Effect of electronic and steric properties of 8-substituted quinolines in gold(III) complexes: Synthesis, electrochemistry, stability, interactions and antiproliferative studies.

In this work the synthesis and characterization of new gold(III) complexes with quinoline ligands are described. These complexes contain different steric and electronic properties of the donor atom at 8-position of the quinoline in order to modulate their stability and their biological activity. Their redox potential, stability in organic and aqueous solvents, and their biological activity in a panel of six different human tumor cell lines are also presented. In addition, interaction studies of the complexes with model biological molecules (pBR322 and L-acetyl-N-cysteine) were carried out, suggesting that their main target are proteins. From these studies, we have found that the gold(III) complex with an N-tosyl-8-aminoquinoline ligand is the most active complex in all the tumor cell lines, including the cisplatin resistant T-47D and WiDr cell lines. Moreover, this complex showed to be the most stable compound in DMSO and saline solution, even after several hours.