Synthesis, characterization and anticancer activities of transition metal complexes with a nicotinohydrazone ligand

The reaction of divalent transition metal salts and (E)-N'-(1-(pyridin-2-yl)ethylidene)nicotinohydrazide (penh) led to the formation of [Mn(penh)₂] (complex 1), [Co(penh)₂] (complex 2), [Cu(penh)₂] (complex 3) and [Cd (penh)₂] (complex 4) complexes. The four complexes were characterized using elemental analyses, infrared spectra and single-crystal X-ray diffraction analyses. Subsequently, the complexes were used for in vitro cell level experiments to determine potential antitumor effects. The results demonstrated that the complexes exhibited a similar structure; however, they were crystallized with distinct space groups. In comparison with the uncomplexed penh ligand, all four complexes were able to markedly decrease the proliferation rate of various types of tumor cell, including the human lung cancer cell line A549, human gastric cancer cell line BGC823 and human esophageal cancer cell line Eca109, in a concentration-dependent manner. Furthermore, the complexes promoted tumor cell apoptosis, as demonstrated in the apoptosis assay, and this was confirmed using electrophoresis.