Mechanism, kinetics, and antimicrobial activities of 2-hydroxy-1-naphthaldehyde semicarbazone as a new Jack bean urease inhibitor

A new inhibitor of jack bean urease, 2-hydroxy-1-naphthaldehyde semicarbazone (HNDSC), was synthesized and its inhibitory mechanism and kinetics with respect to jack bean urease were investigated. HNDSC inhibited the activity of jack bean urease, with the inhibitor concentration leading to 50% activity loss (IC50) of 0.032 ± 0.004 mM. Kinetic analyses showed that HNDSC is a reversible and competitive inhibitor of jack bean urease. Microscopic rate constants were obtained by the progress-of-substrate-reaction method. The results obtained from inhibitory kinetic and fluorescence titration assay methods showed very good agreement that one molecule of HNDSC binds the active unit of the jack bean urease. The inhibition mechanism and kinetic studies indicate that HNDSC could be a candidate for the development of new urease inhibitors. Its antibacterial activities, evaluated against Escherichia coli, Bacillus subtilis, and Staphyloccocus aureus, were highest against E. coli.