Theoretical study of the pH-dependent antioxidant properties of vitamin C.

Molecules acting as antioxidants capable of scavenging reactive oxygen species (ROS) are of utmost importance in the living cell. Vitamin C is known to be one of these molecules. In this study we have analyzed the reactivity of vitamin C toward the [Formula: see text] and [Formula: see text] ROS species, in all acidic, neutral and basic media. In order to do so, density functional theory (DFT) have been used. More concretely, the meta-GGA functional MPW1B95 have been used. Two reaction types have been studied in each case: addition to the ring atoms, and hydrogen/proton abstraction. Our results show that [Formula: see text] is the most reactive species, while [Formula: see text] displays low reactivity. In all three media, vitamin C reactions with two hydroxyl radicals show a wide variety of possible products.