Synthesis, structure, spectra, cytotoxicity and photo induced NO release of four isomeric nitrosylruthenium complexes

Four isomeric nitrosyl ruthenium complexes [RuCl(2mqn)(Val)(NO)] (1–4) were prepared (2mqn, 2-methyl-8-hydroxyquinoline; Val, l-valine) and characterized by ¹H NMR, ¹³C NMR, absorption spectrum, electrospray ionization mass spectrometry, and X-ray crystal diffraction. Time-resolved FT-IR and fluorescence spectroscopy were used to monitor photo-induced NO release in solution, while NO released in living cells was imaged using a selective fluorescent probe. The isomeric complexes showed different levels of cytotoxicity against HeLa cells, and slightly photo-enhanced anti-proliferative activity was observed. The isomeric complexes 1–4 inhibited the growth of HeLa cells by inducing apoptosis and promoted cell cycle arrest in the S phase. Furthermore, they showed relatively lower cytotoxicity against the human liver cell line HL-7702. The different spatial configurations of the complexes is close related with the selective binding of the isomeric complexes with serum albumin, which provide insight into the potential applications of the nitrosyl ruthenium complexes.