A Computational Chemistry Study of Spin Traps.

Many defects in physiological processes are due to free radical damage: reactive oxygen species, nitric oxide, and hydroxyl radicals have been implicated in the parthenogenesis of cancer, diabetes mellitus, and rheumatoid arthritis. We herein characterize the phenyl-N-ter-butyl nitrone (PBN) type spin traps in conjunction with the most studied dimethyl-1-pyrroline-N-oxide (DMPO) type spin traps using the hydroxyl radical. In this study, theoretical calculations are carried out on the two main types of spin traps (DMPO and PBN) at the density functional theory level (DFT). The energies of the optimized structures, hyperfine calculations in gaseous and aqueous phases of the spin traps and the hydroxyl radical adduct are calculated at the B3LYP correlation and at the 6-31G (d) and 6-311G (2df, p) basis sets respectively. The dielectric effect on the performance of the spin trap is determined using the polarized continuum model. Calculations show a localization of spin densities in both cases. However, DMPO spin traps are shown to be more stable and more interactive in aqueous environment