A DFT Study on the Structural and Antioxidant Properties of Three Flavonols

The structural and antioxidant activity properties of three flavonols kaempferol, galangin and morin have been investigated at density functional level of theory with the aim of verifying experimental findings. The potentialities of antioxidant activity are highly related to their capabilities to scavenge free radicals. Two potential working mechanisms of the hydrogen-atom transfer and single-electron transfer are reported by which antioxidants can play their role. Two parameters of the O-H bond dissociation enthalpy (BDE) and ionization potential (IP) in the presence of water medium are computed to estimate the antioxidant capacities. Results indicate that the order of antioxidant efficacies predicted theoretically in this work is in agreement with that reported by experimental results of oxygen radical-scavenging capacity (ORAC) assay. This demonstrates the importance of the hydrogen-atom and single-electron transfer mechanisms to explain their capacities to scavenge peroxyl radical.