Solvent-dependent transformation of aflatoxin B^sub 1^ in soil

To date, all studies of aflatoxin B1 (AFB1) transformation in soil or in purified mineral systems have identified aflatoxins B2 (AFB2) and G2 (AFG2) as the primary transformation products. However, identification in these studies was made using thin layer chromatography which has relatively low reso...

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Bibliographic Details
Published inMycotoxin research Vol. 33; no. 3; p. 197
Main Authors Starr, James M, Rushing, Blake R, Selim, Mustafa I
Format Journal Article
LanguageEnglish
Published Dordrecht Springer Nature B.V 01.08.2017
Subjects
Acidic soils
Aflatoxin B1
Aflatoxins
Catalysts
High performance liquid chromatography
Hydrolysis
Liquid chromatography
Methanol
Moisture
Organic solvents
Replication
Soil environment
Soil moisture
Soils
Solvents
Studies
Thin layer chromatography
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Summary:To date, all studies of aflatoxin B1 (AFB1) transformation in soil or in purified mineral systems have identified aflatoxins B2 (AFB2) and G2 (AFG2) as the primary transformation products. However, identification in these studies was made using thin layer chromatography which has relatively low resolution, and these studies did not identify a viable mechanism by which such transformations would occur. Further, the use of methanol as the solvent delivery vehicle in these studies may have contributed to formation of artifactual transformation products. In this study, we investigated the role of the solvent vehicle in the transformation of AFB1 in soil. To do this, we spiked soils with AFB1 dissolved in water (93:7, water/methanol) or methanol and used HPLC-UV and HPLC-MS to identify the transformation products. Contrasting previous published reports, we did not detect AFB2 or AFG2. In an aqueous-soil environment, we identified aflatoxin B2a (AFB2a) as the single major transformation product. We propose that AFB2a is formed from hydrolysis of AFB1 with the soil acting as an acid catalyst. Alternatively, when methanol was used, we identified methoxy aflatoxin species likely formed via acid-catalyzed addition of methanol to AFB1. These results suggest that where soil moisture is adequate, AFB1 is hydrolyzed to AFB2a and that reactive organic solvents should be avoided when replicating natural conditions to study the fate of AFB1 in soil.
ISSN:0178-7888
1867-1632
DOI:10.1007/s12550-017-0278-x