Platinum(II) complexes with R2edda ligands (R = Me, Et, n-Pr; edda = ethylenediamine-N,N′-diacetate): Synthesis and characterization

Three novel complexes of platinum(II) with R2edda bidentate ligands [PtCl2(R2edda)] (R = Me, Et, n-Pr; edda = ethylenediamine-N,N′-diacetate; 1–3), are synthesized and characterized by IR and NMR spectroscopy and elemental analysis. All complexes exist in three stereoisomeric forms (R,R), (S,S) and (R,S)(S,R). In addition crystal structure of one platinum(IV) complex [PtCl4((n-Pr)2edda)], 4, is presented. Furthermore, in order to assign stereoisomers of 1–3, a reduction of racemic [PtCl4(Et2edda)] by ascorbic acid to [PtCl2(Et2edda)] (2) was performed and analyzed by 1H NMR. Time-depending 1H NMR spectroscopic experiments were implemented to study the stability of ethylenediamine-N,N′-diacetate diesters. Finally, the in vitro cytotoxic activity of complexes 1–3 was studied on 11 tumor cell lines, 518A2 (melanoma), 8505C (human thyroid carcinoma), A253 (head and neck tumor), A431 (cervix), A549 (lung), A2780 (ovarian), MCF-7 (breast) and HT-29, HCT-8, DLD-1, SW1736 (all colon) by the SRB colorimetric assay method. Complex 3 showed the highest action against ovarian (A2780) cells with an IC50 value 51 ± 1 μM.

Graphical abstractThree novel [PtCl2(R2edda)] complexes (R = Me, Et, n-Pr; edda = ethylenediamine-N,N′-diacetate; 1–3) are synthesized and characterized. Hydrolytic stability of ligand precursors, crystal structure of [PtCl4((n-Pr)2edda)] and reduction of rac-[PtCl4(Et2edda)] are presented. The in vitro cytotoxic activity of complexes 1–3 was studied on 11 tumor cell lines.Figure optionsDownload full-size imageDownload as PowerPoint slide