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PubMed1990

Aflatoxin excretion in children with kwashiorkor or marasmic kwashiorkor--a clinical investigation.

A group of five children with kwashiorkor, seven with marasmic kwashiorkor and one underweight child were given an aflatoxin-free diet consisting of maize meal and milk powder. Blood specimens were collected on admission; on day 4 and 10, 24 hour urine and stool samples were collected for the first ten days. Serum, urine and stool samples were analysed for aflatoxins using high performance liquid chromatography with fluorescent detection, after various extraction and clean-up procedures. The children with kwashiorkor and marasmic kwashiorkor excreted aflatoxins in stools for up to 9 and 6 days after admission respectively. No aflatoxins were detected in the stools or urine of the underweight child. In kwashiorkor, urinary excretion ceased after 2 days, while in marasmic kwashiorkor urinary excretion persisted for 4 days. In stools, B1 was the type of aflatoxin detected most frequently in kwashiorkor and least frequently in marasmic kwashiorkor. Aflatoxin M2 was frequently detected in the stools of both groups of children. Estimates of the total amount of aflatoxin excreted by kwashiorkor and marasmic kwashiorkor indicate that these children were harbouring up to 4 micrograms/kg body weight at the time of admission. These findings establish that aflatoxins accumulate in body fluids and tissues in kwashiorkor and marasmic kwashiorkor which is only slowly eliminated.

Aflatoxin B1↗

PubMed1983

Effect of contamination of diets with aflatoxins on growing ducks and chickens.

Growing Alabio ducks and White Leghorn chickens were used in a growth study in which diets containing either soybean meal (SBM), peanut meal (PNM) or fish meal (FM) as protein sources were contaminated with the fungus Aspergillus flavus providing the following aflatoxin levels: 0, 50, 100 and 200 micrograms aflatoxin B1 equivalent per kg ration. There were no differences in responses of growing ducks and chickens (at age of 28 days) to the various protein sources at the zero aflatoxin level. However diets contaminated with Aspergillus flavus and containing 50 micrograms/kg aflatoxin B1 equivalent or more significantly reduced body weight gain and utilisation of dietary protein in ducks as compared with chickens. The higher the aflatoxin content above 50 micrograms/kg the greater was the difference in performance between ducks and chickens. Dietary aflatoxins caused liver damage in ducks while no damage was recorded in chickens. Ducks fed diets containing SBM or PNM were more affected by the same concentration of aflatoxins than those fed diets with FM. When intensification of duck husbandry is envisaged, particularly in humid tropical regions, measures to avoid the deleterious ill effects of aflatoxins are needed.

Aflatoxin B1↗

PubMed1983

Activation and deactivation of aflatoxin B1 in isolated rat hepatocytes.

Isolated rat hepatocytes took up [3H]-aflatoxin B1 during incubation with fifty percent of the aflatoxin B1 covalantly bound to cellular macromolecules. The amount of bound-aflatoxin B1 was proportional to the medium concentration of aflatoxin B1. The specific radioactivity (pmole/mg) of aflatoxin B1 found in the DNA fraction was 20 fold greater than that associated with protein. Metyrapone (0.75 mM) inhibited significantly the uptake and binding whereas 1,2-epoxy-3,3,3-trichloropropane (0.5 mM) enhanced 2-3 fold both the uptake and binding. Glutathione (0.25 mM) reduced these processes. Results indicate that a transformation of aflatoxin B1 is catalyzed by cytochrome P-450 mixed function oxidase and aflatoxin B1-2,3-epoxide so formed is primarily deactivated by epoxide hydrolase. In the isolated hepatocyte depletion of the epoxide by glutathione apparently has an insignificant role in aflatoxin detoxication.

Aflatoxin B1↗

PubMed1996

Postcolumn excitation of aflatoxins using cyclodextrins in liquid chromatography for food analysis.

Measurement of fluorescence increase was used for the comparative quantification of the effect that several cyclodextrins (alpha-, beta-, heptakis-2,6-beta-omicron-dimethyl- and gamma-) produce on the fluorescent response of aflatoxins B1 and G1. This constitutes a new chromatographic method with stability of the mobile phase, and shows general improvements in the chromatographic conditions with respect to other methods (especially those using an iodine reservoir as a postcolumn reactor). A C18-type column was used, with methanol-water (60:40, v/v) as the mobile phase. The excitation phase of the natural fluorescence of aflatoxins, a 10(-2) M solution of each cyclodextrin, was introduced postcolumn. The determination of the elution order aflatoxin G2 > G1 > B2 > B1 was performed for each phase in less than 15 min. As expected using an aqueous-alcoholic medium, an increase in the fluorescence response of aflatoxins with an unsaturated furanic ring was found to occur with all the cyclodextrins studied, except gamma-cyclodextrin. The observed increase was larger for heptakis-2,6-beta-omicron-dimethyl- than for beta-cyclodextrin (to our knowledge, the only cyclodextrin previously described in the literature to serve for the determination of aflatoxins). The difference is of the order of 70.1-fold in the case of aflatoxin G1 and 45.2-fold in the case of aflatoxin B1. The detection limit in the mobile phase used was determined (for aflatoxin B1) for beta-cyclodextrin and 2,6-beta-omicron-dimethylcyclodextrin (signal-to-noise ratio 1:3) to be 4 and 9 mg 1(-1), respectively.

Aflatoxin B1↗

PubMed1983

The neurotoxicity of aflatoxin B1 in the rat.

The effects of repeated intraperitoneal administration of aflatoxin B1 on the peripheral and central nervous systems of rats were investigated. Biochemical markers of neurotoxicity were monitored in nervous tissues following aflatoxin B1 dosage and after the cessation of aflatoxin B1 administration. Aflatoxin B1 increased the activities of beta-glucuronidase and beta-galactosidase in the central and peripheral nervous systems. Repeated exposure of rats to aflatoxin B1 also activated Na+ K+-ATPase and inhibited Mg2+-ATPase. Nervous tissue levels of DNA and total protein increased while the concentrations of RNA and phospholipid were depressed by aflatoxin B1. The alterations in these parameters were specific for each of the tissues examined during the recovery of the rats. The findings indicate that the repeated administration of aflatoxin B1 to rats results in degeneration in the central and peripheral nervous systems that may be related to the overt toxicity observed following aflatoxin administration.

Adenosine Triphosphatases↗

PubMed2001

Chlorophyllin intervention reduces aflatoxin-DNA adducts in individuals at high risk for liver cancer.

Residents of Qidong, People's Republic of China, are at high risk for development of hepatocellular carcinoma, in part from consumption of foods contaminated with aflatoxins. Chlorophyllin, a mixture of semisynthetic, water-soluble derivatives of chlorophyll that is used as a food colorant and over-the-counter medicine, has been shown to be an effective inhibitor of aflatoxin hepatocarcinogenesis in animal models by blocking carcinogen bioavailability. In a randomized, double-blind, placebo-controlled chemoprevention trial, we tested whether chlorophyllin could alter the disposition of aflatoxin. One hundred and eighty healthy adults from Qidong were randomly assigned to ingest 100 mg of chlorophyllin or a placebo three times a day for 4 months. The primary endpoint was modulation of levels of aflatoxin-N(7)-guanine adducts in urine samples collected 3 months into the intervention measured by using sequential immunoaffinity chromatography and liquid chromatography-electrospray mass spectrometry. This aflatoxin-DNA adduct excretion product serves as a biomarker of the biologically effective dose of aflatoxin, and elevated levels are associated with increased risk of liver cancer. Adherence to the study protocol was outstanding, and no adverse events were reported. Aflatoxin-N(7)-guanine could be detected in 105 of 169 available samples. Chlorophyllin consumption at each meal led to an overall 55% reduction (P = 0.036) in median urinary levels of this aflatoxin biomarker compared with those taking placebo. Thus, prophylactic interventions with chlorophyllin or supplementation of diets with foods rich in chlorophylls may represent practical means to prevent the development of hepatocellular carcinoma or other environmentally induced cancers.

Adult↗

PubMed2001

Co-occurrence of aflatoxins B1, B2, G1, G2, zearalenone and fumonisin B1 in Brazilian corn.

Two hundred and fourteen unprocessed corn samples (1997-98 harvest), collected at wholesale markets in different regions in Brazil, were surveyed for the occurrence of mycotoxins. The samples were analysed for aflatoxins B1, B2, G1, G2, zearalenone and fumonisin B1 using in-house validated methods. The occurrence of aflatoxin B1, zearalenone and fumonisin B1 was found in 38.3, 30.4 and 99.1% of the samples, respectively. Aflatoxin B1, zearalenone and fumonisin B1 contamination levels varied from 0.2 to 129, 36.8 to 719, and 200 to 6100 microg/kg, respectively. The co-occurrence of the two carcinogenic mycotoxins aflatoxin B1 and fumonisin B1 was observed in 100% of the aflatoxin-contaminated samples (82 samples). Co-occurrences of aflatoxin B1: zearalenone: fumonisin B1 and aflatoxin B1: aflatoxin B2: fumonisin B1 were found in 18 and 43 samples, respectively.

Aflatoxin B1↗

PubMed2003

Occurrence of aflatoxins M(1) and M(2) in milk commercialized in Ribeirão Preto-SP, Brazil.

Aflatoxins are toxic metabolites found in foods and feeds. When ruminants eat foodstuffs containing aflatoxins B(1) and B(2), these toxins are metabolized and excreted as aflatoxin M(1) and M(2) in milk. The aim was to determine the incidence of these aflatoxins in commercial milk collected from supermarkets in Ribeirão Preto-SP, Brazil, and consisting of 60 ultrahigh temperature (UHT) milk samples and 79 pasteurized milk samples. The milk samples were analysed according to method 986.16 of AOAC International. None of the milk samples analysed were contaminated with aflatoxin M(2), and aflatoxin M(1) was detected in 29 (20.9%) of samples in the range 50-240 ng l(-1). The results show that despite a high occurrence of aflatoxin M(1) in commercial pasteurized and UHT milk sold in Ribeirão Preto in 1999 and 2000, the contamination level of these toxins could not be considered a serious public health problem according to MERCOSUR Technical Regulations. However, levels in 20.9% of the milk samples exceeded the concentration of 50 ng l(-1) permitted by the European Union. Although it is not necessary to continue monitoring the incidence and levels of aflatoxins M(1) and M(2) in milk samples, surveillance could be appropriate.

Aflatoxin M1↗

PubMed2006

Aflatoxins in ginseng roots.

Ginseng roots can be infected by molds during growth, harvest and storage and result in contamination with mycotoxins. In this study, an analytical method for the determination of aflatoxins B(1), B(2), G(1) and G(2), a group of structurally similar mycotoxins, in ginseng root was developed. Test samples were extracted with methanol-water (8?+?2), diluted and passed through an immunoaffinity column packed with antibodies specific for aflatoxins. The purified extract was then derivatized with a mixture of water, trifluoroacetic acid and acetic acid. Aflatoxins were then separated and quantified by reverse phase liquid chromatography (LC) with fluorescence detection. Recoveries of total aflatoxins at 2, 4, 8 and 16 ng/g added to toxin-free 4 to 5-year old dried sliced Wisconsin ginseng were 92, 77, 91 and 83% respectively; and relative standard deviations were 3.6, 8.0, 6.9 and 2.0% respectively. A total of 11 wild simulated and 12 cultivated ginseng root samples were analysed for aflatoxins. All cultivated roots were found to be free of aflatoxin contamination. Two of the wild simulated roots contained total aflatoxins B(1), B(2), G(1) and G(2) at 15.1 and 15.2 ng/g. One moldy ginseng root purchased from a grocery store was found to be contaminated with aflatoxins at 16 ng/g.

Aflatoxin B1↗

PubMedDate not supplied

A survey of aflatoxins in peanut butters, nuts and nut confectionery products by HPLC with fluorescence detection.

A preliminary survey in 1982 of aflatoxin levels in peanut butters indicated that 31 out of 32 samples of major national brand-named products examined contained less than 10 micrograms/kg aflatoxin B1 and that 59% of these were below the limit of detection (2 micrograms/kg). In contrast, of 25 peanut butters from specialist 'Health Food' outlets, 64% contained less than 10 micrograms/kg aflatoxin B1, the remainder ranging from 16 to 318 micrograms/kg, with one sample having a total aflatoxin concentration of 345 micrograms/kg. Subsequent surveys in 1983 and 1984 of 'Health Food' products confirmed that these manufacturers were still experiencing some difficulty in complying with the 30 micrograms/kg total aflatoxin voluntary guideline limit. A further survey in 1984 was carried out of 228 retail samples of nuts and nut confectionery products comprising peanuts (shelled, unshelled, roasted and salted), mixed nuts, almonds (both unblanched and ground), brazils (in shell), hazelnuts (in shell), chocolate-coated peanuts, peanut brittle and coconut ice. The results showed that 74% of the samples contained less than 0.5 microgram/kg of aflatoxin B1 with 3.1% exceeding the guideline tolerance of 30 micrograms/kg total aflatoxins, these being predominantly peanuts and brazils. The highest total levels of aflatoxins observed were in unshelled peanuts containing 4920 micrograms/kg and in a composite sample of visibly moulded brazils containing 17 926 micrograms/kg.

Aflatoxin B1↗

PubMed1992

Aflatoxin M1 in human breast milk from The Gambia, west Africa, quantified by combined monoclonal antibody immunoaffinity chromatography and HPLC.

Maternal to child exposure of aflatoxin M1 in breast milk is an underevaluated risk factor from dietary exposure to aflatoxin B1. A molecular dosimetry study in The Gambia, West Africa, was initiated to explore the relationships between dietary intake of aflatoxins during a 1 week period and a number of aflatoxin biomarkers including aflatoxin metabolite excretion into breast milk. For the breast milk study, five lactating women were identified and milk samples were collected by hand expression once a day during days 3-7 for three women and during days 3-6 for the two other women. Aflatoxin M1 (AFM1) in human milk was measured in all five subjects by a preparative monoclonal antibody immunoaffinity column/HPLC method. In three of the five women, aflatoxin G1 was found. Estimates of the percentage of aflatoxin in the diet excreted as AFM1 in milk ranged from 0.09 to 0.43%. Thus, these data indicate that a rapid methodology exists to assess the levels of AFM1 excretion in human milk and to use this approach as a biomarker for exposure of children to this carcinogen.

Aflatoxin M1↗

PubMed2004

Emericella astellata, a new producer of aflatoxin B, B and sterigmatocystin.

AIMS: To report on aflatoxin B(1) and B(2) production from a species of Emericella. METHODS AND RESULTS: Aflatoxins and sterigmatocystin were determined by high-pressure liquid chromatography (HPLC) with diode array detection and confirmed by HPLC with mass spectrometry detection. Among 30 known species of Emericella only one species produced aflatoxin. Strains originating from the same geographical source material had different patterns of aflatoxin and sterigmatocystin production on different media, indicating that epigenetic factors may be involved in the regulation of aflatoxin production. However, two cultures from the same original genet were very similar. CONCLUSIONS: Emericella astellata can produce small amounts of sterigmatocystin and aflatoxin B(1) and B(2). SIGNIFICANCE AND IMPACT OF THE STUDY: Emericella has been used extensively in genetic studies and therefore the isolates producing aflatoxin can be used to elucidate the genetic, evolutionary and maybe ecological role of aflatoxins using molecular genetic methods.

Aflatoxin B1↗

PubMed1989

[The effect of aflatoxins on growth in pigs and the biological value of the meat].

Twelve pigs were subjected to model trials to study the effect of an aflatoxin-contaminated pig-fattening diet, administered for 26 days. Aflatoxin B1 constituted 55% of the aflatoxins tested. The aflatoxin concentrations used in the trials were 30 and 300 micrograms per 1 kg of feed. No clinical effect of aflatoxin was observed in the pigs. Aflatoxins were found to have adverse effects on proteosynthesis. A decrease in the weight gains of the pigs was accompanied by a decrease in the total plasma protein and, in the group with the higher aflatoxin dose (300 micrograms per 1 kg of feed), also by an increase in the total bilirubin concentration in the blood serum. Perilobular steatosis, dissociation of the liver trabeculae, and more pronounced activation of the reticuloendothelial system were demonstrated by the histological examination of liver tissue. An increase in the content of hydroxyproline was recorded in the muscle of the experimental pigs. It is documented by the results that the aflatoxin dose of 30 micrograms per 1 kg of feed (the recommended maximum admissible concentration for the Czech Socialist Republic) is high enough to reduce the performance of pigs and the biological value of their meat.

Aflatoxin B1↗

PubMedDate not supplied

Evaluation of enzyme-linked immunosorbent assay of cleanup for thin-layer chromatography of aflatoxin B1 in corn, peanuts, and peanut butter.

A simple, rapid enzyme-linked immunoassay (ELISA) was used to evaluate the performance of each step (extraction, filtration, solvent partition, and silica gel column chromatography) of a solvent-efficient thin-layer chromatographic (TLC) method which is undergoing interlaboratory collaborative study for the determination of aflatoxin B1 in corn, raw peanuts, and peanut butter. The apparent average recoveries using the ELISA method were about 30 to 50% higher than those using the TLC method if only the amount of B1 added to the samples was used in the calculations. After the cross-reaction of the antibody with other aflatoxins added to the samples was considered, the amounts recovered approached the levels of aflatoxins added in all 3 commodities tested. With no cleanup treatment, ELISA recoveries at aflatoxin B1 levels above 7.5 ng/g were 84, 79, and 103% for corn, raw peanuts, and peanut butter, respectively. The coefficients of variation were between 5.2 and 25.2%. With each cleanup step in the TLC method, ELISA detected a progressive decrease in recovery from 150.5 to 105.3% (before correction for the presence of other aflatoxins) or from 93.5 to 65.4% (after correction for other aflatoxins) of B1 added to the samples. The ELISA data support the conclusion obtained from previous studies that cleanup treatments were not necessary in the ELISA. When large amounts of other aflatoxins are present, an understanding of the cross-reactivity of antibody with other aflatoxins in the ELISA is essential for final interpretation of the data.

Aflatoxin B1↗

PubMed1981

Studies on the mechanism of aflatoxin B1 inhibition of rat liver nucleolar RNA synthesis.

In an earlier report, it was shown that aflatoxin B1 treatment strongly inhibits rat liver nucleolar RNA synthesis (Yu, F. L. (1977) J. Biol. Chem. 252, 3245-3251). The present paper is an attempt to elucidate the mechanism of this inhibition. Two h after aflatoxin B1 injection (0.3 mg/100 g body weight), rat liver nucleolar RNA synthesis, in vitro, was inhibited by an average of 90%. This inhibition could result from (a) inhibited RNA polymerase I activity per se, (b) impaired nucleolar DNA template, or (c) impaired nucleolar chromatin. Earlier studies found that the total RNA polymerase I activity was not affected by aflatoxin B1 treatment. In the present work the total nucleolar DNAs from control and from aflatoxin B1-treated groups were isolated and compared for template efficiencies in directing RNA synthesis with solubilized RNA polymerase I from the control group. No difference was found. However, when nucleolar chromatin function was analyzed, it was found that aflatoxin B1 treatment resulted in a dramatic reduction in the RNA chain elongation rate to only 13% of the control. The chain number, which is a measure of the number of engaged enzymes transcribing the nucleolar chromatin initiated in vivo, was only slightly reduced (33%). Furthermore since it was found that aflatoxin B1 treatment did not increase RNase activity in the treated nucleoli, the dramatic decrease in RNA chain elongation is therefore believed to be the major mechanism of aflatoxin B1 inhibition of rat liver nucleolar RNA synthesis. DNase I digestion of the nucleolar chromatin suggests that aflatoxin B1 treatment may have altered the conformation of the transcriptionally active regions of the nucleolar chromatin.

Aflatoxin B1↗

PubMed2002

Thermal stabilization of the DNA duplex by adducts of aflatoxin B1.

The trans-8,9-dihydro-8-(N7-guanyl)-9-hydroxyaflatoxin B(1) cationic guanine N7 adduct of aflatoxin B(1) thermally stabilizes the DNA duplex, as reflected in increased T(m) values upon adduction. The magnitude of the increased T(m) value is characteristically 2-3 degrees C. The major rotamer of the neutral guanine N7 adduct trans-8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxy aflatoxin B(1) (the FAPY major adduct) exhibits a 15 degrees C increase in T(m) in 5'-d(CTAT(FAPY)GATTCA)-3'-5'-d(TGAATCATAG)-3'. Site-specific mutagenesis experiments reveal the FAPY major adduct induces G-->T mutations in Escherichia coli at a frequency six times higher than that of the cationic adduct (Smela, M. E.; Hamm, M. L.; Henderson, P. T.; Harris, C. M.; Harris, T. M.; Essigmann, J. M. Proc Natl Acad Sci USA, 99, 6655-6660). Thus, the FAPY major lesion may account substantially for the genotoxicity of AFB(1). Structural studies for cationic and FAPY adducts of aflatoxin B(1) suggest both adducts intercalate above the 5'-face of the modified deoxyguanosine and that in each instance the aflatoxin moiety spans the DNA helix. Intercalation of the aflatoxin moiety, accompanied by favorable stacking with the neighboring base pairs, is thought to account for the increased thermal stability of the aflatoxin cationic guanine N7 and the FAPY major adducts. However, the structural basis for the large increase in thermal stability of the FAPY major adduct in comparison to the cationic guanine N7 adduct of aflatoxin B(1) is not well understood. In light of the site-specific mutagenesis studies, it is of considerable interest. For both adducts, the intercalation structures are similar, although improved stacking with neighboring base pairs is observed for the FAPY major adduct. In addition, the presence of the formamido group in the aflatoxin B(1) FAPY major adduct may enhance duplex stability, perhaps via intrastrand sequence-specific hydrogen bonding interactions within the duplex.

Aflatoxin B1↗

PubMed1988

Aflatoxin contamination of groundnuts in Sudan.

Groundnut samples, collected soon after harvest, from different districts in the irrigated region (Central Sudan) were free from aflatoxins with the method used. Samples collected from the rainfed region (Western Sudan) showed variable levels of aflatoxin ranging from 100% sample contamination in El Hamdi to only 10% in Casgeal. Damaged pods were highly contaminated with A. flavus and accumulated large amounts of aflatoxins. However, sound intact pods, recorded lower fungal contamination and were almost free of aflatoxins. Groundnut products collected from Khartoum North (Bahri) have higher levels of aflatoxins than those collected from Khartoum and Umdorman. Gray and red roasted pods showed higher amounts of aflatoxins, while the groundnut past was the least contaminated. None of the three varieties of groundnuts tested in this work was completely resistant to aflatoxin production. A temperature of 30 degrees C and 86.3% relative humidy (RH) are the optimum conditions for both A. flavus growth and aflatoxin production in groundnuts.

Aflatoxins↗

PubMed1977

Production of aflatoxin by Aspergillus parasiticus NRRL-2999 during growth in the presence of curing salts.

Aspergillus parasiticus NRRL-2999 was inoculated into meat mixtures with curing salts and into yeast extractsucrose (YES) and sucrose-ammonium salts (SAS) broth with and without curing salts to determine if the presence of curing salts significantly affected growth and aflatoxin production by the mold. The effect of individual curing salts or curing salt mixtures on growth and toxin elaboration by the aspergillus was substrate dependent. When YES broth contained 100 ppm of NaNO2, 2% NaCl, or 1 or 2% NaCl plus 200 ppm of NaNO2 or 200 ppm of NaNO3, growth and/or aflatoxin production was depressed. Biosynthesis of aflatoxin B1 was enhanced by presence of 1 and 4% NaCl in YES broth. The SAS broth containing only NaCl or NaCl combined with nitrite or nitrate yielded less aflatoxin than did control broth or no aflatoxin at all. When compared to the control, an increase in growth and amount of aflatoxin occurred in SAS broth which contained 200 ppm of NaNO3. Sausages containing 100 and 200 ppm NaNO2 and no NaCl supported more mold growth and aflatoxin production than did control sausage with 3% NaCl and 100 ppm of NaNO2. Addition of 2 and 3% NaCl and no nitrite to sausage resulted in less aflatoxin than in control sausage.

Aflatoxins↗