SYNTHESIS, CHARACTERIZATION, DFT MODELING AND IN VITRO ANTIMYCOBACTERIAL ACTIVITY ASSAYS OF A SILVER(I)-ISONIAZID COMPLEX

In the present work, a silver(I) complex with the antimycobacterial drug isoniazid (inh) is described. Elemental and thermogravimetric analyses confirmed a 1:1 metal:ligand ratio for the silver-isoniazid (Ag-inh) complex with molecular composition AgC₆H₇N₃O·NO₃. Infrared (IR) analysis suggests a bidentate coordination of isoniazid to silver by the nitrogen of the NH₂ group and by the oxygen of the C=O group, and also confirms the presence of free nitrate anion. Coordination by the NH₂ group was reinforced by NMR measurements. Computational simulations using the density functional theory (DFT) reinforced that the ligand coordinates to the silver atom by the NH₂ and C=O groups. The silver complex presented a minimal inhibitory concentration (MIC₉₀) of 0.78 µg/mL against the standard Mycobacterium tuberculosis strain H37Rv. The data reported herein warrants further investigation on Ag-inh complex as a potential agent against tuberculosis.

Keywords:
metallodrugs; bioinorganic chemistry; molecular modeling; Mycobacterium tuberculosis ; antibacterial assays