Comparative study of the inclusion complexation of uracil and 5-fluorouracil with native and modified cyclodextrins: some theoretical and practical

In this study, the inclusion complexes of α-, β-cyclodextrins and derivatives hydroxypropyl-α-, hydroxypropyl-β-cyclodextrins with uracil and the anti-cancer agent 5- fluorouracil were demonstrated by UV-Vis spectroscopy and quantum chemical calculations. The complexes stability constants and the thermodynamic parameters for the 1:1 stoichiometry inclusion complexes were obtained and compared. The thermodynamic analysis of the studied complexes showed that the inclusion reaction is an exothermic spontaneous reaction and is an enthalpy driven process for the temperature domain of 298K to 313K. Theoretical calculations were performed on complexes to examine the energetic quantities involved in the stability of the complexes. The correlation of the energy parameters obtained from experimental and theoretical data suggests a high affinity between cyclodextrins and both uracil and 5-fluorouracil molecules.