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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

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.


The toxin produced by some strains of the fungus Aspergillus flavus, the most potent carcinogen yet discovered.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Dietary aflatoxin is a potent carcinogen, and the study identifies contaminated maize meal - the main ingredient in ugali - as well as contaminated sorghum, millet, groundnuts and milk, as the most likely sources.
M2 PRESSWIRE-August 5, 2019-: Global Aflatoxins Market: Worldwide Overview By By Species Type Aspergillus Flavus and Aspergillus Parasiticus), Exposure Method (Plant Product, Animal Product, Air Media)
NAN reports that aflatoxin is poisonous carcinogens that are produced by certain moulds which grow in soil.
The substances were evaluated individually for total colony counts, hygiene indicator organisms, pathogenic organisms, and levels of aflatoxin.
"The most long-term, stable solution to controlling pre-harvest aflatoxin contamination is through enhancing the ability of the crop to resist fungal infection or prevent production of aflatoxins by the invading fungi," he says."Mouldy foods are potentially contaminated with aflatoxins and are possibly harmful when consumed.
Distribution of fungal species and aflatoxin contamination in stored maize in four agro ecological zones in Benin, West-Africa.
The widespread presences of aflatoxin [M.sub.1] in cheese may be considered to be potential hazards for human health and that is why it is also important to identify the amount of [AFM.sub.1] in various cheese (cheddar, spread and slice) available in the retail markets.
Aflatoxin is produced by a species of fungus called Aspergillus that thrives in the soil around crops grown in hot, humid environments.
Improved procedure for quantitative determination of aflatoxin in corn and wet milled corn products.
Aflatoxins are poisonous metabolites produced by Aspergillus flavus and Aspergillus parasiticus.
At Mars, we test raw materials for aflatoxin to en- sure that our products are safe.