Cyclic perylene diimide: Selective ligand for tetraplex DNA binding over double stranded DNA.

Synthesized cyclic perylene diimide, cPDI, showed the binding constant of 6.3 × 106 M-1 with binding number of n = 2 with TA-core as a tetraplex DNA in 50 mM Tris-HCl buffer (pH = 7.4) containing 100 mM KCl using Schatchard analysis and showed a higher preference for tetraplex DNA than for double stranded DNA with over 103 times. CD spectra showed that TA-core induced its antiparallel conformation upon addition of cPDI in the absence or presence of K+ or Na+ ions. The cPDI inhibits the telomerase activity with IC50 of 0.3 µM using TRAP assay which is potential anti-cancer drug with low side effect.