Multinuclear NMR spectroscopy and antitumor activity of novel platinum(II) complexes with 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidines

Novel platinum(II) complexes with 5,7-disubstituted-1,2,4-triazolo[1,5-alpyrimidines have been synthesized and characterized by infrared and multinuclear magnetic resonance spectroscopic techniques (H-1, C-13, N-15, Pt-195). The complexes are of two types: [PtC](2)(L)(2)] and [PtCl2(NH3)(L)], where L=5,7-diphenyl-1,2,4-triazolo[1,5-alpyrimidine (dptp) and 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp). Significant N-15 NMR upfield shifts (92-95 ppm) were observed for N(3) atom indicating this nitrogen atom as a coordination site. The molecular structure suggest that Pt(II) ion has the square planar geometry with N(3) bonded 5,7-disubstituted-1,2,4-triazolo[1,5-a]pyrimidines, N-bonded second ligand (NH3 for cis-[PtCl2(NH3)(L)j or, respectively, 5,7-disubstituted-1,2,4-triazolo[1,5-alpyrimidines for cis-[PtCl2L2]) and two cis chloride anions. The antiproliferative activity in vitro of complexes (1-4) have been tested against the cells of four human cell lines: SW707 rectal adenocarcinoma, A549 non-small cell lung carcinoma, T47D breast cancer and HCV29T bladder cancer. The results indicate a moderate antiproliferative activity of (4) against the cells of rectal, breast and bladder cancer and a marked and selective cytotoxic effect of (1-3) against the cells of all studied human cancer lines. (C) 2003 Elsevier Inc. All rights reserved.