Abstract

The interaction between luteolin-7-O-glucoside and duplex DNA was investigated by ESI-MS, ultraviolet and fluorescence spectroscopy in conjunction with fluorescent probe ethidium bromide (EB). We synthetized a critical sequence of GC-rich human survivin promoter DNA for ESI-MS investigation. The stock solutions of DNA and the drug for MS analysis were diluted with methanol/20 mmol/L ammonium acetate (20 : 80, V/V) solvent, giving a final concentration of DNA of 5 and 20 mu mol/L for luteolin-7-O-glucoside. In negative ion mode, we found the duplex DNA/drug complex as well as complex of single-strand oligodeoxynucleotide/luteolin-7-O-glucoside in ESI-MS spectrum. At the same time, it can be seen that the flavonoid shows 1 : 1, 1 : 2 and 1 : 3 binding stoichiometries. In positive ion mode, only 1 : 1 complex was observed from the spectrum. This suggests that the complex between the drug and the duplex has hydrogen bond interaction. The spectra of tandem mass spectrometry reveal that the 5- charged 1 : 1 complex underwent the predominant loss G base and a little of losing a neutral drug. Moreover, for 6- charged 1 : 1 complex of duplex and luteolin-7-O-glucoside, its fragmentation pathway is loss of a 1- charged drug yielding a 5- charged DNA ion. The results of MS/MS data demonstrate that luteolin-7-O-glucoside is an intercalator. UV data were measured by addition of ct-DNA (80 mu mol/L) to Lug (20 mu mol/L)-20 mmol/L ammonium acetate solution. The result shows obvious hypochromic and red shift effect, indicating that the compound may be inserted between the pairs of the DNA helix bases. The fluorescence experiments were obtained by the drug (final concentrations: 0-66.66 mu mol/L) titrating certain EB-DNA system (c((EB))=3 mu mol/L, c((ct-DNA))=9.78 mu mol/L) in 20 mmol/L ammonium acetate solvent. The emission spectra were recorded at an excitation wavelength of 520 nm. The results show that luteolin-7-O-glucoside can quench the fluorescence of EB-DNA system, and the wavelength of EB-DNA hypsochromic shift. The quenching of luteolin-7-O-glucoside on the fluorescence of EB-DNA is a static quenching process, quenching constant K-q = 8.61 X 10(11) L.mol(-1).s(-1) This reveals that luteolin-7-O-glucoside has only one mode to interact with duplex DNA. Based on the above mentioned experimental results, we can conclude that luteolin-7-O-glucoside is an intercalator. These results are expected to provide a basis to understand the DNA-binding properties of flavonoids and useful information for development of new efficient duplex DNA ligands.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.