Synthesis of Potential Platinum(II) Anti-tumor Complexes: Complexes containing Bidentate Pyridyl and Imidazolyl Donors

The synthesis of complexes PtCl2(L2) of some bidentate ligands (L2) containing pyridyl rings connected by a carbon atom, di-2-pyridylmethane (py2CH2) and py2SEt2, and containing both pyridyl and imidazolyl rings, (2,2'-pyridyl)imidazole (pyIm) and py-NMeIm. Preliminary screening of the complexes, including the 2,2'-bipyridyl complex and cis-PtL2Cl2 (L = NH3, pyridine), on cultures of L1210 mouse leukemia cells has been carried out. Results were obtained over a range of concentrations required to give lo-90% inhibition of growth, and the expected sigmoidal curves (percent growth vs. concentration) were obtained. The complex cis-Pt(pyridine)2Cl2 gave an I.D.50 value higher than that of cis-Pt(NH3)2C12, consistent with earlier studies showing that this complex has lower activity than cis-Pt(NH3)2Cl2 against Ehrlich ascites and Sarcoma 180 tumors in mice. The complex Pt(pyIm)C12. H20 gave an I.D.50 value similar to that of cis- Pt(NH3)2Cl2, and below values for the other complexes. These results suggest that further testing with tumor bearing animals is warranted for Pt(pyIm)C12. H20.