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At least 19 recordsLinked to original sources
PubMed1979

[Hygienic significance of sterigmatocystin in vegetable foods. 2. Production of sterigmatocystin by Aspergillus versicolor].

To test the suitability of fruit as an appropriate substrate for the formation of the mycotoxin sterigmatocystin, various fruit products were inoculated with a suspension of spores of a toxicogenic strain of Aspergillus versicolor. After incubation at 22 degrees C for 14 days, the fruits and juices overgrown with mould were homogenized with ethyl acetate and subjected to thinlayer chromatography. Sterigmatocystin had been formed on most products, the largest amounts being found in gooseberry preserves (9.4 microgram/g) and in grapes (10 microgram/g). The experiments show that fruit is generally suited as a substrate for the formation of sterigmatocystin; consequently, the latter is likely to occur in the presence of Aspergillus versicolor.

Aspergillus↗
PubMed1979

[Hygienic significance of sterigmatocystin in vegetable foods. 3. Occurrence of sterigmatocystin].

A total of 142 samples of vegetable foods was examined for the occurrence of sterigmatocystin. The samples examined were fruits and vegetables which had spontaneously gone mouldy or begun to rot under natural conditions on the one hand, and organoleptically impeccable fruit juices and maize specimens on the other hand. The samples were taken at the manufacturing plant or procured on the market in the framework of operative controls. Sterigmatocystin was detected in none of the samples under investigation. From this it may be concluded that the risk of its occurrence in vegetable foods is not very great in our country. Nevertheless, due to its cancerogenic and toxic properties, sterigmatocystin should remain included in the examination for mycotoxins in the framework of food control.

Fruit↗
PubMed1979

[Hygienic significance of sterigmatocystin in vegetable foods. 1. Analytical detection of sterigmatocystin].

The present paper gives a survey of the chemical, physical and biological properties of the mycotoxin sterigmatocystin. It must be regarded as toxic to warm-blooded animals and as cancerogenic. It is likely to occur in foods; therefore, its analytical detection is necessary. With reference to known confirmatory reactions, a method is described for the semi-quantitative determination of sterigmatocystin in fruit and vegetables. This method permits to detect 20 microgram/kg of food by means of thin-layer chromatography, after column-chromatographic purification on silica gel. The identity is confirmed by derivatization to the semi-acetal by treatment with trifluoro-acetic anhydride. The method is suited especially for the routine control of foods.

Animals↗
PubMed1992

Solution structure of the covalent sterigmatocystin-DNA adduct.

Sterigmatocystin and aflatoxin are potent mutagens that contaminate foodstuffs stored under conditions that permit fungal growth. These food mycotoxins can be metabolically activated to their epoxides, which subsequently form covalent adducts with DNA and can eventually induce tumor development. We have generated the sterigmatocystin-d(A1-A2-T3-G4-C5-A6-T7-T8) covalent adduct (two sterigmatocystins per duplex) by reacting sterigmatocystin-1,2-epoxide with the self-complementary d(A-A-T-G-C-A-T-T) duplex and determined its solution structure by the combined application of two-dimensional NMR experiments and molecular dynamics calculations. The self-complementary duplex retains its 2-fold symmetry following covalent adduct formation of sterigmatocystin at the N7 position of G4 residues on each strand of the duplex. The H8 proton of [ST]G4 exchanges rapidly with water and resonates at 9.58 ppm due to the presence of the positive charge on the guanine ring following adduct formation. We have assigned the exchangeable and nonexchangeable proton resonances of sterigmatocystin and the duplex in the covalent adduct and identified the intermolecular proton-proton NOEs that define the orientation and mode of binding of the mutagen to duplex DNA. The analysis was aided by intermolecular NOEs between the sterigmatocystin protons with both the major groove and minor groove protons of the DNA. The molecular dynamics calculations were aided by 180 intramolecular nucleic acid constraints, 16 intramolecular sterigmatocystin constraints, and 56 intermolecular distance constraints between sterigmatocystin and the nucleic acid protons in the adduct. The sterigmatocystin chromophore intercalates between the [ST]G4.C5 and T3.A6 base pairs and stacks predominantly over the modified guanine ring in the adduct duplex. The overall conformation of the DNA remains right-handed on adduct formation with unwinding of the helix, as well as widening of the minor groove. Parallel NMR studies on the sterigmatocystin-d(A1-A2-A3-G4-C5-T6-T7-T8) covalent adduct (two sterigmatocystins per duplex) provide supportive evidence that the mutagen covalently adducts the N7 position of G4 and its chromophore intercalates to the 5' side of the guanine and stacks over it. The present NMR-molecular dynamics studies that define a detailed structure for the sterigmatocystin-DNA adduct support key structural conclusions proposed previously on the basis of a qualitative analysis of NMR parameters for the adduct formed by the related food mutagen aflatoxin B1 and DNA [Gopalakrishnan, S., Harris, T. M., & Stone, M. P. (1990) Biochemistry 29, 10438-10448].

Base Composition↗
PubMed1982

Chemically defined medium for high yields of sterigmatocystin.

Isolate of Aspergillus versicolor strain produced 138 micrograms/ml of sterigmatocystin in a complete synthetic medium containing sucrose, salts, 1-phenylalanine, and Ca-pantothenate. The SSP (sucrose salts phenylalanine) medium apparently provided all necessary ingredients for the production of high levels of sterigmatocystin. For optimal sterigmatocystin formation, the amounts of sucrose and 1-phenylalanine were found to be 200 g and 5 g per liter, respectively. When Ca-pantothenate (0.01 g per liter) added, much higher amounts of sterigmatocystin were recovered, whereas CaCl2 addition (0.01%) drastically reduced the yield. The high levels of sterigmatocystin were recovered in the cultures which incubated stationary at 26 to 29 degrees C for over 12 days. Seven strains or isolates tested yielded high levels of sterigmatocystin in the SSP medium, whereas in each other media such as YES medium and rich medium only one isolate yielded highest amount of sterigmatocystin was found.

Aspergillus↗
PubMed1989

Immunochemical assay applied to mycotoxin biosynthesis: ELISA comparison of sterigmatocystin production by Aspergillus versicolor and Aspergillus nidulans.

Conventional thin layer and instrumental methods for analyzing mycotoxins and their precursors are time-consuming and make the investigation of mycotoxin biosynthesis particularly difficult. As an alternative, sensitive enzyme-liked immunosorbent assays (ELISAs) can be utilized to analyze for these compounds. In this report, sterigmatocystin production in test tube cultures of Aspergillus versicolor ATCC 18643 and Aspergillus nidulans ATCC 32610 were compared using competitive ELISA. Polyclonal antiserum that was prepared against a sterigmatocystin hemiacetal-bovine serum albumin conjugate exhibited greatest specificity for sterigmatocystin hemiacetal and sterigmatocystin with less reactivity for O-methylsterigmatocystin. The antiserum could be used to detect as little as 50 ng/ml sterigmatocystin in ELISA. Direct ELISA could be performed on diluted culture broth and on mycelial extracts solubilized with N,N-dimethylformamide. Aspergillus versicolor ATCC 18643 produced more sterigmatocystin in SLS medium than in YES medium, and showed maximal levels at between 9 to 12 days incubation. Approximately 75% of sterigmatocystin was detectable in mycelium (254 micrograms/ml culture) compared to the extracellular fraction (87 micrograms/ml culture). Aspergillus nidulans exhibited qualitatively similar patterns of growth and toxigenesis in SLS medium but accumulated maximal levels of only 15 micrograms mycelial sterigmatocystin/ml culture and 5 micrograms extracellular sterigmatocystin/ml broth, respectively.

Aspergillus↗
PubMed1996

Analytical methods for the determination of sterigmatocystin in cheese, bread and corn products using HPLC with atmospheric pressure ionization mass spectrometric detection.

Methods have been developed for the determination of sterigmatocystin in bread, maize and cheese using HPLC linked to mass spectrometry (MS) atmospheric pressure chemical ionization for detection and concurrent confirmation of sterigmatocystin at levels down to less than 5 micrograms/kg. Candidate extraction methods were initially checked for recovery and reproducibility by spiking commodities at a level of 200 micrograms/kg of sterigmatocystin and using HPLC with post-column derivatization. Recovery was found to be greater than 90% for bread and maize, and 75% for cheese. Mass spectrometer conditions for detecting sterigmatocystin were established by injecting solutions directly into the mass spectrometer. Extracts of bread, maize grits and cheese prepared by the candidate extraction methods were examined using HPLC/MS using samples spiked at a level of 20 micrograms/kg of sterigmatocystin. Results for bread and maize samples showed that the extraction procedure recovered more than 90% of added sterigmatocystin and produced extracts free of interference from co-extractives, with limits of detection of less than 2 micrograms/kg for both commodities. The HPLC/MS results for cheese extracts gave lower average recoveries of 55%. These results were also more variable. However, the apparent limit of detection for sterigmatocystin in cheese was still about 4 micrograms/kg.

Bread↗
PubMed1988

Production of sterigmatocystin by Aspergillus versicolor isolated from roughage.

A total of 69 samples of hay and straw collected during the winter period of 1984/85 were surveyed for their contamination by Aspergillus versicolor. The percentage of A. versicolor-positive samples was 14.5%. Nineteen A. versicolor strains mainly isolated from roughage were tested for the production of sterigmatocystin. All of the isolates examined were capable of producing different levels of sterigmatocystin on a cracked corn substrate. The majority of these strains were highly toxigenic; 53% of the isolates produced more than 500 mg/kg of sterigmatocystin. These findings suggest that corn is a very suitable substrate for sterigmatocystin production and that particularly in the surface layers of feed stocks and corn silos such toxigenic strains of A. versicolor can produce considerable growth and possibly sterigmatocystin, too.

Animal Feed↗
PubMed1982

High incidence of angiosarcomas in brown-fat tissue and livers of mice fed sterigmatocystin.

BDF1 female mice fed 30 or 120 ppm sterigmatocystin in their diet for 55 or 51 wk, respectively, developed angiosarcomas of the liver and of the dorsal brown-fat tissue. No tumours were observed in five mice from each group, including the controls, killed after 43 wk, but angiosarcomas were observed in mice from the test groups that died or were killed after more than 43 wk of treatment with sterigmatocystin. Thirty-four out of 53 mice (64.2%) fed 30 ppm sterigmatocystin developed hepatic angiosarcomas. Six (11.3%) of those fed 30 ppm sterigmatocystin and 27 out of the 51 mice (52.9%) fed 120 ppm developed angiosarcomas in the dorsal brown-fat tissue. Benign vascular lesions in the liver and a few angiosarcomas of the ovary and lung were also observed in mice of both test groups. No vascular changes were observed in control mice except for peliosis-like lesions in the spleens of two mice. Increases in the incidences of lung and hepatocellular adenomas were also observed in sterigmatocystin-treated mice.

Adipose Tissue, Brown↗
PubMed1998

Correlation between the regulation of sterigmatocystin biosynthesis and asexual and sexual sporulation in Emericella nidulans.

We analyzed the regulation of sterigmatocystin biosynthesis in wild type and mutant strains of Emericella nidulans (= Aspergillus nidulans). A positive correlation between both asexual and sexual sporulation and synthesis of the mycotoxin was observed. Those conditions which favored sporulation stimulated sterigmatocystin formation, and vice versa. Both processes were stimulated by light in a veA+ genetic background. In contrast, they were inhibited by diaminobutanone, an inhibitor of ornithine decarboxylase. The effect of this inhibitor was partially reverted by putrescine addition. Partial supplementation of specific requirements to auxotrophic mutants allowed normal vegetative growth, but interfered with asexual sporulation and sterigmatocystin biosynthesis. Synthesis of the mycotoxin was neither affected in a brlA mutant or in developmental mutants blocked at later steps in sporulation. As in wild type strain, diaminobutanone inhibited sterigmatocystin biosynthesis and cleisthotecia formation in the brlA mutant, and its effect was reverted by addition of putrescine. The inhibitor also affected the transcription of brlA. Our results indicate that sporulation and the synthesis of sterigmatocystin are co-regulated at a step previous to the brlA execution point.

Aspergillus nidulans↗
PubMed2002

Occurrence of toxigenic Aspergillus versicolor isolates and sterigmatocystin in carpet dust from damp indoor environments.

Over the past decade, there has been growing concern regarding the role of toxigenic fungi in damp indoor environments; however, there is still a lack of field investigations on exposure to mycotoxins. The goal of our pilot study was to quantify the proportion of toxigenic Aspergillus versicolor isolates in native carpet dust from damp dwellings with mold problems and to determine whether sterigmatocystin can be detected in this matrix. Carpet dust samples (n = 11) contained from <2.5 x 10(1) to 3.6 x 10(5) (median, 3.1 x 10(4)) A. versicolor CFU/g of dust, and the median proportion of A. versicolor from total culturable fungi was 18%. Based on thin-layer chromatography detection of sterigmatocystin, 49 of 50 A. versicolor isolates (98%) were found to be toxigenic in vitro. By using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry, sterigmatocystin could be detected in low concentrations (2 to 4 ng/g of dust) in 2 of 11 native carpet dust samples. From this preliminary study, we conclude that most strains of A. versicolor isolated from carpet dust are able to produce sterigmatocystin in vitro and that sterigmatocystin may occasionally occur in carpet dust from damp indoor environments. Further research and systematic field investigation are needed to confirm our results and to provide an understanding of the health implications of mycotoxins in indoor environments.

Air Pollution, Indoor↗
PubMed1986

Induction of DNA single-strand breaks and DNA synthesis inhibition in CHO and AWRF cells after exposure to sterigmatocystin and penicillic acid.

Sterigmatocystin is 12 times more toxic to transformed rat fibroblasts (AWRF) than to Chinese hamster ovary cells (CHO). In contrast, penicillic acid is twice more toxic to CHO cells than to AWRF cells. The ability of sterigmatocystin and penicillic acid to inhibit DNA synthesis correlated well with the differences in cytotoxicity of these mycotoxins in the cell lines used. Sterigmatocystin at a concentration of 10 micrograms/ml inhibited DNA synthesis in AWRF cells during a 3-h exposure to 60% of that found in controls, but did not inhibit DNA synthesis in CHO cells. Within the same time interval penicillic acid inhibited DNA synthesis in AWRF cells at concentrations higher than 5 micrograms/ml and in CHO cells at concentrations over 0.5 microgram/ml. Induction of DNA single-strand breaks (SSB) during a 3-h exposure to sterigmatocystin and penicillic acid was comparable in both cell types. The results suggest that sterigmatocystin is metabolized to reactive metabolites that are responsible for the toxicity and DNA synthesis inhibition at a more rapid rate in AWRF cells than in CHO cells. The observed ability to induce SSB indicates that penicillic acid is potentially carcinogenic.

Aflatoxin B1↗
PubMed1978

Complement activity, serum protein, and hepatic changes in guinea pigs given sterigmatocystin or aflatoxin, alone or in combination.

Effects of either sterigmatocystin or aflatoxin, alone or in combination, given orally to guinea pigs were studied. Sterigmatocystin and aflatoxin B1 given alone and in combination at 4.2 mg/day and 0.01 mg/day, respectively, markedly reduced body weight. Although changes in total serum protein were not marked in any of the guinea pigs in this study, sterigmatocystin given alone and aflatoxin given alone significantly ( less than 0.05) decreased alpha2-globulin. The combination of toxins significantly (P less than 0.01) increased albumin and significantly (P less than 0.01) decreased both alpha2- and beta-globulins. Sterigmatocystin depressed complement activity, although not significantly. However, the combination of sterimatocystin with 0.01 mg of aflatoxin B1/day (an amount that does not affect complement activity alone) significantly (P less than 0.01) reduced complement activity. Increased severity of lesions was not found in guinea pigs given aflatoxin at 0.01 mg of B1 equivalents/day in addition to the sterigmatocystin.

Aflatoxins↗
PubMed1976

Gas-liquid chromatography and mass spectrometric ion selective detection of sterigmatocystin in grains.

A method was developed for direct gas-liquid chromatographic-mass spectrometric (GLC-MS) analysis of nonderivatized sterigmatocystin in wheat, rice, barley, and corn. Sterigmatocystin was extracted from spiked grain samples by 2 methods, both of which yielded high recoveries of 14C-labeled sterigmatocystin (greater than 90%). Extracts were cleaned up by gel permeation chromatography on polystyrene with tetrahydrofuran as the eluant. Chromatography of 14C-labeled compound indicated good recoveries (greater than 90%). The GLC-MS system was modified to give an all-glass chromatographic pathway to the ion source. Short glass or quartz columns packed with silicone liquid phase on inert supports gave the best results. Trace levels of sterigmatocystin were very labile in all gas chromatographic systems and levels below 5 ppb in grains were detected only with great difficulty. The GLC-MS system was utilized in the mass fragmentography mode, with selective ion monitoring of the m/e 295, 306, and 324 peaks. These ions were present in only trace levels in all control grain samples, indicating minimal interference from other compounds. The limit of accurate detectability (20 ng) on spiked grain samples was lower than previously reported. Lower levels of sterigmatocystin (1 ppb or 4 ng on column) could be detected in grains by using the mass fragmentography mode, but these levels could not be measured accurately.

Chromatography, Gas↗
PubMed2001

Identification of Aspergillus nidulans genes essential for the accumulation of sterigmatocystin.

The fungus Aspergillus nidulans (Emericella nidulans) was used as a genetic model for the identification of genes required for efficient accumulation of sterigmatocystin (ST). The required gene for sterigmatocystin expression was stc, which is an intermediate penultimate product in the aflatoxin biosynthetic pathway. Genetic analysis included studies of the sexual and parasexual cycles. The allelic segregation rates and recombination frequencies between linked and nonlinked genetic markers were determined by the crossing of the strains UT448 (stc) to UT196 (stc(+)) and UT448 (stc) to UT184 (stc). Low ST accumulation (4.0 ppm) in the UT196 strain and in 7.4% of the meiotic segregants allowed us to map the stc locus at chromosome I, 3.4% distant from riboA1. The diploid UT448 (stc)//UT184 (stc), prepared from nonproducing strains, was analyzed based on the parasexual cycle, and 28% of the haploid segregants accumulated the ST toxin. The results suggest that UT448 carries the stc mutant (or an inactivated) allele and that UT184, although carrying the stc(+) allele, is reactivated only by the R2(+) factor, which is located at chromosome VIII of UT448. In such a configuration, the diploid accumulates large amounts of sterigmatocystin (40 ppm). Another regulator factor (R1), located at the meth-w (II) chromosomic interval, was identified in the UT448 strain. At DNA level in chromosome I, the R1 product acts and blocks the stcZ(+) gene transcription. In a different genotypic configuration, the R1 product interacts with the R2 product (of chromosome VIII), allowing the stcZ(+) gene expression. Furthermore, the diploid UT448 (stc)//UT196 (stc(+)) accumulated the ST toxin at high level (40 ppm), indicating similar interaction between mentioned factors and the stc gene. Obtained data suggest that R1 (II) regulates the stcZ(+) transcription, by interacting with chromosome I (at the DNA level) and that R2 (VIII) controls R1 activity at the cytoplasm level. Based on these results, we propose a regulation model for the sterigmatocystin production.

Aflatoxins↗
PubMed1989

Chromatographic and spectroscopic properties of hemiacetals of aflatoxin and sterigmatocystin metabolites.

Improved fluorescence detection of aflatoxin B1 by chromatographic analysis is accomplished by conversion to the corresponding hemiacetal, aflatoxin B2a. Because the metabolites aflatoxin M1, aflatoxin P1, aflatoxin Q1, sterigmatocystin, and O-methylsterigmatocystin have the same molecular conversion site, we investigated the chromatographic and spectroscopic properties of hemiacetals of these compounds to assist in confirming aflatoxins and sterigmatocystins in human urine. Nuclear magnetic resonance and infrared absorbance were used to confirm the hemiacetal structure for aflatoxin B1 and sterigmatocystin. The ultraviolet absorbance, fluorescence, and chromatographic properties of the metabolites were investigated. Using these data, we optimized the detection and solvent conditions for high-performance liquid chromatography. We determined that, of the conditions studied, maximum sensitivity and resolution for the native aflatoxins were achieved with a mobile phase of methanol, tetrahydrofuran, and water, a C8 column in series with a C18 column, and fluorescence detection with 365 nm excitation and 430 nm emission wavelengths for aflatoxins B1 and M1 and with 500 nm emission wavelength for aflatoxins P1 and Q1. For the analysis of the hemiacetals, a mobile phase of methanol, acetonitrile, and water provided better chromatography and fluorescence detection. Sterigmatocystin and O-methylsterigmatocystin were readily converted to the hemiacetal forms, which, like the aflatoxins, were more polar and, therefore, earlier eluting by reversed-phase HPLC (methanol, acetonitrile, and water, 236 nm absorbance). These data are important to maximize the sensitivity and confidence for detecting the mycotoxin metabolites in biological specimens.

Acetals↗