Structural diversity and biochemical and microbiological characteristics of aflatoxins

Abstract

Among all mycotoxins, Aflatoxin B1 (AFB1) is considered to be the most carcinogenic, and it has been classified by the International Agency for Research on Cancer in Group 1 of human carcinogen. It signifies a high hazard because it contaminates a diversity of agricultural products such as nuts and derivatives, peanuts/hazelnuts, grains, seeds, cottonseed, milk, dairy food. In milk AFB1 is metabolized to aflatoxin M (AFM1) which is 4-hydroxy derivative of AFB1, it is formed in the liver and excreted in the milk into the mammary glands of both human and lactating animals which have been fed with AFB1 contaminated diet. After the food contamination, one part of the aflatoxin B1 which was present in the food is eliminated through the milk. At the molecular level aflatoxin biosynthesis involves several levels of transcriptional and post-transcriptional control, so the main stages subsequent biochemical and genetic constituents of aflatoxin biosynthesis have been demonstrated recently. Recent studies over the last few decades have shown that the metabolism of AFB is an essential component of hepatocarcinogenic, however it was shown that AFB1 is metabolized by cytochrome P450 oxidised to intermediates and other metabolites Therefore, the biotransformation process may also lead to the formation of carcinogenic metabolites.