Quaternary ammonium zinc phthalocyanine: inhibiting telomerase by stabilizing G quadruplexes and inducing G-quadruplex structure transition and formation.

Water-soluble, octacationic zinc phthalocyanine (ZnPc) was found to be a very good G-quadruplex DNA stabilizer by using UV-melting studies and DNA polymerase stop assays, and a potent telomerase inhibitor by using the telomeric repeat amplification protocol (TRAP) assay. The compound's DNA-binding properties were also studied by surface plasmon resonance (SPR). Furthermore, CD experiments demonstrated that ZnPc could induce intramolecular G-quadruplex structure transition from the antiparallel to parallel form. More importantly, ZnPc was found to induce parallel structure formation in cation-deficient conditions. The stability of the induced structure was determined with CD melting assays.