Aflatoxin B1S: Revised Structure for the Sodium Sulfonate Formed by Destruction of Aflatoxin B1 with Sodium Bisulfite1,2

A promising method for the destruction of aflatoxin B1 in commodities is treatment with sodium bisulfite to yield a single major product, aflatoxin B1S. On the basis of nuclear magnetic resonance, ultraviolet and infrared spectra, elemental analysis, mass spectroscopy, deuterium labeling and stability to highly acidic conditions, the structure of aflatoxin B1S was established as the 15 α-sodium sulfonate of aflatoxin B1 The formation of aflatoxin B1 products substituted at the 15 position only is unprecedented and implies an unusual mechanism. The formation of a single trans addition product under conditions that seemingly rule out a previously proposed free radical mechanism suggested a newly proposed ionic reaction mechanism. The completeness of the reaction and the water solubility of aflatoxin B1S support the promising use of bisulfite to destroy aflatoxin.