Antimicrobial Activity of Diphenyl Pyridine Phosphine Gold(I)-thiolate Compounds and their Molecular Docking With Thioredoxin Reductase Enzyme

Background and Objectives Despite several studies and abundant efforts to control microbial agents, humans have not yet been able to eliminate these agents. Recent studies have shown that gold(I) compounds are promising candidates for making antimicrobial drugs. The interest in gold-based drugs is increasing day by day. Inhibition of the thioredoxin reductase (TrxR) enzyme is the most important biological target for antimicrobial gold(I) compounds. Subjects and Methods In this study, the antimicrobial properties of five diphenyl pyridine phosphine gold(I)-thiolate compounds against gram-positive bacteria (P. aeruginosa, E. coli), gram-negative bacteria (S. aureus, B. subtilis), a fungus (C. albicans), and a yeast (S. cerevisiae) were evaluated. The molecular docking studies were carried out using AutoDock 4.2 to find the best compound in the active site of the TrxR enzyme (PDB ID: 4CBQ). Results The gold(I) compounds had a minimum inhibitory concentration (MIC) value ranged from 3 to 100 μg/mL. The most active compound was Au3 which had a MIC of 3.89, 3.15, 4.36, 5.44, 6.13, and 8.37 μg/mL against P. aeruginosa, E. coli, S. aureus, B. subtilis, C. albicans and S. cerevisiae, respectively. Conclusion The gold(I) compounds act better on gram-negative bacteria and yeast strains compared to auranofin as antirheumatic drug. These compounds, especially the Au3, are potentially valuable for the control of antimicrobial agents.