DNA Photocleavage and Binding Modes of Methylene Violet 3RAX and its Derivatives: Effect of Functional Groups

With 4'-amino-N,N-diethylaniline and aniline as starting materials, methylene violet 3RAX 1 and its derivatives 2-5 were synthesised. The five compounds were characterised by IR, UV-vis, and H-1 NMR spectroscopy and mass spectrometry. The binding mode between the synthesised compounds and DNA were investigated. The results show that both compounds 1 and 5 bind to DNA by an intercalative mode, while compounds 2-4 interact with DNA through a mixed binding mode involving groove binding and electrostatic interactions. The photocleavage ability of the five compounds to DNA were calculated to be 38, 40, 30, 20, and 13%, respectively, when their concentration was adjusted to 400 mu M. The singlet oxygen production of compounds measured by the 1,3-diphenylisobenzofuran method was consistent with the trend of DNA photocleavage ability. The DNA studies suggest that the binding mode between methylene violet 3RAX and DNA, the ability of methylene violet 3RAX to generate singlet oxygen, and the DNA photocleavage activity could be adjusted through modification of the amino group on methylene violet 3RAX.