How does the presence of an oxyradical influence the behavior of polyphenolic antioxidant? A case study on gallic acid

Polyphenolic antioxidants are an integral component of the present-day lifestyle due to growing environmental and pollution-related issues. Gallic acid (GA), a popular polyphenolic antioxidant, is widely distributed in different fruits and vegetables. It scavenges free radicals mostly through the hydrogen atom transfer (HAT) mechanism. The present work reports a fundamental understanding of the atom transfer involved in the antioxidant activity of GA in the presence of prototype oxyradicals. In this article, the behavior of GA in the presence of three prototype oxyradicals, based on the availability in biological systems, viz. hydroxyl (•OH), hydroperoxyl (•OOH), and methyl peroxyl (•OOMe) is studied. On radical scavenging, a sharp change in the structural, electronic, and thermodynamic properties of GA is observed. Finally, a new descriptor based on chemical hardness, which describes the stability of the antioxidant molecule during a HAT reaction, is also proposed. [Figure not available: see fulltext.].