Four
dipeptide complexes of the type [PtX(2)(
dipeptide)] x H(2)O (X=Cl, I,
dipeptide=
l-methionylglycine, l-methionyl-
l-leucine) were prepared. The complexes were characterized by (1)H, (13)C, (195)Pt NMR and infrared spectroscopy, DTG and elemental analysis. From the infrared, (1)H and (13)C NMR spectroscopy it was concluded that
dipeptides coordinate bidentately via
sulfur and
amine nitrogen donor atoms. Confirmed with (13)C and (195)Pt NMR spectroscopy, each of the complexes exists in two diastereoisomeric forms, which are related by inversion of configuration at the
sulfur atom. The (1)H NMR spectrum for the
platinum(II) complex with
l-methionylglycine and chloro
ligands exhibited reversible, intramolecular inversion of configuration at the S atom; DeltaG( not equal)=72 kJ mol(-1) at coalescence temperature 349 K was calculated. In vitro cytotoxicity studies using the human tumor cell lines
liposarcoma, lung
carcinoma A549 and
melanoma 518A2 revealed considerable activity of the
platinum(II) complex with
l-methionylglycine and chloro
ligands. Further in vitro cytotoxic evaluation using human
testicular germ cell tumor cell lines 1411HP and H12.1 and colon
carcinoma cell line DLD-1 showed moderate cytotoxic activity for all
platinum(II) complexes only in the
cisplatin-sensitive cell line H12.1.
Platinum uptake studies using atomic absorption spectroscopy indicated no relationship between uptake and activity. Potential antitumoral activity of this class of
platinum(II) complexes is dependent on the kind of
ligands as well as on
tumor cell type.