Synthesis, cytotoxic and antitubercular activities of copper(II) complexes with heterocyclic bases and 3-hydroxypicolinic acid

•Three new complexes with mixed ligands were synthesized and characterized.•The copper complexes are more cytotoxic than the free ligands.•The compounds were also evaluated against M. tuberculosis, and one of compounds displays good antimycobacterial activity.

Two new copper(II) complexes with the deprotonated ligand 3-hydroxypicolinic acid (3-HPA) and heterocyclic bases (1,10-phenanthroline – phen or 2,2′-bipyridine – bpy) were synthesized. [Cu(3-HPA)(phen)ClO4] I and [Cu(3-HPA)(bpy)ClO4] II were characterized by elemental analyses, conductivity measurements, FT-IR, UV–Vis, EPR and High-resolution Electrospray Ionization Mass Spectrometry (HRESIMS). The results indicate that the geometry around the copper ion is distorted square-pyramidal, and that the copper ion is coordinated to 3-HPA via oxygen and nitrogen atoms, and to heterocyclic bases via their two nitrogen atoms. A perchlorate ion weakly bonded occupies the apical position, completing the metal coordination sphere. In this work, the compound [Cu(3-HPA)2] III was also synthesized using a new method, different from that described in the literature. The cytotoxic activity of these compounds against tumor and normal cell lines was investigated. Complex I exhibited a strong antitumor activity, being the most active in the series of studied complexes. The compounds were also evaluated for activity against Mycobacterium tuberculosis, and the complex I displays good antimycobacterial activity, while compounds II and III were only moderately active.

Graphical abstractNew copper complexes with the deprotonated ligand 3-hydroxypicolinic acid (3-HPA) and heterocyclic bases (1,10-phenanthroline – phen or 2,2′-bipyridine – bpy) were synthesized. The cytotoxic activity of these compounds against tumor and normal cell lines was investigated. [Cu(3-HPA)(phen)ClO4] exhibited a strong antitumor activity, being the most active in the series of studied complexes. The compounds were also evaluated for activity against Mycobacterium tuberculosis.Figure optionsDownload full-size imageDownload as PowerPoint slide