A topological study of prodrugs of 5-fluorouracil

Various physicochemical properties are correlated with the first-order connectivity index for a series of prodrug derivatives of 5-fluorouracil. Partition coefficient data available in the literature were complemented by calculated logP values using the CLOGP program. The first-order connectivity index correlated quite well with the experimental logP values (n=16) while the correlation with ClogP improved with the removal of compounds VI, VII and XVII. A molecular modelling study provided data for the molecular area and volume of all prodrugs studied. The regression equations obtained showed that there was good correlation between the topological index and the molecular area and volume. The connectivity index is an adequate topological descriptor. The first-order valence index was preferred over that of order two. Comparison of ClogP values provides group contribution values while the comparison of molecular volume data provides information on the volumes of individual substituents relative to that of hydrogen.