Interaction of Phenanthroline-Containing Copper Complexes with Model Phospholipid Membranes

Medicinal Inorganic Chemistry has provided oncology with metallodrugs for cancer treatment, including several promising candidate drugs. In particular, copper(II) coordination compounds with phenanthroline stand out as potential anticancer agents. In this work, we used Differential Scanning Calorimetry and Electron Spin Resonance to investigate the interaction of the copper phenanthroline complexes [Cu(phen)]2+ and [Cu(L-dipeptide)(phenanthroline) (L-dipeptide: L-Ala-Gly and L-Ala-Phe)) with model lipid membranes (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC, and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) sodium salt, DPPG). Our results showed that the complexes interact with the membrane models, fluidizing them. The [Cu(phen)]2+ presented a different localization than the free ligand phen. The dipeptide modulated the localization of the complex in the membrane and the modifications induced in the physicochemical properties of the lipid vesicles. A stronger interaction with DPPG anionic membranes was observed, which mimic membranes with negatively charged surfaces, as found on several tumor cells.