We have synthesized magnesium (II) phthalocyanines (2a, 3a) and their water-soluble derivatives (2b, 3b). The ct-DNA binding and supercoiled plasmid DNA nuclease properties of the water-soluble compounds were investigated using different methods. All of these results showed that 2b had promising potential as a photosensitizer agent for photodynamic therapy.

In this study, magnesium (II) phthalocyanines (2a, 3a) and their water-soluble derivatives (2b, 3b) were synthesized via multistep reactions. The structures of these phthalocyanines were identified by FT-IR, NMR, MALDI-TOF, and UV–Vis spectroscopy. The ct-DNA binding (UV–Vis absorption, competitive EB binding, and agarose electrophoresis studies) and supercoiled plasmid DNA nuclease properties (hydrolytic, photonuclease, oxidative nuclease, and photooxidative nuclease) of the water-soluble compounds were investigated using different methods. The DNA binding constant (K _b ) values of 2b and 3b were calculated as 8.45 ± (0.25) × 10⁴ and 7.71 ± (0.13) × 10⁴ M⁻¹ at 25°C, respectively. The results showed that 2b had a stronger ct-DNA binding effect than 3b according to K _b and r values. The DNA nuclease studies claimed that both compounds indicated photonuclease activity on plasmid DNA depending on the light dose. Additionally, 2b had a higher photonuclease capacity than 3b. All of these results showed that 2b had promising potential as a photosensitizer agent for photodynamic therapy.