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 ?
Obviously the decline in sales was a result of the requirement for an aflatoxin certificate for Kenyan tea, which has so far been removed," said an official from the directorate.
Pulsed light treatment on a conventional conveyor for 240 seconds at a 5-cm distance reduced aflatoxin levels by 55%.
Kenya Agricultural and Livestock Research Organisation director general Eliud Kireger said an aflatoxin outbreak could also occur in Machakos, lower Meru and parts of North Rift, where temperatures are above 25 degrees Celsius.
At Mars, we test raw materials for aflatoxin to en- sure that our products are safe.
In developed countries, laws limit the partsper-billion (ppb) of aflatoxins allowed in food for humans, livestock and pets.
Table-3: Qualitative analytical of Aflatoxin in fruits and vegetables samples by TLC (Sahar et al.
The most potent toxin is aflatoxin B1 produced by Aspergillus flavus (Abousadi et al.
Aflatoxin is a mycotoxin produced by fungi of Aspergillus species, it is of an important concern in the poultry industry and public health because of serious major economic losses and health problems[1], aflatoxin contaminated poultry diets reduced the poultry efficiency either through poor body performance or through sequels of aflatoxin [2, 3].
Since that time progress has been made in Kenya, including increasing investment and building new partnerships in research and technology to facilitate aflatoxin control measures.