Metronidazole and Tinidazole mechanism of action

Metronidazole undergoes a reductive bioactivation of its nitro group by ferredoxin (present in anaerobic parasites) to form reactive cytotoxic products. The mechanism of tinidazole is assumed to be similar. Some anaerobic protozoal parasites (including amebas) possess ferrodoxin-like, low-redox-potential, electron-transport proteins that participate in metabolic electron removal reactions. The nitro group of metronidazole is able to serve as an electron acceptor, forming reduced cytotoxic compounds that bind to proteins and DNA, resulting in cell death.