In Vitro Activity of Diphenyleneiodonium toward Multidrug-Resistant Helicobacter pylori Strains

Background/Aims: The increased resistance of Helicobacter pylori to antibiotics has increased the need to develop new treatments for this bacterium. The aim of our study was to identify new drugs with anti-H. pylori activity. Methods: We screened a small molecule library-the library of pharmacologically active compounds (LOPAC), which includes 1,280 pharmacologically active compounds-to identify inhibitors of H. pylori growth. The minimal inhibitory concentrations (MICs) of antibiotics against multidrug-resistant H. pylori strains were determined using the agar dilution method. Results: We identified diphenyleneiodonium (DPI) as a novel anti-H. pylori agent. The MIC values for DPI were ＜0.03 µg/mL against all tested H. pylori strains. DPI also exhibited strong antibacterial activity against common gram-negative and gram-positive pathogenic bacteria. Conclusions: DPI may be a candidate anti-H. pylori drug for future development.