aflatoxin

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Related to Aflatoxin b1: Ochratoxin A, Aspergillus flavus, Aflatoxin m1

Aflatoxin

Any of a group of secondary metabolites produced by the common molds Aspergillus flavus and A. parasiticus that cause a toxic response in vertebrates when introduced in low concentration by a natural route. The group constitutes a type of mycotoxin. The naturally occurring aflatoxins are identified in physicochemical assays as intensely blue (aflatoxins B1 and B2) or blue-green (aflatoxins G1 and G2) fluorescent compounds under long-wave ultraviolet light. The common structural feature of the four major aflatoxins is a dihydrodifurano or tetrahydrodifurano group fused to a substituted coumarin group (see illustration). The relative proportions of the four major aflatoxins synthesized by Aspergillus reflect the genetic constitution of the producing strain and the parameters associated with fungal growth. In addition, derivative aflatoxins are produced as metabolic or environmental products. See Toxin

Structures of major naturally occurring aflatoxinsenlarge picture
Structures of major naturally occurring aflatoxins

Aflatoxins are formed through a polyketide pathway involving a series of enzymatically catalyzed reactions. In laboratory cultures, aflatoxins are biosynthesized after active growth has ceased, as is typical for secondary metabolites. By using blocked mutants and metabolic inhibitors, many of the intermediates have been identified as brightly colored anthraquinones.

Aflatoxins are potent molecules with many biological effects. They are toxigenic, carcinogenic, mutagenic, and teratogenic in various animal species. Aflatoxin B1 is usually the most abundant naturally occurring member of the family, and most studies on the pharmacological activity of aflatoxin have been conducted with this congener. Aflatoxin B1 is the most potent hepatocarcinogenic agent known, although the liver by no means is the only organ susceptible to aflatoxin carcinogenesis. Aflatoxin is listed as a probable human carcinogen by the International Agency for Research on Cancer. See Plant pathology

Aflatoxins are a major agricultural problem. Contamination can occur in the field, during harvest, or in storage and processing. Corn, rice, cottonseed, and peanuts are the major crops regularly displaying high levels of aflatoxin contamination. Since A. flavus and A. parasiticus are nearly ubiquitous in the natural environment, numerous other grain, legume, nut, and spice crops, as well as coffee and cocoa, have been reported to contain aflatoxins. Given the potential of aflatoxins as human carcinogens and their known activity as toxins in animal feeds, many international regulatory agencies monitor aflatoxin levels in susceptible crops. Prevention is the main line of defense against aflatoxins entering the food chain. Moisture, temperature, and composition of the substrate are the chief factors affecting fungal growth and toxin production. In the field, insect damage is often involved. Detoxification is a last line of defense. Several commercially feasible methods of ammoniation have been developed for reducing levels of aflatoxin contamination in animal feeds. See Agronomy, Mycotoxin

aflatoxin

[‚af·lə′täk·sin]
(biochemistry)
The toxin produced by some strains of the fungus Aspergillus flavus, the most potent carcinogen yet discovered.
References in periodicals archive ?
Effect of three different anti-mycotoxin additives on broiler chickens exposed to aflatoxin B1. Arch.
In vitro investigation of individual and combined cytotoxic effects of aflatoxin B1 and other selected mycotoxins on the cell line porcine kidney 15.
Ahokas, "Surface Binding of Aflatoxin B1 by Lactic Acid Bacteria," Applied and Environmental Microbiology, vol.
Khan, "Electrochemical immunosensor based on poly(3,4-ethylenedioxythiophene) modified with gold nanoparticle to detect aflatoxin B1," Materials Science and Engineering: C, vol.
Aflatoxicosis and herbal detoxification: the effectiveness of thyme essence on performance parameters and antibody titers of commercial broilers fed aflatoxin B1. Research in Zoology, 4(2): 43-50.
Dzantiev, "Use of gold nanoparticle-labeled secondary antibodies to improve the sensitivity of an immunochromatographic assay for aflatoxin B1," Microchimica Acta, vol.
Meki, A.R., et al., Caspase-3 and heat shock protein-70 in rat liver treated with aflatoxin B1: effect of melatonin.
Aflatoxin B1 was detected in 33 feed samples out of 40 thus with a percent contamination rate of 83%.
Aflatoxin B1 alters the expression of p53 in cytochrome P450-expressing human lung cells.
Ochratoxin A reduces aflatoxin B1 induced DNA damage detected by the comet assay in Hep G2 cells.