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Michael Rychlik - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of an enzyme immunoassay for the detection of the mycotoxin Tenuazonic Acid in sorghum grains and sorghum-based infant food
Mycotoxin Research, 2017Co-Authors: Madeleine Gross, Stefan Asam, Michael RychlikAbstract:An enzyme-linked immunosorbent assay (ELISA) for the Alternaria mycotoxin Tenuazonic Acid (TeA) was evaluated by comparative analysis of naturally contaminated sorghum grains and sorghum-based infant food, using a stable isotope dilution LC-MS assay (SIDA; limit of detection (LOD) 1.0 μg/kg) as the reference method. LODs of the ELISA were 30 μg/kg in sorghum grains and 220 μg/kg in sorghum-based infant cereals. With SIDA, 100% of the samples ( n = 28) had been positive for TeA in a concentration range of 6–584 μg/kg (mean 113 μg/kg). The ELISA consistently detected TeA in all naturally contaminated samples at cut-off levels of 30–60 μg/kg (sorghum) and 200–300 μg/kg (infant cereals), as based on corresponding to SIDA values. Although the ELISA was much less sensitive than the SIDA method, it may be useful as a screening method for sorghum and sorghum-based infant foods and can be employed to identify samples containing elevated concentrations of TeA in food, well below the proposed level of concern (500 μg/kg).
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Quantitative determination of Tenuazonic Acid in pig and broiler chicken plasma by LC-MS/MS and its comparative toxicokinetics
Journal of agricultural and food chemistry, 2015Co-Authors: Sophie Fraeyman, Michael Rychlik, Mathias Devreese, Nathan Broekaert, Thomas De Mil, Gunther Antonissen, Siegrid De Baere, Patrick De Backer, Siska CroubelsAbstract:A liquid chromatography–tandem mass spectrometry (LC-MS/MS) method to quantitate Tenuazonic Acid (TeA) in pig and broiler chicken plasma was successfully developed and validated. Linear matrix-matched calibration curves ranged between 5 and 200 ng/mL. Correlation coefficients, goodness-of-fit coefficients, and within-day and between-day precision and accuracy fell well within the acceptance criteria. The limit of quantitation was 5.0 ng/mL in both pig and broiler chicken plasma. The LC-MS/MS method was applied in a comparative toxicokinetic study in both pigs and broiler chickens. TeA was completely bioavailable after oral administration in both animal species. However, absorption was deemed to be slower in broiler chickens (mean tmax 0.32 h in pigs vs 2.60 h in chickens). TeA was more slowly eliminated in broiler chickens (mean t1/2el 0.55 h in pigs vs 2.45 h in chickens after oral administration), mainly due to the significantly lower total body clearance (mean Cl 446.1 mL/h/kg in pigs vs 59.2 mL/h/kg i...
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Unravelling the disposition of the Alternaria mycotoxin Tenuazonic Acid: a toxicokinetic study in piglets
2014Co-Authors: Sophie Fraeyman, Michael Rychlik, Mathias Devreese, Nathan Broekaert, Thomas De Mil, Siska CroubelsAbstract:Alternaria fungi can contaminate wheat, sorghum, barley and several fruits and vegetables. Alternaria fungi do not only contaminate crops in the field, but also cause spoilage during refrigerated transport and storage. Alternaria species can produce several mycotoxins, such as alternariol (AOH), alternariol monomethyl ether (AME) and Tenuazonic Acid (TeA). These secondary metabolites can be found in food and feed samples. Toxicokinetic studies are necessary to understand the disposition of these mycotoxins in humans and animals.
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Development of analytical methods for the determination of Tenuazonic Acid analogues in food commodities.
Journal of chromatography. A, 2013Co-Authors: Stefan Asam, Yang Liu, Martina Lichtenegger, Kornelija Muzik, Oliver Frank, Thomas Hofmann, Michael RychlikAbstract:Abstract Analogues of the Alternaria mycotoxin Tenuazonic Acid (TA, biosynthesized by the fungus from the amino Acid isoleucine) derived from valine (ValTA), leucine (LeuTA), alanine (AlaTA) and phenylalanine (PheTA) were synthesized and characterized by mass spectrometry (MS) and 1 H nuclear magnetic resonance (NMR) spectroscopy. Concentrations of stock solutions were determined by quantitative 1 H NMR (qHNMR). Two analytical methods based on high performance liquid chromatography (HPLC) and MS detection were developed, one with derivatization with 2,4-dinitrophenylhydrazine (DNPH) and one without derivatization. Limits of detection (LODs) were between 1–3 μg/kg (with derivatization) and 50–80 μg/kg (without derivatization). Respective limits of quantitation (LOQs) were about three times higher. Beside TA, the analogues LeuTA (about 4% of TA content) and ValTA (about 10% of TA content) were found in highly contaminated sorghum infant cereals and sorghum grains. Other analogues were not detected. Quantification of LeuTA and ValTA was performed using [ 13 C 6 , 15 N]-TA as internal standard and matrix matched calibration. Recovery was between 95 ± 11% and 102 ± 10% for both compounds. Precision (relative standard deviation of triplicate sorghum cereal analyses three times during 3 weeks) was 7% for TA (912 ± 60 μg/kg), 17% for LeuTA (43 ± 8 μg/kg) and 19% for ValTA (118 ± 22 μg/kg). These results indicate that several TA-like compounds, which are not yet characterized in aspects of their toxic properties, were detected in sorghum based infant food highly contaminated with TA, already.
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Determination of Tenuazonic Acid in human urine by means of a stable isotope dilution assay
Analytical and bioanalytical chemistry, 2013Co-Authors: Stefan Asam, Katharina Habler, Michael RychlikAbstract:The content of Tenuazonic Acid in human urine was determined by a stable isotope dilution assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02–100. The limits of detection and determination were 0.2 and 0.6 μg/L, respectively. The mean recovery of the stable isotope dilution assay was 102 ± 3 % in the range between 1.0 and 100 μg/L. Interassay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of Tenuazonic Acid: In the first study, Tenuazonic Acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3–17.3 μg/L or 2.3–10.3 ng/mg−1 creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 μg Tenuazonic Acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested Tenuazonic Acid was 54–81 % after 6 h, depending on matrix and volunteer. After 24 h, 87–93 % of the ingested amount of Tenuazonic Acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.
Stefan Asam - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of an enzyme immunoassay for the detection of the mycotoxin Tenuazonic Acid in sorghum grains and sorghum-based infant food
Mycotoxin Research, 2017Co-Authors: Madeleine Gross, Stefan Asam, Michael RychlikAbstract:An enzyme-linked immunosorbent assay (ELISA) for the Alternaria mycotoxin Tenuazonic Acid (TeA) was evaluated by comparative analysis of naturally contaminated sorghum grains and sorghum-based infant food, using a stable isotope dilution LC-MS assay (SIDA; limit of detection (LOD) 1.0 μg/kg) as the reference method. LODs of the ELISA were 30 μg/kg in sorghum grains and 220 μg/kg in sorghum-based infant cereals. With SIDA, 100% of the samples ( n = 28) had been positive for TeA in a concentration range of 6–584 μg/kg (mean 113 μg/kg). The ELISA consistently detected TeA in all naturally contaminated samples at cut-off levels of 30–60 μg/kg (sorghum) and 200–300 μg/kg (infant cereals), as based on corresponding to SIDA values. Although the ELISA was much less sensitive than the SIDA method, it may be useful as a screening method for sorghum and sorghum-based infant foods and can be employed to identify samples containing elevated concentrations of TeA in food, well below the proposed level of concern (500 μg/kg).
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Development of analytical methods for the determination of Tenuazonic Acid analogues in food commodities.
Journal of chromatography. A, 2013Co-Authors: Stefan Asam, Yang Liu, Martina Lichtenegger, Kornelija Muzik, Oliver Frank, Thomas Hofmann, Michael RychlikAbstract:Abstract Analogues of the Alternaria mycotoxin Tenuazonic Acid (TA, biosynthesized by the fungus from the amino Acid isoleucine) derived from valine (ValTA), leucine (LeuTA), alanine (AlaTA) and phenylalanine (PheTA) were synthesized and characterized by mass spectrometry (MS) and 1 H nuclear magnetic resonance (NMR) spectroscopy. Concentrations of stock solutions were determined by quantitative 1 H NMR (qHNMR). Two analytical methods based on high performance liquid chromatography (HPLC) and MS detection were developed, one with derivatization with 2,4-dinitrophenylhydrazine (DNPH) and one without derivatization. Limits of detection (LODs) were between 1–3 μg/kg (with derivatization) and 50–80 μg/kg (without derivatization). Respective limits of quantitation (LOQs) were about three times higher. Beside TA, the analogues LeuTA (about 4% of TA content) and ValTA (about 10% of TA content) were found in highly contaminated sorghum infant cereals and sorghum grains. Other analogues were not detected. Quantification of LeuTA and ValTA was performed using [ 13 C 6 , 15 N]-TA as internal standard and matrix matched calibration. Recovery was between 95 ± 11% and 102 ± 10% for both compounds. Precision (relative standard deviation of triplicate sorghum cereal analyses three times during 3 weeks) was 7% for TA (912 ± 60 μg/kg), 17% for LeuTA (43 ± 8 μg/kg) and 19% for ValTA (118 ± 22 μg/kg). These results indicate that several TA-like compounds, which are not yet characterized in aspects of their toxic properties, were detected in sorghum based infant food highly contaminated with TA, already.
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Determination of Tenuazonic Acid in human urine by means of a stable isotope dilution assay
Analytical and bioanalytical chemistry, 2013Co-Authors: Stefan Asam, Katharina Habler, Michael RychlikAbstract:The content of Tenuazonic Acid in human urine was determined by a stable isotope dilution assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02–100. The limits of detection and determination were 0.2 and 0.6 μg/L, respectively. The mean recovery of the stable isotope dilution assay was 102 ± 3 % in the range between 1.0 and 100 μg/L. Interassay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of Tenuazonic Acid: In the first study, Tenuazonic Acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3–17.3 μg/L or 2.3–10.3 ng/mg−1 creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 μg Tenuazonic Acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested Tenuazonic Acid was 54–81 % after 6 h, depending on matrix and volunteer. After 24 h, 87–93 % of the ingested amount of Tenuazonic Acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.
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Potential health hazards due to the occurrence of the mycotoxin Tenuazonic Acid in infant food
European Food Research and Technology, 2013Co-Authors: Stefan Asam, Michael RychlikAbstract:The mycotoxin Tenuazonic Acid (TA) was analyzed in different infant foods and beverages including tea infusions (fruit, herbal and fennel tea), puree infant food in jars (complementary food and side dishes) and infant cereals (for preparation of meals after addition of water or milk) by means of a stable isotope dilution assay (SIDA). The median content of TA in infant tea infusions (n = 12) was 2 μg/L, but values up to 20 μg/L were found in fennel tea infusions. In puree infant food in jars (n = 12), the median content of TA was 7 μg/kg, but higher values were detected in products containing tomato (25 μg/kg), banana and cherry (80 μg/kg) and sorghum (20 μg/kg). Infant cereals on the basis of wheat and/or oats, rice, spelt and barley (n = 4) did not contain TA in values higher than 30 μg/kg, but if sorghum was the major ingredient (n = 12), the mean content of TA was 550 μg/kg and the maximum level was 1,200 μg/kg. The European Food Safety Authority (EFSA) evaluated the toxicological potential of TA by following the threshold of toxicological concern (TTC) approach yielding a TTC value of 1,500 ng TA/kg body weight per day. Although long-term studies are needed to enlarge the database on TA contamination of sorghum-based infant food, our preliminary study points out to a tendency that the TTC value may be exceeded by infants consuming predominantly sorghum-based food. Nevertheless, further toxicity data on TA are required with high priority to assess potential health hazards.
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Content of the Alternaria mycotoxin Tenuazonic Acid in food commodities determined by a stable isotope dilution assay
Mycotoxin Research, 2012Co-Authors: Stefan Asam, Martina Lichtenegger, Michael RychlikAbstract:The Alternaria mycotoxin Tenuazonic Acid (TA) was quantified in fruit juices ( n = 50), cereals ( n = 12) and spices ( n = 38) using a recently developed stable isotope dilution assay (SIDA). [^13 C_6,^15 N]-TA was used as the internal standard. Method validation revealed low limits of detection (LODs) of 0.15 μg/kg (fruit juices), 1.0 μg/kg (cereals) and 17 μg/kg (spices). The respective limits of quantitation were about three times higher. Recovery was about 100% for all matrices. The precision (relative standard deviation of replicate analyses of naturally contaminated samples) was 4.2% (grape juice; 1.7 μg/kg), 3.5% (whole wheat flour; 36 μg/kg) and 0.9% (curry powder; 215 μg/kg). The median content of TA in the analyzed samples was 1.8 μg/kg (fruit juices), 16 μg/kg (cereals) and 500 μg/kg (spices). Positive samples amounted to 86% (fruit juices), 92% (cereals) and 87% (spices).
Hans-ulrich Humpf - One of the best experts on this subject based on the ideXlab platform.
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determination of exposure to the alternaria mycotoxin Tenuazonic Acid and its isomer allo Tenuazonic Acid in a german population by stable isotope dilution hplc ms3
Journal of Agricultural and Food Chemistry, 2016Co-Authors: Yannick Hovelmann, Sebastian Hickert, Benedikt Cramer, Hans-ulrich HumpfAbstract:The content of the Alternaria toxin Tenuazonic Acid and its isomer allo-Tenuazonic Acid was quantitated in urine of a German cohort (n = 48) using a newly developed and successfully validated solid phase extraction based stable isotope dilution HPLC-MS3 method. Tenuazonic Acid was detected in all of the samples and quantifiable in 97.9% of these samples in a range of 0.16–44.4 ng/mL (average = 6.58 ng/mL) or 0.07–63.8 ng/mg creatinine (average = 8.13 ng/mg creatinine). allo-Tenuazonic Acid was for the first time detected in human urine (95.8% of the samples positive) and quantitated in 68.8% of the samples in a range of 0.11–5.72 ng/mL (average = 1.25 ng/mL) or 0.08–10.1 ng/mg creatinine (average = 1.52 ng/mg creatinine), representing 3.40–25.0% of the sum of both isomers (average = 12.4%). Food-frequency questionnaires were used to document food consumption of study participants to correlate mycotoxin exposure to nutritional habits. Although no statistically significant correlation between consumption of...
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Determination of Exposure to the Alternaria Mycotoxin Tenuazonic Acid and Its Isomer allo-Tenuazonic Acid in a German Population by Stable Isotope Dilution HPLC-MS3
2016Co-Authors: Yannick Hövelmann, Sebastian Hickert, Benedikt Cramer, Hans-ulrich HumpfAbstract:The content of the Alternaria toxin Tenuazonic Acid and its isomer allo-Tenuazonic Acid was quantitated in urine of a German cohort (n = 48) using a newly developed and successfully validated solid phase extraction based stable isotope dilution HPLC-MS3 method. Tenuazonic Acid was detected in all of the samples and quantifiable in 97.9% of these samples in a range of 0.16–44.4 ng/mL (average = 6.58 ng/mL) or 0.07–63.8 ng/mg creatinine (average = 8.13 ng/mg creatinine). allo-Tenuazonic Acid was for the first time detected in human urine (95.8% of the samples positive) and quantitated in 68.8% of the samples in a range of 0.11–5.72 ng/mL (average = 1.25 ng/mL) or 0.08–10.1 ng/mg creatinine (average = 1.52 ng/mg creatinine), representing 3.40–25.0% of the sum of both isomers (average = 12.4%). Food-frequency questionnaires were used to document food consumption of study participants to correlate mycotoxin exposure to nutritional habits. Although no statistically significant correlation between consumption of a specific food and urinary excretion of Tenuazonic Acid could be determined, a trend regarding elevated intake of cereal products and higher excretion of Tenuazonic Acid was evident. On the basis of these results, a provisional mean daily intake (PDI) for both Tenuazonic Acid and allo-Tenuazonic Acid was calculated, being 0.183 and 0.025 μg/kg body weight, respectively. A combined mean PDI for both isomers amounts to 0.208 μg/kg body weight with the highest individual PDI for one of the participants (1.582 μg/kg body weight) slightly exceeding the threshold of toxicological concern assumed for Tenuazonic Acid by the European Food Safety Authority of 1.500 μg/kg body weight. This is the first study to investigate the Tenuazonic Acid content in human urine of a larger sample cohort enabling the calculation of PDIs for Tenuazonic Acid and allo-Tenuazonic Acid
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Detection and Quantitative Analysis of the Non-cytotoxic allo-Tenuazonic Acid in Tomato Products by Stable Isotope Dilution HPLC-MS/MS
Journal of agricultural and food chemistry, 2015Co-Authors: Sebastian Hickert, Benedikt Cramer, Isabel Krug, Hans-ulrich HumpfAbstract:Tenuazonic Acid (1) is a mycotoxin produced mainly by fungi of the genus Alternaria. It occurs in a variety of agricultural products. allo-Tenuazonic Acid (2) is an isomer of 1 that is not chromatographically separated from 1 in most analytical methods. Therefore, both isomers are quantitated as a sum parameter. In this study a QuEChERS (quick, easy, cheap, effective, rugged and safe) based stable isotope dilution HPLC-MS/MS method including the chromatographic separation of both isomers was developed and applied to 20 tomato products from the German market. All products showed contamination with both toxins. 1 was found in a range from 5.3 ± 0.1 to 550 ± 15 μg/kg (average = 120 μg/kg) and 2 in a range from 1.5 ± 0.4– to 270 ± 0.8 μg/kg (average = 58 μg/kg). 2 represents 7.0–44% of the sum of both isomers (average = 29%). This is the first reported occurrence of 2 in food samples. To evaluate and compare the cytotoxicities of 1 and 2, both compounds were isolated from a synthetic racemic mixture. 1 showed...
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Large-Scale Synthesis of Isotopically Labeled 13C2-Tenuazonic Acid and Development of a Rapid HPLC-MS/MS Method for the Analysis of Tenuazonic Acid in Tomato and Pepper Products
Journal of agricultural and food chemistry, 2012Co-Authors: Lilia Lohrey, Benedikt Cramer, Stefanie Marschik, Hans-ulrich HumpfAbstract:Tenuazonic Acid is a fungal secondary metabolite that is produced by a number of Alternaria species and is therefore a natural contaminant of food and feed samples. This paper describes a new strategy for the efficient and economical large-scale synthesis of the isotopically labeled internal standard 13C2-Tenuazonic Acid via a three-step procedure. Furthermore, a new reliable and quick method based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) cleanup is presented for the determination of Tenuazonic Acid in food and feed samples utilizing high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) by application of the stable isotope dilution analysis. This new method has a limit of detection (LOD) of 0.86 μg/kg and a limit of quantitation (LOQ) of 2.89 μg/kg. In total 26 tomato samples and 4 bell pepper samples from the German market were analyzed. Tenuazonic Acid was found in each sample with levels from 3 to 2330 μg/kg.
Sofia Noemi Chulze - One of the best experts on this subject based on the ideXlab platform.
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Effect of environmental factors on Tenuazonic Acid production by Alternaria alternata on soybean-based media.
Journal of applied microbiology, 2009Co-Authors: M. S. Oviedo, Maria Laura Ramirez, Germán Barros, Sofia Noemi ChulzeAbstract:Aims: To determine the effects of water activity (aW; 0·995–0·90), temperature (5, 18, 25 and 30°C), time of incubation (7–35 days) and their interactions on Tenuazonic Acid (TA) production on 2% soybean-based agar by two Alternaria alternata strains isolated from soybean in Argentina. Methods and Results: TA production by two isolates of A. alternata was examined under interacting conditions of aW, temperature and time of incubation on 2% soybean-based agar. Maximum TA production was obtained for both strains at 0·98 aW, but at 30 and 25°C for the strains for RC 21and RC 39, respectively. The toxin concentration varied considerably depending on aW, temperature, incubation time and strain interactions. TA was produced over the temperature range from 5 to 30°C and aW range from 0·92 to 0·995, however at 5 and 18°C little TA was produced at aW below 0·94. Contour maps were developed from these data to identify areas where conditions indicate a significant risk for TA accumulation. Conclusions: The optimum and marginal conditions for TA production by A. alternata on soybean-based agar were identified. The results indicated that TA production by A. alternata is favoured by different temperatures in different strains. Significance and Impact of the Study: Data obtained provide very useful information for predicting the possible risk factors for TA contamination of soybean as the aW and temperature range used in this study simulate those occurring during grain ripening. The knowledge of TA production under marginal or sub-optimal temperature and aW conditions for growth are relevant as improper storage conditions accompanied by elevated temperature and moisture content in the grain can favour further mycotoxin production and lead to reduction in grain quality.
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Effects of food preservatives on Alternaria alternata growth and Tenuazonic Acid production.
Food additives and contaminants, 1999Co-Authors: M Combina, E. Varsavsky, Ana Maria Dalcero, Sofia Noemi ChulzeAbstract:The effects of different organic Acids on Alternaria alternata growth and Tenuazonic Acid production (TeA) were evaluated. Both TeA pure toxin solution and TeA production in solid medium were considered. Sodium benzoate, potassium sorbate and sodium propionate, all preservatives commonly used by food industry in Argentina, were tested. TeA was stable as pure toxin solution when was treated with the salts of organic Acids used. A differential effect was observed when the preservatives were evaluated in relation to A. alternata growth and TeA production in solid medium. Levels above 10 mg/kg of sodium benzoate and potassium sorbate produced a total inhibition of fungal development and toxin biosynthesis. Sodium propionate produced a 59% decrease in A. alternata growth and total inhibition of TeA production only at the highest concentration of preservatives used.
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Microbial interaction ofAspergillus parasiticus andBacillus subtilis withalternaria alternata. production of alternariol, alternariol monomethylether and Tenuazonic Acid on sunflower seeds.
Mycotoxin research, 1998Co-Authors: Miriam Etcheverry, Lilia Reneé Cavaglieri, Sofia Noemi ChulzeAbstract:Production of alternariol, alternariol mono-methylether and Tenuazonic Acid byAlternaria alternata was studied in competition withAspergillus parasiticus andBacillus subtilis on irradiated sunflower seeds at 0.90 aw.
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Effect of water activity and temperature on Tenuazonic Acid production by Alternaria alternata on sunflower seeds
Mycopathologia, 1994Co-Authors: Miriam Etcheverry, Sofia Noemi Chulze, Ana Maria Dalcero, E. Varsavsky, Carina Elizabeth MagnoliAbstract:Alternaria alternata is isolated in high frequency in sunflower seeds both in the field and storage. This species produces several toxic metabolites among them alternariol, alternariol monomethyl ether and Tenuazonic Acid. The accumulation of mycotoxins is regulated by physical, chemical and biological factors and for their production in many commodities nothing is known with regards to these conditions. In sunflower seeds the optimal conditions of temperature and water activity for Tenuazonic Acid production are unknown. The aim of this work was to investigate the effect of temperature and water activity on Tenuazonic Acid production byAlternaria alternata ITEM 539 in sunflower seeds. The temperature conditions evaluated were: 20, 25, and 30 °C and the water activities were 0.97, 0.90, 0.87, 0.80. The Tenuazonic Acid determinations were carried out during the incubation period at intervals of 7 days. Under conditions of constant temperature 25 °C) and variable water activities, 0.90 was the optimal value for Tenuazonic Acid production. At this water activity of the optimal temperature for Tenuazonic Acid production was 25 °C.
Irene Nehls - One of the best experts on this subject based on the ideXlab platform.
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Quantification of the Alternaria mycotoxin Tenuazonic Acid in beer
Food Chemistry, 2010Co-Authors: David Siegel, Matthias Koch, Stefan Merkel, Irene NehlsAbstract:Abstract Tenuazonic Acid (TA) is a major water soluble Alternaria mycotoxin. In the present work, a method for the quantification of TA in beer by liquid chromatography–ion-trap multistage mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine is described. The method is based on a rapid workup procedure and features a LOD of 2 μg/kg without preconcentration using 400 mg of sample. Validation was performed for a working range of 8–500 μg/kg. A total of 43 beers of different brewing styles (pilsener, wheat beer, bock beer, dark beer and alcohol free beer) was analysed. TA was detected in 37 samples, 16 samples were above the LOQ. An average content of 11 μg/kg was found, the highest incidence being 175 ± 13 μg/kg. To our knowledge, this is the first report on the occurrence of TA in beer and beverages in general.
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deacetyl Tenuazonic Acid p toluene sulfonyl hydrazone
Acta Crystallographica Section E-structure Reports Online, 2009Co-Authors: David Siegel, Franziska Blaske, Matthias Koch, Franziska Emmerling, Irene NehlsAbstract:The title compound {systematic name: 4-methyl-N′-[(3E)-2-(1-methylpropyl)-5-oxopyrrolidin-3-ylidene]benzenesulfonohydrazide}, C15H21N3O3S, is the condensation product of deacetyl Tenuazonic Acid (DTA) and p-toluenesulfonohydrazide. The crystal structure consists of chains along [100] linked by N—H⋯O hydrogen bonds.
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Degradation kinetics of the Alternaria mycotoxin Tenuazonic Acid in aqueous solutions.
Analytical and bioanalytical chemistry, 2009Co-Authors: David Siegel, Matthias Koch, Stefan Merkel, Wolfram Bremser, Irene NehlsAbstract:The degradation kinetics of the Alternaria mycotoxin Tenuazonic Acid (l-TA) in aqueous buffer were studied over a period of 4 months at different pH levels (3.5 and 7.0) and temperatures (4, 25 and 40 °C). l-TA and its degradation products were quantified by newly developed high-performance liquid chromatography methods with UV or electrospray multistage mass spectrometry detection. At pH 3.5, significant degradation occurred at 25 and 40 °C, the respective l-TA half-lives being 73.8 ± 0.4 and 14.0 ± 0.1 days. Two degradation processes, epimerization and hydrolysis, were evaluated kinetically. The hydrolytically formed iso-deacetyl TA (iso-DTA, epimeric mixture) was found to be the stable end product of l-TA degradation under the conditions of this study. This indicates that iso-DTA as well as the l-TA epimer u-TA are formed in aqueous beverage matrices.
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Deacetyl Tenuazonic Acid p-toluenesulfonylhydrazone
Acta Crystallographica Section E Structure Reports Online, 2009Co-Authors: David Siegel, Franziska Blaske, Matthias Koch, Franziska Emmerling, Irene NehlsAbstract:The title compound {systematic name: 4-methyl-N′-[(3E)-2-(1-methylpropyl)-5-oxopyrrolidin-3-ylidene]benzenesulfonohydrazide}, C15H21N3O3S, is the condensation product of deacetyl Tenuazonic Acid (DTA) and p-toluenesulfonohydrazide. The crystal structure consists of chains along [100] linked by N—H⋯O hydrogen bonds.
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determination of the alternaria mycotoxin Tenuazonic Acid in cereals by high performance liquid chromatography electrospray ionization ion trap multistage mass spectrometry after derivatization with 2 4 dinitrophenylhydrazine
Journal of Chromatography A, 2009Co-Authors: David Siegel, Matthias Koch, Tatjana Rasenko, Irene NehlsAbstract:Tenuazonic Acid (TA) is a major Alternaria mycotoxin. In the present work a novel approach for the detection of TA in cereals by liquid chromatography-ion-trap multistage mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine is described. The product of the derivatization reaction and its major MS(2) fragments were characterised by Fourier transform-ion cyclotron resonance tandem mass spectrometry. Without preconcentration, the established method features a limit of detection of 10 microg/kg using 2g of sample in a rapid workup procedure. Accuracy, precision and linearity were evaluated in the working range of 50-5000 microg/kg. TA was detected in 13 and quantified in 3 out of 27 cereal samples obtained from a local supermarket, the average content being 49 microg/kg (highest incidence: 851+/-41 microg/kg).
