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PubMed1984

Effects of butylated hydroxytoluene pretreatment on the metabolism and genotoxicity of aflatoxin B1 in primary cultures of adult rat hepatocytes: selective reduction of nucleic acid binding.

To elucidate biochemical mechanisms underlying the anticarcinogenic activity of butylated hydroxytoluene (BHT), studies were undertaken to characterize the influence of BHT pretreatment on the metabolism and genotoxicity of aflatoxin B1 (AFB1) in primary cultures of rat hepatocytes. During a 10-day pretreatment period, adult male rats were fed either a control diet or a diet supplemented with 0.5% BHT. Hepatocytes were subsequently isolated from each animal and cultured in chemically defined medium. Cultures prepared from rats which had been fed BHT metabolized AFB1 more rapidly than did controls. BHT pretreatment also enhanced oxidation of AFB1 to aflatoxin M1 (AFM1), and accelerated the rate of AFM1 conjugation. Covalent binding to DNA and RNA in BHT-pretreated cultures was reduced by 91 and 82%, respectively, while protein binding decreased by only 29%. AFB1 did not stimulate detectable DNA repair synthesis in BHT-pretreated cultures, although stimulation of DNA repair was clearly evident in control cultures. In a separate experiment, consistently higher baseline concentrations of reduced glutathione were observed in BHT-pretreated cells, indicating that BHT pretreatment may enhance formation of detoxified glutathione conjugates of AFB1. These findings suggest that the anticarcinogenic activity of BHT is due in part to preferential enhancement of hepatic detoxification mechanisms, with the result that intracellular concentrations of reactive metabolites are reduced and fewer covalently bound adducts are formed.

Aflatoxin B1↗
PubMed1989

In vitro metabolism of the pro-carcinogen aflatoxin B1 by liver preparations of the calf, nurse shark and clearnose skate.

1. Liver postmitochondrial supernatant preparations of calf, clearnose skate, and nurse shark were able to metabolize the fungal toxin aflatoxin B1 to various metabolites. 2. Calf liver produced aflatoxin M1 and Q1 as the major chloroform soluble metabolites, with small amounts of aflatoxicol formed during incubation. 3. Liver preparations of the elasmobranchs, however, produced aflatoxicol as the major chloroform soluble metabolite with no other metabolite being detected. 4. The water soluble metabolite profiles for the three species were also quite different with the tris diol adduct being produced to a much greater extent in calf liver preparations. 5. Aflatoxicol production by the elasmobranch liver homogenates was reversible with the skate reconverting a large amount (30%) of aflatoxicol to AFB1. The nurse shark, however, appeared to convert a portion of aflatoxicol to an unknown metabolite more polar than AFB1. 6. Calf liver DNA bound approximately 3 x more 3H-AFB1 than shark liver DNA.

Aflatoxin B1↗
PubMedDate not supplied

Identification of a novel dihydroxy metabolite of aflatoxin B1 produced in vitro and in vivo in rats and mice.

HPLC analysis of bile obtained from rats given aflatoxin B1 (AFB) demonstrates the presence of numerous polar metabolites. The glutathione conjugate derived from AFB 8,9-epoxide and the glucuronide conjugate of aflatoxin P1 (AFP) have previously been identified as the two major polar metabolites. The most polar peak present in bile from AFB-treated rats is converted to a less polar peak upon incubation with beta-glucuronidase, which has a parent ion m/e of 314 amu. Treatment of this aglycon with diazomethane produced a product which cochromatographs with aflatoxin M1 (AFM). From these data it is concluded that the most polar peak in bile from AFB-treated rats is the glucuronide conjugate of 4,9a-dihydroxyaflatoxin B1. This dihydroxy AFB metabolite was produced in vitro in mouse microsomal incubations, and time-course studies of its production suggest that it is largely formed by 9a-hydroxylation of AFP, although some may be formed by 4-O-demethylation of AFM. Direct incubation of AFP and AFM with mouse microsomes confirmed that this metabolite can be formed from both AFP and AFM. An HPLC method is described which is capable of base line resolution of this novel dihydroxyaflatoxin metabolite and eight other hydroxylated metabolites of AFB, as well as the glutathione conjugate of AFB 8,9-epoxide.

Aflatoxin B1↗
PubMed1984

Inhibition of aflatoxin B1 carcinogenesis in rainbow trout by flavone and indole compounds.

Several compounds such as flavonoids, selenium, antioxidants and retinoids reportedly reduce the induction of cancer in experimental animals, and some have been suggested to function by affecting the mixed-function oxidase (MFO) system. The following compounds: 50 and 500 p.p.m. beta-naphthoflavone (BNF), 1000 p.p.m. flavone, 1000 p.p.m. of a tangeretin - nobilitin mixture, 1000 p.p.m. beta- ionone , 1000 p.p.m. indole-3-carbinol ( I3C ) and 2000 p.p.m. quercetin were examined for protection against aflatoxin B1 (AFB1) hepatocarcinogenesis, induction of the MFO system and metabolism of AFB1 in rainbow trout. These compounds were fed to fingerling rainbow trout for 8 weeks. At that time the activity of several MFO enzymes and cytochrome P450 content were measured and the trout were exposed for 2 weeks to 20 p.p.b. AFB1 in the same diets. After feeding the test diets without AFB1 for another 6 weeks and basal diet for another 52 weeks, the tumor incidence was determined. The effect of BNF and I3C on in vivo binding of AFB1 to DNA was also measured in separate groups of trout. BNF induced the trout MFO system in a dose-dependent manner, tangeretin - nobilitin was less effective and I3C did not induce. BNF showed significant alterations in the metabolism of AFB1 to aflatoxicol and aflatoxin M1 using cell fractions from pretreated fish. None of the other compounds, including I3C showed such an effect. Despite the apparent lack of in vitro effect of I3C , both BNF and I3C reduced AFB1 - DNA binding in vivo. I3C and BNF provided marked protection against AFB1-induced hepatocarcinogenesis, while the other compounds were less effective. The 58 weeks tumor incidences were 4% for 1000 p.p.m. I3C , 6% for 500 p.p.m. BNF and 18% for 50 p.p.m. BNF, compared to 38% for the AFB1-positive control. These data demonstrate that gross induction of the MFO system was not necessarily required for alterations in DNA adduct formation in vivo or protection against AFB1 carcinogenesis. Both BNF and I3C provided marked protection but only BNF induced the MFO system.

Aflatoxin B1↗
PubMed2004

Evaluation of xenobiotics in human milk and ingestion by the newborn--an epidemiological survey in Lombardy (Northern Italy).

BACKGROUND: Many human milk benefits have been well documented; nevertheless the newborn potential risk to the xenobiotic exposition may be relevant and it requires a biological monitoring in general prevention. Concerning this problem, attention should be paid to mycotoxins and heavy metals. AIM OF THE STUDY: Assessing the presence of the xenobiotics aflatoxins, ochratoxin A, lead and cadmium in human milk, defining their level of contamination and evaluate the potential risk for the newborn derived from this xenobiotic ingestion. METHODS: A study has been carried out on lactating women randomly selected in seven hospitals in Lombardy (Northern Italy). Two hundred and forty-seven puerparae were recruited; 231 women participated in the study. Women's milk samples on the third or fourth day after delivery were tested to determine aflatoxins and ochratoxin A levels. Lead and cadmium were determined in 143 women because supplemental milk could be taken only from these women. RESULTS: Aflatoxin B1 (11.4 ng/l) and aflatoxin M1 (194 ng/l) were found only in one sample,while ochratoxin A was detected in 198 samples (85.7 %) at an average value of 6.01 +/- 8.31 ng/l. A total of 75.7% of samples were positive for lead; the cadmium situation was better with 87.4% of the sample with values below detection limits (2 microg/l). A high percentage of babies (71 %) are exposed to mycotoxin levels on day 6 greater than the TDI value of 0.2 ng/kg b.w. Lead and cadmium presence in human milk presented risk respectively for 8% and 0.7% of newborns on the fourth day; 9.5% and 1.4% on the sixth day. CONCLUSIONS: The study points out that mycotoxins and lead are present in maternal milk, and the data confirm the need to continue biological monitoring in general prevention.

Adolescent↗
PubMed1989

Metabolism of aflatoxin B1 in the bovine olfactory mucosa.

Carcinomas of the ethmoidal region of the nose are observed relatively frequently in cattle in several countries in tropical and subtropical latitudes. Viruses have been implicated as causative agents, but it has been observed that affected animals sometimes suffer from aflatoxicosis, and a role of aflatoxin B1 (AFB1) in the aetiology has also been proposed. We have examined whether the bovine nasal olfactory mucosa has a capacity to metabolize AFB1. The contents of cytochrome P-450 and cytochrome b5, and the NADPH cytochrome c reductase activity in the nasal olfactory mucosa have also been determined. Comparative experiments have been performed with the liver. Incubations with 3H-labelled AFB1 showed that the nasal olfactory mucosa has a much higher capacity than the liver to form lipid-soluble, water-soluble and tissue-bound AFB1-metabolites. High-resolution microautoradiography showed a strong localization of tissue-bound metabolites in the sustentacular cells in the apical portion of the olfactory surface epithelium and in Bowman's glands in the olfactory lamina propria mucosae. Especially in the sustentacular cells the labelling was preferentially located in the nuclei of the cells. Liquid chromatography of chloroform extracts of the nasal olfactory mucosa and the liver incubated with 3H-AFB1 showed formation of several metabolites. The dominating peak in both tissues was aflatoxin M1 (AFM1). However, the amount of AFM1 was higher in the nasal olfactory mucosa than in the liver, and the amounts and proportions of several other metabolites also differed markedly between the two tissues. The level of cytochrome P-450 in the nasal olfactory mucosa was found to be about one quarter of that in the liver, but the NADPH cytochrome c reductase activity was much higher in the nasal olfactory mucosa than in the liver. In addition, the cytochrome b5: cytochrome P-450 ratio was higher in the nasal olfactory mucosa than in the liver. The higher metabolism of AFB1 in the nasal olfactory mucosa than in the liver may be related to differences in the cytochrome P-450 isoenzyme profile. In addition, the microsomal electron transport to cytochrome P-450 may be facilitated by the high reductase: cytochrome P-450 ratio and the high cytochrome b5: cytochrome P-450 ratio in the nasal olfactory mucosa.(ABSTRACT TRUNCATED AT 400 WORDS)

Aflatoxin B1↗
PubMed2001

Absorption, distribution and excretion of aflatoxin-derived ammoniation products in lactating cows.

Peanut meal naturally contaminated with 3.5 mg/kg aflatoxin B1 (AFB1) was spiked with radiolabelled AFB1 (meal 14C-I0) and decontaminated by a small-scale copy of an industrial ammoniation process (meal 14C-I1). During the process 15% of the radioactivity was lost, whereas 90% of the remaining radiolabel could not be extracted from the meal. In the extractable part, AFB1 accounted for 10% of the radiolabel, consistent with a total AFB1 reduction of more than 99%. No degradation products were observed in the extracts. Four lactating cows were fed with a diet containing 15% of either meal 14C-I0 or 14C-I1 for 10 days. On day 9 of this treatment, respectively 23 and 67% of the radiolabel was excreted in the urine and faeces of cows fed meal 14C-I0, as compared with 2 and 101% in the case of cows fed meal 14C-I1. Milk contained respectively 1.35 (meal 14C-I0) and 0.25% (meal 14C-I1) of the radiolabel. Milk samples taken during the equilibrium stage contained respectively 5 and 0.5 ng/ml of AFB1-derived compounds. Aflatoxin M1 (AFM1) accounted for 50-80% of these compounds in the case of milk from cows fed 14C-I0, as compared with 6-20% in the case of 14C-I1. AFB1 to AFM1 carry-over rates for 14C-I0 or 14C-I1 were estimated to be respectively 0.5 and 5.9%. Only liver and kidney samples contained detectable levels of the radiolabel, being respectively 260 and 37 micrograms/kg for cows fed meal 14C-I0, and 10 and 3 micrograms/kg for those fed meal 14C-I1. In the latter case, more than 55% of the radiolabel in the liver could not be extracted, as compared with 90% in the group fed meal 14C-I1. A small part of the extractable radiolabel in the livers of cows fed meal 14C-I0 could be attributed to AFB1 and AFM1 (less than 1% of total radioactivity). In the case of the animals fed 14C-I1 there were indications for the presence of AFB1 and AFM1 (6% of total radioactivity). Decontamination of the highly contaminated (non-radiolabelled) peanut meal by two different industrial ammoniation processes, resulted in a similar reduction of the initial AFB1 levels of 3.5 mg/kg to 15 micrograms/kg. Feeding of diets containing 15% of the non-treated and two treated peanut meals to cows for a period of 10 days, resulted in AFM1 levels in milk of respectively 2.1, 0.04 and 0.07 ng/ml. AFB1 to AFM1 carry-over rates were calculated to be respectively 0.5, 2.0, and 3.6%. It is concluded that the efficient reduction of aflatoxin levels by ammoniation of contaminated peanut meal results in a strong reduction of aflatoxin-related residues in milk and meat of cows, most likely caused by a decreased bioavailability of the degradation products.

Aflatoxins↗
PubMed1989

The effect of inducers of mixed-function oxidases on hepatic microsome-mediated aflatoxin B1 transformation in C3H/10T1/2 cells.

The potent hepatotoxin and hepatocarcinogen aflatoxin B1 (AFB1) is metabolized by different forms of cytochrome P450 associated with the hepatic mixed-function oxidase system. C3H/10T1/2(10T1/2) cells, which have limited inherent capacity to metabolize AFB1, were treated with AFB1 in the presence of hepatic microsomes isolated from chemically treated rats to investigate the effects of the induction of specific cytochromes P450 on AFB1-mediated toxicity and transformation. Relative to uninduced microsomes, phenobarbital (PB) treatment induced AFB1-DNA binding (essentially representing the formation of AFB1-8,9-oxide bound to DNA) 3.2-fold, while pretreatment with Aroclor 1254, 3-methylcholanthrene (3-MC), or 5,6-benzoflavone (beta-NF) preferentially induced aflatoxin M1 (AFM1) formation from 2- to 5-fold. 10T1/2 cells were exposed to a multiple treatment regimen with 4 microM AFB1 and hepatic microsomes from uninduced, PB-, Aroclor 1254-, 3-MC-, or beta-NF-treated rats; respective cumulative toxicities of approximately 90, 95, 70, 60, and 40% control (no microsomes) values resulted. An enhanced AFB1 transformation response correlated with the increasing toxicities observed for the different treatments, with uninduced or PB-induced microsomes yielding approximately four foci/dish, while treatments with Aroclor 1254-, 3-MC-, or beta-NF-induced microsomes resulted in only one to two foci/dish. These results demonstrate that AFB1 is a complete carcinogen in the 10T1/2 system when repetitive incubations are used in conjunction with an appropriate hepatic microsomal activation system. These data also correlate the induction of AFB1-4-hydroxylase with a decrease in AFB1-mediated toxicity and transformation of 10T1/2 cells, and support the hypothesis that the Phase I metabolic conversion of AFB1 to AFM1 in the liver represents an effective detoxification pathway per se.

Aflatoxin B1↗
PubMed1995

In vitro biotransformation of aflatoxin B1 (AFB1) in channel catfish liver.

The biotransformation of the dietary carcinogen aflatoxin B1 (AFB1) was examined in hepatic microsomal and cytosolic fractions from channel catfish, an aquatic species shown to be refractory to AFB1 toxicity and reported to be resistant to AFB1 hepatocarcinogenesis. Catfish liver microsomes catalyzed the in vitro oxidation of AFB1 to the reactive AFB1-8,9-epoxide (AFBO) at high substrate concentrations (128 microM AFB1) but not at low substrate concentrations (16 microM AFB1) which were more representative of environmental exposure. A similar trend was observed for the production of the hydroxylated metabolite aflatoxin M1 (AFM1). In contrast, hepatic microsomes prepared from rainbow trout, a species sensitive to AFB1 toxicity and hepatocarcinogenesis, activated AFB1 at 16 and 128 microM AFB1, with the rate of AFB1 epoxidation by trout microsomes exceeding that of catfish by more than sixfold. Treatment of channel catfish with 5,6-benzoflavone (beta NF, 20 mg/kg) resulted in a threefold increase in AFM1 formation but did not affect AFBO formation. AFB1 was rapidly reduced to aflatoxicol (AFL), a putative detoxification product of AFB1, at both low and high substrate concentrations. The rate of AFL production by channel catfish hepatic cytosol was 40- and 65-fold greater than observed for rainbow trout at 16 and 128 microM AFB1, respectively. Western blotting of catfish cytosols revealed the presence of a catfish cytosolic protein of approximately 25 kDa that displayed immunological cross-reactivity to rat GST Ya, but not to other rat or mouse alpha class GSTs with high AFBO-conjugating activity. Furthermore, catfish cytosolic GSTs did not catalyze the conjugation of AFBO with GSH. The results of these studies indicate that AFB1 is poorly oxidized by channel catfish microsomes, and suggest that the lack of microsomal AFB1 activation together with the rapid conversion of AFB1 to AFL contributes to the apparent resistance of channel catfish to AFB1 toxicity and hepatocarcinogenesis.

Aflatoxin B1↗
PubMed2001

Metabolism of aflatoxin B1 by normal human bronchial epithelial cells.

Aflatoxin B, (AFB1) is a potent hepatocarcinogen in animal models and a suspected carcinogen in humans. High concentrations of AFB, have been found in respirable grain dusts, and may therefore be a risk factor for human lung cancer in certain occupations. To study the potential for AFB, activation in human lung, cytochrome P-450 (CYP)-mediated activation and glutathione S-transferase (GST)-mediated detoxification of AFB1 were examined in cultured normal human bronchial epithelial (NHBE) cells. Cells were exposed to 0. 15 microM or 1.5 microM AFB, for 48 h and media was collected for metabolite analysis by high-performance liquid chromatography (HPLC). At 0. 15 microM, AFB1 was metabolized only to the detoxified metabolite aflatoxin Q1 (AFQ1). At 1.5 microM AFB1, both aflatoxin M1 (AFM1), and AFQ1 were produced. Cells pretreated with 50 degrees M 3-methylcholanthrene (3MC), a CYP 1A inducer, for 72 h prior to 0.15 microM AFB1, produced the activated AFB1 8,9-epoxide (AFBO). Similarly, microsomes prepared from 3MC-pretreated cells formed AFBO, but microsomes from noninduced cells did not. While AFB1-DNA adducts were not detected at low AFB1 concentrations in untreated NHBE, 3MC induction caused the production of AFB1-DNA adducts at 0.015 and 0.15 microM AFB1. Western immunoblots showed that the primary CYP isoforms responsible for AFB1 activation in the liver, 1A and 3A4, to be constitutively expressed in NHBE cells. Expression of CYP 1A was significantly increased in 3MC-pretreated cells, while CYP 3A4 expression increased slightly, but not to the extent of the 1A isoforms. The principal AFBO detoxifying enzyme, glutathione S-transferase (GST), was constitutively expressed in NHBE cells, and was increased approximately twofold by 3MC pretreatment. Cytosolic fractions from neither control nor 3MC-induced NHBE had measurable AFBO conjugating activity, indicating that these cells may lack AFB1-relevant GST activity. From these data, it appears that NHBE cells activate AFB1 inefficiently, but possess CYPs reportedly responsible for metabolism of AFB1. These data support earlier findings showing modest CYP-mediated AFB1 activation in human airways, but indicate that exposure to polycyclic aromatic hydrocarbons (PAHs), such as 3MC, which induce CYP(s) that specifically activate AFB1 may increase the harmful effects of AFB1 exposures in human airways.

Aflatoxin B1↗
PubMed2002

Update of survey, regulation and toxic effects of mycotoxins in Europe.

The most frequent toxigenic fungi in Europe are Aspergillus, Penicillium and Fusarium species. They produce aflatoxin B1 transformed into aflatoxin M1 found in the milk, as well as Ochratoxins and Zearalenone, Fumonisin B1, T-2 toxin, HT-2 toxin and deoxynivalenol (vomitoxin), which are of increasing concern in human health. These mycotoxins are under continuous survey in Europe, but the regulatory aspects still need to be set up and/or harmonised at European level. They are found in foodstuffs and are not destroyed by normal industrial processing or cooking since they are heat-stable. Some of their metabolites are still toxic and may be involved in human diseases. Their toxic effects (liver, kidney and hematopoetic toxicity, immune toxicity, reproduction toxicity, foetal toxicity and teratogenicity, and mainly carcinogenicity) are mostly known in experimental models, the extrapolation to humans being always inaccurate. The inaccuracy of extrapolation to humans may be explained by the lack of adequate food consumption data, lack of knowledge about relative health risks associated with specifically proposed limits and by the possibility of synergism with other mycotoxins present in the same food commodities. Other pathological causes are viral hepatitis, immune or hormonal deficiencies or organ dysfunction. Even when a specific biomarker of a given mycotoxin is identified in humans, it remains difficult to establish the relation with a given illness, because of genetic polymorphism and the possible beneficial influence of diet, and because other environmental toxicants may well interfere. The acceptable daily intake limits are mostly based on animal data and may be too high, due to the differences in the sensitivity of different animal species. The prevention involves first reduction of mycotoxin levels in foodstuffs and further increasing the intake of diet components such as vitamins, antioxidants and substances known to prevent carcinogenesis.

Aflatoxins↗
PubMed1996

The model Ah-receptor agonist beta-naphthoflavone inhibits aflatoxin B1-DNA binding in vivo in rainbow trout at dietary levels that do not induce CYP1A enzymes.

beta-Naphthoflavone (BNF), a well-known Ah-receptor agonist, has been believed to inhibit aflatoxin B1 (AFB1) carcinogenesis in rats and rainbow trout primarily through induction of the cytochrome P450 1A (CYP1A) enzyme subfamily and consequent diversion of AFB1 to the less carcinogenic phase I metabolite aflatoxin M1 (AFM1). This study investigates the dose responsive effects of dietary BNF treatment on CYP1A induction. AFM1 formation, AFB1-8,9-epoxide formation and AFB1-DNA binding in the trout model. Pre-feeding diet containing 10-200 p.p.m. BNF after AFB1 i.p. injection provided dose-dependent induction of CYP1A-dependent ethoxyresorufin-O-deethylase (EROD) activity and inhibition of in vivo AFB1-DNA binding. However, most of the observable inhibition of DNA adduction (45% inhibition) had occurred at 10 p.p.m. BNF without detectable EROD induction; higher doses of BNF up to 200 p.p.m. induced EROD > 6-fold but provided only another 15% inhibition of DNA adduction in vivo. When in vitro AFB1-DNA binding was assessed using liver microsomes from trout fed 10-100 p.p.m. BNF, induced microsomal EROD activity correlated moderately with reduction of in vitro AFB1-DNA binding activity. However, BNF treatment in a low dose range (0.2-10 p.p.m.) also strongly inhibited in vivo hepatic AFB1-DNA binding (69% inhibition at 5 p.p.m. BNF in this experiment), in a dose-dependent manner, in the complete absence of detectable EROD induction. The microsomes from 5 p.p.m. BNF-treated trout had no more EROD activity than control microsomes, and no less capacity for catalyzing AFB1-DNA binding in vitro than control microsomes. Thus, the potent inhibition of hepatic AFB1-DNA binding in vivo by 5 p.p.m. BNF was a result of neither CYP1A enzyme induction nor irreversibly reduced catalytic capacity for AFB1-8,9-epoxide formation. Direct analysis of AFB1 metabolites formed in vitro by liver microsomes from trout fed 10, 100 and 500 p.p.m. BNF showed that low dietary BNF (10 p.p.m.) neither induced microsomal CYP1A-mediated AFM1 formation nor altered AFB1-8,9-epoxide formation compared to the control. By comparison, 100 and 500 p.p.m. BNF pretreatment significantly elevated microsome-catalyzed AFM1 formation in vitro (P < 0.001), and this increase was highly correlated with increased EROD activity (r2 = 0.999, P < 0.001). Upon in vitro addition, BNF was found to be a potent inhibitor of microsome-mediated AFB1-8,9-exo-epoxide formation (IC50 = 2.6 +/- 0.1 microM) and AFB1-DNA binding (inhibition constant Ki = 3.03 +/- 0.25 microM). These findings indicate that CYP1A enzyme induction can contribute modestly to BNF protection against AFB1 in this species both in vivo and in vitro at higher BNF doses, but does not do so at lower doses. Instead, enzyme inhibition by BNF against AFB1 8,9-epoxidation appears to be the predominant protective mechanism at higher BNF doses, and the sole protective mechanism at low doses, in the rainbow trout. These findings demonstrate that mechanisms of chemoprevention can change with anticarcinogen dose, and caution that even potent induction of phase I or phase II activities does not assure that pathway to be a predominant protective mechanism in vivo.

Aflatoxin B1↗
PubMed2006

Monitoring the mycotoxins in food and their biomarkers in the Czech Republic.

Testing of the presence of toxigenic microfungi and mycotoxins in foodstuffs in the food chain is an important part of the food safety strategy in The Czech Republic. At the national level, control of their presence in the entire food chain is assured by Public Health Protection Agencies, by the Veterinary Administration and by the Czech Agriculture and Food Inspection Authority. This article summarizes surveillance activities of Public Health Protection Agencies and mycotoxins findings in dietary raw materials and foodstuffs from the 1990s to 2004 in the Czech Republic. At present, the health risk from the mycotoxins exposure from foodstuffs is assessed to be relatively low in the Czech Republic, especially as far as the foodstuffs of the Czech origin are concerned. It may result in late toxic effects (e. g., carcinogenic risk) following a single or repeated ingestion of low mycotoxins doses from foodstuffs. Nevertheless, the overall situation may change due to the globalization of the food market. In order to minimize the risk associated with mycotoxins and eliminate their impact on Czech public health, continuous monitoring of the presence of toxigenic moulds, mycotoxins, and their biomarkers is necessary, in conjunction with strict respect to European Union legislation.

Aflatoxin B1↗
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↗
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↗
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↗