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Is Usnic Acid a Promising Radical Scavenger?
journal contribution
posted on 2020-07-07, 14:39 authored by Nguyen
Thi Hoa, Mai Van Bay, Adam Mechler, Quan V. VoUsnic
acid (UA) is a natural product found in the lichen genera.
Because of the phenolic groups in its structure, UA is suspected to
be an antioxidant. Therefore, in this study, the radical scavenging
of UA was investigated in physiological environments in silico by using kinetic calculations. It was found that the overall rate
constant for the hydroxyl radical scavenging activity was approximately
109 M–1 s–1 in all
environments, whereas the HOO• and CH3OO• radical scavenging activities were only significant
in the polar environments with k in the range of
103–104 M–1 s–1. The results also revealed that the HO• scavenging
activity followed the single electron transfer (SET) and radical adduct
formation mechanisms; however, the SET pathway (for the dianion HU2–) played a dominant role in the scavenging of other
studied radicals, including CH3O•, CCl3O•, CCl3OO•, NO2, SO4•–, and
N3•. The activity of UA against these
radicals was as high as that of typical phenolic acids such as ferulic
acid, p-coumaric acid, caffeic acid, dihydrocaffeic
acid, and sinapinic acid (kf ∼
108 M–1 s–1) in polar
solvents. Thus, UA is a promising natural antioxidant in aqueous environments.