The hydroperoxyl and superoxide anion radical scavenging activity of anthocyanidins in physiological environments: Theoretical insights into mechanisms and kinetics

The HOO(center dot)and O-2(center dot)-scavenging activities of 12 natural anthocyanidins were investigated in physiological environments by using DFT calculations. The results suggest high HOO center dot scavenging activity in aqueous medium with overall rate constants in the range of k(overall) = 1.58 x 10(8) -7.59 x 109 M-1 s(-1), whereas in lipid medium only weak activity is predicted. O-2(center dot)-scavenging is also fast in water with k(app) = similar to 10(9) M-1 s(-1). Like in the case of many other antioxidants that contain acidic moieties, the anion states (H(3)A(-) and H(2)A(2-)) and the single electron transfer mechanism play a dominant role in the HOO center dot scavenging activity of anthocyanidins in water at pH = 7.4. Analysis of the mechanism suggests that the O-2(center dot-) and HOO center dot radical scavenging can occur as a regeneration cycle that might increase the protective efficiency of anthocyanidins against oxidative stress.

Automated summary

The study found that anthocyanidins have high HOO· scavenging activity in water but weak activity in lipid medium. In water at pH = 7.4, the anion states and single electron transfer mechanism play a dominant role in the scavenging activity of anthocyanidins.