Photodynamic effects of isosteric water-soluble phthalocyanines on human nasopharynx KB carcinoma cells

The photodynamic activity of water-soluble cationic zinc(II) phthalocyanines using human nasopharynx carcinoma (KB cells) was investigated. A sulfur-linked cationic dye, named: 2,9(10),16(17),23(24)-tetrakis[(2-trimethylammonium)ethylsulfanyl]phthalocyaninatozinc(II) tetraioidide ( 13) is the most active of four sensitizer assays and shows a singlet oxygen quantum yield of 0.58 and a higher bathochromic shift of 10 nm for the Q-band as compared with the oxygen-linked cationic aliphatic phthalocyanine: 2,9(10),16(17),23(24)-tetrakis[(2-trimethylammonium)ethoxy]phthalocyaninatozinc(II) tetraioidide ( 11) and the best photo-stability in water in comparison with their tetra-α-substituted counterparts 1,8(11),15(18),22(25)-tetrakis[(2-trimethylammonium)ethoxy]phthalocyaninatozinc(II) tetraioidide ( 12) and 1,8(11),15(18),22(25)-tetrakis[(2-trimethylammonium)ethylsulfanyl]phthalocyaninatozinc(II) tetraioidide ( 14). Phthalocyanine 13, partially localized in lysosomes, led to cell photoinactivation in a concentration- and light dose-dependent manner. After photodynamic treatment, compound 13 induced an apoptotic response – as indicated by morphological cell changes – an increase in the activity of caspase-3 and the cleavage of poly-ADP-ribose-polymerase substrate (PARP). β-Sulfur-linked cationic aliphatic phthalocyanine 13 shows a Φ Δ = 0.58 and λ max = 686 nm, no dark cytotoxicity and triggers lysosomal-induced apoptosis after irradiation leading to 90% cell death. [Display omitted]