Liquid chromatographic and infrared studies on ethylenediamineplatinum(II) guanosine complexes

The complexes of platinum are of great interest in anticancer research and chemotherapy. The investigation of the binding properties of the different adducts formed from platinum complexes and DNA bases by liquid chromatographic separation and the spectroscopic identification of chromatographic fractions frequently requires a large amount of analytical material. It is shown that the combination of ion-pair reversed-phase chromatography and infrared spectroscopy combined with theoretical methods like molecular modelling and normal coordinate analysisi allows the separation and characterization of 7 ethylenediamineplatinum(II) (Pt(en)) guanosine complexes in Pt(en) guanosine reaction mixtures in the micro range. The classification of the monofunctional N1, N3, N7 and the bifunctional N7-N1 (two species), N7-N3, N7-N7 adducts was confirmed with the quantitative interpretation of the chromatographic peak area in dependence of the different Pt(en)/guanosine ratio and the thermodynamic stability of the adduct compounds obtained by molecular modelling calculations. Additionally it was distinguished between the N7 and N1/N3 coordination of the Pt(en) guanosine complexes by vibrational spectroscopy and normal coordinate analysis.