Electrochemical and spectroscopic study of the interaction of indirubin with DNA

The interaction of indirubin with DNA was studied by differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV) at the bare or DNA-modified electrode and UV-vis or IR spectra. As a result of intercalating of this drug into the double helical structure of DNA, the DPV of indirubin shows that peak potentials shift and peak currents decrease with the addition of DNA. UV-vis spectra exhibits that the absorption intensity of indirubin at 538.7 nm(-1) decreases, which indicates that the anticancer herbal drug indirubin binds DNA. In addition, IR-spectra of DNA and DNA-indirubin adduct imply indirubin interacts with the phosphate groups of DNA by hydrogen bond or electrostatic interaction. Under our experiment conditions, the decrease of peak current is proportional to DNA concentration, which can be applied to estimate DNA concentration. The results indicate that the herbal drug indirubin can interfere with the DNA by intercalating into the double helix of DNA and interacting with the phosphate groups of DNA.