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Michael Rychlik
Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Coopers Plains, QLD 4108, Australia

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Journal article
Published: 15 December 2020
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Prenylated flavonoids from hops (Humulus lupulus) have become of interest in recent years due to a range of bioactivities. The potential health benefits of prenylated flavonoids include anti-cancerous activities and treatment of the metabolic syndrome among others. Since prenylated flavonoids from hops have shown pharmaceutical potential in clinical trials, robust analytical methods to determine their concentrations in food, supplements, and beverages are required. One such, the gold standard of analytical methods, is stable isotope dilution analysis due to its ability to compensate matrix effects and losses during sample work-up. As no commercial standards were available, the synthesis of seven different prenylated flavonoid isotopes utilizing various strategies (microwave assistance, acid base catalyst in the presence of deuterated substance and lastly, the use of Strykers catalyst) is described. The produced prenylated flavonoid isotopes were then applied in the first stable isotope dilution analysis method that quantified six natural prenylated flavonoids (Isoxanthohumol, Isoxanthohumol-C, 8-Prenylnaringenin, 6- Prenylnaringenin, Xanthohumol, and Xanthohumol-C) in beer, hop tea and hops to prove its applicability. The SIDA-LC-MS/MS method was validated resulting in LODs and LOQs for all analytes between 0.04 and 3.2 μg/L. Moreover, due to the simple clean-up the developed method allows the prospect for measuring clinical samples in the future.

ACS Style

Lance Buckett; Simone Schinko; Corinna Urmann; Herbert Riepl; Michael Rychlik. Stable Isotope Dilution Analysis of the Major Prenylated Flavonoids Found in Beer, Hop Tea, and Hops. 2020, 7, 1 .

AMA Style

Lance Buckett, Simone Schinko, Corinna Urmann, Herbert Riepl, Michael Rychlik. Stable Isotope Dilution Analysis of the Major Prenylated Flavonoids Found in Beer, Hop Tea, and Hops. . 2020; 7 ():1.

Chicago/Turabian Style

Lance Buckett; Simone Schinko; Corinna Urmann; Herbert Riepl; Michael Rychlik. 2020. "Stable Isotope Dilution Analysis of the Major Prenylated Flavonoids Found in Beer, Hop Tea, and Hops." 7, no. : 1.

Original research article
Published: 15 December 2020 in Frontiers in Nutrition
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Prenylated flavonoids from hops (Humulus lupulus) have become of interest in recent years due to a range of bioactivities. The potential health benefits of prenylated flavonoids include anti-cancerous activities and treatment of the metabolic syndrome among others. Since prenylated flavonoids from hops have shown pharmaceutical potential in clinical trials, robust analytical methods to determine their concentrations in food, supplements, and beverages are required. One such, the gold standard of analytical methods, is stable isotope dilution analysis due to its ability to compensate matrix effects and losses during sample work-up. As no commercial standards were available, the synthesis of seven different prenylated flavonoid isotopes utilizing various strategies (microwave assistance, acid base catalyst in the presence of deuterated substance and lastly, the use of Strykers catalyst) is described. The produced prenylated flavonoid isotopes were then applied in the first stable isotope dilution analysis method that quantified six natural prenylated flavonoids (Isoxanthohumol, Isoxanthohumol-C, 8-Prenylnaringenin, 6- Prenylnaringenin, Xanthohumol, and Xanthohumol-C) in beer, hop tea and hops to prove its applicability. The SIDA-LC-MS/MS method was validated resulting in LODs and LOQs for all analytes between 0.04 and 3.2 μg/L. Moreover, due to the simple clean-up the developed method allows the prospect for measuring clinical samples in the future.

ACS Style

Lance Buckett; Simone Schinko; Corinna Urmann; Herbert Riepl; Michael Rychlik. Stable Isotope Dilution Analysis of the Major Prenylated Flavonoids Found in Beer, Hop Tea, and Hops. Frontiers in Nutrition 2020, 7, 1 .

AMA Style

Lance Buckett, Simone Schinko, Corinna Urmann, Herbert Riepl, Michael Rychlik. Stable Isotope Dilution Analysis of the Major Prenylated Flavonoids Found in Beer, Hop Tea, and Hops. Frontiers in Nutrition. 2020; 7 ():1.

Chicago/Turabian Style

Lance Buckett; Simone Schinko; Corinna Urmann; Herbert Riepl; Michael Rychlik. 2020. "Stable Isotope Dilution Analysis of the Major Prenylated Flavonoids Found in Beer, Hop Tea, and Hops." Frontiers in Nutrition 7, no. : 1.

Proceedings
Published: 09 November 2020 in Proceedings
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Folate (Vitamin B9) is critical for a range of biological functions in adults and children, including DNA, protein and neurotransmitter synthesis. It is also essential for the healthy development of the fetus in early pregnancy and for the prevention of neural tube defects, such as spina bifida. Strawberries are considered a tasty and healthy fruit consumed all over the world and may potentially be an important dietary source of natural folates. However, the relative importance of strawberry as a dietary source will depend on the total folate concentration, vitamer profile, storage stability and bioavailability to humans. Red Rhapsody, an important commercial strawberry cultivar in Australia, was screened for its folate content and storage stability by stable isotope dilution assay (SIDA). Total folate content ranged from 90–118 μg/100 g fresh weight (fw), which was well above the value in the Australian Food Composition Database (39 μg/100 g fw). 5-Methyltetrahydrofolate, the biologically active form in humans, was the principal vitamer present. Furthermore, folate remained relatively stable during refrigerated (4 °C) storage (loss of only 28% after 14 days of storage). This information is relevant for consumers since the inherent perishability of strawberry fruit makes refrigerated storage common practice in Australian households.

ACS Style

Julius Rami; Caroline Dumler; Nadine Weber; Michael Rychlik; Gabriele Netzel; Hung Trieu Hong; Olivia Wright; Tim J. O’Hare; Michael E. Netzel. Folate in Red Rhapsody Strawberry—Content and Storage Stability. Proceedings 2020, 70, 47 .

AMA Style

Julius Rami, Caroline Dumler, Nadine Weber, Michael Rychlik, Gabriele Netzel, Hung Trieu Hong, Olivia Wright, Tim J. O’Hare, Michael E. Netzel. Folate in Red Rhapsody Strawberry—Content and Storage Stability. Proceedings. 2020; 70 (1):47.

Chicago/Turabian Style

Julius Rami; Caroline Dumler; Nadine Weber; Michael Rychlik; Gabriele Netzel; Hung Trieu Hong; Olivia Wright; Tim J. O’Hare; Michael E. Netzel. 2020. "Folate in Red Rhapsody Strawberry—Content and Storage Stability." Proceedings 70, no. 1: 47.

Journal article
Published: 02 September 2020 in Food Chemistry
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Folate is a fundamental vitamin for metabolism in plants and humans. A modelling approach has been developed to characterize the reactivity of folates in cowpea seeds during germination at 30 °C, using a water-to-seed ratio of 1:1 (w/w). For this purpose, the concentrations of folic acid, 10-formylfolic acid, 5-methyltetrahydrofolate, 5-formyltetrahydrofolate and tetrahydrofolate were determined in seeds during germination times up to 96 h. Two reaction models were sequentially built and adjusted to experimental data to describe changes in concentration in cowpea seed during two germination phases: before 14 h and after 48 h. Results showed intense enzymatic interconversion of all folate vitamers into 5-methyltetrahydrofolate before 14 h of germination and high enzymatic production of 5-methyltetrahydrofolate, 5-formyltetrahydrofolate and tetrahydrofolate after 48 h of germination. This study suggests that a long germination process could be more beneficial than soaking to increase the production of bioavailable folates within the seed for human consumption.

ACS Style

Fanny Coffigniez; Michael Rychlik; Christian Mestres; Lisa Striegel; Philippe Bohuon; Aurélien Briffaz. Modelling folates reaction kinetics during cowpea seed germination in comparison with soaking. Food Chemistry 2020, 340, 127960 .

AMA Style

Fanny Coffigniez, Michael Rychlik, Christian Mestres, Lisa Striegel, Philippe Bohuon, Aurélien Briffaz. Modelling folates reaction kinetics during cowpea seed germination in comparison with soaking. Food Chemistry. 2020; 340 ():127960.

Chicago/Turabian Style

Fanny Coffigniez; Michael Rychlik; Christian Mestres; Lisa Striegel; Philippe Bohuon; Aurélien Briffaz. 2020. "Modelling folates reaction kinetics during cowpea seed germination in comparison with soaking." Food Chemistry 340, no. : 127960.

Research paper
Published: 14 August 2020 in Analytical and Bioanalytical Chemistry
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Vitamin B6 comprises an important set of molecules tightly interwoven with the human amino acid, fatty acid, and carbohydrate metabolism. Analytical methods striving for the quantification of individual B6 vitamers so far mostly rely on methods based on HPLC in combination with fluorescence detection, but their application encounters multiple difficulties due to the chemical divergence of the single vitamers. The present study describes the development of a method based on LC-MS/MS and stable isotope dilution assay (SIDA) for the simultaneous quantification of five vitamers (PN, PL, PM, PMP, and PNG) of the B6 group in food samples. [13C3]-PN, [13C3]-PL, and [13C6]-PNG were applied as internal standards for the analysis of PN, PL, and PNG. PM and PMP were quantified via matrix-matched calibration referring to [13C3]-PN. The developed method was validated using starch matrix. The limits of detection and quantification ranged from 0.0028 to 0.02 mg/kg and from 0.0085 to 0.059 mg/kg, respectively, for all analytes. Calculated recoveries varied from 92 to 111%. Intra-injection precisions ranged from 0 to 9%, inter-day precisions from 4 to 10%, and intra-day precisions from 4 to 10%. A total of 14 plant-based food samples including fruits, vegetables, and cereals were examined for their content of vitamin B6 using the validated method. Furthermore, the first quantitation of PNG without enzymatic steps or divergent internal standards was undertaken utilizing LC-MS/MS and SIDA.

ACS Style

Thomas Bachmann; Andrea Maurer; Michael Rychlik. Development of a LC-MS/MS method using stable isotope dilution for the quantification of individual B6 vitamers in fruits, vegetables, and cereals. Analytical and Bioanalytical Chemistry 2020, 412, 7237 -7252.

AMA Style

Thomas Bachmann, Andrea Maurer, Michael Rychlik. Development of a LC-MS/MS method using stable isotope dilution for the quantification of individual B6 vitamers in fruits, vegetables, and cereals. Analytical and Bioanalytical Chemistry. 2020; 412 (26):7237-7252.

Chicago/Turabian Style

Thomas Bachmann; Andrea Maurer; Michael Rychlik. 2020. "Development of a LC-MS/MS method using stable isotope dilution for the quantification of individual B6 vitamers in fruits, vegetables, and cereals." Analytical and Bioanalytical Chemistry 412, no. 26: 7237-7252.

Journal article
Published: 23 July 2020 in Metabolites
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Folates are a group of B9 vitamins playing an important role in many metabolic processes such as methylation reactions, nucleotide synthesis or oxidation and reduction processes. However, humans are not able to synthesize folates de novo and thus rely on external sources thereof. Baker’s yeast (Saccharomyces cerevisiae) has been shown to produce high amounts of this vitamin but extensive identification of its folate metabolism is still lacking. Therefore, we optimized and compared different sample preparation and purification procedures applying solid phase extraction (SPE). Strong anion exchange (SAX), C18 and hydrophilic–lipophilic-balanced (HLB) materials were tested for their applicability in future metabolomics studies. SAX turned out to be the preferred material for the quantitative purification of folates. Qualification of several folate vitamers was achieved by ultra-high pressure liquid chromatography quadrupole time of flight mass spectrometry (UHPLC-Q-ToF-MS) measurements and quantification was performed by liquid chromatography tandem mass spectrometry (LC-MS/MS) applying stable isotope dilution assays (SIDAs). The oxidation product s-pyrazino-triazine (MeFox) was included into the SIDA method for total folate determination and validation. Applying the best protocol (SAX) in regard to folate recovery, we analyzed 32 different vitamers in different polyglutamate states up to nonaglutamates, of which we could further identify 26 vitamers based on tandem-MS (MS2) spectra. Total folate quantification revealed differences in formyl folate contents depending on the cartridge chemistry used for purification. These are supposedly a result of interconversion reactions occurring during sample preparation due to variation in pH adjustments for the different purification protocols. The occurrence of interconversion and oxidation reactions should be taken into consideration in sample preparation procedures for metabolomics analyses with a focus on folates.

ACS Style

Lena Gmelch; Daniela Wirtz; Michael Witting; Nadine Weber; Lisa Striegel; Philippe Schmitt-Kopplin; Michael Rychlik. Comprehensive Vitamer Profiling of Folate Mono- and Polyglutamates in Baker’s Yeast (Saccharomyces cerevisiae) as a Function of Different Sample Preparation Procedures. Metabolites 2020, 10, 301 .

AMA Style

Lena Gmelch, Daniela Wirtz, Michael Witting, Nadine Weber, Lisa Striegel, Philippe Schmitt-Kopplin, Michael Rychlik. Comprehensive Vitamer Profiling of Folate Mono- and Polyglutamates in Baker’s Yeast (Saccharomyces cerevisiae) as a Function of Different Sample Preparation Procedures. Metabolites. 2020; 10 (8):301.

Chicago/Turabian Style

Lena Gmelch; Daniela Wirtz; Michael Witting; Nadine Weber; Lisa Striegel; Philippe Schmitt-Kopplin; Michael Rychlik. 2020. "Comprehensive Vitamer Profiling of Folate Mono- and Polyglutamates in Baker’s Yeast (Saccharomyces cerevisiae) as a Function of Different Sample Preparation Procedures." Metabolites 10, no. 8: 301.

Journal article
Published: 09 July 2020 in Biomolecules
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Alternaria molds simultaneously produce a large variety of mycotoxins, of which several were previously reported to induce enzymes of phase I metabolism through aryl hydrocarbon receptor activation. Thus, we investigated the potential of naturally occurring Alternaria toxin mixtures to induce Cytochrome P450 (CYP) 1A1/1A2/1B1 activity. Two variants of an extract from cultured Alternaria alternata, as well as the toxins alternariol (AOH), alternariol monomethyl ether (AME), altertoxin I (ATX-I), and altertoxin II (ATX-II), were tested singularly and in binary mixtures applying the 7-ethoxy-resorufin-O-deethylase (EROD) assay in MCF-7 breast cancer cells. Sub-cytotoxic concentrations of the two toxin mixtures, as well as ATX-I, ATX-II and AOH, exhibited dose-dependent enhancements of CYP 1 activity. ATX-I and ATX-II interacted synergistically in this respect, demonstrating the two perylene quinones as major contributors to the extract’s potential. Binary mixtures between AOH and the two altertoxins respectively exhibited concentration-dependent antagonistic as well as synergistic combinatory effects. Notably, AME showed no efficacy towards EROD enzyme activity or impact on other toxins’ efficacy. Hence, this study provides insights into synergistic and other combinatory effects of Alternaria toxins in natural co-occurrence scenarios in the context of AhR signalling pathway activation in breast cancer cells.

ACS Style

Julia Hohenbichler; Georg Aichinger; Michael Rychlik; Giorgia Del Favero; Doris Marko. Alternaria alternata Toxins Synergistically Activate the Aryl Hydrocarbon Receptor Pathway In Vitro. Biomolecules 2020, 10, 1018 .

AMA Style

Julia Hohenbichler, Georg Aichinger, Michael Rychlik, Giorgia Del Favero, Doris Marko. Alternaria alternata Toxins Synergistically Activate the Aryl Hydrocarbon Receptor Pathway In Vitro. Biomolecules. 2020; 10 (7):1018.

Chicago/Turabian Style

Julia Hohenbichler; Georg Aichinger; Michael Rychlik; Giorgia Del Favero; Doris Marko. 2020. "Alternaria alternata Toxins Synergistically Activate the Aryl Hydrocarbon Receptor Pathway In Vitro." Biomolecules 10, no. 7: 1018.

Journal article
Published: 08 July 2020 in Journal of Experimental Botany
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Folates are one of the essential micronutrients for all living organisms. Due to inadequate dietary intake, folate deficiency remains prevalent in humans. Genetically diverse germplasms can potentially be used as parents in breeding programs and also for understanding the folate regulatory network. Therefore, we investigated the natural genetic diversity of folates and their physiological regulation in pak choi (Brassica rapa subsp. Chinensis) germplasm. The total folate concentration ranged from 52.7 μg 100 gFW–1 to 166.9 μg 100 gFW–1, with 3.2-fold variation. The main folate vitamer was represented by 5-CH3-H4folate, with 4.5-fold variation. The activities of GTP cyclohydrolase I and aminodeoxy chorismate synthase, the first step of folate synthesis, were high in high folate accessions and low in low folate accessions. Analysis of the transcription levels of 11 genes associated with folate metabolism demonstrated that the difference in folate concentrations may be primarily controlled at the post-transcriptional level. A general correlation between total folate and their precursors was observed. Folate diversity and chlorophyll content were tightly regulated through the methyl cycle. The diverse genetic variation in pak choi germplasm indicated the great genetic potential to integrate breeding programs for folate biofortification and unravel the physiological basis of folate homeostasis in planta.

ACS Style

M J I Shohag; Yanyan Wei; Jie Zhang; Ying Feng; Michael Rychlik; Zhenli He; Xiaoe Yang. Genetic and physiological regulation of folate in pak choi (Brassica rapa subsp. Chinensis) germplasm. Journal of Experimental Botany 2020, 71, 4914 -4929.

AMA Style

M J I Shohag, Yanyan Wei, Jie Zhang, Ying Feng, Michael Rychlik, Zhenli He, Xiaoe Yang. Genetic and physiological regulation of folate in pak choi (Brassica rapa subsp. Chinensis) germplasm. Journal of Experimental Botany. 2020; 71 (16):4914-4929.

Chicago/Turabian Style

M J I Shohag; Yanyan Wei; Jie Zhang; Ying Feng; Michael Rychlik; Zhenli He; Xiaoe Yang. 2020. "Genetic and physiological regulation of folate in pak choi (Brassica rapa subsp. Chinensis) germplasm." Journal of Experimental Botany 71, no. 16: 4914-4929.

Journal article
Published: 04 July 2020 in Food Chemistry
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Quantification of the specific folate vitamers to estimate total folate in foods is not standardized. A collaborative study, including eight European laboratories, was conducted in order to determine the repeatability and reproducibility of the method for folate quantification in foods using the plant-origin γ-glutamyl hydrolase as part of the extraction procedure. The seven food samples analyzed represent the food groups; fruits, vegetables, dairy products, legumes, offal, fish, and fortified infant formula. The homogenization step was included, and six folate vitamers were analyzed using LC-MS/MS. Total folate content, expressed as folic acid equivalent, was 17–490 μg/100 g in all samples. Horwitz ratio values were within the acceptable range (0.60–1.94), except for fish. The results for fortified infant formula, a certified reference material (NIST 1869), confirmed the trueness of the method. The collaborative study is part of a standardization project within the Nordic Committee on Food Analysis (NMKL).

ACS Style

Petra Ložnjak Švarc; Eystein Oveland; Hanna Sara Strandler; Susanna Kariluoto; Esther Campos-Giménez; Elise Ivarsen; Isabelle Malaviole; Carla Motta; Michael Rychlik; Lisa Striegel; Jette Jakobsen. Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS. Food Chemistry 2020, 333, 127447 .

AMA Style

Petra Ložnjak Švarc, Eystein Oveland, Hanna Sara Strandler, Susanna Kariluoto, Esther Campos-Giménez, Elise Ivarsen, Isabelle Malaviole, Carla Motta, Michael Rychlik, Lisa Striegel, Jette Jakobsen. Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS. Food Chemistry. 2020; 333 ():127447.

Chicago/Turabian Style

Petra Ložnjak Švarc; Eystein Oveland; Hanna Sara Strandler; Susanna Kariluoto; Esther Campos-Giménez; Elise Ivarsen; Isabelle Malaviole; Carla Motta; Michael Rychlik; Lisa Striegel; Jette Jakobsen. 2020. "Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS." Food Chemistry 333, no. : 127447.

Journal article
Published: 19 June 2020 in Toxins
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Ruminal microbiota of cattle are not able to detoxify all mycotoxins. In addition, detoxification can be hampered by adverse ruminal conditions (e.g., low ruminal pH). Hence, in the cattle husbandry, mycotoxin binders and modifiers could be used to prevent animal exposure to mycotoxins. In this study, an in vitro rumen model, including feed matrix, was established as first screening tool to test the efficacy of five products claiming to detoxify mycotoxins. The detoxifiers had different modes of action: (a) binding (three products); (b) enzymatic detoxification of zearalenone (ZEN; one product, ZenA); and (c) bacterial transformation of trichothecenes (one product, BBSH 797). For the mycotoxin binders, the binding to the mycotoxins enniatin B (ENN B), roquefortine C (ROQ-C), mycophenolic acid (MPA), deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEN) were tested at a dose recommended by the manufacturers. The in vitro model demonstrated that all binders adsorbed ENN B to a certain extent, while only one of the binders also partially adsorbed ROQ-C. The binders did not change the concentrations of the other mycotoxins in the ruminal fluid. The enzyme ZenA detoxified ZEN very quickly and prevented the formation of the more toxic metabolite α-zearalenol (α-ZEL), both at normal (6.8) and low ruminal pH (5.8). The addition of BBSH 797 enhanced detoxification of DON and NIV, both at normal and low ruminal pH. The in vitro rumen model demonstrated that the addition of ZenA seems to be a very promising strategy to prevent estrogenic effects of ZEN contaminated feed, and BBSH 797 is efficient in the detoxification of trichothecenes.

ACS Style

Sandra Debevere; Dian Schatzmayr; Nicole Reisinger; Markus Aleschko; Geert Haesaert; Michael Rychlik; Siska Croubels; Veerle Fievez. Evaluation of the Efficacy of Mycotoxin Modifiers and Mycotoxin Binders by Using an In Vitro Rumen Model as a First Screening Tool. Toxins 2020, 12, 405 .

AMA Style

Sandra Debevere, Dian Schatzmayr, Nicole Reisinger, Markus Aleschko, Geert Haesaert, Michael Rychlik, Siska Croubels, Veerle Fievez. Evaluation of the Efficacy of Mycotoxin Modifiers and Mycotoxin Binders by Using an In Vitro Rumen Model as a First Screening Tool. Toxins. 2020; 12 (6):405.

Chicago/Turabian Style

Sandra Debevere; Dian Schatzmayr; Nicole Reisinger; Markus Aleschko; Geert Haesaert; Michael Rychlik; Siska Croubels; Veerle Fievez. 2020. "Evaluation of the Efficacy of Mycotoxin Modifiers and Mycotoxin Binders by Using an In Vitro Rumen Model as a First Screening Tool." Toxins 12, no. 6: 405.

Journal article
Published: 20 April 2020 in Toxins
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Reference standards for Alternaria mycotoxins are rarely available, especially the modified mycotoxins alternariol-3-glucoside (AOH-3-G), alternariol-9-glucoside (AOH-9-G), and alternariol monomethylether-3-glucoside (AME-3-G). To obtain these three glucosides as analytical standards for method development and method validation, alternariol and alternariol monomethylether were enzymatically glycosylated in a whole-cell biotransformation system using a glycosyltransferase from strawberry (Fragaria x ananassa), namely UGT71A44, expressed in Escherichia coli (E. coli). The formed glucosides were isolated, purified, and structurally characterized. The exact amount of the isolated compounds was determined using high-performance liquid chromatography with UV-detection (HPLC-UV) and quantitative nuclear resonance spectroscopy (qNMR). This method has proved to be highly effective with biotransformation rates of 58% for AOH-3-G, 5% for AOH-9-G, and 24% for AME-3-G.

ACS Style

Sophie Scheibenzuber; Thomas Hoffmann; Isabelle Effenberger; Wilfried Schwab; Stefan Asam; Michael Rychlik. Enzymatic Synthesis of Modified Alternaria Mycotoxins Using a Whole-Cell Biotransformation System. Toxins 2020, 12, 264 .

AMA Style

Sophie Scheibenzuber, Thomas Hoffmann, Isabelle Effenberger, Wilfried Schwab, Stefan Asam, Michael Rychlik. Enzymatic Synthesis of Modified Alternaria Mycotoxins Using a Whole-Cell Biotransformation System. Toxins. 2020; 12 (4):264.

Chicago/Turabian Style

Sophie Scheibenzuber; Thomas Hoffmann; Isabelle Effenberger; Wilfried Schwab; Stefan Asam; Michael Rychlik. 2020. "Enzymatic Synthesis of Modified Alternaria Mycotoxins Using a Whole-Cell Biotransformation System." Toxins 12, no. 4: 264.

Journal article
Published: 01 March 2020 in Toxins
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Pyrrolizidine alkaloids (PA) and their N-oxides (PANO) are a group of toxic secondary plant metabolites occurring predominantly as contaminants in (herbal) teas, honeys and food supplements, as well as in spices and culinary herbs. Depending on the botanical origin of the contaminating plant, the pattern of PA/PANO can strongly vary within a sample. The current study aimed to broaden the existing data on the occurrence of PA/PANO in spices and culinary herbs. For this, 305 authentic samples covering 15 different matrices mainly harvested in 2016 or 2017 and originating from 36 countries were investigated for the presence of 44 PA/PANO. Fifty-eight percent of the samples contained at least one PA/PANO. The average sum content over all samples was 323 µg/kg (median of 0.9 µg/kg, 95% percentile of 665 µg/kg). The highest amount of 24.6 mg/kg was detected in an oregano sample. Additionally, conspicuous analyte patterns were discovered in samples from similar cultivation regions, indicating related botanical sources of PA/PANO contaminations. Particularly, oregano and cumin from Turkey often contained high amounts of PA/PANO. The results were used to assess the acute and chronic health risks related to PA/PANO intake via spices and culinary herbs, indicating a potential health risk in particular for adults and children with high consumption or when considering worst-case contamination scenarios of a sum content of 5500 µg/kg.

ACS Style

Florian Kaltner; Michael Rychlik; Manfred Gareis; Christoph Gottschalk. Occurrence and Risk Assessment of Pyrrolizidine Alkaloids in Spices and Culinary Herbs from Various Geographical Origins. Toxins 2020, 12, 155 .

AMA Style

Florian Kaltner, Michael Rychlik, Manfred Gareis, Christoph Gottschalk. Occurrence and Risk Assessment of Pyrrolizidine Alkaloids in Spices and Culinary Herbs from Various Geographical Origins. Toxins. 2020; 12 (3):155.

Chicago/Turabian Style

Florian Kaltner; Michael Rychlik; Manfred Gareis; Christoph Gottschalk. 2020. "Occurrence and Risk Assessment of Pyrrolizidine Alkaloids in Spices and Culinary Herbs from Various Geographical Origins." Toxins 12, no. 3: 155.

Perspective article
Published: 28 February 2020 in Frontiers in Nutrition
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Predictions about the future knowledge of the “complete” food metabolome may be assayed based on the laws of Moore and Kurzweil, who foresee a technological development on exponential behavior. The application of these laws allows us to extrapolate and predict roughly when each single metabolite in foods could be (1) known, (2) detectable, and (3) identifiable. To avoid huge additional uncertainties, we restrict the range of metabolites to those in unprocessed foods. From current metabolite databases and their coverage over time, the conservative number of all considered food metabolites can be estimated to be 500,000, predicting them being known by around 2025. Assuming these laws and extrapolating the current developments in chromatography and mass spectrometry technology, the year 2032 can be estimated, when single molecule detection will be possible in “routine” mass spectrometry. A possible forecast for the identification of all food metabolites, however, is much more difficult and estimated at the earliest in 2041 as the year when this may be achieved. However, the real prediction uncertainty is extreme and is discussed in the essay presented here.

ACS Style

Michael Rychlik; Philippe Schmitt-Kopplin. Reading From the Crystal Ball: The Laws of Moore and Kurzweil Applied to Mass Spectrometry in Food Analysis. Frontiers in Nutrition 2020, 7, 1 .

AMA Style

Michael Rychlik, Philippe Schmitt-Kopplin. Reading From the Crystal Ball: The Laws of Moore and Kurzweil Applied to Mass Spectrometry in Food Analysis. Frontiers in Nutrition. 2020; 7 ():1.

Chicago/Turabian Style

Michael Rychlik; Philippe Schmitt-Kopplin. 2020. "Reading From the Crystal Ball: The Laws of Moore and Kurzweil Applied to Mass Spectrometry in Food Analysis." Frontiers in Nutrition 7, no. : 1.

Journal article
Published: 05 February 2020 in Carbohydrate Research
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Various 5’-β-saccharides of pyridoxine, namely the mannoside, galactoside, arabinoside, maltoside, cellobioside and glucuronide, were synthesized chemically according to Koenigs-Knorr conditions using α4,3-O-isopropylidene pyridoxine and the respective acetobromo glycosyl donors with AgOTf (3.0 eq.) and NIS (3.0 eq.) as promoters at 0 °C. Furthermore, 5’-β-[13C6]-labeled pyridoxine glucoside (PNG) was prepared starting from [13C6]-glucose and pyridoxine. Additionally, two strategies were examined for the synthesis of 5’-β-pyridoxal glucoside (PLG).

ACS Style

Thomas Bachmann; Christian Schnurr; Laura Zainer; Michael Rychlik. Chemical synthesis of 5’-β-glycoconjugates of vitamin B6. Carbohydrate Research 2020, 489, 107940 .

AMA Style

Thomas Bachmann, Christian Schnurr, Laura Zainer, Michael Rychlik. Chemical synthesis of 5’-β-glycoconjugates of vitamin B6. Carbohydrate Research. 2020; 489 ():107940.

Chicago/Turabian Style

Thomas Bachmann; Christian Schnurr; Laura Zainer; Michael Rychlik. 2020. "Chemical synthesis of 5’-β-glycoconjugates of vitamin B6." Carbohydrate Research 489, no. : 107940.

Journal article
Published: 05 February 2020 in Toxins
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Ruminants are generally considered to be less susceptible to the effects of mycotoxins than monogastric animals as the rumen microbiota are capable of detoxifying some of these toxins. Despite this potential degradation, mycotoxin-associated subclinical health problems are seen in dairy cows. In this research, the disappearance of several mycotoxins was determined in an in vitro rumen model and the effect of realistic concentrations of those mycotoxins on fermentation was assessed by volatile fatty acid production. In addition, two hypotheses were tested: (1) a lower rumen pH leads to a decreased degradation of mycotoxins and (2) rumen fluid of lactating cows degrade mycotoxins better than rumen fluid of non-lactating cows. Maize silage was spiked with a mixture of deoxynivalenol (DON), nivalenol (NIV), enniatin B (ENN B), mycophenolic acid (MPA), roquefortine C (ROQ-C) and zearalenone (ZEN). Fresh rumen fluid of two lactating cows (L) and two non-lactating cows (N) was added to a buffer of normal pH (6.8) and low pH (5.8), leading to four combinations (L6.8, L5.8, N6.8, N5.8), which were added to the spiked maize substrate. In this study, mycotoxins had no effect on volatile fatty acid production. However, not all mycotoxins fully disappeared during incubation. ENN B and ROQ-C disappeared only partially, whereas MPA showed almost no disappearance. The disappearance of DON, NIV, and ENN B was hampered when pH was low, especially when the inoculum of non-lactating cows was used. For ZEN, a limited transformation of ZEN to α-ZEL and β-ZEL was observed, but only at pH 6.8. In conclusion, based on the type of mycotoxin and the ruminal conditions, mycotoxins can stay intact in the rumen.

ACS Style

Sandra Debevere; An Cools; Siegrid De Baere; Geert Haesaert; Michael Rychlik; Siska Croubels; Veerle Fievez. In Vitro Rumen Simulations Show a Reduced Disappearance of Deoxynivalenol, Nivalenol and Enniatin B at Conditions of Rumen Acidosis and Lower Microbial Activity. Toxins 2020, 12, 101 .

AMA Style

Sandra Debevere, An Cools, Siegrid De Baere, Geert Haesaert, Michael Rychlik, Siska Croubels, Veerle Fievez. In Vitro Rumen Simulations Show a Reduced Disappearance of Deoxynivalenol, Nivalenol and Enniatin B at Conditions of Rumen Acidosis and Lower Microbial Activity. Toxins. 2020; 12 (2):101.

Chicago/Turabian Style

Sandra Debevere; An Cools; Siegrid De Baere; Geert Haesaert; Michael Rychlik; Siska Croubels; Veerle Fievez. 2020. "In Vitro Rumen Simulations Show a Reduced Disappearance of Deoxynivalenol, Nivalenol and Enniatin B at Conditions of Rumen Acidosis and Lower Microbial Activity." Toxins 12, no. 2: 101.

Abstract
Published: 02 February 2020 in Proceedings
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Folate, an important B-group vitamin, is considered a critical vitamin in many countries, with folate deficiency being associated with neural tube defects in newborns. Strawberries and avocados are considered a healthy, tasty snack by many consumers, and may potentially be an important dietary source of natural folates, depending on variety and growing environment. A selection of Australian-grown strawberry varieties and breeding lines, as well as commercial avocado cultivars, were screened for their folate content and vitamer profile by stable isotope dilution assay. Total folate content ranged from 69–170 μg/100 g fresh weight (fw) for strawberries and 76–196 μg/100 g fw for avocados, which was well above the values in the Australian Food Composition Database (39 μg/100 g fw for strawberries and 90 μg/100 g fw for avocados, respectively). Furthermore, folate concentration in the outer strawberry tissue was found to be 1.7-fold higher than the inner tissue of the fruit, whereas the inner avocado tissue had 1.4-fold higher folate than the outer green edible tissue. 5-Methyltetrahydrofolate, the biologically active form in humans, was the principal vitamer present. With these high folate concentrations, a punnet (250 g) of Australian-grown strawberries or 200 g of Australian-grown avocados would deliver the FSANZ recommended dietary intake (RDI) for folate (400 μg dietary folate equivalents/day/adult). Furthermore, the differences between outer and inner tissue could indicate that flatter, longer strawberries may have greater potential to accumulate folate than fruit with a more spherical shape, whereas more folate could be accumulated in a rounder-shaped avocado.

ACS Style

Michael E. Netzel; Caroline Dumler; Nadine Weber; Lisa Striegel; Michael Rychlik; Hung T. Hong; Tim O’Hare. The Inside and out of Folate in Strawberries and Avocados. Proceedings 2020, 36, 86 .

AMA Style

Michael E. Netzel, Caroline Dumler, Nadine Weber, Lisa Striegel, Michael Rychlik, Hung T. Hong, Tim O’Hare. The Inside and out of Folate in Strawberries and Avocados. Proceedings. 2020; 36 (1):86.

Chicago/Turabian Style

Michael E. Netzel; Caroline Dumler; Nadine Weber; Lisa Striegel; Michael Rychlik; Hung T. Hong; Tim O’Hare. 2020. "The Inside and out of Folate in Strawberries and Avocados." Proceedings 36, no. 1: 86.

Original research article
Published: 21 January 2020 in Frontiers in Bioengineering and Biotechnology
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A multitude of human nutritional supplements based on Chlorella vulgaris biomass has recently been introduced to the specialty food market. In this study, an analysis of total folate contents in Chlorella sp. and a series of marine microalgae was conducted to evaluate folate content in alternative algae-based food production strains. For the first time, total folate content and vitamer distribution in microalgae were analyzed by stable isotope dilution assay (SIDA) using LC-MS/MS, which has demonstrated its superiority with respect to folate quantification. Consistently, high folate contents were detected in all examined microalgae samples. High folate concentrations of 3,460 ± 134 μg/100 g dry biomass were detected in freshly cultivated Chlorella vulgaris, notably also in other well-researched microalgae strains. To that end, the highest folate content currently documented for any algae sample was measured in the marine microalgae Picochlorum sp. isolate with values of 6,470 ± 167 μg/100 g dry biomass. This calls for alternative products based on other algae biomass. Our data indicate that freshwater and marine microalgae provide extremely high concentrations of folates, which warrant further studies on the regulation of pteroylpolyglutamates in algae as well as on bioaccessibility, absorption, and retention in humans.

ACS Style

Dirk Volker Woortman; Tobias Fuchs; Lisa Striegel; Monika Fuchs; Nadine Weber; Thomas B. Brück; Michael Rychlik. Microalgae a Superior Source of Folates: Quantification of Folates in Halophile Microalgae by Stable Isotope Dilution Assay. Frontiers in Bioengineering and Biotechnology 2020, 7, 481 .

AMA Style

Dirk Volker Woortman, Tobias Fuchs, Lisa Striegel, Monika Fuchs, Nadine Weber, Thomas B. Brück, Michael Rychlik. Microalgae a Superior Source of Folates: Quantification of Folates in Halophile Microalgae by Stable Isotope Dilution Assay. Frontiers in Bioengineering and Biotechnology. 2020; 7 ():481.

Chicago/Turabian Style

Dirk Volker Woortman; Tobias Fuchs; Lisa Striegel; Monika Fuchs; Nadine Weber; Thomas B. Brück; Michael Rychlik. 2020. "Microalgae a Superior Source of Folates: Quantification of Folates in Halophile Microalgae by Stable Isotope Dilution Assay." Frontiers in Bioengineering and Biotechnology 7, no. : 481.

Research article
Published: 04 December 2019 in Molecular Nutrition & Food Research
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Scope Alternaria fungi are widely distributed plant pathogens infecting grains and vegetables and causing major harvest losses in Methods and Results Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS) and LC‐MS/MS were combined for the non‐targeted and targeted analysis of the metabolome of three A. alternata isolates and one A. solani isolate. Due to the ultra‐high resolution of FTICR‐MS, unique molecular formulae were assigned to measured m/z signals. The molecular formulae were matched to entries of the databases Antibase and KEGG. The non‐targeted analysis of the fungal extracts revealed variations in the secondary metabolite profile of A. alternata and A. solani. Differences in the biosynthesis of dibenzo‐α‐pyrones, perylene quinones, tentoxin, and tenuazonic acid of the A. alternata and A. solani isolates were determined applying targeted LC‐MS/MS. Conclusion FTICR‐MS analyses revealed clear differences in the metabolic profile of the A. solani and the A. alternata isolates. This article is protected by copyright. All rights reserved

ACS Style

Marina Gotthardt; Basem Kanawati; Frank Schmidt; Stefan Asam; Richard Hammerl; Oliver Frank; Thomas Hofmann; Philippe Schmitt‐Kopplin; Michael Rychlik. Comprehensive Analysis of the Alternaria Mycobolome Using Mass Spectrometry Based Metabolomics. Molecular Nutrition & Food Research 2019, 64, e1900558 .

AMA Style

Marina Gotthardt, Basem Kanawati, Frank Schmidt, Stefan Asam, Richard Hammerl, Oliver Frank, Thomas Hofmann, Philippe Schmitt‐Kopplin, Michael Rychlik. Comprehensive Analysis of the Alternaria Mycobolome Using Mass Spectrometry Based Metabolomics. Molecular Nutrition & Food Research. 2019; 64 (3):e1900558.

Chicago/Turabian Style

Marina Gotthardt; Basem Kanawati; Frank Schmidt; Stefan Asam; Richard Hammerl; Oliver Frank; Thomas Hofmann; Philippe Schmitt‐Kopplin; Michael Rychlik. 2019. "Comprehensive Analysis of the Alternaria Mycobolome Using Mass Spectrometry Based Metabolomics." Molecular Nutrition & Food Research 64, no. 3: e1900558.

Journal article
Published: 13 September 2019 in Chemistry – A European Journal
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The photochemical transformation of Maillard reaction products (MRPs) under simulated sunlight into mostly unexplored photoproducts is reported herein. Non-enzymatic glycation of amino acids leads to a heterogeneous class of intermediates with extreme chemical diversity, which is of particular relevance in processed and stored food products as well as in diabetic and age-related protein damage. Here, three amino acids (lysine, arginine, and histidine) were reacted with ribose at 100 °C in water for ten hours. Exposing these model systems to simulated sunlight led to a fast decay of MRPs. The photodegradation of MRPs and the formation of new compounds have been studied by fluorescence spectroscopy and nontargeted (ultra)high-resolution mass spectrometry. Photoreactions showed strong selectivity towards the degradation of electron-rich aromatic heterocycles, such as pyrroles and pyrimidines. The data show that oxidative cleavage mechanisms dominate the formation of photoproducts. The photochemical transformations differed fundamentally from "traditional" thermal Maillard reactions and indicated a high amino acid specificity.

ACS Style

Daniel Hemmler; Michael Gonsior; Leanne C. Powers; James W. Marshall; Michael Rychlik; Andrew J. Taylor; Philippe Schmitt-Kopplin. Simulated Sunlight Selectively Modifies Maillard Reaction Products in a Wide Array of Chemical Reactions. Chemistry – A European Journal 2019, 25, 13208 -13217.

AMA Style

Daniel Hemmler, Michael Gonsior, Leanne C. Powers, James W. Marshall, Michael Rychlik, Andrew J. Taylor, Philippe Schmitt-Kopplin. Simulated Sunlight Selectively Modifies Maillard Reaction Products in a Wide Array of Chemical Reactions. Chemistry – A European Journal. 2019; 25 (57):13208-13217.

Chicago/Turabian Style

Daniel Hemmler; Michael Gonsior; Leanne C. Powers; James W. Marshall; Michael Rychlik; Andrew J. Taylor; Philippe Schmitt-Kopplin. 2019. "Simulated Sunlight Selectively Modifies Maillard Reaction Products in a Wide Array of Chemical Reactions." Chemistry – A European Journal 25, no. 57: 13208-13217.

Journal article
Published: 07 September 2019 in Toxins
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Ruminants are less susceptible to the effects of mycotoxins than monogastric animals as their rumen microbiota are claimed to degrade and/or deactivate at least some of these toxic compounds. However, the mycotoxin degradation is not well-known yet. For this, a sensitive, specific, and accurate analytical method is needed to determine mycotoxins in the rumen fluid. This study aims to develop and thoroughly validate an ultra-performance liquid chromatography tandem mass spectrometry method for the quantitative determination in the rumen fluid of some of the most relevant mycotoxins found in maize silage in Western Europe: deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEN), mycophenolic acid (MPA), roquefortine C (ROQ-C) and enniatin B (ENN B), as well as their metabolites deepoxy-deoxynivalenol (DOM-1), α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), zearalanone (ZAN), α-zearalanol (α-ZAL) and β-zearalanol (β-ZAL). As feed is often present in the rumen fluid samples, the potential interaction of feed particles with the mycotoxin extraction and analysis was investigated. Extraction recovery and matrix effects were determined in the rumen fluid with and without maize silage. Differences in those parameters between rumen fluid alone and rumen fluid with maize silage highlight the importance of using matrix-matched calibration curves for the quantification of mycotoxins in rumen fluid samples. A cross-validation of the method with rumen fluid and maize silage demonstrates that this analytical method can be applied in research on rumen fluid samples to investigate the degradation of the reported mycotoxins by rumen microbiota if matrix-matched calibration is performed.

ACS Style

Sandra Debevere; Siegrid De Baere; Geert Haesaert; Michael Rychlik; Veerle Fievez; Siska Croubels. Development of an UPLC-MS/MS Method for the Analysis of Mycotoxins in Rumen Fluid with and without Maize Silage Emphasizes the Importance of Using Matrix-Matched Calibration. Toxins 2019, 11, 519 .

AMA Style

Sandra Debevere, Siegrid De Baere, Geert Haesaert, Michael Rychlik, Veerle Fievez, Siska Croubels. Development of an UPLC-MS/MS Method for the Analysis of Mycotoxins in Rumen Fluid with and without Maize Silage Emphasizes the Importance of Using Matrix-Matched Calibration. Toxins. 2019; 11 (9):519.

Chicago/Turabian Style

Sandra Debevere; Siegrid De Baere; Geert Haesaert; Michael Rychlik; Veerle Fievez; Siska Croubels. 2019. "Development of an UPLC-MS/MS Method for the Analysis of Mycotoxins in Rumen Fluid with and without Maize Silage Emphasizes the Importance of Using Matrix-Matched Calibration." Toxins 11, no. 9: 519.