Dejan Milenković, Jelena Đorović, Edina Avdović, Žiko Milanović, Marko Antonijević (DOI: 10.24874/jsscm.2020.01.08)

 

Abstract

 

In the present paper, M05-2X/6-311+G(d,p) level of theory was used to investigate antiradical activity of cyanidin towards highly damaging radical species (^.OH, ^.OCH₃, ^.OOH and ^.OOCH₃). The applied method successfully reproduces the values of reaction enthalpies (ΔH_BDE, ΔH_IP, and ΔH_PA). These parameters are important to determine which of the mechanisms are preferred. Reaction enthalpies related to the antioxidant mechanisms of the investigated species were calculated in water and DMSO. The enthalpies of reactions indicate the preferred radical scavenging mechanisms in polar (water) and polar aprotic (DMSO) solvents. Single- electron transfer followed by proton transfer (SET-PT) is not a favorable reaction pathway under any conditions. Both remaining mechanisms, HAT and SPLET, are suitable for the reaction of cyanidin with ^•OH and ^•OCH₃ in all solvents under investigation. On the other hand, in the reaction of cyanidin with ^•OOH and ^•OOCH₃, the SPLET mechanism is possible in both solvents. Simulation of the reaction of the cyanidin anion with the hydroxy radical confirmed that position 3` of Cy‒O^- is the most suitable for reaction with ^•OH through electron transfer mechanism (ET) in both solvents.

 

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