Synthesis, spectroscopic characterization and in vitro antibacterial and antiviral activities of novel silver(I) complexes with mafenide and ethyl-mafenide

Abstract

Two novel silver(I) complexes with the antibacterial sulfa drugs mafenide (Maf) and ethyl-mafenide (eMaf) are presented in this article. Elemental analysis indicated the 1:1 metal:ligand compositions AgC7H9N2O2S for Ag-Maf and AgC8H11N2O2S for Ag-eMaf. Infrared (IR), and 1H and 13C nuclear magnetic resonance (NMR) spectroscopic analyses indicated coordination of the sulfa drugs to silver(I) by the nitrogen and oxygen atoms of the deprotonated sulfonamide (SO2NH) group in a bidentate chelate mode. The proposition of the coordination mode of the sulfa drugs to silver(I) was also supported by a combination of experimental and theoretical (DFT) data. The Ag-Maf and Ag-eMaf complexes exhibited antibacterial activity over Staphylococcus aureus, Burkholderia cepacia, Staphylococcus epidermidis, and Pseudomonas aeruginosa aerobic bacteria, with MIC (minimum inhibitory concentration) in the range 21.3–170 µmol L−1, being comparable to the commercial drug silver-sulfadiazine (SSD). Antiviral studies against Chikungunya virus (CHIKV) showed that the complexes exhibit anti-CHIKV activity at non-cytotoxic concentrations to the host cells. Biophysical studies based on gel electrophoresis indicated that the complexes do not interact with albumin and lysozyme, which suggests that proteins are not the main targets of the compounds.