DFT investigation of the reaction of cyanidin with hydroxyl radical

Cyanidin, as one important plant pigment, was theoretically (at M05-2X/6-311+G(d, p) level of theory) investigated for its ability to scavenge potentially, highly damaging hydroxyl radical. The applied method successfully reproduces the bond dissociation enthalpy (BDE), the ionization potential (IP) and proton affinity (PA). The HAT mechanism is most favorable reaction pathway for antioxidative action of cyanidin in the gas phase. On the other hand, the SPLET mechanism is most favorable reaction pathway for antioxidative action of cyanidin in the aqueous phase. Mechanistic investigations of antioxidative action of cyanidin in reaction with the hydroxyl radical confirmed that HAT is the dominant reaction pathway in the gas phase, and that the 4´ position is most reactive.