Synthesis, characterization, and cytotoxic effects of new copper complexes using Schiff-base derivatives from natural sources

Copper(II) complexes are interesting for cancer treatment due to their unique properties, including their redox potential, possible coordination structures with different ligands, the most diverse geometries, and different biomolecule reactivity. The present work synthesized new copper(II) complexes with Schiff-base (imine) type ligands using natural aldehydes such as cinnamaldehyde, vanillin, or ethyl vanillin. The ligands were obtained through the reaction of these aldehydes with the amines 1,3-diaminopropane, 2,2-dimethyl-1,3-propanediamine, or 1,3-diamino-2-propanol and characterized by 1H and 13C NMR, FTIR and ESI-HRMS. The complexation reaction used copper(II) as perchlorate salt, obtaining six new copper(II) complexes. The complexes were characterized using FTIR, UV-vis, elemental analysis, ESI-HRMS, and EPR. In addition, the interaction with the copper(II) complexes and serum albumin was investigated by electronic absorption, showing complex incorporation in the albumin structure. The cytotoxicity of the complexes was evaluated using MTT assay in neuroblastoma cell lines SH-SY5Y, CHP 212, and glioblastoma LN-18, and presented EC50 values between 90 and 300 μM. Based on our results, a square-planar copper(II) complex derived from Schiff-base cinnamaldehyde was found here to possess significant potential as an anti-cancer treatment. Further investigation is required to explore this compound's benefits in cancer co-treatment approaches fully.