Copper complexes of imidazole-2-, pyrrole-2-and indol-3-carbaldehyde thiosemicarbazones: Inhibitory activity against fungi and bacteria

Copper complexes of thiosemicarbazones of imidazole-2-carbaldehyde, pyrrole-2-carbaldehyde and indole-3-carbaldehyde were synthesised and characterised. The antimicrobial properties of the free ligands and their complexes were evaluated against yeasts, moulds and bacteria (Gram-positive and Gram-negative). Some copper chelates exhibited a moderate inhibitory activity, better than that of the corresponding free ligands. In particular, the pyrrole derivative [Cu(HL2)2] proved to be a wide spectrum agent, showing an interesting inhibition of the growth of all Gram-positive bacteria and fungi tested at concentrations of 12–50 microg/mL. In contrast, a selective effect was observed for imidazole and indole chelates against fungi and Gram-positive bacteria, respectively.