A series of water-soluble cationic phthalocyanine derivatives (1–10) were designed and synthesized to develop novel and potent telomerase inhibitors. These phthalocyanine derivatives as inhibitors of telomerase were investigated via modified telomerase repeat amplification protocol (TRAP) assay. The TRAP assay indicates that these cationic compounds had strong telomerase inhibitory activity (IC50< 1.65 μM). To determine ...