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Encyclopedia > Aflatoxin
Chemical structure of aflatoxin B1
Chemical structure of aflatoxin B1

Aflatoxins are naturally occurring mycotoxins that are produced by many species of Aspergillus, a fungus, most notably Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are toxic and carcinogenic. After entering the body, aflatoxins are metabolized by the liver to a reactive intermediate, aflatoxin M1, an epoxide. Aflatoxin is frequently misspelled as alfatoxin. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Chemical structure refers to the spatial arrangement of atoms in a molecule and the chemical bonds that hold the atoms together. ... Mycotoxin (from Gk. ... Species Aspergillus caesiellus Aspergillus candidus Aspergillus carneus Aspergillus clavatus Aspergillus deflectus Aspergillus flavus Aspergillus fumigatus Aspergillus glaucus Aspergillus nidulans Aspergillus niger Aspergillus ochraceus Aspergillus oryzae Aspergillus parasiticus Aspergillus penicilloides Aspergillus restrictus Aspergillus sojae Aspergillus sydowi Aspergillus terreus Aspergillus ustus Aspergillus versicolor Aspergillus is a genus of around 200 filamentous fungi... Divisions Chytridiomycota Zygomycota Glomeromycota Ascomycota Basidiomycota Deuteromycota Fungi (singular fungus) are a kingdom of eukaryotic organisms. ... Binomial name Aspergillus flavus Aspergillus flavus is a fungus associated with aspergillosis of the lungs and sometimes believed to cause corneal, otomycotic, and nasoorbital infections. ... Aspergillus parasiticus is a mold known to produce aflatoxin, although strains of it exist that do not produce this carcinogen. ... The term carcinogen refers to any substance, radionuclide or radiation which is an agent directly involved in the promotion of cancer or in the facilitation of its propagation. ... An epoxide is a cyclic ether with only three ring atoms. ... Note: This page contains IPA phonetic symbols in Unicode. ...

Contents

Contamination conditions

Aspergillus fumigatus as seen under the electron microscope
Aspergillus fumigatus as seen under the electron microscope

Aflatoxin producing members of Aspergillus are common and widespread in nature. They can colonize and contaminate grain before harvest or during storage. Host crops are particularly susceptible to infection by Aspergillus following prolonged exposure to a high humidity environment or damage from stressful conditions such as drought, a condition which lowers the barrier to entry. Image File history File links Aspergillus. ... Image File history File links Aspergillus. ... This article does not cite its references or sources. ...


The native habitat of Aspergillus is in soil, decaying vegetation, hay, and grains undergoing microbiological deterioration and it invades all types of organic substrates whenever conditions are favorable for its growth. Favorable conditions include high moisture content (at least 7%) and high temperature.


Crops which are frequently affected include cereals (maize, sorghum, pearl millet, rice, wheat), oilseeds (peanut, soybean, sunflower, cotton), spices (chile peppers, black pepper, coriander, turmeric, ginger), and tree nuts (almond, pistachio, walnut, coconut, brazil nut). This article is about cereals in general. ... Corn redirects here. ... Species About 30 species, see text Sorghum is a genus of about 30 species of grasses raised for grain, native to tropical and subtropical regions of Eastern Africa, with one species native to Mexico. ... Binomial name Pennisetum glaucum (L.) R. Br. ... Species Oryza glaberrima Oryza sativa Rice is two species of grass (Oryza sativa and Oryza glaberrima) native to tropical and subtropical southern & southeastern Asia and in Africa. ... Species T. aestivum T. boeoticum T. compactum T. dicoccoides T. dicoccon T. durum T. monococcum T. spelta T. sphaerococcum T. timopheevii References:   ITIS 42236 2002-09-22 For the indie rock group see: Wheat (band). ... Vegetable oil or vegoil is fat extracted from plant sources. ... Binomial name Arachis hypogaea L. The peanut, or groundnut (Arachis hypogaea) is a species in the legume family Fabaceae native to South America. ... Binomial name Glycine max (L.) Merr. ... Binomial name Helianthus annuus L. The sunflower (Helianthus annuus) is an annual plant in the family Asteraceae, with a large flower head (inflorescence). ... chloe is andy roddicks biggest fan at bebo cmstfan ... Screen shot of Spice OPUS, a fork of Berkeley SPICE SPICE (Simulation Program with Integrated Circuit Emphasis) is a general purpose analog circuit simulator. ... The chile pepper, chili pepper, or chilli pepper, or simply chile, is the fruit of the plant Capsicum from the nightshade family, Solanaceae. ... Binomial name Piper nigrum L. Black pepper (Piper nigrum) is a flowering vine in the family Piperaceae, cultivated for its fruit, which is usually dried and used as a spice and seasoning. ... Binomial name Coriandrum sativum L. Percentages are relative to US RDI values for adults. ... Binomial name Curcuma longa Linnaeus Turmeric (Curcuma longa, also known as tumeric) is a spice commonly used in curries and other South Asian cooking. ... Binomial name Zingiber officinale Roscoe Ginger is used extensively as a spice in cuisines throughout the world. ... Hazelnuts from the Common Hazel Chestnut Walnuts A nut can be both a seed and a fruit. ... Binomial name Prunus dulcis (Mill. ... Binomial name Pistacia vera L. The pistachio (Pistacia vera, Anacardiaceae; sometimes placed in Pistaciaceae) is a small tree up to 10 m tall, native to mountainous regions of central and southwestern Asia such as the Kopet Dag mountains of Turkmenistan southwest to northeastern Iran and western Afghanistan. ... “Walnut Tree” redirects here. ... Binomial name Cocos nucifera L. For other uses, see Coconut (disambiguation). ... Binomial name Bertholletia excelsa Humb. ...


The toxin can also be found in the milk of animals which are fed contaminated feed.


Virtually all sources of commercial peanut butter contain minute quantities of aflatoxin,[1] but it is usually far below the US Food and Drug Administration's (FDA) recommended safe level. The Food and Drug Administration (FDA) is an agency of the United States Department of Health and Human Services and is responsible for regulating food (humans and animal), dietary supplements, drugs (human and animal), cosmetics, medical devices (human and animal) and radiation emitting devices (including non-medical devices), biologics, and...


Pathology

High-level aflatoxin exposure produces an acute necrosis, cirrhosis, and carcinoma of the liver exhibited by hemorrhage, acute liver damage, edema, alteration in digestion, and absorption and/or metabolism of nutrients. Necrosis (in Greek Νεκρός = Death) is the name given to accidental death of cells and living tissue. ... Cirrhosis is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrotic scar tissue as well as regenerative nodules, leading to progressive loss of liver function. ... Hepatic tumors are tumors or growths on or in the liver (medical terms pertaining to the liver often start in hepato- or hepatic from the Greek word for liver, hepar). ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Edema (American English) or oedema (British English), formerly known as dropsy or hydropsy, is swelling of any organ or tissue due to accumulation of excess lymph fluid, without an increase of the number of cells in the affected tissue. ...


No animal species is immune to the acute toxic effects of aflatoxins including humans; however, humans have an extraordinarily high tolerance for aflatoxin exposure and rarely succumb to acute aflatoxicosis.


Chronic, subclinical exposure does not lead to as dramatic of symptoms as acute aflatoxicosis. Children, however, are particularly affected by aflatoxin exposure which leads to stunted growth and delayed development[citation needed]. Chronic exposure also leads to a high risk of developing liver cancer, as the metabolite aflatoxin M1 can intercalate into DNA and alkylate the bases through its epoxide moiety. Intercalation induces structural distortions. ... Alkylation is the transfer of an alkyl group from one molecule to another. ... Look up moiety in Wiktionary, the free dictionary. ...


Medical research indicates that a regular diet including apiaceous vegetables such as carrots, parsnips, celery and parsley, reduces the carcinogenic effects of aflatoxin[2]. Genera See text Ref: Hortiplex 2003-11-14 The Apiaceae, the carrot or parsley family, are a family of usually aromatic plants with hollow stems, including parsley, carrot, and other relatives. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ...


Detection of aflatoxin in humans

There are two techniques that have been used most often to detect levels of aflatoxin in humans.


The first method is measuring the AFM1-guanine adduct in the urine of subjects. Presence of this breakdown product indicates exposure to aflatoxin in the past 24 hours. However, this technique has a significant flaw in that it only produces a positive result in approximately one-third of positive test subjects. Additionally, due to the half-life of this metabolite, the level of AFM1-guanine measured can vary significantly from day to day, based on diet, and thus is not useful for assessing long term exposure. Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA; the others being adenine, cytosine, thymine, and uracil. ... Wikipedia does not yet have an article with this exact name. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ...


Another technique that has been used is a measurement of the AFB1-albumin adduct level in the blood serum. This approach is significantly more accurate, as positive results are generated in 90% of positive test subjects. This test is also useful for measuring long-term exposure, as it remains positive for two to three months. You may be looking for albumen, or egg white. ...


Aflatoxin in pets

Aflatoxin in dry dog food manufactured by Diamond Pet Foods was responsible for at least 23 dog deaths due to liver failure between Dec 2005 and early 2006. In an April 12, 2006 letter FedEx'd from the Department of Health and Human Resources to a manufacturing plant <http://www.fda.gov/foi/warning_letters/g5811d.pdf>, the FDA warned Gary Schell, president of Schell and Kampeter Inc., 103 N. Olive Street in Meta, Missouri that independent testing of three samples of incoming corn to their processing plant showed between 90 and 1851 ppb, while paperwork on three (of four samples) showed aflatoxins levels <20 ppb, and other sample was not recorded. The results of this letter are unknown.


Similar/non-existant oversite may be responsible for other pet food related deaths due to kidney failure in early 2007. The mycotoxin, ochratoxin A, is known to cause kidney/renal failure in animals. The following 2005 test results show low levels of ochratoxin A, but there were no FDA specs for levels of permissable ochratoxin in pet food at the time [so high levels could slip through). <http://64.233.167.104/search?q=cache:OGAdkeU5OU0J:www.afdo.org/afdo/upload/SummaryofMycotoxins-1.18.07.pdf+pet+food+ochratoxin+%22wheat+gluten%22&hl=en&ct=clnk&cd=2&gl=us>. As of Mar 19, 2007, it's unknown if the company (Menu Foods) or independent agencies have tested any suspected/affected owners' pet food for O.A.


Major types of aflatoxins and their metabolites

At least 13 different types of aflatoxin are produced in nature. Aflatoxin B1 is considered the most toxic and is produced by both Aspergillus flavus and Aspergillus parasiticus. Aflatoxin G1 and G2 are produced exclusively by A. parasiticus. While the presence of Aspergillus in food products does not always indicate harmful levels of aflatoxin are also present, it does imply a significant risk in consumption of that product. Binomial name Aspergillus flavus Aspergillus flavus is a fungus associated with aspergillosis of the lungs and sometimes believed to cause corneal, otomycotic, and nasoorbital infections. ... Aspergillus parasiticus is a mold known to produce aflatoxin, although strains of it exist that do not produce this carcinogen. ... Species Aspergillus caesiellus Aspergillus candidus Aspergillus carneus Aspergillus clavatus Aspergillus deflectus Aspergillus flavus Aspergillus fumigatus Aspergillus glaucus Aspergillus nidulans Aspergillus niger Aspergillus ochraceus Aspergillus oryzae Aspergillus parasiticus Aspergillus penicilloides Aspergillus restrictus Aspergillus sojae Aspergillus sydowi Aspergillus terreus Aspergillus ustus Aspergillus versicolor Aspergillus is a genus of around 200 filamentous fungi...


Aflatoxins M1, M2 were originally discovered in the milk of cows fed on moldy grain. These compounds are products of conversion process in the animal's liver. However, aflatoxin M1 is present in the fermentation broth of Aspergillus parasiticus.

  • Aflatoxin B1 & B2 : produced by Aspergillus flavus and A. parasiticus.
  • Aflatoxin G1 & G2 : produced by Aspergillus parasiticus.
  • Aflatoxin M1 : metabolite of aflatoxin B1 in humans and animals (exposure in ng can come from mother's milk).
  • Aflatoxin M2 : metabolite of aflatoxin B2 in milk of cattle fed on contaminated foods.
  • Aflatoxicol.

The nanogram is an SI unit of mass (symbol ng) defined as: 1 ng = 1 × 10-12 kilogram (1 × 10-9 gram) A nanogram is one billionth (1/1,000,000,000) of a gram. ...

Interaction of aflatoxin with the Hepatitis B virus

Studies have shown that concurrent infection with the Hepatitis B virus (HBV) during aflatoxin exposure increases the risk of hepatocellular carcinoma (HCC). As HBV interferes with the ability of hepatocytes to metabolize aflatoxins, an aflatoxin M1-DNA conjugate exists for a longer period of time in the liver, increasing the probability of damage to tumor supressor genes such as p53. This effect is synergistic with the resulting damage far greater than just the sum of aflatoxin or HBV individually. (Williams, 2004) Hepatitis B is a disease of the liver and is caused by the Hepatitis B virus (HBV), a member of the Hepadnavirus family[1] and one of several unrelated viral species which cause viral hepatitis. ... Hepatocellular carcinoma (HCC, also called hepatoma) is a primary malignancy (cancer) of the liver. ... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... The liver is an organ in some animals, including vertebrates (and therefore humans). ... TP53 bound to a short DNA fragment. ...


Decreasing HBV infection levels through vaccination is an effective and simple approach that can be taken to reduce these harmful synergistic effects, thus decreasing the impact of chronic aflatoxin exposure. This strategy may prove to be highly effective – many regions of the world which have high aflatoxin rates, such as western Africa and China, also have high HBV infection rates[3]. Vaccination is the process of administering weakened or dead pathogens to a healthy person or animal, with the intent of conferring immunity against a targeted form of a related disease agent. ... West Africa is the region of western Africa generally considered to include these countries: Benin Burkina Faso Cameroon Côte dIvoire (Ivory Coast) Equatorial Guinea Gabon The Gambia Ghana Guinea Guinea-Bissau Liberia Mali Niger Nigeria Republic of the Congo (Congo-Brazzaville) Senegal Sierra Leone Togo Chad, Mauritania, and...


Manufacturers

As for January 2007, there are but two primary manufacturers (as distinguished from re-packers and re-sellers) of pure aflatoxins known:

  • SigmaAldrich
  • Fermentek, the only one that produces aflatoxin M2

Fermentek Ltd. ...

See also

Aflatoxin total synthesis concerns the total synthesis of a group of organic compounds called aflatoxins. ... A foodborne illness (also foodborne disease) is any illness resulting from the consumption of contaminated food. ...

Notes

  1. ^ quantity can range from 0ppb-20ppb for direct human consumption, although feedlot food for finishing beef cattle/swine/poultry can acceptably reach 300ppb; http://scientificteaching.wisc.edu/products/PeanutFiles/library/places/FoodDrugAdmin.htm
  2. ^ University of Washington, Apiaceous vegetable constituents inhibit human cytochrome P-450 1A2 (hCYP1A2) activity and hCYP1A2-mediated mutagenicity of aflatoxin B1., 2006 Sep;44(9):1474-84. (PMID 16762476)
  3. ^ Williams JH, Phillips TD, Jolly PE, Stiles JK, Jolly CM, Aggarwal D. Human aflatoxicosis in developing countries: a review of toxicology, exposure, potential health consequences, and interventions. Am J Clin Nutr 2004;80:1106-22. (PMID 15531656)

External links

  • Links to external chemical sources
  • Aflatoxin Test Kits

  Results from FactBites:
 
Aflatoxin (1159 words)
Aflatoxin M1and M2 are major metabolites of aflatoxin B1 and B2 respectively, found in milk of animals that have consumed feed contaminated with aflatoxins.
Aflatoxins are normally refers to the group of difuranocoumarins and classified in two broad groups according to their chemical structure; the difurocoumarocyclopentenone series (AFB1, AFB2, AFB2A, AFM1, AFM2, AFM2A and aflatoxicol) and the difurocoumarolactone series (AFG1, AFG2, AFG2A, AFGM1, AFGM2, AFGM2A and AFB3).
In the presence of mineral acids, aflatoxin B1 and G1 are converted in to aflatoxin B2A and G2A due to acid-catalyzed addition of water across the double bond in the furan ring.
Aflatoxins-Home Page (3075 words)
Aflatoxins have been associated with various diseases, such as aflatoxicosis, in livestock, domestic animals and humans throughout the world.
Aflatoxins have received greater attention than any other mycotoxins because of their demonstrated potent carcinogenic effect in susceptible laboratory animals and their acute toxicological effects in humans.
Aflatoxins often occur in crops in the field prior to harvest.
  More results at FactBites »

 
 

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