Silver complex of 1,10-phenanthroline containing 2-formylpyridine-N(4)-ethylthiosemicarbazone: study of toxicity using alternative methods and microbiological activity against Helicobacter pylori

Abstract

<i>Helicobacter pylori</i> is associated with gastric disorders, and the increase in bacterial resistance has sparked interest in the search for new antimicrobial compounds. The current study investigated the effect of the silver metal complex [Ag(phen)(PETSC)](NO₃)∙HCl∙2H₂O (phen = 1,10-phenanthroline; PETSC = 2-formylpyridine-N(4)-ethyl-thiosemicarbazone), termed the Compound against <i>H. pylori</i>. The antibacterial activity exhibited a minimum inhibitory concentration of 6.25 μg/mL. The checkerboard titration method assessed the combination of the Compound with amoxicillin and tetracycline, which presented antagonistic and indifferent effects, respectively. Time Kill kinetics were bactericidal after 12 h of treatment. Biofilm inhibition results showed antibacterial activity and bacterial morphological changes were observed by scanning electron microscopy. <i>In vitro</i>, cytotoxicity in normal gastric cells showed IC₅₀ of 0.6733 μg/mL. The alternative <i>in vivo</i> test using <i>Galleria mellonella</i> showed acute toxicity at a dose of 150 mg/kg. Therefore, technological strategies can be an alternative to overcome the cytotoxicity since the Compound has a bactericidal effect against <i>H. pylori</i>.