DFT with B3LYP/6-311++G(d,p) level were used
for all calculations in this work. In biological system, 5-FU-
3H2O has the highest stabilization energy compared to 5-FU-
3NH3, 5-FU dimer, and 5-FU monomer. The chemical interactions
of 2′-deoxyribose radical with uracil and 5-FU radicals
to form 2′-deoxyuridine and 2′-deoxy-5-fluorouridine show
that the difference in stabilization energies, ΔE, for their formation
are quite low which facilitates the exchange reactions
in DNA structure. Size, shape density distributions, and chemical
reactivity sites of 5-FU were obtained by mapping electron
density isosurface with electronic surface. Additionally,
the intermolecular hydrogen bonding in 5-FU (sugarphosphate)
backbone system was simulated by NBO analysis
to describe the role of intermolecular hydrogen bonding on the
structure and chemical reactivity of 5-FU in biological systems.
Molecular docking study of the interaction between 5-
FU and human serum albumin (HSA) indicated that 5-FU
binds to HSAwith low affinity and low specificity compared
to other anticancer drugs.