aflatoxin


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Related to aflatoxin: Aflatoxin b1

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 ?
Aflatoxin is carcinogenic and may be present in grains and animal feeds.
The FDA said aflatoxin is a by-product of molds that could grow on peanuts if they are not properly dried, causing them to rot.
5 billion people worldwide are exposed to aflatoxin at unsafe levels, and chronic exposure has been linked to liver damage and related cancers; but its role in the spread of infectious disease could make it even more deadly.
When macrophages were exposed to aflatoxin B1 and B2, followed by bacterial stimulation, they produced very high levels of IL-6 and low levels of IL-10 compared with controls.
Conditions increasing the likelihood of acute aflatoxicosis in humans include limited availability of food, environmental conditions that favor fungal development in crops and commodities, and lack of regulatory systems for aflatoxin monitoring and control.
But Agriculture Minister Michalis Polynikis was yesterday forced to admit that aflatoxin had been found in milk from two cattle farms in Kiti - one of which is the main dairy producer and supplier in Cyprus -- after it was revealed by Phileleftheros newspaper.
Effect of graded levels of aflatoxin and their combination on the performance and immune response of broilers.
A man surnamed Gong from the Guangzhou Administration of Industry and Commerce General Office confirmed Monday that aflatoxin was found in five batches of Nanshan Bywise formula sold in Guangzhou.
Exploiting this rivalry, called "biocompetitive exclusion," offers an effective way to diminish aflatoxin levels in both soil and corn kernels, says Abbas, who coauthored a 2011 Crop Protection paper with Accinelli and his colleagues at UB's Department of Agro-Environmental Science and Technology in Bologna, Italy.
flavus, along with detectable levels of aflatoxin, was attained
We guarantee that all of our products are free from Sudan 1 and we are now successfully pioneering the reduction of pesticides and aflatoxins to levels below detection.
SCIENTISTS at the USA's Agricultural Research Service (ARS) have discovered a way to keep the cancer-causing compound aflatoxin at bay from nuts, such as almonds and pistachios.