Low-dimensional compounds containing bioactive ligands. Part XIV: High selective antiproliferative activity of tris(5-chloro-8-quinolinolato)gallium(III) complex against human cancer cell lines

Abstract

Four gallium(III) complexes, [Ga(ClQ)₃]⋅MeOH (1 - MeOH), [Ga(ClQ)₃] (1), [Ga(BrQ)₃] (2), [Ga(dIQ)₃] (3) and [Ga(CQ)₃] (4), were prepared (H-ClQ = 5-chloro-8-quinolinol, H-BrQ = 7-bromo-8-quinolinol, H-dIQ = 5,7-diiodo-8-quinolinol, H-CQ = 5-chloro-7-iodo-8-quinolinol) and characterised by elemental analysis, IR and NMR spectroscopy. Single crystal structure analysis of 1 - MeOH confirmed that the complex has a molecular structure with gallium(III) metal ion coordinated in mer-fashion by N- and O-donor atoms of three ClQ ligands. Stability of all complexes in DMSO was proved by ¹H NMR spectroscopy. The in vitro antiproliferative activity of 1 was evaluated against the A2780, MBA-MB-231 and HCT116 cell lines. Complex 1 displays higher antiproliferative activity (IC₅₀ values in the range 2.1-6 μm) compared to the ClQ ligand and cisplatin; and a significant selective antiproliferative potency (IC₅₀ = 136 μm, for normal MRC5pd30 cell line). Radical scavenging experiments revealed that complex 1 exhibits the highest antioxidant activity of the prepared complexes as well as the ligands.

Keywords: 5,7-Diiodo-8-quinolinol; 5-Chloro-7-iodo-8-quinolinol; 5-Chloro-8-quinolinol; 7-Bromo-8-quinolinol; Antiproliferative activity; Antiradical activity; Gallium(III) complexes.