Structure-activity studies reveal efficient inactivation of urease by Ebsulfur-based compounds

Antimicrobial resistance is one of the most significant global health threats of the 21st century, demanding urgent strategies for the development of novel therapeutic approaches. Urease, a nickel-dependent enzyme absent in the human proteome, represents an attractive target for drug development because several urease-expressing bacterial pathogens play a critical role in pathogenesis. Alternative strategies, such as drug repurposing, are necessary to uncover the potential of antimicrobial molecules. In this context, the organo‑selenium compound Ebselen has shown promising urease-inhibitory properties, but its therapeutic application is limited by toxicity concerns. Ebsulfur, a sulfur analog of Ebselen, offers a potentially safer alternative. In this study, we evaluated three Ebsulfur derivatives for their ability to inhibit urease from Sporosarcina pasteurii and Canavalia ensiformis. Biochemical assays demonstrated that these compounds effectively inactivate both bacterial and plant urease in the low micromolar range. The X-ray crystal structures of Sporosarcina pasteurii urease co-crystallized with two of the derivatives, determined at 1.95-1.96 Å resolution, suggested a mechanism involving di‑sulfuration of the catalytically essential αCys322 residue. These findings provide insight into the potential of Ebsulfur derivatives as antimicrobial agents, addressing the persistent lack of progress in antibiotic development, and contribute to the development of alternative antimicrobial strategies targeting resistant pathogens.