THEORETICAL STUDY OF THE SPIN DENSITY DISTRIBUTION OF THE GREEN TEA CATECHIN RADICALS

Abstract

The geometries and spin densities of green tea catechin radicals are calculated using unrestricted B3LYP hydrid density functional calculations. The radicals which have the smallest value of Maximum Spin Density (MSD) are referred to the most stable radical species deriving from the absolute minimum energy of investigated compounds. In this study, we have calculated these values in gas phase and water solution. For green tea catechins, their stable radicals have MSD values lying at 0.37 -0.38 in gas phase, and 0.33 0.34 in water. Calculating some flavonoid stable radicals, it was found that the MSD values lie at 0.31 – 0.37 in gas phase, and 0.29 - 0.37 in water solution. These calculated data were compared with experimental data and were found to be in good agreement in predicting the stability of radicals. On the basic of the computed MSD values, the stability of radicals can be explored and give a relative trend of the activity and scavenging of antioxidant radicals. Key words: antioxidants, phenolics, flavonoids, catechins, spin density.