Spectrofluorimetric study of the binding of codeine to nucleic acids

The characteristics of the interaction between codeine (CD) and nucleic acids were studied by ultraviolet–visible spectra and fluorescent spectra. It shows that there is a powerful ability in nucleic acids to quench the fluorescence intensity of codeine. The fluorescence quenching data were analyzed according to Stern–Volmer equation and Förster’s nonradiative energy transfer mechanism. Thus the binding constant and the thermodynamic parameters between codeine and nucleic acids were obtained. The results show that codeine interacts with nucleic acids in a mode of groove binding and –OCH3 of the codeine molecular combines with the groove of nucleic acids through hydrogen bond or van der Waals force.