Synthesis, Characterization and in Vitro Antitumor Activity of Platinum(II) Oxalato Complexes Involving 7-Azaindole Derivatives as Coligands

The platinum(II) oxalato complexes [Pt(ox)(naza)(2)] (1-3) were synthesized and characterized by elemental analysis (C, H, N), multinuclear NMR spectroscopy (H-1, C-13, N-15, Pt-195) and electrospray ionization mass spectrometry (ESI-MS); naza = 4-chloro-7-azaindole (4Claza; 1), 3-bromo-7-azaindole (3Braza; 2) or 4-bromo-7-azaindole (4Braza; 3). The prepared substances were screened for their in vitro antitumor activity on the osteosarcoma (HOS) and breast adenocarcinoma (MCF7) human cancer cell lines, where 2 showed moderate antitumor effect (IC50 = 27.5 mu M, and 18.3 mu M, respectively). The complex 2 was further tested on a panel of six others human cancer cell lines, including the malignant melanoma (G361), cervix carcinoma (HeLa), ovarian carcinoma (A2780), cisplatin-resistant ovarian carcinoma (A2780R), lung carcinoma (A549) and prostate adenocarcinoma (LNCaP). This substance was found to be moderate antitumor effective against G361 (IC50 = 17.3 mu M), HeLa (IC50 = 31.8 mu M) and A2780 (IC50 = 19.2 mu M) cell lines. The complex 2 was also studied by NMR for its solution stability and by ESI-MS experiments for its ability to interact with biomolecules, such as cysteine, glutathione or guanosine 5'-monophosphate.