The interaction of epirubicin-Cu system with calf thymus DNA has been investigated using UV spectra, fluorescent spectra, viscosity, cyclic voltammetry, etc. Hypochromism was observed in the UV spectra of the system in the presence of the DNA. The Scatchard plots showed competitive inhibition aganist ethidium bromide (EB) binding to DNA. The relative viscosity and thermal deformation temperature of DNA increased with addition of the epirubicin-Cu system. The fluorescence polarization of the DNA-EB system increased with addition of the epirubicin-Cu system. Determination of cyclic voltammetry showed that the DNA made the epirubicin-Cu formal potential positively shift. Then the interaction of the epirubicin-Cu system with pBR322 DNA was studied by the method of gel electrophoresis. The result showed that the epirubicin-Cu system could cleave pBR322 DNA very effectively. So it can be concluded that the binding mode of the epirubicin-Cu system with CT DNA belongs to intercalation action.

Key words: epirubicin-Cu system, calf thymus DNA, Scatchard plot