Copper Chelation by Syringic Hydrazones: A Promising Strategy for Combating Oxidative Stress-Related Diseases

Oxidative stress is a critical factor in vascular damage and the development of diseases such as atherosclerosis. This study investigates the complexation properties of two syringic hydrazones, (E)-4-Hydroxy-3,5-dimethoxybenzaldehyde -1,3-benzothiazol-2-ylhydrazone 1 and (E)-4-Hydroxy-3,5-dimethoxybenzaldehyde phthalazin-1-ylhydrazone hydrochloride 2, with copper ions (CuSO4·5H2O and CuCl2·2H2O). Using UV spectrophotometry, we determined stability constants and stoichiometries of the complexes formed. Compound 1 forms three distinct types of complexes (ML, ML2, and M2L) with higher stability constants compared to those formed by compound 2, particularly when using CuCl2·2H2O. These findings extend our previous work, where syringic hydrazones demonstrated potent antioxidant properties through scavenging DPPH● and ABTS●+ radicals, inhibiting superoxide anion generation, and reducing TBARS formation in human cell-mediated LDL oxidation. These results highlight the dual potential of syringic hydrazones as radical scavengers and metal chelators.