Highly Antiproliferative Latonduine and Indolo[2,3-c]quinoline Derivatives: Complex Formation with Copper(II) Markedly Changes the Kinase Inhibitory Profile

[Image: see text] A series of latonduine and indoloquinoline derivatives HL(1)–HL(8) and their copper(II) complexes (1–8) were synthesized and comprehensively characterized. The structures of five compounds (HL(6), [CuCl(L(1))(DMF)]·DMF, [CuCl(L(2))(CH(3)OH)], [CuCl(L(3))]·0.5H(2)O, and [CuCl(2)(H(2)L(5))]Cl·2DMF) were elucidated by single crystal X-ray diffraction. The copper(II) complexes revealed low micro- to sub-micromolar IC(50) values with promising selectivity toward human colon adenocarcinoma multidrug-resistant Colo320 cancer cells as compared to the doxorubicin-sensitive Colo205 cell line. The lead compounds HL(4) and 4 as well as HL(8) and 8 induced apoptosis efficiently in Colo320 cells. In addition, the copper(II) complexes had higher affinity to DNA than their metal-free ligands. HL(8) showed selective inhibition for the PIM-1 enzyme, while 8 revealed strong inhibition of five other enzymes, i.e., SGK-1, PKA, CaMK-1, GSK3β, and MSK1, from a panel of 50 kinases. Furthermore, molecular modeling of the ligands and complexes showed a good fit to the binding pockets of these targets.