Computational Study: Antioxidant Activity of Aspulvinone E Toward Hydroperoxyl and Hydroxyl Radicals

In this study, the antioxidant mechanisms of aspulvinone E were systematically examined via quantum chemical calculations. Thermodynamic and kinetic analyses identified the H-3 hydroxyl group as the most reactive site for hydrogen atom transfer (HAT), exhibiting the lowest Gibbs free energy values for abstraction by •OOH and •OH radicals. Radical adduct formation (RAF) studies confirmed site-specific reactivity, favoring C1 addition by •OOH and C3 addition by •OH. Electronic properties—including moderate ionization potential, high electron affinity, and favorable softness and electrophilicity parameters—position the molecule as a responsive electron donor. HOMO distribution localized over phenyl and furanone moieties highlights targeted radical scavenging enhanced by hydroxyl functionalization. Overall, the combined thermodynamic, kinetic, and electronic profiles suggest that aspulvinone E possesses site-specific reactivity and enhanced stability, making it a promising candidate for antioxidant applications and further biological evaluation.