Prostaglandin H synthase-dependent epoxidation of aflatoxin B1

This report demonstrates that aflatoxin B1 (AFB1) is cooxidized by prostaglandin H (PGH) synthase to form 2,3-dihydro-2,3-epoxy-aflatoxin B1 oxide. Using ram seminal vesicle microsomes as a source of PGH synthase, our results demonstrate that AFB1 is converted to a mutagen during arachidonate turnover that we identify as the epoxide by isolating adducts formed to DNA. The efficiency of AFB1 epoxidation by PGH synthase is assessed and compared with mixed-function oxidase-dependent metabolic activation of this compound.