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PubMed1996

Transformation of the mycotoxin ochratoxin A in plants: 1. Isolation and identification of metabolites formed in cell suspension cultures of wheat and maize.

The metabolism of the mycotoxin ochratoxin A in plant cells was investigated using cell suspension cultures of wheat and maize. A number of metabolites were detected by HPLC-chromatography with fluorescence detection. The main metabolites were ochratoxin alpha, ochratoxin A methyl ester, two isomers of hydroxyochratoxin A, and the glucosides and methyl esters of both hydroxyochratoxin A isomers. The compounds were isolated by TLC and preparative HPLC and identified by mass spectrometry and specific enzymic reactions.

Biotransformation↗

PubMed1996

Mycotoxin fumonisin B1 stimulates nitric oxide production in a murine macrophage cell line.

Fumonisin B1 (FB1), a mycotoxin, is a common fungal contaminant of corn and corn products. This sphingolipid-like compound causes a variety of animal diseases and is a suspected human carcinogen. Cellular targets of FB1 include hepatocytes and renal and immune cells. The effects of FB1 on nitric oxide (NO) production induced by lipopolysaccharide (LPS) were investigated in the present study by using a murine macrophage cell line as a model system. Stimulation of NO production was observed for increasing concentrations of FB1 (1, 10, and 100 microM) and either 0.005 or 0.01 microgram/ml LPS. Although with an increasing dose of FB1 the total protein content decreased for the stimulated and the unstimulated cells, the NO production remained elevated for the stimulated cells. It can be hypothesized that the potentiation of the LPS-dependent NO production by FB1 treatment could be due to direct interaction between FB1 and NO synthases and LPS receptors or to a disrupted sphingolipid metabolism.

Animals↗

PubMed1997

Evaluation of Alternaria and its mycotoxins during ensiling of sunflower seeds.

Sunflower (Heliantus annuus) is an important crop in the economy of Argentina due to its high production and demand from domestic and export markets. The aim of this study was to evaluate the presence of Alternaria species and its mycotoxins in ensiled sunflower seeds. The sampling was carried out in three periods: at the beginning of ensiling, on the second month and finally on the fourth month. The mycological analysis was made with disinfected seeds, cultured on Dichloran-Rose Bengal-Chloramphenicol (DRBC) and Dichloran-Chloramphenicol-Malt Extract-Agar (DCMA). The toxins were analyzed by thin layer chromatography (TLC). A alternata was the main fungal species isolated. The incidence of Alternaria species and the levels of alternariol and tenuazonic acid decreased as the time of ensiling increased. Alternariol monomethyl ether was detected in two samples from the second and third sampling periods.

Alternaria↗

PubMed1996

Detection and characterization of fumonisin mycotoxins by liquid chromatography/electrospray ionization using ion trap and triple quadrupole mass spectrometry.

Electrospray ionization (ESI) high-performance liquid chromatography/mass spectrometry using both ion trap and triple quadrupole mass spectrometers has been utilized for the detection and characterization of fumonisin mycotoxin impurities in a purified sample of fumonisin B1 (FB1). Multi-stage tandem mass spectrometry (MSn) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) of FB1 and the fifteen synthetically prepared methyl esters of FB1 on the ion trap instrument allowed investigation of the numerous fragmentation pathways available for this compound class. Data-dependent LC/MS/MS precursor-ion scan to product-ion scan experiments, based on the ion trap MSn experiments, were carried out on a triple quadrupole instrument and facilitated the detection of twelve, and the structural characterization of eight, minor impurities on the purified sample of FB1. Data-dependent LC/MS/MS full scan to product-ion scan experiments on the ion trap instrument resulted in the detection and characterization of fifteen further impurities in the purified sample of FB1; this number included the four uncharacterized impurities detected in the triple quadrupole LC/MS/MS experiments.

Chromatography, High Pressure Liquid↗

PubMed1999

Mycotoxins (trichothecenes, zearalenone and fumonisins) in cereals associated with human red-mold intoxications stored since 1989 and 1991 in China.

Two corn powder samples implicated in the human food poisoning that occurred in Guangxi province in 1989, and eight wheat and two barley samples linked to an episode that involved about 130,000 people in gastrointestinal disorders in Anhui province in 1991 were analyzed for trichothecenes including deoxynivalenol (DON), nivalenol (NIV) and their esters, zearalenone (ZEA) and fumonisins (FMs) by gas chromatography/mass spectroscopy and high performance liquid chromatography, and T-2 toxin by enzyme-linked immunosorbent assays. DON was detected in all samples as a major trichothecene (16-51,450 microg kg(-1)), and NIV was in one corn, one barley and all wheat at relatively low levels (10-6935 microg kg(-1)). ZEA was found in all corn and barley, and six wheat samples (46-3079 microg kg(-1)). In addition, 3-acetyl-DON (2544 microg kg(-1)) and 15-acetyl-DON (2537 microg kg(-1)) were detected separately in one corn and one wheat sample. The highest levels of these mycotoxins were found in one wheat sample associated with the human intoxication in Anhui province. FMs in corn were below 1000 microg kg(-1). Risks of DON and ZEA on the people who consumed the causative cereals were assessed.

Carboxylic Acids↗

PubMed1977

The role of nicotinamide and of certain other modifying factors in diethylnitrosamine carcinogenesis: fusaria mycotoxins and "spontaneous" tumors in animals and man.

Pretreatment of rats with large doses of nicotinamide, which has been shown to increase the incidence of pancreatic islet-cell tumors after streptozotocin and after heliotrine, appears to promote the development of kidney neoplasias in rats given several doses of diethylnitrosamine. Nicotinamide, one of the B vitamins, and a constituent of NAD coenzymes, will prevent the depletion of NAD coenzymes by alkylating agents. It may protect the animal to some extent from the acute effects of hepatocarcinogens but not from the induction of tumors, although it may change the localization of the latter. The possible mechanisms involved in the action of nicotinamide and of certain other modifying agents are discussed. Attention is drawn to the possibility that pituitary, mammary and certain other tumors that sometimes occur among the controls, as well as among experimental animals, may be due to the occasional presence in laboratory animal diets of estrogenic and/or toxic secondary metabolites of the field fungi, Fusaria. Mycotoxins, such as zearalenone and the trichothecenes, are also likely to contaminate human foods; this could explain why multiple tumors in man occur mainly in the sex organs and in the digestive tract.

Animals↗

PubMed1992

Synthesis of novel thieno[2,3-d]pyrimidine, thieno[2,3-b]pyridine and thiazolo[3,2-a]thieno[2,3-d]pyrimidine derivatives and their effect on the production of mycotoxins.

The thiophene derivative 1 reacts with the active methylene reagents 2a-c to afford the thieno[2,3-d]pyrimidine derivatives 6a,b and 8, respectively. 1 reacts with phenacyl bromide 2d to afford the N-alkylation product 9 and reacts with phenacyl thiocyanate 2e to afford the N-(thiazol-2-yl) derivative 10, which was further cyclized into thiazolo[3,2-a]thieno[2,3-d]pyrimidine derivative 12. Compound 1 reacts also with the cinnamonitriles 3a,b to afford the thieno[2,3-b]pyridines 15a,b, respectively. 1 undergoes either acetylation or hydrolysis to afford the thieno[2,3-b]pyridine derivative 19 and the thiophene derivative 22, respectively. Some of the new compounds show inhibitory effect to the production of mycotoxins and to fungal growth.

Aspergillus↗

PubMed1982

Presence of four Fusarium mycotoxins and synthetic material in 'yellow rain'. Evidence for the use of chemical weapons in Laos.

Analysis of a 'yellow rain' sample by selected ion monitoring revealed the presence of three trichothecenes: T-2 toxin, diacetoxyscirpenol and 4-deoxynivalenol in concentrations of at least 48, 42 and 58 ppm, respectively. The concentration of zearalenone, another Fusarium mycotoxin, was estimated to be at least 265 ppm. Evidence for a formulation which contained polyethylene glycol was also obtained.

Chemical Warfare Agents↗

PubMed1986

Mass spectral investigations on trichothecene mycotoxins. I. Application of negative ion chemical ionization techniques for the simultaneous and accurate analysis of simple trichothecenes in picogram levels.

A fast and sensitive gas chromatographic/negative ion chemical ionization mass spectrometric method for the simultaneous detection and quantification of several simple trichothecene mycotoxins and related molecules with good precision has been developed. The method consists of the conversion of the polar trichothecenes into their volatile and stable heptafluorobutyryl esters, followed by gas chromatographic/mass spectrometric analysis of the derivatives. The derivatives were ionized under chemical ionization conditions and the negative ions were monitored. The samples were screened for the presence of trichothecenes by monitoring one characteristic ion by selected ion monitoring for each analyte. The detected compounds were confirmed by monitoring 5-6 characteristic ions by selected ion monitoring whenever the amount of analyte present was insufficient to obtain a full scan negative ion chemical ionization mass spectrum. Two semi-synthetic trichothecenes, 4-deoxyverrucarol and 16-hydroxyverrucarol, were investigated and found to be adequate internal standards both for detection and quantification of these toxic compounds. Femtogram and low picogram (1-5 pg) quantities of these compounds could be detected and confirmed, respectively, by this procedure. A short clean-up procedure using Sep-Pak (silica gel) cartridges was developed and found to be applicable for the analysis of some real samples. Several spiked and real samples were analysed by this method, with excellent sensitivity and precision.

Chemical Phenomena↗

PubMedDate not supplied

Mycotoxin identification in moldy dwellings.

The objective of this study was to assess the level of macrocyclic trichothecenes (MCT), one of the most potent mycotoxins, on wall surfaces, floor dust and air samples from moldy dwellings. The study was based on an index group comprising 15 flooded dwellings contaminated by Stachybotrys chartarum or Chaetomium and a control group comprising nine dwellings without molds on visual inspection and mold sampling. Three samples were collected from each dwelling: a sample from the moldy wall, using a swab, a floor dust sample on a 0.5 m(2) surface with a cloth and an air sample using a pump comprising a 1 microm Teflon filter. The MCT level was measured using a monoclonal, antibody-based ELISA test. Compared with measurements performed in index dwellings, higher MCT values were measured on floor dust samples from moldy dwellings (P = 0.02). Samples from wall surfaces demonstrated nearly significant differences (P = 0.06). No significant differences were observed for air samples (P = 0.15), but some samples showed increased MCT levels. Significant correlations were observed between the levels measured on wall surfaces, floor dust and air samples (P = 0.02 to 0.05). In contrast, no correlation was observed between moldy surface and MCT levels. In conclusion, this paper reports for the first time direct evidence for the presence of MCT in moldy dwellings.

Air Microbiology↗

PubMed2003

Derivatization reaction of the mycotoxin moniliformin with 1,2-diamino-4,5-dichlorobenzene: structure elucidation of an unexpected reaction product by liquid chromatography/tandem mass spectrometry and liquid chromatography/nuclear magnetic resonance spectroscopy.

The derivatization reaction of the mycotoxin moniliformin with 1,2-diamino-4,5-dichlorobenzene was previously introduced to improve distinctly the sensitivity of an assay applying high-performance liquid chromatography prior to fluorescence detection. In the course of the implementation of this derivatization approach into a liquid chromatographic/mass spectrometric method, an unexpected derivatization product has now been discovered by mass spectrometry. In order to elucidate its structure, detailed investigations with liquid chromatography/tandem mass spectrometry and liquid chromatography coupled on-line with NMR spectroscopy were performed. These studies give evidence for a heterocyclic structure that has been formed by the loss of one water and one carbon monoxide molecule. A reasonable mechanism for this derivatization reaction is proposed.

Benzene Derivatives↗

PubMed1993

Survey of mycoflora and mycotoxins in Egyptian soybean seeds.

After four months in commercial storage, 100 soybean samples from different places of Egyptian Governorates were assayed for filamentous fungal growth at two incubation temperatures (28 and 45 degrees C). 73 species and 8 varieties belonging to 32 genera were isolated by the dilution plate method. At 28 degrees C, the common species were Aspergillus flavus, A. fumigatus, A. niger and A. alutaceus, followed by A. terreus, Penicillium chrysogenum, P. citrinum, Mucor hiemalis, M. racemosus, Emericella nidulans, Rhizopus stolonifer, Nectria haematococca and Scopulariopsis brevicaulis. At 45 degrees C, A. fumigatus was the dominant species followed by Rhizomucor pusillus, Emericella nidulans and Neosartorya fischeri. Penicillium which was one of the most abundant genus at 28 degrees C, absent at 45 degrees C. The seeds were assayed for aflatoxin, ochratoxin A, sterigmatocystin, T-2 and zearalenone by thin layer chromatographic analysis. Aflatoxin was detected in 35% of soybean seed samples (5-35 micrograms/kg). The other mycotoxins were not detected.

Egypt↗

PubMed2005

Structural elucidation and analysis of thermal degradation products of the Fusarium mycotoxin nivalenol.

The major class of mycotoxins produced by Fusarium moulds are trichothecenes, a large group of sesquiterpenes sharing the same basic chemical structure, a 12,13-epoxytrichothec-9-ene ring system. Their toxic effects range from causing diarrhoea, vomiting and gastro-intestinal inflammation to noncompetitive inhibition of the biosynthesis of proteins in eukaryotic cells. Trichothecenes in general are relatively stable compounds, their degradation is observed only at high temperatures and prolonged heating time. In order to investigate the stability of the trichothecene nivalenol (NIV) under food processing conditions such as cooking or baking, we performed model heating experiments and screened the residue for degradation products using gas chromatography-mass spectrometry (GC-MS). Heating of nivalenol, especially under mild alkaline conditions, gave a mixture of four compounds (norNIV A, norNIV B, norNIV C, and NIV lactone), which where isolated and identified by nuclear magnetic resonance (NMR) and MS experiments. Although their formation was also demonstrated in heating experiments with spiked flour samples, only norNIV B was detectable in a screening of several commercially available samples, possibly due to the very low contamination with nivalenol. Furthermore, cell culture experiments using immortalized human kidney epithelial (IHKE) cells showed that the four compounds are less cytotoxic (formazan dye cytotoxicity assay) compared to nivalenol. Whereas nivalenol revealed an EC50 at 0.9 micromol, all other compounds did not show any significant effect up to 100 micromol.

Cell Line, Transformed↗

PubMed1995

Use of monoclonal antibodies for the analysis of mycotoxins.

Hybridomas producing monoclonal antibodies against aflatoxin M1, ochratoxin A, zearalenone, T-2 toxin, diacetoxyscirpenol, 3-acetyl-deoxynivalenol, fusarenon X, and roridin A were developed after immunization of BALB/c mice and fusion of the splenocytes with myeloma cells. The antibodies were characterized in terms of immunoglobulin subclass, sensitivity, and specificity. The use of these antibodies in competitive enzyme immunoassays, either as microtiter plate assays or membrane-based quick tests, as well as for the production of immunoaffinity columns is described. The advantages and disadvantages of monoclonal antibodies compared to polyclonal antisera for the improvement of mycotoxin analysis are discussed.

Animals↗

PubMed2006

Detection of new fumonisin mycotoxins and fumonisin-like compounds by reversed-phase high-performance liquid chromatography/electrospray ionization ion trap mass spectrometry.

Fumonisins were produced in a rice culture infected with Fusarium verticillioides. To decrease the possibility of the formation of artifacts, the fumonisins were analyzed by reversed-phase high-performance liquid chromatography with electrospray ionization ion trap tandem mass spectrometry (RP-HPLC/ESI-IT-MS2) immediately after the extraction of the culture material without any sample clean-up. In addition to already known fumonisins, numerous new fumonisin mycotoxins and fumonisin-like compounds were detected. On the basis of the IT-MS2 data, detailed fragmentation pathways including new mechanisms were proposed for the different series of fumonisins. The retention times, the masses of the protonated molecules and of the product ions including the backbones and the characteristic neutral mass losses from the protonated molecules of the new compounds suggested their structures (applying the well-known designation): iso-FA1a,b, iso-FB1a-d, iso-FB2,3a-e, PHFB2a-c, PHFB4a-d, FB5/iso-FB5a-d, FBK1 2TCA, FBK4 2TCA, FC2, iso-FC2,3, PHFC4, FD and FBX series. The relative quantities of fumonisins and fumonisin-like compounds found in the sample extract were expressed as percentages of FB1 (0.02-100%). The backbone of the compound denoted FD contained fewer carbon atoms than the well-known fumonisins with the C19 or C20 backbone and may well be a precursor of the longer compounds. For the compounds denoted FBX (12 compounds), one or two OH groups attached to the fumonisin backbone were esterified by carboxylic acids other than tricarballylic acid, such as cis-aconitic acid, oxalylsuccinic acid and oxalylfumaric acid.

Chromatography, High Pressure Liquid↗

PubMed2006

Development and validation of a liquid chromatography/tandem mass spectrometric method for the determination of 39 mycotoxins in wheat and maize.

This paper describes the first validated method for the determination of 39 mycotoxins in wheat and maize using a single extraction step followed by liquid chromatography with electrospray ionization triple quadrupole mass spectrometry (LC/ESI-MS/MS) without the need for any clean-up. The 39 analytes included A- and B-trichothecenes (including deoxynivalenol-3-glucoside), zearalenone and related derivatives, fumonisins, enniatins, ergot alkaloids, ochratoxins, aflatoxins and moniliformin. The large number and the chemical diversity of the analytes required the application of the positive as well as the negative ion ESI mode in two consecutive chromatographic runs of 21 min each. The solvent mixture acetonitrile/water/acetic acid 79 + 20 + 1 (v/v/v) has been determined as the best compromise for the extraction of the analytes from wheat and maize. Raw extracts were diluted 1 + 1 and were injected without any clean-up. Ion-suppression effects due to co-eluting matrix components were negligible in the case of wheat, whereas significant signal suppression for 12 analytes was observed in maize, causing purely proportional systematic errors. Method performance characteristics were determined after spiking blank samples on multiple levels in triplicate. Coefficients of variation of the overall process of <5.1% and <3.0% were obtained for wheat and maize, respectively, from linear calibration data. Limits of detection ranged from 0.03 to 220 microg/kg. Apparent recoveries (including both the recoveries of the extraction step and matrix effects) were within the range of 100 +/- 10% for approximately half of the analytes. In extreme cases the apparent recoveries dropped to about 20%, but this could be compensated for to a large extent by the application of matrix-matched standards to correct for matrix-induced signal suppression, as only a few analytes such as nivalenol and the fumonisins exhibited incomplete extraction. For deoxynivalenol and zearalenone, the trueness of the method was confirmed through the analysis of certified reference materials.

Chromatography, High Pressure Liquid↗

PubMed1996

Inhibition of protein serine/threonine phosphatases by fumonisin B1, a mycotoxin.

Fumonisin B1 (FB1), a mycotoxin produced by the fungus Fusarium moniliforme, which is a common contaminant of corn, is suspected to be a cause of human esophageal cancer. FB1 is hepatotoxic and hepatocarcinogenic in rats, and although the mechanisms involved have not been clarified, the latter is associated with a weak initiating activity. The effects of FB1 on the activity of protein serine/threonine phosphatases (PPs) (PP1, PP2A, PP2B, PP2C and PP5/T/K/H) were investigated in the present study. Inhibition of dephosphorylation was noted for all five PPs with IC50 values of 80 microM-3000 microM. Among the five PPs examined, PP5 was most sensitive with an IC50 of 80 microM. This concentration is comparable to that estimated to be reached in the rat body by feeding FB1 to obtain hepatic tumors. Inhibition of PP5 could thus play important roles in the toxicity and carcinogenic action of FB1.

Animals↗

PubMed1996

Activation of mitogen-activated protein kinase by the carcinogenic mycotoxin fumonisin B1.

Recent studies indicate that the mycotoxin and putative carcinogen fumonisin B1 stimulates mitogenesis in Swiss 3T3 fibroblasts. Because mitogen-activated protein kinase (MAPK) is a key enzyme in the signal transduction pathways activated by many mitogens, we hypothesized that fumonisin B1 might modulate MAPK activity. Consistent with other reports, we observed that fumonisin B1 is synergistic with insulin for mitogenesis in Swiss 3T3 cells. We also observed that: (1) fumonisin B1 stimulates rapid, transient activation of MAPK; and (2) the dose-response curve for fumonisin B1-stimulated activation of MAPK is similar to the dose-response curve for the mitogenic effects of fumonisin B1. In contrast to fumonisin B1, insulin stimulates minimal activation of MAPK in Swiss 3T3 cells. The observation that fumonisin B1 and insulin differ with respect to the modulation of MAPK activity suggests a possible mechanism for their synergistic stimulation of mitogenesis in Swiss 3T3 cells.

3T3 Cells↗