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

Abstract

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.