DNA/BSA BINDING STUDY OF DINUCLEAR GOLD(III) COMPLEXES WITH AROMATIC NITROGEN-CONTAINING HETEROCYCLES AS BRIDGING LIGANDS

In recent decades, a special attention has been devoted to gold(III) complexes as potential antitumor agents due to their structural similarity to platinum(II) complexes. One of the possible mechanisms of the mode of antitumor activity of gold(III) complexes could include their interaction with DNA. However, the effectiveness of the therapeutic agents also depends on the degree of its binding to proteins present in the blood plasma, because, in this way, it is transported to the cell. Considering this, we investigated the interactions of three dinuclear gold(III) complexes of the general formula [{AuCl3}2(μ– L)], L = 4,4’-bipy (4,4’-bipyridine, Au1), bpe (1,2-bis(4-pyridyl)ethane, Au2) and dpe (1,2-bis(4- pyridyl)ethene, Au3) with calf thymus DNA (ct-DNA) and bovine serum albumin (BSA). The main aim of the study was to evaluate the binding affinities of gold(III) complexes Au1–3 towards these biomolecules for possible insights on their mode of biological activity. The values of binding constants (KA) of Au1–3 to ct-DNA are higher than those for BSA, indicating greater affinity of the complexes towards this nucleic acid. The partition coefficient (logP) value for Au1 is higher compared to the corresponding values for the other two complexes, what is in accordance with a higher cellular uptake efficiency of this complex.