Sugar moiety has a synergistic effect on hydroxylated xanthone for better antioxidant activity of mangiferin

Abstract

The structure–antioxidant relationship of mangiferin was elucidated by means of quantum chemistry calculations. The density functional theory level of theory was used for antioxidant pharmacophore selection. According to the obtained geometry by using the DFT/B3LYP/6-31+G(d,p) values, HOMO, ionization potential, bond dissociation energy, stabilization energy, and spin density distribution, the catechol moiety is more important for the antioxidant capacity than the resorcinol moiety. However, the sugar is a strong electron-withdrawing group due to its hydrogen bond formation with the resorcinol moiety of xanthone ring. The hydrogen transfer is more important for the antioxidant activity than the electron transfer. The hydrogen abstractions in the ortho positions are more favored than the meta positions. Thus, our results show a synergistic effect between xanthone and sugar rings.