Antioxidative activity of chlorogenic acid relative to trolox in aqueous solution – DFT study

Abstract

© 2018 Elsevier Ltd Chlorogenic acid (5CQA) is a dietary polyphenol known for its high biological activity. Antioxidative behavior of 5CQA relative to trolox (Tx) toward the HO[rad] and CH3OO[rad] radicals in aqueous solution at pH = 7.4 was simulated using density functional theory. This is the first study where behavior of monoanion and dianion of 5CQA at physiological conditions is described. Both anionic forms undergo only hydrogen atom transfer (HAT) mechanism with CH3OO[rad]. With HO[rad], anionic forms of 5CQA conform to the HAT, radical adduct formation, sequential proton loss electron transfer, and single electron transfer – proton transfer mechanisms. Contribution of dianion to scavenging HO[rad] is comparable to that of more abundant monoanion. The calculated rate constant for overall reaction of 5CQA with HO[rad] is in perfect agreement with the corresponding experimental value. In comparison to Tx, 5CQA is more reactive toward HO[rad], but less reactive toward CH3OO[rad].