[14C]Aflatoxin B1 as an indicator of toxin destruction during ammoniation of contaminated peanut meal

Lee, Louise S.; Conkerton, E. J.; Ory, Robert L.; Bennett, Joan W.

doi:10.1021/jf60223a047

Cited by 16 publications

(14 citation statements)

References 8 publications

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“…AFD 1 was shown to possess mutagenic properties, although to a lesser extent than the parent compound (Schroeder et al 1985). In the case of decontaminated feedstuOE s, however, these compounds appear to represent at best only a very minor fraction of the degraded a¯atoxin B 1 and most compounds appear to be bound to feed components (Lee and Cucullu 1978, Lee et al 1979, Grove et al 1984, Park 1984, Schroeder et al 1985, Martinez et al 1994. Toxicological studies with trout and rats con® rm the decreased toxicity of the decontaminated products but in general lack the sensitivity to prove the safety of the products (Brekke et al 1977, Norred and Morrisey 1983, Frayssinet and LafargeFrayssinet 1990, Bailey et al 1994.…”

Section: Introductionmentioning

confidence: 99%

Genotoxicity testing of extracts from aflatoxin-contaminated peanut meal, following chemical decontamination

Hoogenboom

Polman

Neal

et al. 2001

Food Add. Contaminants

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One of the most important concerns in the decontamination of aflatoxin-containing feed commodities is the safety of the products for food-producing animals and for human consumption of products derived from these animals. A new method, based on the use of florisil and C18 solid phase extraction columns, was developed for the preparation of extracts from decontaminated peanut meal, which allowed testing with in vitro genotoxicity assays without interference of the residual aflatoxin B1. Recovery of degradation products in the extracts was evaluated by the use of radiolabelled [14C]-aflatoxin B1 (AFB1) added to naturally-contaminated peanut meal (3.5 mg AFB1/kg). The meal was treated by a small-scale version of an industrial decontamination process based on ammoniation. Following decontamination, more than 90% of the label could not be extracted from the meal. AFB1 accounted for about 10% of the radiolabel present in the extractable fraction, indicating a total AFB1 reduction of more than 99%. Decontamination of the meal by a number of other small- and industrial-scale ammonia-based processes resulted in similar efficiencies. Application of the extraction procedure resulted in AFB1-rich and AFB1-poor fractions, the latter containing half of the extractable decontamination products but less than 1% of the residual AFB1. Testing in the Salmonella/microsome mutagenicity assay (TA 100, with S9-mix) of the original crude extracts and AFB1-rich fractions prepared from non-treated and decontaminated meal, showed the positive results expected from the AFB1 contents as determined by HPLC analysis. Analysis and testing of the AFB1-poor fractions showed that the various decontamination processes not only resulted in a successful degradation of AFB1 but also did not produce other potent mutagenic compounds. Slight positive results obtained with these extracts were similar for the untreated and treated meals and may be due to unknown compounds originally present in the meal. Results obtained with an unscheduled DNA synthesis (UDS) and Comet assay with rat hepatocytes supported this conclusion. Positive results obtained with the micronucleus assay, using immortalized mouse hepatocytes (GKB), did not clearly reflect the mycotoxin levels and require further examination. It is concluded that the newly developed extraction procedure yields highly reproducible fractions and hence is very suitable for examining the possible formation of less potent degradation products of aflatoxins in short-term genotoxicity tests.

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Section: Introductionmentioning

confidence: 99%

Genotoxicity testing of extracts from aflatoxin-contaminated peanut meal, following chemical decontamination

Hoogenboom

Polman

Neal

et al. 2001

Food Add. Contaminants

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“…Presumably the breakdown products of the a¯atoxins could be irreversibly bound to constituents present in the matrix of this meal. Previous studies have indicated the binding of AFB 1derived materials to the matrix as a consequence of detoxi® cation by ammoniation (Lee et al 1979, Schroeder et al 1985. This hypothesis has further been supported by the results of bovine feeding trials using this decontaminated meal (Hoogenboom et al submitted).…”

Section: Discussionmentioning

confidence: 53%

Differences detected in vivo between samples of aflatoxincontaminated peanut meal, following decontamination by two ammonia-based processes

Neal

Judah

Carthew

et al. 2001

Food Additives and Contaminants

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A sample of peanut meal, highly contaminated with aflatoxins, has been subjected to decontamination by two commercial ammonia-based processes. The original contaminated and the two decontaminated meals were fed to rats for 90 days. No lesions associated with aflatoxin-induced hepatocarcinogenesis were detected histologically following feeding with the two detoxified meals. There were, however, clear differences between the two meals in respect of growth rates of the rats. In addition, feeding one of the detoxified meals resulted in hepatic abnormalities detected using novel immunohistochemical reagents. Differences between the two detoxified meals were also indicated by the results of studies using meals 'spiked' with [14C]-aflatoxin B1 prior to being subjected to the detoxification processes. The meals differed in the bioavailability of the label. It was concluded that peanut meal where an initial, unacceptable level of contamination with aflatoxins had been reduced by two ammonia-based processes to comparable, acceptable levels, may still have different effects in vivo when incorporated into animal diets.

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“…28 Aflatoxin is produced by Aspergilli and is one of the most potent human carcinogens known. [29][30][31][32] In 2012, a fungal meningitis outbreak caused by contaminated steroid injections occurred in the United States and claimed 63 lives of over 750 cases reported at the time of writing (http://www.cdc.gov/hai/outbreaks/meningitis-map-lare.html). The index case in this epidemic was caused by A. fumigatus.…”

Section: Introductionmentioning

confidence: 99%

Crystal structures of the fungal pathogen Aspergillus fumigatus protein farnesyltransferase complexed with substrates and inhibitors reveal features for antifungal drug design

et al. 2014

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Species of the fungal genus Aspergillus are significant human and agricultural pathogens that are often refractory to existing antifungal treatments. Protein farnesyltransferase (FTase), a critical enzyme in eukaryotes, is an attractive potential target for antifungal drug discovery. We report high-resolution structures of A. fumigatus FTase (AfFTase) in complex with substrates and inhibitors. Comparison of structures with farnesyldiphosphate (FPP) bound in the absence or presence of peptide substrate, corresponding to successive steps in ordered substrate binding, revealed that the second substrate-binding step is accompanied by motions of a loop in the catalytic site. Re-examination of other FTase structures showed that this motion is conserved. The substrate-and product-binding clefts in the AfFTase active site are wider than in human FTase (hFTase). Widening is a consequence of small shifts in the a-helices that comprise the majority of the FTase structure, which in turn arise from sequence variation in the hydrophobic core of the protein. These structural effects are key features that distinguish fungal FTases from hFTase. Their variation results in differences in steady-state enzyme kinetics and inhibitor interactions and presents opportunities for developing selective anti-fungal drugs by exploiting size differences in the active sites. We illustrate the latter by comparing the interaction of ED5 and Tipifarnib with hFTase and AfFTase. In AfFTase, the wider groove enables ED5 to bind in the presence of FPP, whereas in hFTase it binds only in the absence of substrate. Tipifarnib binds similarly to both enzymes but makes less extensive contacts in AfFTase with consequently weaker binding.

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[14C]Aflatoxin B1 as an indicator of toxin destruction during ammoniation of contaminated peanut meal

Cited by 16 publications

References 8 publications

Genotoxicity testing of extracts from aflatoxin-contaminated peanut meal, following chemical decontamination

Genotoxicity testing of extracts from aflatoxin-contaminated peanut meal, following chemical decontamination

Differences detected in vivo between samples of aflatoxincontaminated peanut meal, following decontamination by two ammonia-based processes

Crystal structures of the fungal pathogen Aspergillus fumigatus protein farnesyltransferase complexed with substrates and inhibitors reveal features for antifungal drug design

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