Quantitation of Aflatoxin Metabolites

Quantitation of Aflatoxin Metabolites (AFB1, AFB2, AFG1 and AFG2) in Food Commodities and Their Diminution with Various Detoxifying Agents


1.1. Mycotoxins

The mycotoxins are extreme toxic metabolites produced by certain fungi that can infect and proliferate on various agricultural commodities in the field and or during storage [1]. The occurrence of these toxins on grains, nuts and other commodities susceptible to mold infestation is influenced by environmental factors such as temperature, humidity, and extent of rainfall during the pre-harvesting, harvesting, and post-harvesting periods. Mycotoxins may exhibit various toxicological manifestations; some are teratogenic, mutagenic and /or carcinogenic in susceptible animal species and are associated with various diseases in domestic animals, livestock, and humans in many parts of the world [2]

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The naturally occurring toxins such as mycotoxins pose profound challenges to food safety. Mycotoxins are substances produced by moulds that contaminate various agricultural commodities either before harvest during harvest and under post harvest conditions (WHO, 1999). 1.2. Aflatoxin The mycotoxins of public health importance within the region are aflatoxin [3]. Aflatoxin are secondary metabolites with high toxic and carcinogenic properties produced predominantly by three species of mould Aspergillus flavus, Aspergillus parasiticus and Aspergillus nomius, that are widely distributed in nature and form aflatoxin at temperature ranging from 12 to 42oC and relative humidity higher than 80% [4] . The discovery of aflatoxins dates back to the year 1960 following the severe outbreak of the turkey ‘X’ disease in the UK which resulted in the deaths of more than 100000 turkeys and other farm animals [1]. The cause of the disease was attributed to a feed containing Brazilian peanuts which were heavily infested with A. flavus. Subsequent analysis of the feed using thin-layer chromatography (TLC) revealed that a series of fluorescent compounds later termed aflatoxins were responsible for the outbreak [1] - [3]. The main responsible chemical forms toxin metabolites were identified as aflatoxin B1, B2, G1, G2, and M1. 1.1. Aflatoxin Physical Properties The classification of the indices B and G is not structure-related and has its origin in the color of the fluorescence under UV-light (B=blue and G=green) while structural differences of the terminal furan ring determine the numerical index. M1 is the predominant metabolite of AFB1 in milk from lactating humans and animals that consume AFB1-contaminated food or feed Hence, the name aflatoxin, an acronym has been formed from the following combination: the first letter, ‘A’ for the genus Aspergillus, the next set of three letters ‘FLA’, for the species flavus, and the noun ‘TOXIN’ meaning poison [5]. Table 1.1 Physical Properties of Aflatoxins Metabolites.

Aflatoxins Mol. formula Mol. Weight(g) M.P oF
B1 C17H12O6 312 265-269
B2 C17H14O6 314 286-289
G1 C17H12O7 328 244-246
G2 C17H14O7 330 237-240
M1 C17H12O7 328 299
M2 C17H14O7 330 293
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