An immunochemical approach is described for the detection of versicolorin (VA) and other aflatoxin precursors in Aspergillus parasiticus cultures. VA was purified from A. parasiticus ATCC 36537 cultures by semipreparative high performance liquid chromatography and confirmed by mass spectrometry and ultraviolet (UV) absorption. To be rendered immunogenic, VA was converted to a hemiacetal and conjugated to bovine serum albumin (BSA) by reductive alkylation. Rabbit polyclonal antiserum prepared against the VA hemiacetal-BSA conjugate was employed in a competitive ELISA using VA hemiacetal-horseradish peroxidase conjugate as the marker ligand. Based on the amount of VA analogue required to inhibit binding by 50% in competitive ELISA, cross-reactivity relative to VA for VA hemiacetal, averufanin, averantin, norsolorinic acid, averufin, sterigmatocystin, and aflatoxin B1 were 106, 85, 7, 6, 2, <1, and <1%, respectively. The ELISA was used to monitor enhanced production of VA equivalents by A. parasiticus ATCC 36537 in a modified culture procedure. The VA antibody should be extremely useful in the biochemical and genetic investigation of aflatoxin biosynthesis.

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