhibitor URB597 impairs melanoma growth through a supra-additive action.

BACKGROUND: The incidence of melanoma is considerably increasing worldwide. Frequent failing of classical treatments led to development of novel therapeutic strategies aiming at managing advanced forms of this skin cancer. Additionally, the implication of the endocannabinoid system in malignancy is actively investigated. METHODS: We investigated the cytotoxicity of endocannabinoids and their hydrolysis inhibitors on the murine B16 melanoma cell line using a MTT test. Enzyme and receptor expression was measured by RT-PCR and enzymatic degradation of endocannabinoids using radiolabeled substrates. Cell death was assessed by Annexin-V/Propidium iodine staining. Tumors were induced in C57BL/6 mice by s.c. flank injection of B16 melanoma cells. Mice were injected i.p. for six days with vehicle or treatment, and tumor size was measured each day and weighted at the end of the treatment. Haematoxylin-Eosin staining and TUNEL assay were performed to quantify necrosis and apoptosis in the tumor and endocannabinoid levels were quantified by HPLC-MS. Tube formation assay and CD31 immunostaining were used to evaluate the antiangiogenic effects of the treatments. RESULTS: The N-arachidonoylethanolamine (anandamide, AEA), 2-arachidonoylglycerol and N- palmitoylethanolamine (PEA) reduced viability of B16 cells. The association of PEA with the fatty acid amide hydrolase (FAAH) inhibitor URB597 considerably reduced cell viability consequently to an inhibition of PEA hydrolysis and an increase of PEA levels. The increase of cell death observed with this combination of molecules was confirmed in vivo where only co-treatment with both PEA and URB597 led to decreased melanoma progression. The antiproliferative action of the treatment was associated with an elevation of PEA levels and larger necrotic regions in the tumor. CONCLUSIONS: This study suggests the interest of targeting the endocannabinoid system in the management of skin cancer and underlines the advantage of associating endocannabinoids with enzymatic hydrolysis inhibitors. This may contribute to the improvement of long-term palliation or cure of melanoma.

LC-MS/MS Validation and Quantification of Cyanotoxins in Algal Food Supplements from the Belgium Market and Their Molecular Origins.

Food supplements are gaining popularity worldwide. However, harmful natural compounds can contaminate these products. In the case of algae-based products, the presence of toxin-producing cyanobacteria may cause health risks. However, data about the prevalence of algal food supplements on the Belgian market and possible contaminations with cyanotoxins are scarce. Therefore, we optimized and validated a method based on Ultra High Performance Liquid Chromatography-Tandem Mass Spectrometry to quantify eight microcystin congeners and nodularin in algal food supplements. Our analytical method was successfully validated and applied on 35 food supplement samples. Nine out of these samples contained microcystin congeners, of which three exceeded 1 µg g-1, a previously proposed guideline value. Additionally, the mcyE gene was amplified and sequenced in ten products to identify the taxon responsible for the toxin production. For seven out of these ten samples, the mcyE gene could be amplified and associated to Microcystis sp. EFSA and posology consumption data for algal-based food supplements were both combined with our toxin prevalence data to establish different toxin exposure scenarios to assess health risks and propose new guideline values.

A Summer of Cyanobacterial Blooms in Belgian Waterbodies: Microcystin Quantification and Molecular Characterizations.

In the context of increasing occurrences of toxic cyanobacterial blooms worldwide, their monitoring in Belgium is currently performed by regional environmental agencies (in two of three regions) using different protocols and is restricted to some selected recreational ponds and lakes. Therefore, a global assessment based on the comparison of existing datasets is not possible. For this study, 79 water samples from a monitoring of five lakes in Wallonia and occasional blooms in Flanders and Brussels, including a canal, were analyzed. A Liquid Chromatography with tandem mass spectrometry (LC-MS/MS) method allowed to detect and quantify eight microcystin congeners. The mcyE gene was detected using PCR, while dominant cyanobacterial species were identified using 16S RNA amplification and direct sequencing. The cyanobacterial diversity for two water samples was characterized with amplicon sequencing. Microcystins were detected above limit of quantification (LOQ) in 68 water samples, and the World Health Organization (WHO) recommended guideline value for microcystins in recreational water (24 µg L-1) was surpassed in 18 samples. The microcystin concentrations ranged from 0.11 µg L-1 to 2798.81 µg L-1 total microcystin. For 45 samples, the dominance of the genera Microcystis sp., Dolichospermum sp., Aphanizomenon sp., Cyanobium/Synechococcus sp., Planktothrix sp., Romeria sp., Cyanodictyon sp., and Phormidium sp. was shown. Moreover, the mcyE gene was detected in 75.71% of all the water samples.

A Targeted UHPLC-MS/MS Method Validated for the Quantification of Ergot Alkaloids in Cereal-Based Baby Food from the Belgian Market.

Following pending new legislation in the European Union setting a maximum of 20 ng g-1 for the total sum of ergot alkaloids in dry cereal-based baby food, a new UHPLC-MS/MS method was developed. It is suitable for the quantification of six ergot alkaloids: Ergocornine, ergocristine, ergometrine, ergosine, ergotamine, α-ergocryptine, and their corresponding epimers. The method is able to reliably detect individual ergot alkaloids at a level as low as 0.5 ng g-1. The method uses a modified QuEChERS extraction approach before UHPLC-MS/MS analysis. The method showed good sensitivity, accuracy, and precision. It has been applied to 49 samples from the Belgian market. In 26 samples, not a single ergot alkaloid was detected while in 23 out of 49 samples at least one ergot alkaloid was detected with 2 samples containing 12 ergot alkaloids. Ergometrine was the alkaloid most frequently detected i.e., 16 out of 49 samples. Only one sample, testing positive for all 12 ergot alkaloids, would be non-conforming to the newly proposed Maximum Residue Level (MRL).

Determination of ochratoxin A in edible pork offal: intra-laboratory validation study and estimation of the daily intake via kidney consumption in Belgium.

Pork-derived products can contribute to the overall ochratoxin A (OTA) intake via carry-over from contaminated feed or via mould spoilage of meat products (salami, dry-cured ham, sausage). An analytical method using liquid chromatography coupled with mass spectrometry (LC-MS/MS) was developed and validated in accordance with the specifications laid down by European Commission. It offered quantification limits of 0.2 for kidney, liver and 0.4 µg/kg for black sausage. Spiking experiments of blank samples at 5-10 µg/kg showed recoveries ranging from 88 to 101%, 89 to 97% and 80 to 85% for kidney, liver and black sausage, respectively. The respective intra-laboratory repeatabilities ranged between 9.8-11.1%, 9.4-14.4% and 9.7-14.2%, and extended measurement uncertainties MU(k = 2) were 33%, 35% and 43% for kidney, liver and black sausage. Next, the validated method was applied to kidney (110), liver (20) and black sausage (20) samples collected in Belgium in the period 2012-2019. Neither liver nor black sausage samples were contaminated with OTA. Kidney samples (37.3%) were OTA contaminated at the mean level of 0.22 ± 0.25 µg/kg (up to 1.91 µg/kg). These data combined with the offal consumption in the Belgian population revealed average daily OTA exposures ranged from 0.167 and 0.319 ng/kg bw for 3 age groups (3-9, 10-17 and 18-64 years). Taking into account, the OTA non-neoplastic and neoplastic effects, risk characterization assessed via the margin of exposure for reference endpoints revealed no potential health risk for the consumers. As the presence of low OTA content in foods together with other mycotoxins or derivatives may interactively potentiate its toxicity, monitoring of OTA and its metabolites in meat and meat by-products is advised.

Organisation of Multi-Mycotoxin Proficiency Tests: Evaluation of the Performances of the Laboratories Using the Triple A Rating Approach.

In accordance with the International Standard Organization ISO 17043, two proficiency tests (PTs) for the simultaneous determination of aflatoxins (AFB1, AFB2, AFG1, AFG2); deoxynivalenol; fumonisins FB1, FB2, and B3; ochratoxin A, the T-2 toxin; and the HT-2 toxin were conducted in 2019 and 2020 using cornflakes and rusk flours that were prepared in house. The homogeneity and the stability of these materials were verified according to the criteria laid down in ISO 13528 using randomly selected samples. Most of the targeted toxins were found to be homogenously distributed in both materials with no significant changes during the timescale of the PTs. Next, the materials were distributed to approximately 25 participating laboratories from Europe, Canada, and the United States. The obtained datasets were computed using robust statistics. The outliers were checked and removed, and the toxin concentrations were assigned as the consensus value of the results of the participants at Horwitz ratios <1.2. The z scores were generated for all mycotoxins, and the results were pooled to calculate the relative sum of squared z scores (SZ2) indexes and were clustered according to the triple A rating. Overall, at least 80% of the participating laboratories achieved good and acceptable performances. The most frequent categories assigned to good performances (SZ2 ≤ 2) were AAA (51%) and BAA (13%). Clusters of BBA + CBA (6%) included laboratories reporting acceptable z scores <90% of the total z scores for less than 90% or 50% of the mycotoxins targeted in the 2 matrices. The triple A rating seems to be appropriate in evaluating the performances of laboratories involved in multi-mycotoxin analyses. Accredited and non-accredited analytical methods achieved good and acceptable performances.

Citrinin Determination in Food and Food Supplements by LC-MS/MS: Development and Use of Reference Materials in an International Collaborative Study.

The development of incurred reference materials containing citrinin (CIT) and their successful application in a method validation study (MVS) in order to harmonize CIT determination in food and food supplements are demonstrated. CIT-contaminated materials made of red yeast rice (RYR), wheat flour, and Ginkgo biloba leaves (GBL), as well as food supplements made of red yeast rice (FS-RYR) and Ginkgo biloba leaves (FS-GBL), were manufactured in-house via fungal cultivation on collected raw materials. The homogeneity and stability from randomly selected containers were verified according to the ISO 13528. CIT was found to be homogenously distributed and stable in all contaminated materials, with no significant degradation during the timescale of the MVS when storage was performed up to +4 °C. Next, an MVS was organized with eighteen international laboratories using the provided standard operating procedure and 12 test materials, including three RYRs (blank, <50 µg/kg, <2000 µg/kg), two wheat flours (blank, <50 µg/kg), two GBL powders (blank, <50 µg/kg), three FS-RYRs (blank, <50 µg/kg, <2000 µg/kg), and two FS-GBLs (blank, <50 µg/kg). The results of seven CIT-incurred materials showed acceptable within-laboratory precision (RSDr) varying from 6.4% to 14.6% and between-laboratory precision (RSDR) varying from 10.2% to 37.3%. Evidenced by HorRat values < 2.0, the results of the collaborative trial demonstrated that the applied analytical method could be standardized. Furthermore, the appropriateness of producing CIT reference materials is an important step towards food and feed quality control systems and the organization of proficiency tests.