A series of gold(I) complexes of the general composition [Au(naza)(PPh₃)] (1-8) was prepared and thoroughly characterized (e.g., electrospray ionization (ESI) mass spectrometry and multinuclear nuclear magnetic resonance (NMR) spectroscopy). The N1-deprotonated anions of 7-azaindole or its derivatives (naza) are coordinated to the metal centre through the N1 atom of their pyrrole ring, as proved by a single crystal X-ray analysis of the complexes [Au(3I5Braza)(PPh₃)] (7) and [Au(2Me4Claza)(PPh₃)]·½H₂O (8'). The in vitrocytotoxicity of the complexes 1-8 was studied against both the cisplatin-sensitive and -resistant variants of the A2780 human ovarian carcinoma cell line, as well as against the MRC-5 human normal fibroblast cell line. The complexes 4, 5, and 8, containing deprotonated 3-iodo-7-azaindole, 5-bromo-7-azaindole, and 2-methyl-4-chloro-7-azaindole (2Me4Claza), respectively, showed significantly higher potency (IC50 = 2.8-3.5 µM) than cisplatin (IC50 = 20.3 µM) against the A2780 cells and markedly lower effect towards the MRC-5 non-cancerous cells (IC50 = 26.0-29.2 µM), as compared with the mentioned A2780 cancer cells. The results of the flow cytometric studies of the A2780 cell cycle perturbations revealed a G₂-cell cycle phase arrest of the cells treated by the representative complexes 1 and 5, which is indicative of a different mechanism of action from cisplatin (induced S-cell cycle phase arrest). The stability of the representative complex 8 in the water-containing solution as well as its ability to interact with the reduced glutathione, cysteine and bovine serum albumin was also studied using ¹H and 31P-NMR spectroscopy (studied in the 50% DMF-d₇/50% D₂O mixture) and ESI+ mass spectrometry (studied in the 50% DMF/50% H₂O mixture); DMF = dimethylformamide. The obtained results are indicative for the release of the N-donor azaindole-based ligand in the presence of the used biomolecules.

Department of Cell Biology and Genetics Regional Centre of Advanced Technologies and Materials Faculty of Science Palacký University Olomouc Šlechtitelů 27 783 71 Olomouc Czech Republic

Department of Inorganic Chemistry Regional Centre of Advanced Technologies and Materials Faculty of Science Palacký University Olomouc 17 listopadu 12 771 46 Olomouc Czech Republic

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