New palladium(II) and platinum(II) 5,5-diethylbarbiturate complexes with 2-phenylpyridine, 2,2 '-bipyridine and 2,2 '-dipyridylamine: synthesis, structures, DNA binding, molecular docking, cellular uptake, antioxidant activity and cytotoxicity

Novel palladium(II) and platinum(II) complexes of 5,5-diethylbarbiturate (barb) with 2-phenylpyridine (Hppy), 2,2'-bipyridine (bpy) and 2,2'-dipyridylamine (dpya) have been prepared and characterized by elemental analysis, IR, UV-Vis, NMR and ESI-MS. Single-crystal diffraction measurements show that complex 1 consists of binuclear [Pd-2(mu-barb-kappa N,O)(2)(ppy-kappa N,C)(2)] moieties, while complexes 3-5 are mononuclear, [M(barb-.kappa)(2)(L-kappa N,N')] (L = bpy or dpya). 6 has a composition of [Pt(dpya-kappa N,N')(2)][Ag(barb-kappa N)(2)](2)center dot 4H(2)O and 2 was assumed to have a structure of [Pt(barb-kappa N)(Hppy-kappa N)(ppy-kappa N,C)]center dot 3H(2)O. The complexes were found to exhibit significant DNA binding affinity by a non-covalent binding mode, in accordance with molecular docking studies. In addition, complexes 1 and 2 displayed strong binding with supercoiled pUC19 plasmid DNA. Cellular uptake studies were performed to assess the subcellular localization of the selected complexes. A moderate radical scavenging activity of 1 and 2 was confirmed by DPPH and ABTS tests. Complexes 1, 2, and 5 showed selectivity against HT-29 (colon) cell line.