Insight from the Theory of the Multitarget Antioxidant Potency of Toluquinol

Abstract

Although substantial evidence supports the antioxidant potency of polyphenols, their broader activities remain poorly understood. This study examined the antioxidant potency of toluquinol by evaluating its primary, secondary, and tertiary activities by using density functional theory. The formal hydrogen atom transfer mechanism at position 4 of toluquinol was identified as the most important mechanism in terms of the primary antioxidant potency in both lipid and aqueous media. The kinetic results indicated that toluquinol exhibited good (k_OOH = 5.67 × 10⁶ M^–1 s^–1) and excellent (k_OOH = 1.03 × 10⁷ M^–1 s^–1) primary antioxidant potencies in lipid and aqueous media, respectively. Toluquinol scavenges two radicals during each regeneration cycle in aqueous media. However, the secondary antioxidant potency results revealed that toluquinol could not prevent the Haber–Weiss reaction, indicating a lack of secondary antioxidant potency. Tertiary antioxidant potency calculations demonstrated that toluquinol could repair amino acid residues and DNA damaged by oxidative stress, with reaction rate constants limited by diffusion rates. This theoretical multitarget antioxidant potency study of toluquinol enhances our understanding of the physiological significance of such antioxidant molecules, which could be utilized in treating disorders associated with oxidative stress.