Nitroimidazoles are imidazole heterocycles with a nitro group that have been used to combat anaerobic bacterial and parasitic infections. Perhaps the most common example is metronidazole (flagyl). Other heterocycles such as nitrothiazoles (thiazole) are also used for this purpose. Nitroheterocycles may be reductively activated in hypoxic cells, and then undergo redox recycling or decompose to toxic products.
references
Annu. Rev. Pharmacol. Toxicol. 1989. 29:165~7