Modification of the known structures of photosensitizers (PS) in purpose to improve their properties is an important direction in the development of new agents for photodynamic therapy (PDT). Among the approaches, the incorporation of different metals in the structure of the PS molecule can be distinguished. In this research, we investigated the photophysichemic and photobiological properties of tetrakis(3-methyl-1-phenyl-pyrazole-4-yl)-tetracyanoporphyrazine (PzPyr) and its metal complexes containing iron and palladium cations in the center of the macrocycle.

Two absorption bands were observed for the studied compounds: in the short-wavelength (Soret band) and long-wavelength (Q-band) regions, and fluorescence in the red region of the spectrum with peak at 620-650 nm. The compounds demonstrated a significant increase in fluorescence intensity in a more viscous medium, which suggests that they belong to the class of fluorescent molecular rotors.

We did not observe any visible differences in the accumulation dynamics for PzPyr and FePzPyr – the maximum accumulation occurred 1 hour after the start of incubation, indicating a high rate of uptake by A431 cells. At the same time, PdPzPyr showed a longer accumulation time of more than 5 hours.

Evaluation of the cytotoxicity of the compounds showed that they exhibit a low level of dark toxicity, while maintaining visible photodynamic activity A431 cells. The addition of a metal cation resulted in a significant increase in the photodynamic index compared to the free base. Inhibitory analysis demonstrated that FePzPyr and PdPzPyr are able to induce cell death along the immunogenic pathway.

Analysis of the compounds has shown that they can be used as potential drugs, and the addition of a metal atom opens up broad prospects for improving the effectiveness of PDT, for example, by activating immunogenic cell death pathways.

FSWR-2023-0032