Synthesis, characterization, in vitro cytotoxicity of novel metallo phthalocyanines with four methylpropiophenonyl clusters and their effects on Caenorhabditis elegans thermotolerance

Phthalocyanines (Pcs) have the potential to be used in many medical applications. Novel Zn (II), Co (II), and Cu (II) phthalocyanines (Pcs) 4, 5, and 6, respectively, containing four methylpropiophenonyl units at the peripheral positions were described. Pcs were synthesized by cyclotetramerization of the previously prepared precursor 2-hydroxy-4'-[2-(3,4-dicyanophenoxyethoxy)]-2-methylpropiophenone 3 with the presence of metal salts under nitrogen atmosphere. The compounds were characterized by elemental analysis, IR (Infrared spectroscopy), UV–visible spectroscopy, and Laser Desorption ionization time-of-flight mass spectroscopy (LDI-TOF–MS) methods. The compounds were tested for in vitro cytotoxicity in cultured human cells, and thermotolerance in Caenorhabditis elegans (C. elegans). Standard MTT assays were carried out for cytotoxicity testing using HeLa and L929 cells. Results showed that there was no significant decrease in the cell viability with zinc (II), cobalt (II), and copper (II) phthalocyanines (ZnPc, CoPc, and CuPc) at 0.25 μM concentration. C. elegans survival assay with ZnPc, CoPc, and CuPc under heat stress showed that although a dose-dependent statistically significant toxicity was observed for ZnPc and CuPc, CoPc was not toxic at all concentrations tested and even increased the survival of worms at the 0.050–0.250 µM concentration range. Therefore, CoPc can be a lead compound for further preclinical studies for its potential in photodynamic therapy (PDT) and anti-aging purposes.