Estudios de interacciones entre moléculas antioxidantes y moléculas relacionadas con radicales oxidativos mediante cálculos mecano cuánticos y simulaciones de dinámica molecular

Abstract

Flavonoids are relevant because of their antioxidant activity, nevertheless the relation between the structure and activity is not well understood. Using a quantum mechanic model we determine the equilibrium structures of molecules related to free oxygen radicals. We used the RHF/6-311G model and GAMESS software to perform the calculations. We found that the quercine, fisetine, cafeic and feluric acids had a planar equilibrium structures. The genisteine and the floratine showed a deviation of 47.2◦C and 90.9◦C from planar structure. The molecular electrostatic potencial (MEP) from the RHF/6-311G approximation revealed that for flat molecules, the electronic delocalization extended all along the structure. The MEP permitted to determine favorable regions for reactions around the hidroxil groups in rings A and B. The molecular dynamic simulations for the interactions of quercine-O2 and quercine-H2O showed that the first interactions are weak and the second is done via hydrogen bound in 4’-OH y 7-OH. The criterion for reactivity on the basis of the partial charge magnitude of oxygen in hidroxil groups suggested that the most reactive region is located on 4’-OH, this fact is in accordance with experimental data and theoretical studies. The average distance for the hydrogen bound was 1,76 Å with and angle of 111,6 ◦C for the hidroxil group.