Synthesis, structures, DNA-binding and anticancer activities of some copper(I)-phosphine complexes

Copper(I) complexes with a phenanthroline-phosphine set of ligands were synthesized by refluxing methanolic solutions of CuBr2 with at least a four fold molar excess of the phosphine ligands, followed by the treatment of the formed {CuBr(PR3)(3) complexes [R = phenyl (1a), 4-fluorophenyl (1b), cyclohexyl (1c) or 4-methoxyphenyl (1d)]} with 1 molar equivalent of 1,10-phenanthroline in DCM. The tris(4-methoxyphenyl)phosphine ligand afforded the complex [Cu(P[C6H4-4-OMe](3))(2)(phen)]Br (2d), while the other phosphines produced complexes with the general formula CuBr(PR3)(phen) [R = phenyl (2a), 4-fluorophenyl (2b) or cyclohexyl (2c)]. The new complexes were characterized by elemental analysis, 31P NMR spectroscopy and mass spectrometry. Additional confirmation of the structures of 1b, 2b, 2c and 2d were determined by single crystal X-ray diffraction. A DNA-binding study of the complexes 2a2d against ct-DNA showed binding constant values that correspond to the intercalation mode of binding. The notable variations in the binding constants of the complexes suggest some contribution from the phosphine ligands. The lipophilicity of the complexes was evaluated theoretically and the calculated log P value of complex 2d is positive and high, being in the same range of relatively easy membrane penetrating drugs. The calculated log P values of complexes 2a2c are negative, indicating a low membrane permeability. Complexes 2a2d were examined against four different cancer cell lines. The choice of the phosphine ligand appears to influence the copper(I)-phosphine anticancer activities against the different cancer cell lines. The data suggested that complexes 2a and 2d show potential anticancer activity against prostate and breast cancers. The four copper complexes were docked against four different proteins associated with prostate or breast cancers activities, highlighting some of the structural-DNA interactions. (C) 2018 Elsevier Ltd. All rights reserved.