Photodynamic therapy of zinc sulfonated phthalocyanine on murine transplanted tumors, its tissue distribution, and damaging effect on DNA of cancer cell

Zinc sulfonated phthalocyanine (ZnSPc) 10 mg.kg-1 was injected iv into mice bearing S-180 and RA795 lung carcinoma, after 24 h tumor site were irradiated with red light. In mice bearing S-180, tumor regression rate was 31.8-43.5%, tumor growth inhibition rate was 57.4%. The highest concentration was in tumor tissue 24 h after injection of this dye, on d 5 it still retained relatively highest concentration. However, in most other tissues the dye was not detected at this time, disappearance of ZnSPc from plasma was rapid, it showed an open two compartment model, t1/2 alpha 135.8 min, t1/2 beta 70.1 h, Vd 1.92 x 10(-3) L. In blood, most ZnSPc was bound with plasma protein, the peak light absorption showed blue shift. ZnSPc 2.5 micrograms.ml-1 plus light, percent of DNA double strands greatly decreased, this indicated that DNA was one of target sites for ZnSPc photodynamic action.