Photocleavage of DNA and adenine–thymine inclined binding by a novel ruthenium(II) complex with 3,4-dibromo-imidazo[4,5-f][1,10]phenanthroline ligand

• A novel complex with A–T inclined DNA selectivity.
• The complex binds to four kinds of DNA by intercalation with high binding affinities.
• The more effective DNA cleavage is induced by visible light than by UV-light.
• GoldView™ nucleic acid dye was used instead of EB in the competition assays.
• 1O2 mediated lesion of DNA by the complex.

A new ruthenium(II) complex [Ru(phen)2(ODBIP)]2 + (phen = 1,10-phenanthroline; ODBIP = 3,4-dibromo-imidazo[4,5-f][1,10]phenanthroline) has been synthesized. Binding of this complex to poly(dG–dC) DNA, supercoiled pBR322 plasmid DNA, calf thymus DNA (CT DNA), and poly(dA–dT) DNA was investigated by spectroscopic methods. The photocleavage on pBR322 DNA was also studied by agarose gel electrophoresis, and the cleavage mechanisms were further explored. The results indicated that [Ru(phen)2(ODBIP)]2 + preferentially bound to DNA at adenine–thymine base pairs by intercalation, and the complex exhibited higher DNA cleavage efficiency under visible light irradiation than under UV light irradiation. The singlet oxygen may be responsible for the DNA photocleavage.

A new ruthenium(II) complex [Ru(phen)2(ODBIP)]2 + has been synthesized. Binding of this complex to poly(dG–dC) DNA, pBR322-DNA, CT-DNA and poly(dA-dT) DNA was studied and the complex preferentially bound to DNA at adenine–thymine base pairs by intercalation. The multi-wavelength visible-light induced more efficient photocleavage of DNA by complex than UV-light (upper-left). The competition assays performed with GoldView™ nucleic acid dye instead of ethidium bromide (EB) (lower-left) provided further evidence for the intercalative binding mode between the complex and DNA.Figure optionsDownload as PowerPoint slide