Synthesis and biological activity of iron(II), iron(III), nickel(II), copper(II) and zinc(II) complexes of aliphatic hydroxamic acids

Aliphatic hydroxamic acids (HA) with varying numbers of carbon atoms, C₂, C₆, C₈, C₁₀, C₁₂ and C₁₇, and corresponding Fe(II), Fe(III), Ni(II), Cu(II) and Zn(II) complexes have been synthesized and characterized by various methods, including structural determination by single crystal X-ray diffraction and theoretical calculations. The biological activities of HA and their complexes have been assessed on a panel of pathogens, including eight bacteria strains and one fungus. The C₁₂ aliphatic HA displayed the lowest minimum inhibitory concentrations (MIC) towards several microbial strains and a selective antifungal activity. This antifungal selectivity was further improved considering the Ni(II), Cu(II) and Zn(II) complexes of C₁₂ HA showed higher IC₅₀ values, thus less impact on the SiHa human cell line viability. This work warrants further investigation to understand the underlying mechanism of action and potential biological applications of HA and the derived metal complexes.