Phenylthio-substituted phthalocyanines as new photosensitizers for photodynamic therapy

摘要

Current work is devoted to investigation of tetra-3-phenylthio-tetra-5-t-butylphthalocyanine [(PhS)4(t-Bu)4PcH2], aluminium hydroxyde tetra-3-phenylthiophthalocyanine [(PhS)4PcAlOH] and zinc tetra-3-phenylthiophthalocyanine [(PhS)4PcZn] as potential photosensitizers of near-infrared range. Investigations were performed on F1 mice bearing Erlich tumor. Photosensitizers were administered intravenously in liposomal form at doses of 4-10 mg/kg. Dynamic and selectivity of sensitizers' accumulation in tumor were estimated in vivo from fluorescence and absorption spectra of sensitized tissue. Photosensitizers have shown high selectivity of accumulation in tumor comparing to normal tissue of mice. Maxima of selectivity for (PhS)4(t-Bu)4PcH2, (PhS)4PcZn and (PhS)4PcAlOH achieve the values up to 2.5:1, 5:1 and 8:1 respectively. All photosensitizers completely clear from the normal tissue in 7-8 days. For PDT investigations tumors were irradiated using 732 nm laser with power density of 100-500 mW/cm2 and light dose density up to 400 J/cm2. The photodynamic efficiency was estimated using the parameter of tumor growth inhibition (TGI). All photosensitizers had shown high photodynamic efficiency of relatively large tumors. PDT using (PhS)4PcAlOH and (PhS)4(t-Bu)4PcH2 caused pronounced TGI exceeding 80%. Using (PhS)4PcZn caused moderate TGI of 60%. Investigations have shown that liposomal forms of phenylthiosubstituted phthalocyanine derivatives may be used to develop new efficient photosensitizers for PDT.