Interaction studies of Epirubicin with DNA using spectroscopic techniques

Epirubicin (EPR) is an anticancer chemotherapeutic drug which exerts its cytotoxic effect by inhibiting DNA synthesis and DNA replication. We report the structural and conformational effect of EPR binding on DNA duplex under physiological conditions. Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–visible) spectroscopy and circular dichroism (CD) spectroscopy were used to determine the binding mode and binding constant of EPR with DNA. The effect of EPR–DNA complexation on stability and secondary structure of DNA was studied. FTIR measurements showed that EPR–DNA interaction occurs through guanine and cytosine bases. External binding of EPR with DNA was observed through phosphate backbone. UV–visible measurements revealed the intercalative mode of binding of EPR with DNA. The binding constant was estimated to be K = 3.4 × 104 which is indicative of moderate binding between EPR and DNA helix. FTIR and CD studies suggested partial transition from B-conformation of DNA to A-conformation of DNA after EPR binding to DNA duplex.