Photoinduced DNA Cleavage and Photocytotoxic of Phenanthroline-Based Ligand Ruthenium Compounds

The photophysical and biological properties of two new phenanthroline-based ligand ruthenium complexes were investigated in detail. Their DNA interaction modes were determined to be the intercalation mode using spectra titration and viscosity measurements. Under irradiation, obvious photo-reduced DNA cleavages were observed in the two complexes via singlet oxygen generation. Furthermore, complex 2 showed higher DNA affinity, photocleavage activity, and singlet oxygen quantum yields than complex 1. The two complexes showed no toxicity towards tumor cells (HeLa, A549, and A375) in the dark. However, obvious photocytotoxicities were observed in the two complexes. Complex 2 exhibited large PIs (phototherapeutic indices) (ca. 400) towards HeLa cells. The study suggests that these complexes may act as DNA intercalators, DNA photocleavers, and photocytotoxic agents.

Automated summary

The study found that the two new phenanthroline-based ligand ruthenium complexes show good performance in interacting with DNA, with complex 2 demonstrating higher DNA affinity and photocleavage activity. The complexes showed no toxicity towards tumor cells in the dark, but demonstrated obvious photocytotoxicities, with complex 2 exhibiting large phototherapeutic indices towards HeLa cells. These complexes may act as DNA intercalators, DNA photocleavers, and photocytotoxic agents.