Synthesis, characterization and biological activity of novel copper complexes containing a β-carboline derivative and amino acids

Copper complexes have long been considered as a promising class of anticancer or antibacterial therapeutics. In this paper, two novel copper(II) complexes containing a β-carboline derivative and amino acids, namely [Cu(1-Im-βc)(L-Val)]ClO4·0.5H2O (Cu1) and [Cu(1-Im-βc)(L-Phe)]ClO4·0.5H2O (Cu2), where 1-Im-βc = 1-(2-imidazolyl)-β-carboline, L-Val = L-valine, and L-Phe = L-phenylalanine, were designed and synthesized. The complexes were characterized by elemental analysis, infrared spectroscopy, molar conductivity measurements, and mass spectrometry to determine their spatial structures and compositions. Both complexes bind to DNA by insertion. The complexes also show a good affinity for human serum albumin (HSA). In addition, the antitumor activity of the two complexes against lung cancer cells (A549), cervical cancer cells (HeLa), and breast cancer cells (MBA-MD-231) is significantly superior to that of the traditional antitumor drug, cisplatin. Finally, the anticancer mechanism results show that the complexes can induce apoptosis in HeLa cells, which is associated with mitochondrial damage, oxidative stress caused by reactive oxygen species (ROS) production, and activation of the caspase protein family. This study demonstrates that the introduction of aromatic heterocyclic alkaloid ligands with a broad spectrum of biological activities and water-soluble amino acid ligands into copper complexes can regulate their amphiphilic properties and biological activity, so as to obtain highly efficient copper-based therapeutics.