Binding Of AFB1 Research Articles

Comparative Study of Binding Pockets in Human CYP1A2, CYP3A4, CYP3A5, and CYP3A7 with Aflatoxin B1, a Hepato-Carcinogen, by Molecular Dynamics Simulation & Principal Component Analysis.

Aflatoxin B1 is a harmful hepatocarcinogen which is metabolized in our body by Cytochrome P450 enzymes, namely CYP1A2, CYP3A4, CYP3A5, and CYP3A7, into toxic (exo-8, 9-epoxide) and nontoxic (AFQ1, endo-epoxide) products. We have found from the literature that due to cooperativity, the rate of metabolic reactions increases in CYP1A2 and CYP3A4 involving more than one site of proteins to form two products at a given time, whereas the interaction of CYP3A5 and CYP3A7 is still unknown. Our work aims to study these four enzymes with AFB1 based on binding site pocket characterization and to find the probable resultant products at each binding site. We used computational approaches like homology modeling, molecular docking to form mono and double ligated systems, molecular dynamic simulations to analyze the potential energies (vdW & electrostatic), PCA, RMSF, and residue-wise interactions at the active as well as allosteric sites of these four enzymes. We found that CYP1A2, CYP3A4, and CYP3A5 were more hydrophobic at the first site and may induce epoxidation reaction to form toxic products, whereas the second site would be expected to be more polar and comprising charged interactions, thus enhancing non-toxic hydroxylated products. However, in CYP3A7, the first site favors hydroxylation, whereas the second site is involved in higher hydrophobic interactions. Thus, in the fetus where AFB1 is metabolized only by CYP3A7, a lower concentration of toxic metabolites will be expected, while in adults exhibiting CYP1A2, CYP3A4 and CYP3A5 may increase the concentration of the toxic metabolites due to the combined effect of these enzymes, consequently increasing liver toxicity. We believe that AFB1 binding characteristics will be helpful for medicinal chemists in the process of designing a new drug.

Comparison between surface hydrophobicity of heated and thermosonicated cells to detoxify aflatoxin B1 by co-culture Lactobacillus plantarum and Lactobacillus rhamnosus in sourdough: Modeling studies

The capacity and stability binding of aflatoxin B1 under various temperature and time conditions of dough proofing were evaluated. Single and co-culture Lactobacillus plantarum ATCC 8014 and Lactobacillus rhamnosus ATCC 7469 were inoculated in various modes, mainly viable, heat-, and ultrasound-inactivated along with the combination of viable + heat- or ultrasound-inactivated cells. The highest AFB1 adsorption in order was thermosonication- treated Lb. plantarum + Lb. rhamnosus (8.042 μg kg−1) > heat treated Lb. plantarum + Lb. rhamnosus (6.90 μg kg−1) > live Lb. plantarum + Lb. rhamnosus (5.533 μg kg−1) after 24 h incubation at 37 °C. Regarding to circular dichroism spectra results, α-helix and β-turn of LAB cells showed highly increasing pattern in thermosonicated LAB (22.1% and 25.8%) compared to live (16.8% and 23.7%) and heated (21.3% and 24.2%) cells, respectively. The surface hydrophobicity (%) increased from 37.7 to 45.1% for viable LAB to 67.2–80.5% and 54.5–65.9% following inactivation by thermosonication and heating, respectively. The results obtained by AFB1 binding stability on cell surfaces displayed that in ultrasound-treated bacteria, 18.3–33.3% of the bounded AFB1 was released from the cells, which is significantly lower than heat-treated cells (31.1–46.5%) and viable cells (49.9–64.8%).

Interference of anthocyanin extracted from black soybean coats on aflatoxin B1-human serum albumin in the binding process

ABSTRACT The effect of the anthocyanin cyanidin-3-O-glucoside (C3G) and its main gastrointestinal metabolites (PCA and PGA) on the binding of AFB1 and HSA were studied via spectrometry. C3G is relatively stable in the gastric environment, and the intestinal environment promotes its metabolism into PCA and PGA. Binary fluorescence experiments showed that both AFB1 and C3G, including PCA and PGA, can react with HSA. AFB1, C3G and PCA can bind at site I and site II of HSA; PGA binds at site II. The presence of C3G/PCA/PGA inhibits the degree of quenching. C3G/PCA does not change the quenching mechanism; it is still static quenching; however, dynamic quenching occurs in the (AFB1-HSA)-PGA system. In addition, the apparent binding constant and number of binding sites of AFB1-HSA also diminish to different degrees. C3G and its metabolites (PCA and PGA) interfere with the interaction between AFB1 and HSA, and can reduce AFB1 transport at pH 7.4 in vitro. Abbreviations: C3G: cyanidin-3-O-glucoside; M: metabolite; PCA: protocatechuic acid; PGA: phloroglucinol aldehyde; AFB1: aflatoxin B1; HSA: human serum albumin.

A Lateral Flow Strip Based on a Truncated Aptamer-Complementary Strand for Detection of Type-B Aflatoxins in Nuts and Dried Figs.

Type-B aflatoxins (AFB1 and AFB2) frequently contaminate food, especially nuts and fried figs, and seriously threaten human health; hence, it is necessary for the newly rapid and sensitive detection methods to prevent the consumption of potentially contaminated food. Here, a lateral flow aptasensor for the detection of type-B aflatoxins was developed. It is based on the use of fluorescent dye Cy5 as a label for the aptamer, and on the competition between type-B aflatoxins and the complementary DNA of the aptamer. This is the first time that the complementary strand of the aptamer has been used as the test line (T-line) to detect type-B aflatoxins. In addition, the truncated aptamer was used to improve the affinity with type-B aflatoxins in our study. Therefore, the lengths of aptamer and cDNA probe were optimized as key parameters for higher sensitivity. In addition, binding buffer and organic solvent were investigated. The results showed that the best pair for achieving improved sensitivity and accuracy in detecting AFB1 was formed by a shorter aptamer (32 bases) coupled with the probe complementary to the AFB1 binding region of the aptamer. Under the optimal experimental conditions, the test strip showed an excellent linear relationship in the range from 0.2 to 20 ng/mL with a limit of detection of 0.16 ng/mL. This aptamer-based strip was successfully applied to the determination of type-B aflatoxins in spiked and commercial peanuts, almonds, and dried figs, and the recoveries of the spiked samples were from 93.3%−112.0%. The aptamer-complementary strand-based lateral flow test strip is a potential alternative tool for the rapid and sensitive detection of type-B aflatoxins in nuts and dried figs. It is of help for monitoring aflatoxins to avoid the consumption of unsafe food.

Preparation and characterization of yeast cell wall beta-glucan encapsulated humic acid nanoparticles as an enhanced aflatoxin B1 binder

This study aimed to assess the effect of encapsulating humic acid inside yeast cell walls (YCW) to detoxify AFB1 in in vitro gastrointestinal models. Glucan Mannan Lipid Particles (GMLPs) from Saccharomyces cerevisiae cell walls showed the highest AFB1 adsorption in simulated gastric fluid (SGF) after 10 min, and in simulated intestinal fluid (SIF) after 1 h. GMLPs are hollow 3–4 micron porous microspheres that provide an efficient system for the synthesis and encapsulation of AFB1-absorbing nanoparticles (NPs). Humic acid nanoparticles (HA-NPs) were synthesized within the GMLP cavity by complexation with ferric chloride. Encapsulating HA-NPs in GMLPs increased HA-NP stability in SIF. The hybrid GMLP HA-NP formulation synergistically enhanced AFB1 binding compared to individual GMLP and HA components in SGF and in SIF. Cytotoxicity on a murine macrophage cell line demonstrated that GMLP HA-NP-AFB1 complexes were stable in both SGF and SIF, detoxified AFB1 and are suitable for in vivo testing.

A simple fluorescent aptamer based assay coupled with fluorescence scanning capillary array for aflatoxin B1.

We developed a simple aptamer fluorescence assay for aflatoxin B1 (AFB1) detection by using an array of capillaries. The 34-nt aptamer having a single fluorescein (FAM) label on the 24th T nucleotide generated a remarkable fluorescence increase upon AFB1 binding. The use of fluorescence scanning capillary array allowed for the analysis of multiple samples with low sample consumption, showing advantages of simplicity, rapidity and high throughput analysis. The detection limit of AFB1 reached 0.5 nM. This assay has great potential for analysis in food safety and environmental monitoring.

Calcium montmorillonite clay reduces AFB1 and FB1 biomarkers in rats exposed to single and co‐exposures of aflatoxin and fumonisin

Aflatoxins (AFs) and fumonisins (FBs) can co-contaminate foodstuffs and have been associated with hepatocellular and esophageal carcinomas in humans at high risk for exposure. One strategy to reduce exposure (and toxicity) from contaminated foodstuffs is the dietary inclusion of a montmorillonite clay (UPSN) that binds AFs and FBs in the gastrointestinal tract. In this study, the binding capacity of UPSN was evaluated for AFB1, FB1 and a combination thereof in Fischer 344 rats. Rats were pre-treated with different dietary levels of UPSN (0.25% or 2%) for 1 week. Rats were gavaged with a single dose of either 0.125 mg AFB1 or 25 mg FB1 per kg body weight and a combination thereof in the presence and absence of an aqueous solution of UPSN. The kinetics of mycotoxin excretion were monitored by analyzing serum AFB1 -albumin, urinary AF (AFM1) and FB1 biomarkers over a period of 72 h. UPSN decreased AFM1 excretion by 88-97%, indicating highly effective binding. FB1 excretion was reduced, to a lesser extent, ranging from 45% to 85%. When in combination, both AFB1 and FB1 binding occurred, but capacity was decreased by almost half. In the absence of UPSN, the combined AFB1 and FB1 treatment decreased the urinary biomarkers by 67% and 45% respectively, but increased levels of AFB1 -albumin, presumably by modulating its cytochrome metabolism. UPSN significantly reduced bioavailability of both AFB1 and FB1 when in combination; suggesting that it can be utilized to reduce levels below their respective thresholds for affecting adverse biological effects.

Assessing the ability of Saccharomyces cerevisiae to bind aflatoxin B1 from contaminated medium

PurposeThis study was conducted with the aim of examining the ability of Saccharomyces cerevisiae to remove AFB1 from liquid media in order to use data in food and feed systems.Design/methodology/approachThe binding of AFB1 to Saccharomyces cerevisiae in the late exponential and early stationary phases was studied for viable, heat killed and acid killed yeast. AFB1 at concentrations (5, 10 and 20 μg/l) was added to the yeast culture (109 cfu/ml) in yeast mold broth medium and incubated at 25°C for 4, 12 and 24 hrs. The aflatoxin binding capacity of the strain was quantified by the amount of unbound AFB1 using ELISA technique.FindingsThe detoxification rate for different treatments reported as follows: acid treated cells > heat treated cells > viable cells. Also, the most reduction in AFB1 concentration happened within the first four hours of incubation with no significant increase in AFB1 binding on further incubation because of saturation of active sites in yeast cells. According to the results, either form of Saccharomyces cerevisiae (viable or nonviable) is effective in aflatoxin binding from medium and the binding has a physical nature.Social implicationsThe findings reduce the public concern about aflatoxin B1 contamination in foods and feeds having high risk of aflatoxin contamination.Originality/valueNo research had been done to assess the ability of Saccharomyces cerevisiae in the mentioned forms to detoxify AFB1.

Saccharomyces cerevisiae strains retain their viability and aflatoxin B1 binding ability under gastrointestinal conditions and improve ruminal fermentation

The aim was to evaluate both the ability of yeast strains to survive and bind AFB1 under ruminant gastrointestinal conditions and the effect of these yeast strains on ruminal fermentation. Yeast viability was studied under simulated gastrointestinal conditions. AFB1 binding ability was evaluated at different pH values as present in the ruminant gastrointestinal tract. The effect of yeast strains on cellulose digestion and volatile fatty acids production by ruminal bacteria was also evaluated. All yeast strains were able to survive under gastrointestinal conditions and to adsorb AFB1 at the different pH assayed. The strain RC016 showed the highest binding percentage at the three tested pH. The number of cellulolytic bacteria in ruminal fluid increased in the presence of RC008 and RC016 yeast strains. The concentration of acetate and propionate after ruminal fermentation increased with the addition of RC008 and RC016 strains; this effect was less significant with RC009 strain. Strains RC008 and RC016 are potential probiotic to be included in animal feed: they help to increase fibber digestibility and could reduce AFB1 bioavailability in the gastrointestinal tract. Viable S. cerevisiae RC008 and RC016 strains with both probiotic and mycotoxins adsorption properties could be used as feed additives in ruminant feedstuff.

Screening of Lactobacillus casei strains for their ability to bind aflatoxin B1

It has been proposed that the consumption of lactic acid bacteria capable of binding or degrading foodborne carcinogens would reduce human exposure to these deleterious compounds. In the present study, the ability of eight strains of Lactobacillus casei to bind aflatoxin B1 in aqueous solution was investigated. Additionally, the effect of addition of bile salts to the growth medium on aflatoxin B1 binding was assessed. The eight strains tested were obtained from different ecological niches (cheese, corn silage, human feces, fermented beverage). The strains exhibited different degrees of aflatoxin binding; the strain with the highest AFB1 binding was L. casei L30, which bound 49.2% of the available aflatoxin (4.6μg/mL). In general, the human isolates bound the most aflatoxin B1 and the cheese isolates the least. Stability of the bacterial–aflatoxin complex was assessed by repeated washings. Binding was to a limited degree (0.6–9.2% release) reversible; the L. casei 7R1–aflatoxin B1 complex exhibited the greatest stability. L. casei L30, a human isolate, was the strain least sensitive to the inhibitory effects of bile salts. Exposure of the bacterial cells to bile significant increased aflatoxin B1 binding and the differences between the strains was reduced.

An in vitro Investigation of Aflatoxin B1 Biological Control by Lactobacillus plantarum

This study assessed the binding of Aflatoxin B1 (AFBI) from contaminated solution by Lactobacillus plantarum PTCC 1058. This strain and AFB1 was incubated (1, 24, 48, 90 h at 37 degrees C) and the amount of unbound AFB1 was quantities by HPLC. The concentration of AFB1 in solution was 0.5 ppm. The stabilities of the bacteria/AFB1 complexes were evaluated by determining the amount of AFB1 remaining bound following three washes. Effect of Incubation time on AFB1 Binding on viable and dead cells were evaluated at 1, 24, 48, 72 and 90 h time points. In 1 h 45% and in 90 h 100% AFB1 was removed from solution by this strain. Autoclaved bacteria didn't remove AFB1 from solutions efficiently (31% in 1 h and 15% in 24 h). Bacteria in logarithmic growth phase retained 92% of the AFB1 initially bound after three washes. Bacterial binding of AFB1 by this strain was rapid and they were in logarithmic growth phase. These findings further support the ability of specific strains of lactic acid bacteria to bind selected dietary contaminants.

In vitro inhibition of human P450 enzymes by prenylated flavonoids from hops, Humulus lupulus

1. Several unique flavonoid compounds have recently been isolated from hops, Humulus lupulus, and their presence has been detected in beer. Their chemical structures are similar to other plant-derived compounds, many present in the human diet, that have been shown to have cancer chemopreventive properties due, in part, to inhibition of cytochrome P450 enzymes that activate carcinogens. Additionally, preliminary studies have shown these flavonoids (at 100 muM) to be inhibitory of P450-mediated activation reactions in a variety of in vitro systems. Thus, the in vitro effects of these phytochemicals on cDNA-expressed human CYP1A1, CYP1B1, CYP1A2, CYP3A4 and CYP2E1 were currently examined by the use of diagnostic substrates and the carcinogen AFB1. 2. At 10 muM, the prenylated chalcone, xanthohumol (XN), almost completely inhibited the 7-ethoxyresorufin O-deethylase (EROD) activity of CYP1A1. At the same concentration, other hop flavonoids decreased the EROD activity by 90.8-27.0%. 3. At 10 muM, XN completely eliminated CYP1B1 EROD activity, whereas the other hop flavonoids showed varying degrees of inhibitory action ranging from 99.3 to 1.8%. 4. In contrast, the most effective inhibitors of CYP1A2 acetanilide 4-hydroxylase activitywere the two prenylated flavonoids, 8-prenylnaringenin (8PN) and isoxanthohumol (IX), which produced > 90% inhibition when added at concentrations of 10 mu M. 5. CYP1A2 metabolism of the carcinogen AFB1 was also inhibited by IX and 8PN as shown by decreased appearance of dihydrodiols and AFM1 as analysed by hplc. IX and 8PN also decreased covalent binding of radiolabelled AFB1 to microsomal protein in a concomitant manner. 6. XN, IX and 8PN, however, were poor inhibitors of CYP2E1 and CYP3A4 as measured by their effect on chorzoxazone hydroxylase and nifedipine oxidase activities respectively. 7. These results suggest that the hop flavonoids are potent and selective inhibitors of human cytochrome P450 and warrant further in vivo investigations.

Mechanism of biochemical action of substituted 4-methylbenzopyran-2-ones. Part II: Mechanism-based inhibition of rat liver microsome-mediated aflatoxin B1–DNA binding by the candidate antimutagen 7,8-diacetoxy-4-methylcoumarin

7,8-Diacetoxy-4-methylcoumarin (DAMC), with no prerequisite for oxidative biotransformation has been reported to produce suicide inactivation of microsomal cytochrome P-450-catalysed formation of aflatoxin B1-8,9-oxide that binds to DNA. Parenteral administration of DAMC to rats caused significant inhibition of AFB1 binding to hepatic DNA in vivo as well as AFB1-induced micronuclei formation in bone marrow cells. These results highlight the antimutagenic potential of DAMC.

Bioactivation of aflatoxin B1 in the nasal and tracheal mucosa in swine.

Whole-body autoradiography of 3H-labeled aflatoxin B1 in young pigs showed a localization of bound label in the nasal olfactory and respiratory mucosa, in the tracheo-laryngeal mucosa, and in the conjunctiva, in addition to the liver. Whole-body and microautoradiography also showed a labeling of pigmented tissues, which can be ascribed to a melanin binding of AFB1. In vitro experiments with microsomal preparations of various tissues from sows revealed that the nasal respiratory and olfactory mucosa had the highest capacity to form DNA-bound aflatoxin B1-metabolites. The tracheal mucosa and the liver, in order, had lesser binding capacity. The lung was found to be devoid of aflatoxin B1-bioactivating capacity. In vitro microautoradiography revealed bound label in specific cell types in the nose and trachea and in some cells of the conjunctiva. A drastic decrease in the aflatoxin B1-DNA binding was observed when microsomal preparations of the nasal respiratory and olfactory mucosa were incubated in the presence of reduced glutathione, but without any addition of cytosolic glutathione-S-transferases. In incubations of liver microsomes under these conditions a somewhat lower inhibition of the aflatoxin B1-DNA binding was seen. Our results demonstrate that the nasal olfactory and respiratory mucosa and the tracheal mucosa have a higher capacity than the liver to bioactivate aflatoxin B1 in swine. Our data further show that microsomal-associated glutathione-S-transferases with a high capacity to catalyze the conjugation of the reactive aflatoxin B1-epoxide to reduced glutathione are present in the nasal olfactory and respiratory mucosa of swine.

Anti‐idiotype and anti‐anti‐idiotype antibodies generated from polyclonal antibodies against aflatoxin b1

Polyclonal anti‐idiotype antibodies (anti‐id, pAb2) for aflatoxin were generated from mice ascites after immunization with affinity‐purified rabbit polyclonal antibody (pAbl) against aflatoxin B1 (pAFB1). After affinity chromatography purification, pAb2 were subjected to various analyses, and were used to generate anti‐anti‐id antibodies (pAb3) in the ascites of Balb/c mice. ELISA analyses revealed that the anti‐id antibodies bound specifically to the original pAb1, but not to other types of monoclonal antibodies or normal mouse IgG. The inhibition of binding of AFB1 to pAb1 by pAb2 was demonstrated in both regular and biotin‐avidin amplified enzyme‐linked immunosorbent assay (ELISA) systems in which AFB1‐bovine serum albumin (BSA) was coated on to the microtiter plate. The concentrations causing 50% inhibition (ID50) of the binding of pAbl to AFB1‐BSA by pAb2 were found to be 6.5 and 1.7 μg/assay respectively. Inhibition of the binding of pAb1 to the solid‐phase pAb2 by free AFB1 (ID50 = 0.63 μ/assay) wa...

HMG-CoA reductase inhibitor and cholestyramine induce hepatic LDL receptor and are effective for lowering plasma cholesterol in homozygous Watanabe heritable hyperlipidemic rabbits

Male Fisher 344 rats were fed diets containing either 20% corn oil, 20% coconut oil or 18% cocomnut oil plus 2% corn oil for 3 wk. A single dose of [3H]aflatoxin B1 ([3H]AFB1) was administered ip and the biliary excretion of afflatoxin metabolites and the binding of 3H to nucleic acids were studied. In other experiments the in vitro metabolism of AFB1 by liver postmitochondrol supernatants prepared from rats fed the different sources of dietry fat was determined. The major nonextractable aqueous metabolite of AFB1 was the aflatoxin B1-glutathione conjugate (AFB1-GSH). Variation in the source of dietry fat did not affect production of the conjugate, nor was in vivo binding of AFB1 to nucleic acids affected. Aflatoxin P1 (AFP1)—mostly conjugated—and aflatoxin M1 (AFM1) were also identified in the bile, and the quantities of these metabolites produced were unaffected by the dietary treatments. The metabolites recovered in the in vitro study included aflatoxins Q1, P1 and M1. The corn oil diet produced a higher microsomal cytochrome P-450 level than the coconut oil diet. Associated with the higher level of cytochrome P-450 was increased in vitro coversion of AFB1 and AFM1, but not ot AFP1. The in vitro production of aqueous metabolites and the covalent binding of metabolites to protein was unaffected by the dietary treatments. The results of the in vivo studies suggest that the formation of the putative carcinogenic metabolite, AFB1-epoxide, which undergoes detoxification through glutathione conjugation, is not affected by the type of dietary fat. These observations further suggest that dietary fat, in particular unsaturated fat, affects AFB1 carcinogenisis through a mechanism other than by alteration of the metabolic activaqtion of AFB1.

Absence of p53 mutation at codon 249 in duck hepatocellular carcinomas from the high incidence area of Qidong (China).

Dietary aflatoxin and hepatitis B virus infection may play a role in generating the p53 tumor suppressor gene codon 249 hotspot mutation found in human hepatocellular carcinomas (HCCs) from Qidong (China) and southern Africa. No data are available on the HCC site-specific mutation of the p53 gene in hepadnavirus-infected animals exposed to AFB1. We have searched for the presence of p53 gene codon 249 mutations in both duck hepatitis B virus (DHBV) positive and negative HCCs of domestic ducks from Qidong, where the human p53 hotspot is so prevalent, as well as in duck HCCs experimentally induced by AFB1. Direct sequencing of DNA amplification products encompassing p53 codon 249 did not reveal any mutations in 11 HCCs from Qidong ducks, regardless of the status of DHBV infection. In addition no mutation was detected in four HCCs from AFB1-treated ducks. This contrasts with the human data; however, in humans, the mutation and the preferential binding of AFB1 to codon 249 occurs at the third nucleotide G, while in duck, the codon 249 lacks this G residue. The DNA sequence of adjacent codons is also different in the two species even though the amino acid sequence is identical. This may explain the low frequency of mutation we have observed. In addition, species differences in metabolism and DNA repair could influence the occurrence of codon 249 mutations.

Nuclear Translocation of Aflatoxin B1-Protein Complex

The in vitro binding of [3H]-AFB1 to various proteins was studied by equilibrium dialysis. At 23 ± 1°C, [3H]-AFB1 binding activity (mmol/mol) decreased as follows: pyruvate kinase > albumin-NLS > albumin > carbonic anhydrase > RNase > histones. The nuclear translocation and activation of AFB1 and AFB-protein complexes was investigated using isolated rat liver nuclei in the presence of ATP and a NADPH regenerating system. Proteins containing NLS such as histones and albumin-NLS facilitated AFB1 translocation into the nucleus where activation and adduct formation took place.

The Structure of the Aflatoxin B1-DNA Adduct at N7 of Guanine. Theoretical Intercalation and Covalent Adduct Models

Two theoretical models are proposed for the conformational structure of both intercalated and covalent adduct complexes of aflatoxin B1, designated AFB1, with N7 of guanine of DNA. The covalent adduct model requires the DNA to kink a minimum of 39 degrees about the covalent site of the C8 and N7 atoms comprising the bond of the covalent complex. The preference of AFB1 for specific G bases within a sequence of GC content followed that of experimental studies with the added feature that for binding to the third G base of a tetramer sequence from the 3'-end, the AFB1 displayed enhanced binding at the 3' site of the targeted guanosine. Binding of AFB1 to the second G base of a tetramer sequence from the 3'-end leads to preference for a 5' site of the targeted guanosine. Inhibition of AFB1's interaction with the targeted DNA in the presence of intercalated ethidium bromide is explained by these proposed models.

Differential Effects of Phenolic Antioxidants on the Metabolism of Aflatoxin B1

AbstractAntioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are known to inhibit AFB1-DNA binding thereby protecting liver against the chronic effects of the carcinogen. It is believed that they inhibit liver mixed function oxidases while including GSH S-transferases. Both BHA and BHT are poor inducers of pulmonary GSH S-transferases. BHA pretreatment, but not BHT reduced the pulmonary microsome-mediated AFB1 binding to DNA in vitro. Therefore the influence of these antioxidants on GSH - conjugation of AFB1 is limited to liver. Inhibition of AFB1-DNA binding mediated by BHT-treated microsomes is probably due to alterations in microsomal enzymes.