Mycophenolic acid (MPA) is frequently found, often in high concentrations, in a broad range of food and feed matrices. Apart from the well-known contamination of blue-veined cheeses caused by the use of toxinogenic Penicillium roqueforti strains for manufacturing, a broad range of other Penicillium spp. is able to produce this immunosuppressive toxin. Therefore, MPA has been proposed to be a suitable marker for Penicillium-infected food commodities. In the present work, a high-affinity monoclonal antibody (mAb) for the specific detection of MPA was developed by immunizing mice with a MPA-protein conjugate coupled by an activated ester method. Under the conditions of a direct competitive enzyme immunoassay (EIA), 50% inhibition and detection limits of MPA standard curves were 1.2 and 0.3 ng/ml, respectively. Furthermore, the mAb could be successfully employed for the production of an immunoaffinity (IA) column enabling the efficient enrichment of MPA from processed foodstuffs. By combining the IA clean-up with a polyclonal antibody-based EIA, an ultrasensitive analysis method could be established which allowed the reliable and reproducible detection of MPA in artificially contaminated tomato ketchup as a model matrix at concentrations as low as 0.1 ng/g.
Keywords: Enzyme immunoassay; Food; Immunoaffinity columns; Monoclonal antibodies; Mycophenolic acid.