Synthesis, characterization and the anticancer activity of six lanthanides(III) complexes with 5,7-dihalogenated-8-quinolinol and 2,2’-bipyridine derivatives

Six new lanthanide(III) complexes, namely [Gd III (QL1) 3 (BL1)] ( Gd1 ), [Gd III (QL1) 3 (BL2)] ( Gd2 ), [Lu III (QL2) 2 (BL3)(NO 3 )] ( Lu1 ), [Lu III (QL2) 2 (BL2)(NO 3 )] ( Lu2 ), [Yb III (QL3) 2 (BL2)(NO 3 )] ( Yb1 ), and [Yb III (QL4) 2 (BL2)(NO 3 )] ( Yb2 ) coordinated with 5,7-dibromo-8-quinolinol (H-QL1), 5,5′-dimethyl-2,2′-bipyridyl (BL1), 4,4′-di-tert-butyl-2,2′-bipyridine (BL2), 5,7-dibromo-2-methylquinolin-8-ol (H-QL2), 2,2′-bipyridine (BL3), 5,7-dichloro-8-hydroxyquinoline (H-QL3), and 5,7-dichloro-8-hydroxy-2-methylquinoline (H-QL4), were prepared. The Ln III complexes Gd1 , Gd2 , Lu1 , Lu2 , Yb1 and Yb2 showed high cytotoxicity toward cervical (HeLa), ovarian (SK-OV-3) and lung (NCI-H460) cancer cells with IC 50 values from 0.18 ± 0.14 to 8.02 ± 1.71 μM. In addition, Yb1 and Yb2 impaired mitochondrial functions, decreased mitochondrial membrane potential, and altered the levels of mitochondrial related-proteins. The apoptosis-inducing capability was in the order of Yb2 > Yb1 . Such observed differences in biological activities could be caused by the electronic effect of the methyl group of H-QL4 in Yb2 . Graphic abstract