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Anti-aflatoxin mutagenic factors in corn
C Y Weng1, A J Martinez, D L Park
1Department of Nutritional Sciences, University of Arizona, Tucson 85721, USA.
Food Additives and Contaminants
|April 1, 1997
Summary
Corn extracts containing aflatoxins did not show mutagenic potential in the Ames test, suggesting unknown interfering materials in corn bind aflatoxins, blocking their activity. Further research is needed to understand this phenomenon.
Area of Science:
- Food Science
- Toxicology
- Analytical Chemistry
Background:
- Aflatoxins are toxic secondary metabolites produced by Aspergillus fungi.
- Aflatoxin contamination in food, particularly corn, poses a significant health risk.
- The mutagenic potential of aflatoxins is well-established, but their behavior in complex food matrices is less understood.
Purpose of the Study:
- To investigate the mutagenic potential of aflatoxins in naturally contaminated corn extracts using the Ames test.
- To determine if ammonia treatment affects the mutagenicity of aflatoxins in corn.
- To identify potential interfering substances in corn that may mask aflatoxin mutagenicity.
Main Methods:
- Sequential fractionation and partition of corn extracts (aflatoxin-free, contaminated, and ammonia-treated contaminated).
- Mutagenicity testing using the Ames test (TA100 tester strain) with 2-aminofluorene (2-AF) and pure aflatoxin B1 (AFB1) as positive controls.
- Preparative thin-layer chromatography (TLC) to separate components of dichloromethane (CH2Cl2) extracts, followed by Ames testing with S9 activation.
Main Results:
- Pure AFB1 induced a mutagenic response in the Ames test, but all tested isolates from contaminated corn, including ammonia-treated samples, showed no mutagenic activity.
- CH2Cl2 extracts from contaminated corn, even when spiked with pure AFB1, failed to elicit a mutagenic response.
- TLC separation of CH2Cl2 extracts did not reveal mutagenic fractions, indicating the presence of non-aflatoxin interfering materials.
Conclusions:
- Naturally occurring "unknown interfering materials" in corn can bind or co-extract with aflatoxins, inhibiting their mutagenic activity in the Ames test.
- The observed lack of mutagenicity is not due to ammonia treatment but rather to these interfering substances.
- The TLC method employed was insufficient to separate these interfering materials from aflatoxins, necessitating further investigation into their nature and mechanism of action.