Photophysical properties and in vitro and in vivo photoinduced antitumor activity of cationic salts of meso-tetrakis(N-alkyl-3-pyridyl)bacteriochlorins

• Cationic salts of meso-tetrakis (N-alkyl-3-pyridyl)bacteriochlorins were synthesized.
• Synthetic photosensitizers having strong absorption in the long wavelength region.
• High PDT efficacy of synthetic bacteriochlorin photosensitizers in vitro.
• Synthetic bacteriochlorins rapidly accumulate in mouse tumor tissue.
• PS possess high PDT activity against in mice bearing Lewis lung carcinoma.

Physico-chemical properties, biodistribution in animal tissues, and PDT efficacy of bacteriochlorin photosensitizers, namely cationic salts of synthetic meso-tetrakis(N-alkyl-3-pyridyl)bacteriochlorins were studied in НЕр2 cell line and in the LLC mouse model. The tested compounds showed high stability in the dark and high in vitro phototoxicity against НЕр2 cells (the half maximal inhibitory concentration LD50 in the range from 0.34 ± 0.03 to 1.5 ± 0.03 μm).Synthetic bacteriochlorins rapidly accumulate in mouse tumor tissue with tumor-to-normal tissue fluorescence contrast ratios of 2.3–3.3, possess high PDT activity against LLC cells: inhibition of tumor growth, TGI 85.8–100%, increase in life span, ILS 105.7–129.2%, response rate, RR 50–100%. The highest PDT efficacy was found for meso-tetrakis[1-(4′-bromobutyl)-3-pyridyl]bacteriochlorin tetrabromide (IC50 0.34 ± 0.03 μm in vitro, TGI and RR 100% in vivo).