Effect of dehydrogenation or dihydrogenation of Cα-Cβ Bond of hydroxystilbenes to their hydrogen atom donating activity: A DFT approach

Nenadis, N., Stavra, K.

Abstract

In the present study Density functional theory/Becke’s three-parameter hybrid functional combined with the Lee-Yang-Parr correlaOon functional (DFT/B3LYP) was used to examine the effect of Cα-Cβ bond nature (single, double, triple) in the backbone of hydroxystilbenes to their hydrogen atom transfer (HAT) ability. Tested compounds were trans-resveratrol and its derivatives, for which there are some scarce experimental findings, as well as piceatannol and related compounds. For this purpose bond dissociation enthalpy values were computed in the gas phase to study the effect of the structure free from any external influence and in liquid (benzene, water) phase. Benzene was used as a model of a lipid substrate. Simple phenol, which is usually non- reactive, was used as a reference. The double bond, resulting in molecular planarity, was predicted to favor the single hydrogen transfer. The triple bond, resulting in a linear backbone, was predicted to decrease the ease of such transfer. The saturation of the bond, resulting in loss of planarity, was expected to decrease more the activity. The impact of saturation was predicted to be too negative for trans-resveratrol. However, for piceatannol, an improvement of HAT efficiency was proposed only under stepwise HAT. Such a finding was related to the ease of allylic hydrogen atom donation after the formation of the o-quinone.

Keywords

DFT, resveratrol, piceatannol, HAT, radical scavenging

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TC23 - Metrology in Food and Nutrition

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