Aflatoxicol is a metabolite of aflatoxin B1, one of the mycotoxins from Aspergillus flavus and A. parasiticus. Aflatoxins are toxic and probably among the most carcinogenic substances known. They are common and widespread in nature and can colonize and contaminate grain before harvest or during storage. (9)
belongs to the class of organic compounds known as angular furanocoumarins. These are furanocoumarins, with a structure characterized by a furan ring angularly fused to a coumarin.
Oral, dermal, inhalation, and parenteral (contaminated drugs). (5)
Mechanism of Toxicity
Aflatoxins produce singlet oxygen upon their exposure to UV (365-nm) light. Singlet oxygen in turn activates them to mutagens and DNA binding species. Aflatoxin metabolites can intercalate into DNA and alkylate the bases through their epoxide moiety, binding particularity to N7-guanine bases. In addition to randomly mutating DNA, this is thought to cause mutations in the p53 gene, an important gene in preventing cell cycle progression when there are DNA mutations, or signaling apoptosis. (7, 2, 3)
Metabolism
Aflatoxins are metabolized in the liver by the cytochrome P-450-dependent polysubstrate mono-oxygenase system to less toxic metabolites. The main reactions in aflatoxin metabolism are hydroxylation, oxidation, and demethylation. (4)
Not directly listed by IARC. Aflatoxin B1 is carcinogenic to humans (Group 1). (6)
Uses/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. 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). The toxin can also be found in the milk of animals which are fed contaminated feed. Thus, aflatoxins are usually encountered in thecontext of chronic exposure, via food intake or secondary to the handling of foodstuffs. (9)
Minimum Risk Level
Not Available
Health Effects
The main target organ in mammals is the liver so aflatoxicosis is primarily a hepatic disease. Protracted exposure to aflatoxins may cause liver damage and necrosis, cholestasis, and hepatomas. Moreover, protracted exposure to aflatoxins has been associated with hepatocellular carcinoma, acute hepatitis, Reye's syndrome, bile duct cell proliferation, periportal fibrosis, hemorrhages, mucous membrane jaundice, fatty liver changes, cirrhosis in malnourished children, and kwashiorkor. However, aflatoxins accumulate in the presence of liver disease, and the association with hepatic cancer is confounded by the occurrence of hepatitis-B. Thus, it is not clear in these various instances whether aflatoxin is a primary cause of the disease, is an innocent bystander which accumulates secondary to the disease process, or is a contributing cause in conjunction with other factors. It is also mutagenic and teratogenic. Inhaled aflatoxins may produce pulmonary adenomatosis. Aflatoxins modify the immune system by affecting antibody formation, complement, cell-mediated immunity, and phagocytosis. (1, 9)
Symptoms
A broad range of symptoms can be found depending upon dosage, including, vomiting, abdominal pain, hemorrhage, and pulmonary edema. (8)
Treatment
Administration of phonobarbital enhances hepatic transformation activities and also protects against AFB-induced toxicity, carcinogenicity and DNA binding in vivo. In cases of ingestion, feeding large quantities of an adsorbent such as activated charcoal may be used. Antioxidants such as ellagic acid and inducers of some cytochromes P450, such as indole-3-carbinol, may give a protective effect. (1, 8)
