Nitroreduction of 6-nitrobenzo[a]pyrene: a potential activation pathway in humans

6-Nitrobenzoa]pyrene, an environmental pollutant, was metabolized by human intestinal microflora to 6-nitrosobenzoa]pyrene and 6-aminobenzoa]pyrene. The two-electron reduction product 6-nitrosobenzoa]pyrene exhibited strong direct-acting mutagenicity in the Salmonella typhimurium assay. These results imply that 6-nitrobenzoa]pyrene can be hazardous to human health via a nitroreduction activation pathway and opens the possibility that other nitro-polycyclic aromatic hydrocarbons that are not direct-acting mutagens may be activated in vivo by a similar mechanism.