Nitroreductase is an enzyme that catalyzes the reduction of a nitro group. Some synonyms for this word include nitroreductases, nitroreductase enzymes, or nitroreductase proteins. These enzymes are commonly found in bacteria and plants, and are involved in the process of metabolizing aromatic and aliphatic compounds. Nitroreductase activity has been found to be important in the activation of prodrug therapies and in the degradation of environmental pollutants. Other related terms include nitroreductase inhibitors, which are compounds that can block the activity of nitroreductase enzymes, and nitroreductase assays, which are laboratory tests used to measure the activity of these enzymes.