7-O-Galloyltricetifavan: a promising natural radical scavenger.

7-O-Galloyltricetifavan (7OGT), a natural flavonoid, is isolated from the leaves of Pithecellobium clypearia. The compound exhibits a variety of biological activities. This study details the evaluation of the HOO• antiradical activity of 7OGT by quantum chemistry calculations. The HOO• trapping activity of 7OGT in the gas phase (reference state) was discovered to follow the formal hydrogen transfer mechanism with a rate constant of k = 4.58 × 108 M-1 s-1. In physiological environments, 7OGT is predicted to be an excellent HOO• radical scavenger with k overall = 2.65 × 108 and 1.40 × 104 M-1 s-1 in water and pentyl ethanoate solvents, respectively. The HOO• antiradical activity of 7OGT in water at physiological pH is approximately 2000 times that of Trolox and substantially higher than that of other well-known natural antioxidants such as trans-resveratrol or ascorbic acid. Thus, 7OGT is an excellent natural antioxidant in polar environments.