Binding characteristics and interactive region of 2-phenylpyrazolo[1,5-c]quinazoline with DNA

The interaction between 2-phenylpyrazolo[1,5-c]quinazoline (PQ) and DNA under physiological conditions was investigated using multi-spectroscopic techniques, atomic force microscopy and gel electrophoresis. The thermodynamic parameters were estimated and were discussed in detail. The results of fluorescence-quenching experiments indicated that the main interactive force between PQ and DNA was a hydrophobic interaction and that it was a static quenching process. Potassium iodide and single-strand (ss)DNA quenching studies, together with circular dichroism spectra implied groove binding of PQ with DNA. Atomic force microscopy and gel electrophoresis experiments suggested that there were no major conformational changes in DNA upon interaction with PQ. In addition, UV/vis absorption titration of DNA bases confirmed that PQ bound with DNA mainly through a minor groove interaction and preferentially interacted with adenine and thymine. We anticipate that this work will provide useful information for the application of quinazoline derivatives in the fields of medicinal and pharmaceutical chemistry.