Insight into the cytotoxicity of polynuclear Cu(I) camphor complexes

Three new polynuclear Cu(I) camphor complexes, [(CuBr)2{(p-H2NC6H4)NC10H14O}]n (2d), [(CuCl)4{m-C6H4(NC10H14O)2}]n (5f) and [(CuBr)4{p-C6H4(NC10H14O)2}]n (6e), were synthesized and their cytotoxicity, as well as that of the former reported compounds [(CuX)2(YNC10H14O)]n (X = Cl; Y = NMe2 (1a), NH2 (1b), NHMe (1c), (H2NC6H4)NC10H14O (1d); X = Br; Y = NMe2 (2a)), [{Cu(Me2NNC10H14O)}2(μ-X)2] (X = Cl (3a), Br (4a)) and [(CuCl)4{p-C6H4(NC10H14O)2}] (5f), were evaluated against the human colon adenocarcinoma cancer cell line HT29 using the colorimetric method (MTT assay). The calculated IC50 values indicate that all the complexes have cytotoxic activity that ranges from high to moderate or low, depending on the characteristics of the camphor ligand and the halide co-ligand. The complexes [(CuCl)4{m-C6H4(NC10H14O)2}] (5f, IC50 = 32.0 + 1.1 μM) and [(CuCl)2(H2NNC10H14O)]n (1b, IC50 = 37.0 ± 1.1 μM) display the lowest IC50 values, while [(CuBr)2{(p-H2NC6H4)NC10H14O}]n (2d, IC50 = 119.9 ± 1.1 μM) displays the highest one. The IC50 value for 5f approaches that of cisplatin (26.3 + 1.1 μM). No cytotoxic activity was detected for the camphor compounds H2NNC10H14O (b) and m-C6H4(NC10H14O)2 (f), used as ligands.In selected cases, the copper accumulation in the cells was evaluated. No direct relationship was found between the copper uptake and the cytotoxicity of the complexes.

Graphical abstractThe cytotoxic activity of Cu(I) camphor complexes against the cancer cell line HT29 depends on their structure, characteristics of the camphor ligand and the halide co-ligand. The polymer [(CuCl)4{m-C6H4(NC10H14O)2}] displays a IC50 value similar to that of cisplatin.Figure optionsDownload full-size imageDownload as PowerPoint slide