On the free radical scavenging mechanism of protocatechuic acid, regeneration of the catechol group in aqueous solution
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- Galano, A. & Pérez-González, A. Theor Chem Acc (2012) 131: 1265. doi:10.1007/s00214-012-1265-0
The free radical scavenging activity of protocatechuic acid has been studied in aqueous and lipid solutions, using the density functional theory. It was found to be a moderately good protector in non-polar environments (lipid), while in aqueous solution it is predicted to be an excellent peroxyl radical scavenger. In such media, the pH has an important role in the free radical scavenging activity of protocatechuic acid. At physiological pH, after the first peroxyl radical is scavenged, and in the presence of a good electron-donor species, such as the superoxide radical anion, the latter is consumed and protocatechuic acid is regenerated. This means that, under such conditions, it has the ability of scavenging several radical equivalents, two per cycle. An equivalent cyclic process can be assumed as possible also for other scavengers with the catechol moiety. If this assumption is confirmed, the role of compounds with a catechol moiety as free radical scavengers might be even more important that what has been assumed so far.