Anticancer gallium(III) complexes with halogen- and nitroderivatives of 8- hydroxyquinoline

Six gallium(III) complexes with halogen- or nitroderivatives of 8-hydroxyquinoline, [Ga(ClQ)3] (1), [Ga(BrQ)3] (2), [Ga(dIQ)3] (3), [Ga(CQ)3] (4), [Ga(NQ)3] (5) and [Ga(ClNQ)3]·MeOH were prepared as possible anticancer drugs (HClQ = 5-chloro-8-hydroxyquinoline, HBrQ = 7-bromo-8-roxyquinoline, HdIQ = 5,7-diiodo-8-hydroxyquinoline, HCQ = 5-chloro-7-iodo-8-ydroxyquinoline, HNQ = 5-nitro-8-hydroxyquinoline and HClNQ = 5-chloro-7-nitro-8-hydroxyquinoline). X-ray single crystal structure analysis of [Ga(ClQ)3]·MeOH (1 – MeOH) and 5 showed that both complexes are molecular complexes with Ga(III) coordinated in mer-fashion by N- and O-donor atoms of three ClQ and NQ ligands, respectively. The in vitro antiproliferative activity of 1 and 5 was evaluated against the human ovarian carcinoma cisplatin-sensitive A2780, breast carcinoma MDA-MB-231, and human colorectal carcinoma HCT-116 cell lines and their selectivity was verified on MRC5 pd30 cells from normal lung tissue. Complexes 1 and 5 display higher antiproliferative activity (IC50 values in the range 2.1–7 μM) compared to the respective ligands, used Ga(III) salts, cisplatin and oxaliplatin, and a significant selective antiproliferative potency (IC50 = 149 and 32 μM, respectively for MRC5pd30 cell line).