Six Kinds Of Coumarin Active Ingredient And Dna Interactions

Objective The interaction between coumarin (COU), umbelliferone (UMB), aesculetin (AES), hymecromone (HYM),osthole (OST), xanthotoxin (XAN) and DNA were investigated under simulative physiological condition and the binding mode of six active components of coumarin with DNA were explored from different perspectives.Methods The changes of the UV-vis absorbance and the electrochemical property before and after the interaction between six active components of coumarin and DNA were studied by the ultraviolet difference spectra and cyclic voltammetry. The parameters of the interaction between six active components of coumarin and DNA were obtained by the fluorescence quenching titration, and the influence of six common metal ions such as Cu2+ on the interaction of COU, UMB, AES, HYM with DNA and the influence of six rare earth ions such as Eu3+ on the interaction of OST and XAN with DNA were investigated also. A resonance light-scattering method had been used for the study on the interaction of DNA with UMB, AES, HYM, OST and XAN. The effects of UMB, AES, HYM, OST and XAN on DNA were studied using viscosimetry. The interactions of UMB, AES, HYM and OST with plasmid DNA were studied by agarose gel electrophoresis. Furthermore, the major mode of six active components of coumarin and DNA were determined by the experiments of ion strength, I- quenching effect, the comparison of single and double stranded DNA bound to active components of coumarin and DNA thermal denaturation.Results The results of ultraviolet spectroscopy showed that the 1:1 compounds were formed between six active components of coumarin and metal ions. Both hypochromism and red shift were observed in the interaction of COU with DNA while other five components of coumarin had only hypochromism. The results of fluorescence spectrometry revealed that the fluorescence of BR-DNA was quenched with addition of COU, which indicated that a strong competition for DNA binding between COU and BR existed. While the fluorescence of other five active components of coumarin was quenched by DNA and the mechanism of fluorescence quenching was static quenching. The 1:1 complexes were formed between six active components of coumarin and DNA, meanwhile, their binding constants were 3.76×104,2.13×104,5.27×102, 1.44×104,9.30×103 and 2.60×103 L·mol-1, respectively. As to UMB, AES, HYM, OST and XAN, hydrogen bond and van der Waals interaction were the predominant binding force, while the interaction between HYM and DNA was mainly driven by electrostatic interaction. When DNA was added, long range assembly of UMB, AES, HYM, OST, XAN on the molecular surfaces of nucleic acid, resulted in an enhanced resonance light-scattering peak. The results of viscosimetry showed that the relative viscosity of DNA unchanged with the increase in the concentration of the complexes. The result of agarose gel electrophoresis revealed that the complexes had no obvious cleaving efficiency to pBR322 DNA.Conclusion Six active components of coumarin all have interaction with DNA. The interaction between six active components of coumarin and DNA was differently influenced by metal ions. The results of DNA denaturation temperature test and salt effects further demonstrated that the binding mode of COU and DNA were the intercalation and electrostatic interaction. Based on the experiments of UV spectra, ion strength effect, I- quenching effect, the comparison of single and double stranded DNA bound to active components of coumarin, DNA denaturation temperature and DNA viscosity, the binding mode between complexes with DNA were groove binding.