DNA Binding, Nuclease/Photonuclease, and Phototoxicty Properties of Water Soluble Silicon (IV) Phthalocyanine

Photodynamic therapy (PDT) is known as a method in which photosensitizers produce reactive oxygen species in the presence of light and oxygen, leading to cell death. In this paper, DNA interaction properties of bis[4-({8)-[3-(trimethylamino)phenoxy]octyl}oxy)] substituted silicon (IV) phthalocyanine (GsB-SiPc) were examined using a UV-Vis spectrophometer and agarose gel electrophoresis techniques. Afterwards, cytotoxic/phototoxic effects of GsB-SiPc were examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays on A549 cells. The results showed that GsB-SiPc bound to ct-DNA via a groove binding mode. In nuclease/photonuclease experiments, GsB-SiPc had low nuclease activity in the dark but it showed high photonuclease activity in the presence of light, depending on compound concentration and light dose. In addition, GsB-SiPc demonstrated remarkable phototoxicity toward human lung adenocarcinoma (A549) cell line at 50 and 100 µM in the presence of light. The in vitro data revealed the potential of GsB-SiPc as a photodynamic therapy agent for the treatment of lung cancer. These findings need to be supported by further studies.