Nitroxoline (8-Hydroxy-5-nitroquinoline, 5-nitroquinolin-8-ol, 5-Nitro-8-quinolinol, 5-Nitro-8-hydroxyquinoline) is a urinary antibacterial agent active against susceptible gram-positive and gram-negative organisms commonly found in urinary tract infections. Nitroxoline impairs tumor progression in vitro and in vivo by inhibiting cathepsin B activity.