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PubMed1978

This layer chromatographic determination of aflatoxin B1 in corn silage.

A procedure is described for the purification and quantitation of aflatoxin B1 in corn silage. The toxin is extracted and partially purified using parts of the AOAC minicolumn detection method. The extract is further cleaned up on a 2-step minicolumn and is then analyzed by using thin layer chromatography. Essentially all interferences are removed when the procedure is applied to moldy and non-moldy corn silage. The estimated limit of detection is 5 microgram aflatoxin B1/kg corn silage, and 73 +/- 8% of the added aflatoxin B1 (20 and 85 microgram/kg) was recovered. No aflatoxin B1 was detected in 270 samples collected from 19 silage piles in late fall 1976 and early spring 1977. This procedure also removes interferences associated with moldy corn and mixed feeds.

Aflatoxins↗

PubMed1980

Determination of aflatoxins in compound feedstuffs containing citrus pulp.

A method is described for determining aflatoxins B1, B2, G1, and G2 in compound feedstuffs containing citrus pulp. A finely ground sample is extracted with methylene chloride in a blender and cleaned with lead acetate. An aliquot of the cleaned extract is partitioned into methylene chloride and evaporated to dryness. The residue is dissolved in 0.5 mL chloroform. A 10 muL sample is applied to a thin layer chromatographic (TLC) plate and developed in 2 dimensions. Aflatoxins B1, B2, G1, and G2 are resolved and quantitated visually. The average recoveries were 96, 104, 98, and 102%, respectively. As little as 5 micrograms aflatoxin B1 or G1/kg, and 1.5 micrograms aflatoxin B2 or G1/kg can be determined by this procedure.

Aflatoxins↗

PubMed1980

Extraction, cleanup, and quantitative determination of aflatoxins in corn.

A method is proposed for extraction and cleanup of corn samples for the quantitation of 4 aflatoxins by high pressure liquid chromatography (HPLC). After aqueous methanol extraction, ammonium sulfate treatment, and partition of aflatoxins into chloroform, sample extracts are partially purified on Sep-Pak cartridges or small columns packed with HPLC grade silica; cleanup requires only 13 mL solvent/sample. Aflatoxins B1, B2, G1, and G2 in the purified extract are resolved in ca 10 min by normal phase HPLC on a microparticulate (5 mum) silica gel column with a 50% water-saturated chloroform-cyclohexane-acetonitrile-ethanol solvent, and are measured by ultraviolet fluorescence in a silica gel-packed flowcell. Recoveries of added aflatoxins B1, B2, G1, and G2 were 84-118% at levels of 1.5-125 micrograms/kg.

Aflatoxins↗

PubMed1980

Different tissue responses of mixed function oxidases and detoxifying enzymes to aflatoxin B1 administration in the rat.

The carcinogenic effects of aflatoxin B1 have been related to the formation of an active intermediate metabolite, an epoxide produced via the cytochrome P-450-mediated mixed function oxidase. The toxicity of this intermediate is dependent on metabolic transformations by enzymes such as aryl hydrocarbon hydroxylase, glutathione S-transferase and glutathione peroxidase. Like the mixed function oxygenase, these enzymes are inducible, and dependent on the action of specific drugs and inducers. The present study describes the effect of a single sublethal i.p. dose (6 mg/kg body wt) of aflatoxin B1 on the specific activities of microsomal demethylases, aryl hydrocarbon hydroxylase (AHH), glutathione S-transferase and glutathione peroxidase in rat liver, kidney, lung, brain and adrenals. The enzymes were assayed 24 h after the toxin treatment. Among the different tissues, only liver AHH showed an induction on toxin treatment whereas those of kidney and brain declined. Microsomal demethylase was also high in liver and low in kidney. However, no significant alteration was induced by aflatoxin B1 on glutathione S-transferase and glutathione peroxidase activities in the various tissues examined except the adrenals, which showed a significant increase. The present study revealed that the reaction sequence for metabolic transformation of aflatoxin B1 is more complex than foreseen from the activities of these inducible metabolite-transforming enzymes.

Aflatoxins↗

PubMed1994

Observations on aflatoxins and the liver status of Ghanaian subjects.

To find out if the presumed intake of dietary aflatoxins (AFB1 and AFG1) has adverse effect on the liver of Ghanaians, the toxins were measured in serum, urine and faecal specimens obtained from a group of apparently healthy Ghanaian adults. Liver status of the subjects was monitored with serum alphafeto protein (AFP), alpha-l-antitrypsin (AAT) and direct: total bilirubin ratio. Aflatoxin G1, AFB1 and AFQ1, AFM1 (both metabolites of AFB1) were detected in one or more of the body specimens in 35% of the subjects (AFB1+ group). Sixty-five percent (26 out of 40) of the subjects had only AFG1 in their body specimens (AFB1- group). Serum levels of AFP (greater than 20.0 ng/ml, AAT (greater than 170.0 mg/dl) and direct: total bilirubin ratio (greater than 0.5) which indicate absence of predisposition to liver cancer in all the subjects but suggestive of liver inflammation were noted in both the AFB1+ and AFB1- subjects. The pattern of distribution of the aflatoxins in the subjects suggests that the suspected liver inflammation may involve other factors and may not only be due to the present intake levels of aflatoxins.

Adult↗

PubMedDate not supplied

Incidence of aflatoxins in animal feedstuffs: a decade's scenario in India.

During the period 1983-1993, 4818 samples of agricultural commodities, comprising cereals, oilseed cakes, compound feeds, and other ingredients, were examined for aflatoxin contamination. High quantities of aflatoxins were found in groundnut cake, deoiled groundnut cake, maize, and mixed feeds. Highest incidence of aflatoxin contamination was observed in groundnut cake (96.35%) and deoiled groundnut cake (96.20%), and the highest level of aflatoxin B1, 8260 ppb, was observed in maize.

Aflatoxins↗

PubMedDate not supplied

Liquid chromatographic determination of aflatoxin M1 in milk powder using immunoaffinity columns for cleanup: interlaboratory study.

A liquid chromatographic method for determining low aflatoxin M1 concentrations in milk was evaluated in an International Dairy Federation (IDF) interlaboratory study. The study involved 16 participants from 11 countries. The method, chosen after a comparison of several methods by a preparatory group, uses an immunoaffinity column for cleanup. As the sample passes through the column, antibodies selectively bind with aflatoxin M1 (antigen) present and form an antibody-antigen complex. All other components of the sample matrix are washed off the column with water. Then, aflatoxin M1 is eluted from the column with acetonitrile, which is collected. Final determination is carried out by reversed-phase liquid chromatography with fluorescence detection. Over the tested range (80-600 ng aflatoxin M1/kg milk powder), an RSDR ranging from 11 to 23% was obtained by analyzing 24 samples (blind duplicates), 2 samples of which were blanks.

Aflatoxin M1↗

PubMedDate not supplied

Aflatoxin contamination in foods and foodstuffs in Tokyo: 1986-1990.

Aflatoxins were determined in 3054 samples of foods or foodstuffs, including cereals, nuts, beans, spices, dairy products, dry fruits, and edible oil. Samples were collected in Tokyo from 1986 to 1990. Aflatoxins were found in rice products, adlay, corn, crude sugar, peanut products, pistachio nuts, brazil nuts, sesame products, butter beans, white pepper, red pepper, paprika, nutmeg, and mixed spices. The highest incidence of aflatoxin contamination was observed in nutmeg (80%), and the highest level of aflatoxin B1 was observed in pistachio nuts (1382 ppb).

Aflatoxins↗

PubMed1977

Aflatoxins in Egyptian foodstuffs.

Six samples each of wheat, corn, lentils, beans, fenugreek, peanuts, and cottonseed cake from various areas of Egypt were analyzed for aflatoxins both at the time of collection and after 12 months' storage. Aflatoxin was found at low levels (3 to 12 ppb total aflatoxins in 14 of 42 samples, as follows: 1 sample each of corn, lentils, and beans; 2 peanut samples; 3 fenugreek samples; and 6 cottonseed cake samples. None of the samples contained aflatoxins above 11.7 ppb.

Aflatoxins↗

PubMed1977

Aflatoxin and zearalenone occurrence in dry-milled corn products.

Eighty-two corn dry-milling establishments in 20 states were surveyed concerning control practices for preventing the use of corn contaminated with aflatoxin or zearalenone. Prime products and by-products from each establishment were analyzed for these mycotoxins to determine whether a correlation exists between control practices and product contamination. No zearalenone was detected in any product; there was little awareness of the potential for contamination with this mycotoxin. No correlation was found between control practices and aflatoxin contamination encountered, but there was a positive correlation between aflatoxin contamination and the geographical source of the corn. Reported experimental findings in regard to the distribution of aflatoxin between prime product and by-product were generally corroborated.

Aflatoxins↗

PubMed1977

Aflatoxin in Tunisian aleppo pine nuts.

Twenty-six of 50 Aleppo pine nuts samples collected throughout Tunisia showed relatively high levels of contamination by aflatoxin. Some samples contained as much as 2000 ppb aflatoxin B1, and very few contained less than 100 ppb. Total aflatoxins as high as 7550 ppb were found. A traditional pudding, widely consumed in Tunisia, which was prepared from contaminated nuts still contained more than 80% of the aflatoxin originally present in the nuts.

Aflatoxins↗

PubMed1996

Immunosuppressant activity of aflatoxin ingestion in rabbits measured by response to Mycobacterium bovis antigen I. Cell mediated immune response measured by skin test reaction.

Thirty New Zealand 2-mo-old rabbits were divided into 5 groups. Groups 1 and 2 were fed 2 ppm aflatoxin B1 daily for 5 w before sensitization and continued for another 7 w. Groups 1 and 3 were infected with Bacillus of Calmette and Guerin while groups 2 and 4 were sensitized with killed cells of Mycobacterium bovis. Group 5 did not receive any treatment (control). Citrated whole blood samples were collected from all groups before treatment and at 5, 8 and 12 w during the experiment. The lymphoblastogensis assay was done presensitization and at 3 and 7 w post-sensitization for all groups. The lymphocyte stimulation indices and diameter of skin reactions were significantly reduced in the aflatoxin-treated groups (P < 0.001). In addition, 3/12 rabbits (25%) from the aflatoxin groups (groups 1 and 2) failed to produce any detectable response to the tuberculin test. Aflatoxin inhibited lymphocyte proliferation and negatively influenced the tuberculin skin test.

Administration, Oral↗

PubMedDate not supplied

Variability associated with analytical methods used to measure aflatoxin in agricultural commodities.

A total of 1019 analytical precision estimates obtained from method-performance (collaborative) studies for mycotoxins published through 1991 were sorted by type of variance measurement, type of analytical method, and type of agricultural commodity. Precision estimates for total aflatoxin were sorted into 2 precision measurements (among-laboratories and within-laboratory), 3 analytical methods (thin-layer chromatography [TLC], liquid chromatography [LC], and enzyme-linked immunosorbent assay [ELISA]), and 11 agricultural commodities. Sufficient data existed to study the analytical variability (precision) associated with 36 sorted combinations (of a possible 66). In all but one combination (within-laboratory, barley, and TLC), the variance (V) was a function of total aflatoxin concentration (C). A power function of the form V = aCb, where a and b are constants, describes the relationship between variance and aflatoxin concentration. The coefficients a and b were determined from regression analysis. When results were pooled across all agricultural commodities, LC had the lowest analytical variability while ELISA had the highest. For a given method, among-laboratories variability was approximately double the within-laboratory variability. These analytical variability estimates can be coupled with previously determined variability estimates of sampling and sample preparation to determine the performance associated with specific test procedures used to inspect agricultural commodities for aflatoxin.

Aflatoxins↗

PubMed1977

Aflatoxin in corn: evaluation of filter fluorometer reading of minicolumns.

A minicolumn method using a filter fluorometer was compared with thin layer chromatography for determining aflatoxin in corn. The minicolumn-fluorometer method identified many more samples as aflatoxin-positive than the AOAC CB method. Some corn samples contain a blue-fluorescing substance that interferes with minicolumn chromatography of aflatoxins. Aflatoxin levels measured by the minicolumn-fluorometer method did not correspond to those obtained by the CB method.

Aflatoxins↗

PubMedDate not supplied

Determination of aflatoxin B1 in pistachio kernels and shells.

A method was developed for accurate measurement of aflatoxin B1 in the edible portion of pistachio nuts. Twenty-nine samples of kernels with and without their shells were slurried with a Mega Ultra Turrax. A subsample of the homogenate was extracted with water-methanol, defatted with petroleum ether, purified with a silica solid-phase extraction column, and redissolved in methanol. After separation on an octadecyl column and postcolumn reaction with on-line electrochemically generated bromine, the aflatoxin B1 derivative was detected fluorometrically. The shells contained less than 1% of the aflatoxin B1 found in the edible kernel, and they accounted for 41.7-46.8% of the weight of the whole pistachio. These observations indicate it is possible to analyze an entire sample, up to 25 kg, as a whole and still be able to judge whether it meets the legal tolerance limit of 5 micrograms aflatoxin B1/kg edible part, as set by the Dutch Food Act.

Aflatoxin B1↗

PubMed1997

Influence of gamma rays and sodium chloride on aflatoxin production by Aspergillus flavus.

The rate of Aspergillus flavus growth and production of aflatoxin in yeast extract sucrose medium generally decreased as the concentrations of NaCl increased from 2 to 12%. Maximum production and accumulation of aflatoxin at 28 degrees C occurred after 7 days in the presence of NaCl concentrations. The number of colony forming units of A. flavus after 1.0 or 2.0 kGy irradiation was lower than in the unirradiated controls and the mould was eliminated at 3.0 kGy. Aflatoxin B1 decreased from the control level of 46 micrograms kg(-1) to 10 micrograms kg(-1) at an irradiation dose level of 2.0 kGy. Viable gamma irradiated conidia (2.0 kGy) of A. flavus showed increased sensitivity to NaCl concentrations, indicating gamma-ray injury. The levels of aflatoxin produced by 2.0 kGy irradiated conidia of A. flavus decreased in the presence of 2, 4 or 6% NaCl, and the detoxification rate was 94.1, 100 and 100%, respectively, after 21 days of incubation at 28 degrees C compared with the effect of gamma-rays or sodium chloride alone.

Aflatoxin B1↗

PubMed1976

The effect of pre-treatment with phenobarbitone on the activation of aflatoxin B1 by rat liver.

Microsomes prepared from rats pre-treated with phenobarbitone are more effective in activating aflatoxin B1 in vitro to a metabolite which inhibits RNA polymerase than are microsomes obtained from control animals. This result is in contrast with the situation in vivo where pre-treatment with phenobarbitone protects against inhibition of RNA synthesis by aflatoxin B1. The hypothesis is advanced that, in vivo, the activation of aflatoxin B1 which is significant in terms of inhibition of nucleic acid synthesis largely occurs on the outer nuclear membrane, and that by increasing activation by the microsomes, phenobarbitone pre-treatment reduces the amount of aflatoxin B1 available for the nuclear activation.

Aflatoxins↗

PubMed1982

Comparison of the ability of three Aspergillus strains to form aflatoxins on bakery products and on nutrient agar.

The growth of Aspergillus parasiticus NRRL 2999, A. parasiticus NRRL 3000 and A. flavus NRRL 3251 on whole wheat bread and on cake ('Rührkuchen') was compared and the formation of the aflatoxin B1, B2, G1, G2 and M2 on these substrates and, for purpose of comparison, on malt extract agar was determined. On cake the moulds grew better than on bread and formed the highest yields of aflatoxins. Malt extract agar was the most unfavourable substrate for toxin production. The ratio M1/B1 on bread and cake was in the order of 0.1-0.4 and was higher than the data reported for grains. The highest yields of aflatoxin B1 (1.0 micrograms/g) were produced by A. flavus NRRL 3251 on cake.

Aflatoxin B1↗