Polyhalogenated benzo- and naphthoquinones were found to be potent inhibitors of pure ureases from Bacillus pasteurii and Canavalia ensiformis. They also inhibited ureases in whole cells of Helicobacter pylori, Klebsiella oxytoca and Proteus mirabilis. Inhibition was non-competitive with K i values in the micromolar range or below. Inhibition was irreversible as shown by equilibrium dialysis. Inhibitory power decreased considerably when halogens were replaced by –OH, –CN, alkoxy or alkyl groups.
