Simplified Synthesis and Stability Assessment of Aflatoxin B1-Lysine and Aflatoxin G1-Lysine

Aflatoxins B-1 (AFB(1)) and G(1) (AFG(1)) are carcinogenic mycotoxins that contaminate crops such as maize and groundnuts worldwide. The broadly accepted method to assess chronic human aflatoxin exposure is by quantifying the amount of aflatoxin adducted to human serum albumin. This has been reported using ELISA, HPLC, or LC-MS/MS to measure the amount of AFB(1)-lysine released after proteolysis of serum albumin. LC-MS/MS is the most accurate method but requires both isotopically labelled and unlabelled AFB(1)-lysine standards, which are not commercially available. In this work, we report a simplified synthetic route to produce unlabelled, deuterated and C-13(6) N-15(2) labelled aflatoxin B-1-lysine and for the first-time aflatoxin G(1)-lysine. Additionally, we report on the stability of these compounds during storage. This simplified synthetic approach will make the production of these important standards more feasible for laboratories performing aflatoxin exposure studies.