Survey of pork, poultry, coffee, beer and pulses for ochratoxin A

Ultra-sensitive determination of Ochratoxin A in coffee and tea samples using a novel semi-automated in-syringe based coagulant-assisted fast mycotoxin extraction (FaMEx) technique coupled with UHPLC-MS/MS

In this study, we demonstrated a novel semi-automated in-syringe-based coagulant-assisted liquid-liquid microextraction (IS-CGA-LLME) as fast mycotoxin extraction (FaMEx) technique coupled with ultra-high-performance liquid chromatography connected with a tandem-mass spectrometer (UHPLC-MS/MS) for the quantification of mycotoxin (Ochratoxin A, OT-A) in coffee and tea samples. IS-CGA-LLME is a three-step extraction process that includes extraction of OT-A from sample matrix using low-volume solvent extraction, then the extractant was cleaned-up using a coagulation process, and finally, the decolorized/matrix removed sample solution was processed for LLME for target analyte's pre-concentration. The final extractant was analyzed using UHPLC-MS/MS for OT-A quantification. Under the optimized experimental conditions, highly sensitive detection and quantification limits were obtained at 0.001 and 0.003 ng g^-1 for OT-A with excellent extraction recovery (93-111%) and precision <10%. These results proved that the developed method is a simple, highly sensitive, semi-automated, low-matrix effect and efficient procedure for the determination of mycotoxins in food samples.

Mycotoxins and Essential Oils-From a Meat Industry Hazard to a Possible Solution: A Brief Review

The preservation of food supplies has been humankind's priority since ancient times, and it is arguably more relevant today than ever before. Food sustainability and safety have been heavily prioritized by consumers, producers, and government entities alike. In this regard, filamentous fungi have always been a health hazard due to their contamination of the food substrate with mycotoxins. Additionally, mycotoxins are proven resilient to technological processing. This study aims to identify the main mycotoxins that may occur in the meat and meat products "Farm to Fork" chain, along with their effect on the consumers' health, and also to identify effective methods of prevention through the use of essential oils (EO). At the same time, the antifungal and antimycotoxigenic potential of essential oils was considered in order to provide an overview of the subject. Targeting the main ways of meat products' contamination, the use of essential oils with proven in vitro or in situ efficacy against certain fungal species can be an effective alternative if all the associated challenges are addressed (e.g., application methods, suitability for certain products, toxicity).

Investigation of ochratoxin a in blood sausages in the Czech Republic: Comparison with data over Europe

Blood sausages consisting of groats, pork, porcine offal, fat, blood, and spices are very popular in the Czech Republic. All these ingredients are potential sources of dietary exposure to ochratoxin A (OTA). OTA has a strong affinity to serum proteins in porcine blood. Thus, the contamination of blood sausages with OTA can be expected. This study aims to evaluate OTA in 200 samples of porcine blood sausages purchased at the Czech market during 2020-2021. The analytical method high-performance liquid chromatography coupled with fluorescence detection with pre-treatment using immunoaffinity columns was employed to determine OTA. The limit of detection was 0.03 ng/g and the limit of quantification 0.10 ng/g. Recovery was 71.6 %. All samples were positive at contents ranging from 0.15 to 5.68 ng/g with a mean of 1.47 ng/g, and a median of 1.26 ng/g. A total of 66% of these samples contained OTA content exceeding the maximum limit of 1 ng/g set in Italy. This study demonstrates that the Czech population is exposed to OTA from blood sausages. The proposed preliminary action limit for OTA in blood sausages should be set at 1 ng/g. No regulatory limits for OTA in blood sausages have been established yet in the European Union legislation. To protect human health, further monitoring of OTA in these products is necessary.

Ochratoxin A in Slaughtered Pigs and Pork Products

Ochratoxin A (OTA) is a mycotoxin that is produced after the growth of several Aspergillus and Penicillium spp. in feeds or foods. OTA has been proved to possess nephrotoxic, hepatotoxic, teratogenic, neurotoxic, genotoxic, carcinogenic and immunotoxic effects in animals and humans. OTA has been classified as possibly carcinogenic to humans (Group 2B) by the IARC in 2016. OTA can be mainly found in animals as a result of indirect transmission from naturally contaminated feed. OTA found in feed can also contaminate pigs and produced pork products. Additionally, the presence of OTA in pork meat products could be derived from the direct growth of OTA-producing fungi or the addition of contaminated materials such as contaminated spices. Studies accomplished in various countries have revealed that pork meat and pork meat products are important sources of chronic dietary exposure to OTA in humans. Various levels of OTA have been found in pork meat from slaughtered pigs in many countries, while OTA levels were particularly high in the blood serum and kidneys of pigs. Pork products made from pig blood or organs such as the kidney or liver have been often found to becontaminated with OTA. The European Union (EU) has established maximum levels (ML) for OTA in a variety of foods since 2006, but not for meat or pork products. However, the establishement of an ML for OTA in pork meat and meat by-products is necessary to protect human health.

Aspergillus derived mycotoxins in food and the environment: Prevalence, detection, and toxicity

Aspergillus species are the paramount ubiquitous fungi that contaminate various food substrates and produce biochemicals known as mycotoxins. Aflatoxins (AFTs), ochratoxin A (OTA), patulin (PAT), citrinin (CIT), aflatrem (AT), secalonic acids (SA), cyclopiazonic acid (CPA), terrein (TR), sterigmatocystin (ST) and gliotoxin (GT), and other toxins produced by species of Aspergillus plays a major role in food and human health. Mycotoxins exhibited wide range of toxicity to the humans and animal models even at nanomolar (nM) concentration. Consumption of detrimental mycotoxins adulterated foodstuffs affects human and animal health even trace amounts. Bioaerosols consisting of spores and hyphal fragments are active elicitors of bronchial irritation and allergy, and challenging to the public health. Aspergillus is the furthermost predominant environmental contaminant unswervingly defile lives with a 40-90 % mortality risk in patients with conceded immunity. Genomics, proteomics, transcriptomics, and metabolomics approaches useful for mycotoxins' detection which are expensive. Antibody based detection of toxins chemotypes may result in cross-reactivity and uncertainty. Aptamers (APT) are single stranded DNA (ssDNA/RNA), are specifically binds to the target molecules can be generated by systematic evolution of ligands through exponential enrichment (SELEX). APT are fast, sensitive, simple, in-expensive, and field-deployable rapid point of care (POC) detection of toxins, and a better alternative to antibodies.

Mycotoxins in artisanal beers: An overview of relevant aspects of the raw material, manufacturing steps and regulatory issues involved

The consumption of artisanal beer has increased worldwide. Artisanal beers can include malted or unmalted wheat, maize, rice and sorghum, in addition to the basic ingredients. These grains can be infected by toxigenic fungi in the field or during storage and mycotoxins can be produced if they find favorable conditions. Mycotoxins may not be eliminated throughout the beer brewing and be detected in the final product. In addition, modified mycotoxins may also be formed during beer brewing. This review compiles relevant information about mycotoxins produced by Aspergillus, Fusarium and Penicillium in raw material of artisanal beer, as well as updates information about the production and fate of mycotoxins during the beer brewing process. Findings highlight that malting conditions favor the production of mycotoxins by the fungi contaminating cereals. Therefore, good agricultural and postharvest mitigation strategies are the most effective options for preventing the growth of toxigenic fungi and the production of mycotoxins in cereals. However, the final concentration of mycotoxin in artisanal beer is difficult to predict as it depends on the initial concentration contained in the raw material and the processing conditions. The current lack of limits of mycotoxins in artisanal beer underestimates possible risks to human health. In addition, modified mycotoxins, not detected by conventional methods, may be formed in artisanal beers. Maximum tolerated limits for these contaminants must be urgently established based on scientific data about transfer of mycotoxins throughout the artisanal beer brewery process.

Effects of mycotoxin-contaminated feed on farm animals

Mycotoxins are secondary products produced by fungi in cereals and are frequently found in the livestock industry as contaminants of farm animal feed. Studies analyzing feed mycotoxins have been conducted worldwide and have confirmed the presence of mycotoxins with biological activity, including aflatoxin, ochratoxin A, fumonisin, zearalenone, and deoxynivalenol, in a large proportion of feed samples. Exposure to mycotoxins can cause immunotoxicity and impair reproductive function in farm animals. In addition, exposure of tissues, such as the kidneys, liver, and intestines, to mycotoxins can exert histopathological changes that can interfere with animal growth and survival. This review describes previous studies regarding the presence of major mycotoxins in the feed of farm animals, especially pigs and poultry. Moreover, it describes the adverse effects of mycotoxins in farm animals following exposure, as well as the biological activity of mycotoxins in animal-derived cells. Mycotoxins have been shown to regulate signaling pathways, oxidative stress, endoplasmic reticulum stress, apoptosis, and proliferation in porcine and bovine cells. A clear understanding of the effects of mycotoxins on farm animals will help reduce farm household economic loss and address the health concerns of people who consume these meat and dairy products.

Influence of Saccharomyces cerevisiae to ameliorate adverse effects of ochratoxin on biochemical profile and immune response in broiler chickens

To establish the ochratoxicosis ameliorating efficacy of dietary Saccharomyces cerevisiae (SC), day-old broiler chicks (240) were divided into 6 treatment groups (T1, control (basal diet); T2, T1 + 200 ppb OTA; T3, T1 + 0.05% SC; T4, T1 + 0.1% SC; T5, T2 + 0.05% SC and T6, T2 + 0.1% SC). Each diet was fed to 5 replicated groups of 8 birds each from 1 to 42 days of age. The total serum protein and haemoglobin (Hb) in T2 and T5 were lower than that of control (T1). The serum protein and Hb content in group T6 was higher than that of T2 and statistically similar to that of control. The serum uric acid, creatinine, ALP, SGOT, SGPT and H/L ratio in ochratoxin fed group (T2) was higher than that of T1. The serum uric acid, creatinine, ALP, SGOT, SGPT and H/L ratio in T6 was lower than that of T2 and statistically similar to that of T1. The CMI and HA titre value in ochratoxin fed group (T2) was lower than that of T1. The CMI and HA titre value in T5 and T6 was lower than T1 but higher than T2. It was concluded that ochratoxin contamination at 200 ppb level in broiler diet altered the biochemical parameters and immune response. Inclusion of Saccharomyces cerevisiae at 0.1% level to the ochratoxin contaminated diet ameliorated the adverse effects of ochratoxicosis on biochemical parameters and immune response of broiler chickens.

Occurrence and Risk Assessment of Mycotoxins through Polish Beer Consumption

Poland is one of Europe's leading producers and exporters of beer. The study, herein, describes the measurement of ochratoxin A, deoxynivalenol, nivalenol, T-2 toxin, HT-2 toxin, diacetoxyscirpenol, and zearalenone levels in 69 Polish beers. Analytical methodologies based on high performance liquid chromatography (HPLC) with tandem mass spectrometry (MS/MS) and fluorescence detection were developed, validated, and used to perform the above determinations. The most prevalent mycotoxins were deoxynivalenol (96%), ochratoxin A (93%), and HT-2 toxin (74%), respectively. Three quarters of the samples contained at least three analytes. The mean ochratoxin A concentration was 0.057 (SD 0.065) ng/mL, and in four beer samples its level exceeded 0.2 ng/mL, a value postulated in the literature to be the maximum limit. Deoxynivalenol was found at a maximum level of 56.2 ng/mL, and its mean concentration was 17.1 (SD 9.0) ng/mL. An evaluation of the estimated daily intake (EDI) of mycotoxins from beer in different European populations was made using food-consumption data prepared by WHO. Based on the mean ochratoxin A concentration in beers, the EDI represented 0.8-1.1% of the tolerable daily intake (TDI), while in a worst-case scenario (maximum concentration) it reached 5.0-7.5% of TDI. For deoxynivalenol, the EDI was in the range of 4.1-6.0% of TDI, whereas, based on maximum values, it reached the level of 14-21% of TDI. There were no significant differences between "scenarios" in the HT-2 case (mean-5.0-7.5% of TDI; maximum-6.5-9.7% of TDI) due to the fact that its concentration was near the limit of quantification (LOQ) value taken for calculation. The significance of these results are discussed, herein.

Effect of Cinnamaldehyde on Morphological Alterations of Aspergillus ochraceus and Expression of Key Genes Involved in Ochratoxin A Biosynthesis

Ochratoxin A (OTA) is a potent nephrotoxic, hepatotoxic, and teratogenic compound which is a significant mycotoxin contaminates cereals during storage. Aspergillus ochraceus is the most common producer of OTA in cereals and cereal-derived products. Cinnamaldehyde is a natural substance derived from plant cinnamon playing an important role in the reduction of OTA contamination. In this study, the antifungal and antitoxigenic effect of cinnamaldehyde was investigated with its mechanisms of inhibition of fungal growth at the morphological and ultrastructural levels, and inhibition of OTA biosynthesis at the transcriptional level. Significant A. ochraceus growth was inhibited at 0.4⁻1.6 mmol/L with fumigation. A. ochraceus exposed to 0.4 mmol/L of cinnamaldehyde indicated irreversible harmful morphological and ultrastructural modifications such as the folding of the cell, the loss of integrity of the cell wall, the disruption of plasma membrane, the destruction of the mitochondria, and the absence of intracellular organelles. These alterations may be attributed to its inhibition of enzymatic reactions that regulate cell wall synthesis, thus disturbing the morphogenesis and growth of A. ochraceus. In the presence of cinnamaldehyde, the tested biosynthetic and regulatory genes like pks, nrps, veA, laeA and velB were highly downregulated. Moreover, the downregulation effect of cinnamaldehyde increased proportionally with the concentrations. These results suggest that the decrease of OTA production by cinnamaldehyde is attributed to the downregulation of the transcriptional levels of OTA biosynthetic and regulatory genes besides the inhibition of fungal growth. The study reveals the mechanisms of the antifungal and antitoxigenic activities of cinnamaldehyde against A. ochraceus, and further emphasizes that cinnamaldehyde could be a safe and effective natural agents against OTA contamination during cereals storage.

Ochratoxin A determination in swine muscle and liver from French conventional or organic farming production systems

Consumers generally considered organic products to be healthier and safer but data regarding the contamination of organic products are scarce. This study evaluated the impact of the farming system on the levels of ochratoxin A (OTA) in the tissues of French pigs (muscle and liver) reared following three different types of production (organic, Label Rouge and conventional). Because OTA is present at trace levels in animal products, a sensitive ultra-high performance liquid chromatography-tandem mass spectrometry method using stable isotope dilution assay was developed and validated. OTA was detected or quantified (LOQ of 0.10 μg kg^-1) in 67% (n = 47) of the 70 pig liver samples analysed, with concentrations ranging from <0.10 to 3.65 μg kg^-1. The maximum concentration was found in a sample from organic production but there were no significant differences in the content of OTA between farming systems. OTA was above the LOQ in four out of 25 samples of the pork muscles. A good agreement was found between OTA levels in muscle and liver (liver concentration = 2.9 × OTA muscle concentration, r = 0.981).

Development and validation of LC-MS/MS method for the determination of Ochratoxin A and its metabolite Ochratoxin α in poultry tissues and eggs

The objective of this study was to develop a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of Ochratoxin A (OTA) and Ochratoxin α (OTα) in poultry tissues and eggs. The two toxins were extracted by a mixture of acetonitrile/water, purified with a reversed phase C18 solid phase extraction column (SPE) and determined by LC-MS/MS. The LC-MS/MS method performances were evaluated in terms of linearity in solvent and in matrix (ranged from 0.5 to 15.10 µg L^-1 for OTA and from 0.60 to 17.85 µg L^-1 for OTα), limit of detection (LOD), limit of quantitation (LOQ), specificity, accuracy and precision in repeatability conditions. Recovery experiments were performed by spiking poultry liver, kidney, muscle and eggs around 1 µg kg^-1 and 10 µg kg^-1. LODs were 0.27 and 0.26 µg kg^-1 while LOQs were fixed at 1.0 and 1.2 µg kg^-1 for OTA and OTα, respectively. Main recoveries for OTA ranged from 82 to 109% and for OTα ranged from 55 to 89%. The values of within-laboratory relative standard deviation (RSD_r) were equal to or below 20%. Considering the results obtained and that all analytical performance criteria were fulfilled, the new extraction and purification method developed for OTA and OTα determination in animal tissues and eggs was found appropriate for control laboratories and research activities designed to ensure food safety.

Transfer of ochratoxin A from raw black tea to tea infusions prepared according to the Turkish tradition

BACKGROUND

Ochratoxin A (OTA) is a natural contaminant of food including tea with multiple toxic effects, which poses a threat to human health. In terms of lifestyle, the Turkish population is a frequent visitor of tearooms, and the traditional Turkish tea preparation is one of the most popular ways of preparing tea infusion.

RESULTS

The aim of this study was to investigate OTA transfer from raw black tea to the tea infusion prepared according to the Turkish tradition. A high-performance liquid chromatography method with a limit of quantification of 0.35 ng g-1 was used for OTA determination. The OTA amount in raw black teas from Turkey ranged from ≤0.35 ng g-1 up to 56.7 ng g-1 . An homogenised sample of black tea naturally contaminated with 55.0 ng g-1 was used to prepare infusions. The OTA transfer from the black tea to the infusion was found to be 41.5% ± 7%.

CONCLUSION

These data are important for the realisation of a 'Total Diet study' (TDS). The TDS can be a complementary tool to estimate the population dietary exposure to OTA across the entire diet by analysing main foods prepared 'as consumed' (tea infusions) and not 'as purchased' (raw tea). © 2017 Society of Chemical Industry.

Molecular Modeling of the Major DNA Adduct Formed from Food Mutagen Ochratoxin A in NarI Two-Base Deletion Duplexes: Impact of Sequence Context and Adduct Ionization on Conformational Preference and Mutagenicity

Exposure to ochratoxin A (OTA), a possible human carcinogen, leads to many different DNA mutations. As a first step toward understanding the structural basis of OTA-induced mutagenicity, the present work uses a robust computational approach and a slipped mutagenic intermediate model previously studied for C⁸-dG aromatic amine adducts to analyze the conformational features of postreplication two-base deletion DNA duplexes containing OT-dG, the major OTA lesion at the C⁸ position of guanine. Specifically, a total of 960 ns of molecular dynamics simulations (excluding trial simulations) were carried out on four OT-dG ionization states in three sequence contexts within oligomers containing the NarI recognition sequence, a known hotspot for deletion mutations induced by related adducts formed from known carcinogens. Our results indicate that the structural properties and relative stability of the competing "major groove" and "stacked" conformations of OTA adducted two-base deletion duplexes depend on both the OTA ionization state and the sequence context, mainly due to conformation-dependent deviations in discrete local (hydrogen-bonding and stacking) interactions at the lesion site, as well as DNA bending. When the structural characteristics of the OT-dG adducted two-base deletion duplexes are compared to those associated with previously studied C⁸-dG adducts, a greater understanding of the effects of the nucleobase-carcinogen linkage, and size of the carcinogenic moiety on the conformational preferences of damaged DNA is obtained. Most importantly, our work predicts key structural features for OT-dG-adducted deletion DNA duplexes, which in turn allow us to develop hypotheses regarding OT-dG replication outcomes. Thus, our computational results are valuable for the design and interpretation of future biochemical studies on the potentially carcinogenic OT-dG lesion.

Ochratoxin A Concentrations in a Variety of Grain-Based and Non-Grain-Based Foods on the Canadian Retail Market from 2009 to 2014

The extent of ochratoxin A (OTA) contamination of domestically produced foods sold across Canada was determined from 2009 to 2014 with sampling and testing occurring each fiscal year. Cereal-based, fruit-based, and soy-based food samples (n = 6,857) were analyzed. Almost half of the samples (3,200; 47%) did not contain detectable concentrations of OTA. The remaining 3,657 samples contained OTA at 0.040 to 631 ng/g. Wheat, oats, milled products of other grains (such as rye and buckwheat), and to a lesser extent corn products and their derived foods were the most significant potential sources of OTA exposure for the Canadian population. Wine, grape juice, soy products, beer, dairy-based infant formula, and licorice candy were not significant contributors to OTA consumption. Spices had the highest OTA concentrations; but because so little is ingested, these foods are not considered to be a significant source of OTA. In contrast, infant formulas and cereals can be important dietary sources of OTA. Infant cereals containing oats and infant formulas containing soy had detectable concentrations of OTA, some of which exceeded the proposed Canadian guidelines. The prevalence and concentrations of OTA in major crops (wheat, corn, and oats) varied widely across years. Because these foods were purchased at retail stores, no information was available on the OTA concentrations in the raw materials, the storage conditions before purchase of the samples, or the origin of the ingredients (may include blends of raw materials from different years and/or different geographical regions of Canada); therefore, impact of these factors could not be assessed. Overall, 2.3% of the samples exceeded the proposed Canadian OTA regulatory limits and 2.7% exceeded the current European Union (EU) OTA regulatory limits. These results are consistent with a Health Canada exposure assessment published in 2010, despite the inclusion of a wider range of products and confirm the safety of foods widely available across Canada.

Screening and Identification of Novel Ochratoxin A-Producing Fungi from Grapes

Ochratoxin A (OTA) contamination has been established as a world-wide problem. In this study, the strains with the ability of OTA production were screened by analyzing the green fluorescence of the isolates colonies from the grapes in Zhenjiang with 365 nm UV light and confirmed by HPLC with fluorescent detection (HPLC-FLD). The results showed that seven isolates acquired the characteristic of the fluorescence, of which only five showed the ability of OTA production as confirmed by HPLC-FLD analysis. The five OTA-producing strains were identified based on comparative sequence analysis of three conserved genes (ITS, BenA and RPB2) of the strains, and they are Talaromyces rugulosus (O1 and Q3), Penicillium commune (V5-1), Penicillium rubens (MQ-5) and Aspergillus aculeatus (MB1-1). There are two Penicillium species of the five OTA-producing strains and our study is the first to report that P. rubens, T. rugulosus and A. aculeatus can produce OTA. This work would contribute to comprehensively understanding the fungi with an OTA-producing ability in grapes before harvest and then take effective measures to prevent OTA production.

Review: Ochratoxin A (OTA) in Wines, Musts and Grape Juices: Occurrence, Regulations and Methods of Analysis

This work gives a general overview of ochratoxin A (OTA) occurrence in wines and the methodology for OTA analysis. The results of more than two thousand samples taken from the literature have been taken into account to quite extensively describe the present situation of OTA contamination of wine. According to these data, OTA is much more commonly detected in red wines than in rosé and white wines, and OTA concentration is remarkably higher than in the latter ones. Thus OTA could be detected in 45% (median 34%) of white wine samples, whereas it was detected in 66% (median 66%) of rosé and 71% (median 90%) of red wine samples. When comparing the wines from Northern and Southern regions, the latter showed a higher contamination than those from the Northern area. It has been suggested that OTA accumulation could be due to fungi belonging to the genus Aspergillus in wines from Southern European countries because the crops are exposed to elevated temperatures, which favour growth of OTA-producing Aspergillus species over Penicillium. High performance liquid chromatography (HPLC) associated with fluorescence detection preceded by extraction of OTA using commercially available immunoaffinity columns (IAC) is currently the most applied method for OTA determination in wines.

Occurrence of Ochratoxigenic Fungi and Ochratoxin A in Green Coffee from Different Origins

Fungal infection and ochratoxin A (OTA) contamination were determined in green coffee samples from different origins, in which OTA-producing fungi were also identified. About 72% of the beans analysed by direct plating presented fungal infection, including species of Aspergillus, Penicillium and Rhizopus. The genus Aspergillus was presented in more than 90% of infected coffee beans. Aspergillus ochraceus and Aspergillus section Nigri isolates represented 2.8 and 65.4%, respectively from the total number of isolates from the coffee beans. The capacity to produce OTA was determined in 260 isolates of A. section Nigri and 19 of A. ochraceus by the agar plug method, giving positive results for 6% of the A. section Nigri isolates and 16% of the A. ochraceus. OTA production was analysed by high performance liquid chromatography. OTA contamination of green coffee beans was analysed by enzyme immunoassay. OTA levels in all samples analysed were above the limit of detection (0.6 mg/kg), with a mean OTA concentration of 6.7 mg/kg.

Ochratoxin A: 50 Years of Research

Since ochratoxin A (OTA) was discovered, it has been ubiquitous as a natural contaminant of moldy food and feed. The multiple toxic effects of OTA are a real threat for human beings and animal health. For example, OTA can cause porcine nephropathy but can also damage poultries. Humans exposed to OTA can develop (notably by inhalation in the development of acute renal failure within 24 h) a range of chronic disorders such as upper urothelial carcinoma. OTA plays the main role in the pathogenesis of some renal diseases including Balkan endemic nephropathy, kidney tumors occurring in certain endemic regions of the Balkan Peninsula, and chronic interstitial nephropathy occurring in Northern African countries and likely in other parts of the world. OTA leads to DNA adduct formation, which is known for its genotoxicity and carcinogenicity. The present article discusses how renal carcinogenicity and nephrotoxicity cause both oxidative stress and direct genotoxicity. Careful analyses of the data show that OTA carcinogenic effects are due to combined direct and indirect mechanisms (e.g., genotoxicity, oxidative stress, epigenetic factors). Altogether this provides strong evidence that OTA carcinogenicity can also occur in humans.

Functional Characterization of New Polyketide Synthase Genes Involved in Ochratoxin A Biosynthesis in Aspergillus Ochraceus fc-1

Ochratoxin A (OTA), a potentially carcinogenic mycotoxin which contaminates grains, is produced by several Aspergillus species. A comparative sequence analysis of the OTA-producing Aspergillus ochraceus fc-1 strain and other Aspergillus species was performed. Two new OTA-related polyketide synthase (PKS) (AoOTApks) genes were identified. The predicted amino acid sequence of AoOTApks-1 displayed high similarity to previously identified PKSs from OTA-producing A. carbonarius ITEM 5010 (67%; [PI] No. 173482) and A. niger CBS 513.88 (62%; XP_001397313). However, the predicted amino acid sequence of AoOTApks-2 displayed lower homology with A. niger CBS 513.88 (38%) and A. carbonarius ITEM 5010 (28%). A phylogenetic analysis of the β-ketosynthase and acyl-transferase domains of the AoOTApks proteins indicated that they shared a common origin with other OTA-producing species, such as A. carbonarius, A. niger, and A. westerdijkiae. A real-time reverse-transcription PCR analysis showed that the expression of AoOTApks-1 and -2 was positively correlated with the OTA concentration. The pks gene deleted mutants ∆AoOTApks-1 and ∆AoOTApks-2 produced nil and lesser OTA than the wild-type strain, respectively. Our study suggests that AoOTApks-1 could be involved in OTA biosynthesis, while AoOTApks-2 might be indirectly involved in OTA production.

Ochratoxin A in stored U.S. barley and wheat

Ochratoxin A (OTA) is a mycotoxin of significant health concern that is present in a variety of cereal grains and other foods around the world. Although OTA contamination can occur prior to harvest, it is largely considered a storage issue that can be controlled through the implementation of proper storage practices. Barley, durum, and hard red spring wheat samples that had been stored for various lengths of time were collected (n = 262) over a period of 2 years by multiple commercial grain companies located in the northwestern and northern Great Plains regions of the United States. Samples were analyzed for OTA concentration using high-performance liquid chromatography with fluorescence detection. OTA was detected in 12.2% of the samples, and of those samples, 81.3% had been stored for ≥6 months. One sample of barley and four samples of wheat exceeded 5 ng/g of OTA.

Ochratoxin A in food and urine: a nationwide Portuguese two-year study

Several toxic effects have been described after exposure to ochratoxin A (OTA), which can enter the human diet directly through food or through animal products via carry-over from contaminated feed. To assess the exposure of the Portuguese population to OTA, a study over a two-year period was conducted. It involved analysis of 472 morning urine samples from inhabitants of four regions, together with a survey of regional bread (738) and pork (254) samples. These foodstuffs are two staple foods in the Portuguese and Mediterranean diet that present a high and widespread consumption by the majority of the population. The bread samples analysed showed a low level of contamination, although the contamination range was broad and some of the samples exceeded the maximum level established in the European Union. Maize bread (broa), especially when made by mixing with rye, was the most contaminated, followed by whole grain-, rye- and wheat-based bread. However, the latter contributed more to OTA exposure, because they were more commonly consumed. Even though the occurrence was rather low, the average OTA amount in pork was relatively high compared to previous national and other surveys. The observed high within-subject variability of OTA in urine limited the use of this biomarker of exposure at the individual level, but not on a population or subgroup of subjects scale. Among the studied population, a widespread exposure was confirmed by the high frequency of OTA contamination in urine, although characterised by a low average contamination level. Independent of region or population, pork appears to be the main contributor to the daily OTA intake in Portugal. These data were clearly in contrast with previous studies showing that cereals and their derived products were the major contributors, while food of animal origin only contributed a small part to the total human dietary OTA exposure.

Transfer of ochratoxin A into tea and coffee beverages

Ochratoxin A (OTA) is nephrotoxic, hepatotoxic, immunotoxic, neurotoxic, reprotoxic, teratogenic, and carcinogenic (group 2B), being characterized by species and sex differences in sensitivity. Despite the fact that OTA is in some aspects a controversial topic, OTA is the most powerful renal carcinogen. The aim of this study was to make a small survey concerning OTA content in black tea, fruit tea, and ground roasted coffee, and to assess OTA transfer into beverages. OTA content was measured using a validated and accredited HPLC-FLD method with a limit of quantification (LOQ) of 0.35 ng/g. The OTA amount ranged from LOQ up to 250 ng/g in black tea and up to 104 ng/g in fruit tea. Black tea and fruit tea, naturally contaminated, were used to prepare tea infusions. The transfer from black tea to the infusion was 34.8% ± 1.3% and from fruit tea 4.1% ± 0.2%. Ground roasted coffee naturally contaminated at 0.92 ng/g was used to prepare seven kinds of coffee beverages. Depending on the type of process used, OTA transfer into coffee ranged from 22.3% to 66.1%. OTA intakes from fruit and black tea or coffee represent a non-negligible human source.

Assessment and characterisation of yeast-based products intended to mitigate ochratoxin exposure using in vitro and in vivo models

The aim of this paper was to evaluate the capacity of several yeast-based products, derived from baker's and brewer's yeasts, to sequester the mycotoxin ochratoxin A (OTA) and to decrease its rate of absorption and DNA adduct formation in vivo. The experimental protocol included in vitro binding studies using isotherm models, in vivo chicken experiments, in which the serum and tissue concentrations of OTA were analysed in the absence and presence of the test compounds, and the profile of OTA-derived metabolites and their associated DNA adducts were determined. Additionally in vitro cell culture studies (HK2 cells) were applied to assess further the effects for yeast cell product enriched with glutathione (GSH) or selenium. Results of the in vitro binding assay in a buffer system indicated the ability of the yeast-based products, as sequester of OTA, albeit at a different level. In the in vitro experiments in chickens, decreased serum and tissue concentrations of treated animals confirmed that yeast-based products are able to prevent the absorption of OTA. A comparison of the binding affinity in a standard in vitro binding assay with the results obtained in an in vivo chicken experiment, however, showed a poor correlation and resulted in a different ranking of the products. More importantly, we could show that yeast-based products actively modulate the biotransformation of OTA in vivo as well as in vitro in a cell culture model. This effect seems to be attributable to residual enzymatic activities in the yeast-based products. An enrichment of yeast cell wall products with GSH or selenium further modulated the profile of the generated OTA metabolites and the associated pattern of OTA-induced DNA adducts by increasing the conversion of OTA into less toxic metabolites such as OTA, OTB and 4-OH-OTA. A reduced absorption and DNA adduct formation was particularly observed with GSH-enriched yeast, whereas selenium-enriched yeasts could counteract the OTA-induced decrease in cell viability, but at the same time increased the OTA-DNA adducts formation. These findings indicate the need for an in-depth characterisation of yeast-based products used as mycotoxin-mitigating feed additives, in in vivo models with target animal species taking into account not only their ability to sequester toxins in the gastrointestinal tract but also their potential effects on the biotransformation of mycotoxins.

Structural and energetic characterization of the major DNA adduct formed from the food mutagen ochratoxin A in the NarI hotspot sequence: influence of adduct ionization on the conformational preferences and implications for the NER propensity

The nephrotoxic food mutagen ochratoxin A (OTA) produces DNA adducts in rat kidneys, the major lesion being the C8-linked-2′-deoxyguanosine adduct (OTB-dG). Although research on other adducts stresses the importance of understanding the structure of the associated adducted DNA, site-specific incorporation of OTB-dG into DNA has yet to be attempted. The present work uses a robust computational approach to determine the conformational preferences of OTB-dG in three ionization states at three guanine positions in the NarI recognition sequence opposite cytosine. Representative adducted DNA helices were derived from over 2160 ns of simulation and ranked via free energies. For the first time, a close energetic separation between three distinct conformations is highlighted, which indicates OTA-adducted DNA likely adopts a mixture of conformations regardless of the sequence context. Nevertheless, the preferred conformation depends on the flanking bases and ionization state due to deviations in discrete local interactions at the lesion site. The structural characteristics of the lesion thus discerned have profound implications regarding its repair propensity and mutagenic outcomes, and support recent experiments suggesting the induction of double-strand breaks and deletion mutations upon OTA exposure. This combined structural and energetic characterization of the OTB-dG lesion in DNA will encourage future biochemical experiments on this potentially genotoxic lesion.

Survey of ochratoxin A in freshly harvested durum and hard red spring wheat in the United States, 2011 and 2012

Ochratoxin A (OTA) is a toxin produced by some Penicillium and Aspergillus species around the world in a variety of food and feed, especially cereal grains, before harvest but primarily during storage. Durum and hard red spring (HRS) wheat samples were collected right after harvest as part of the U. S. regional crop quality survey in both 2011 (n = 560) and 2012 (n = 654) from the upper Great Plains. All samples were analyzed for OTA contamination using high-performance liquid chromatography with fluorescence detection. Overall, 2.1% of the samples were positive for OTA. In 2011, OTA was detected in 1.0% of the durum wheat samples but was not found in HRS wheat. In 2012, 8.3 and 1.4% of the durum and HRS wheat samples, respectively, were positive for OTA. Of the 25 samples that had detectable OTA, 3 samples (12%), all of which were durum wheat, had OTA that exceeded 5 ng/g.

Influence of fermentation and drying materials on the contamination of cocoa beans by ochratoxin A

Ochratoxin A (OTA) is a mycotoxin produced mainly by species of Aspergillus and Penicillium. Contamination of food with OTA is a major consumer health hazard. In Côte d’Ivoire, preventing OTA contamination has been the subject of extensive study. The current study was conducted to evaluate the influence of fermentation and drying materials on the OTA content in cocoa. For each test, 7000 intact cocoa pods were collected, split open to remove the beans, fermented using 1 of 3 different materials, sun-dried on 1 of 3 different platform types and stored for 30 days. A total of 22 samples were collected at each stage of post-harvesting operations. The OTA content in the extracted samples was then quantified by high-performance liquid chromatography. OTA was detected in beans at all stages of post-harvesting operations at varying levels: pod-opening (0.025 ± 0.02 mg/kg), fermentation (0.275 ± 0.2 mg/kg), drying (0.569 ± 0.015 mg/kg), and storage (0.558 ± 0.04 mg/kg). No significant relationships between the detected OTA level and the materials used in the fermentation and drying of cocoa were observed.

Modeling the conformational preference of the carbon-bonded covalent adduct formed upon exposure of 2'-deoxyguanosine to ochratoxin A

The conformational flexibility of the C8-linked guanine adduct formed from attachment of ochratoxin A (OTA) was analyzed using a systematic computational approach and models ranging from the nucleobase to the adducted DNA helix. A focus was placed on the influence of the C8-modification of 2'-deoxyguanosine (dG) on the preferred relative arrangement of the nucleobase and the C8-substituent and, more importantly, the anti/syn conformational preference with respect to the glycosidic bond. Although OTA is twisted with respect to the base in the nucleobase model, addition of the deoxyribose sugar induces a further twist and restricts rotation about the C-C linkage due to close contacts between OTA and the sugar. The nucleoside model preferentially adpots a syn orientation (by 10-20 kJ mol(-1) depending on the OTA conformation) due to the presence of an O5'-H···N3 interaction. However, when this hydrogen bond is eliminated, which better mimics the DNA environment, a small (<5 kJ mol(-1)) anti/syn energy difference is predicted. Inclusion of the 5'-monophosphate group leads to an up to 20 kJ mol(-1) preference for the syn (nucleotide) conformation due to stabilizing base-phosphate interactions involving the amino group of guanine. Nevertheless, MD simulations and free energy analysis predict that both syn- and anti-conformations of OTB-dG are equally stable in helices when paired opposite cytosine. These results indicate that the adduct will likely adopt a syn conformation in an isolated nucleoside and nucleotide, while a mixture of syn and anti conformations will be observed in DNA duplexes. Since the syn conformation could stabilize base mismatches upon DNA replication or Z-DNA structures with varied biological outcomes, future computational and experimental work should elucidate the consequences of the conformational preference of this potentially harmful DNA lesion.

Determination of ochratoxin A in wine by means of immunoaffinity and aminopropyl solid-phase column cleanup and fluorometric detection

A new analytical method for the determination of ochratoxin A (OTA) in red wine has been developed by using a double-extract cleanup and a fluorometric measurement after spectral deconvolution. Wine samples were diluted with a solution containing 1% polyethylene glycol and 5% sodium hydrogencarbonate, filtered, and purified by immunoaffinity and aminopropyl solid-phase column. OTA contents in the purified extract were determined by a spectrofluorometer (excitation wavelength, 330 nm; emission wavelength, 470 nm) after deconvolution of fluorescence spectra. Average recoveries from wine samples spiked with OTA at levels ranging from 0.5 to 3.0 ng/mL were 94.5-105.4% with relative standard deviations (RSD) of <15% (n = 4). The limit of detection (LOD) was 0.2 ng/mL, and the total time of analysis was 30 min. The developed method was tested on 18 red wine samples (naturally contaminated and spiked with OTA at levels ranging from 0.4 to 3.0 ng/mL) and compared with AOAC Official Method 2001.01, based on immunoaffinity column cleanup and HPLC with fluorescence detector. A good correlation (r(2) = 0.9765) was observed between OTA levels obtained with the two methods, highlighting the reliability of the proposed method, the main advantage of which is the simple OTA determination by a benchtop fluorometer with evident reductions of cost and time of analysis.

Functional characterization of the polyketide synthase gene required for ochratoxin A biosynthesis in Penicillium verrucosum

The ochratoxin A (OTA) polyketide synthase otapks gene has been cloned from Penicillium verrucosum. A P. verrucosum mutant in which the otapksPV gene has been interrupted cannot synthesize ochratoxin A. The protein is most similar to the citrinin polyketide synthase CtnpksMa from Monascus anka (83% identity at the amino acid level). Different nutritional conditions influence OTA production in P. verrucosum, with the addition of glycerol and galactose to MCB resulting in approximately 19 and 32 fold increases in OTA production respectively. These effects are mirrored in increased levels of otapksPV gene transcription. In contrast, the addition of glucose to MCB containing galactose results in an approximate 10 fold repression in OTA production, with this repression again being mirrored in decreased levels of otapksPV gene transcription. Thus the effects of different carbon sources on OTA production in P. verucosum appear to be regulated at the level of gene transcription. Two additional open reading frames, otaE and otaT, were identified in the 5' and 3' flanking regions of otapksPV, respectively. The otaT and otaE genes are co-expressed with P. verrucosum otapksPv, indicating a possible role for these genes in OTA biosynthesis. Furthermore, otaT and otaE were identified as putative homologues of the M. anka citrinin transporter ctnC (72% amino acid identity) and M. anka citrinin oxidoreductase ctnB (83% amino acid identity); suggesting that the genes involved in OTA production in P. verrucosum may be very similar to those involved in citrinin production in M. anka.

Occurrence of Ochratoxin A in the wild boar (Sus scrofa): chemical and histological analysis

Ochratoxins are fungal secondary metabolites that may contaminate a broad variety of foodstuffs, such as grains, vegetables, coffee, dried fruits, beer, wine and meats. Ochratoxins are nephrotoxins, carcinogens, teratogens and immunotoxins in rats and are also likely to be in humans. In 2009/2010, a survey of the presence of Ochratoxin A (OTA) in regularly hunted wild boars in the Calabria region of southern Italy detected OTA in 23 animals in the kidney, urinary bladder, liver and muscles: 1.1 &#177; 1.15, 0.6 &#177; 0.58, 0.5 &#177; 0.54 and 0.3 &#177; 0.26 &#956;g/kg, respectively. Twelve tissue samples showed levels of OTA higher than the guideline level (1 &#956;g/kg) established by the Italian Ministry of Health. In five wild boars, gross-microscopic lesions were described for the organs displaying the highest concentrations of OTA determined by HPLC-FLD analysis, i.e., the kidney, liver and urinary bladder.

A brief study of toxic effects of some medicinal herbs on kidney

Increased use of complementary and alternative herbal medicines in the treatment of various diseases.Some herbal therapies may be causes of potential toxicity that may be renal toxicity caused by the ingestion of herbs. The goal of this study is the toxic and beneficial effects of medicinal herbs on renal health by which evidence for benefit or toxicity has been found. Included are nephrotoxicity from aristolochic acid and other components within herbs, herb-drug interactions, heavy metal toxicity in herbs and adulterants during careless preparation of herbal medicine, resulting in adverse renal effects and renal toxicity from contaminants within the extracts. The review aims to provide knowledge and guide to encourage future toxicity studies on the kidney by medicinal herbs.

Occurrence of ochratoxin A in domestic beers and wines from Tunisia by immunoaffinity clean-up and liquid chromatography

A survey on the occurrence of ochratoxin A (OTA) in wines and beers produced in Tunisia was carried out. Wines and beers were analysed using immunoaffinity column clean-up and high-performance liquid chromatography coupled to a fluorometric detector. OTA was detected in 29 wine samples, with an incidence of contamination of 85%. The OTA levels ranged between 0.09 and 1.5 µg/L. Neither of the studied samples showed levels above the European regulatory limit (2 µg/L). OTA was detected in 17 beer samples with an incidence of contamination of 45%. The OTA levels ranged between 0.04 and 0.35 µg/L. The OTA dietary intake by the consumption of wine and beer may be considered as negligible. The obtained results showed high incidence of OTA in Tunisian wines and beers; however, there are no toxicological risks for Tunisian consumers through their consumption of such processed products using cereals and grapes.

Polyketide synthase gene aolc35-12 controls the differential expression of ochratoxin A gene aoks1 in Aspergillus westerdijkiae

Ochratoxine A (OTA), a potential human carcinogen is produced by several species of Aspergillus and Penicillium, including Aspergillus westerdijkiae. In this study a putative polyketide synthase gene aolc35-12 has been partially cloned from A. westerdijkiae. The predicted amino acid sequence of the 3.22 kb clone was found to have a high degree of similarity to other previously identified polyketide synthase genes from various OTA-producing fungi including Aspergillus ochraceus, Aspergillus niger, Aspergillus carbonarius and Penicillium nordicum. The aolc35-12 gene was disrupted and inactivated by insertion of Escherichia coli hygromycin B phosphotransferase gene, which resulted in an OTA negative mutant aoΔlc35-12. Genetic complementation confirmed aolc35-12 as OTA-polyketide synthase gene. Furthermore, study of the differential expression of aolc35-12 and a previously identified OTA-polyketide synthase gene, i.e. aoks1, in the wild-type A. westerdijkiae and aoΔlc35-12 mutant revealed that aolc35-12 could code for a certain polyketide compound complementary for the expression of aoks1 and hence for the activation of OTA biosynthesis system in A. westerdijkiae.

Mutagenicity of ochratoxin A and its hydroquinone metabolite in the SupF gene of the mutation reporter plasmid Ps189

Ochratoxin A (OTA) is a mycotoxin that enhances renal tumor formation in the outer medulla of male rat kidney. Direct DNA damage and subsequent mutagenicity may contribute to these processes. In this study we have determined whether OTA in the absence or presence of activated rat liver microsomes (RLM) or redox-active transition metals (Fe(III) or Cu(II)) causes promutagenic DNA damage in the supF gene of the mutation reporter plasmid pS189 replicating in human Ad293 cells. In addition, we have assessed the mutagenicity of the hydroquinone metabolite (OTHQ) of OTA in the absence or presence of cysteine without added cofactors. Our results show that oxidation of OTA, either by RLM or by transition metal ions, activates OTA to a directly genotoxic mutagen(s). The Fe(III)/OTA system was the most potent mutagen in our experimental system, causing a 32-fold increase in mutant fraction (MF) above the spontaneous control MF. The Cu(II)/OTA system caused a 9-fold increase in MF, while a 6-10-fold increase in MF was observed for OTA in the presence of RLM. The OTHQ metabolite is also mutagenic, especially in the presence of cysteine, in which a 6-fold increase in MF was observed. Our data provide further insight into OTA bioactivation that may account for its in vivo mutagenicity in male rat kidney.