Synthesis and comparative photodynamic properties of two isosteric alkyl substituted zinc(II) phthalocyanines

Abstract

The synthesis and photophysical parameters of two novel isosteric cationic zinc(II) phthalocyanines: 2,9(10),16(17),23(24)-tetrakis[(N-butyl-N-methylammoniumethylsulfanyl]phthalocyaninatozinc(II) tetraiodide (6) and 2,9(10),16(17),23(24)-tetrakis[(N-dibutyl-N-methylammonium)ethoxy]phthalocyaninatozinc(II) tetraiodide (7) were investigated. Maximum absorption values were 686.5 nm and 678 nm for 6 and 7, respectively, whereas singlet molecular oxygen generation was 0.42 and 0.67, respectively. The photodynamic effect and the cellular uptake of both phthalocyanines were evaluated on human nasopharynx KB carcinoma cells. After light exposure, phthalocyanine 6 showed a higher cytotoxic activity than 7. In addition, a higher intracellular uptake of 6 and a preferential localization within lysosomes were demonstrated. The production of a greater amount of reactive oxygen species after phthalocyanine 6 irradiation would be responsible for its potent phototoxic action on KB cells.