In the present study, the repair activity of trans-resveratrol toward 2'-deoxyguanosine (dGuo) radicals in polar and nonpolar solvents was studied using density functional theory. The hydrogen transfer/proton coupled electron transfer and single electron transfer (SET) mechanisms between trans-resveratrol and dGuo-radicals were considered. Taking into consideration the molar fraction of neutral trans-resveratrol (ROH) and anionic trans-resveratrol (RO), the overall rate constants for repairing dGuo-radicals by trans-resveratrol are 9.94 × 10 and 2.01 × 10 dm mol s in polar and nonpolar solvents, respectively, and the overall rate constant of repairing cation radical (dGuo) by trans-resveratrol via an SET mechanism is 7.17 × 10 dm mol s. The repair activity of RO toward dGuo-radicals is better than that of ROH, but the repair activity of ROH toward dGuo is better than that of RO. Unfortunately, neither ROH nor RO can repair the 2'-deoxyribose radicals of dGuo. It can therefore be concluded that trans-resveratrol is an effective antioxidant for repairing base radicals of dGuo and dGuo. The study can help us understand the repair activity of trans-resveratrol toward dGuo radicals.

Repair of oxidizing hydroxyl adduct radicals of DNA bases (base-OH-adduct) by eleven hydroxyl-trans-stilbenes via single electron transfer under physiological conditions are investigated using density functional theory. For eleven hydroxyltrans-stilbenes (PSOHs), their anions make all the contributions to repairing oxidizing base-OH-adduct radicals. Ten PSOHs show better beneficial antioxidant effect than trans-resveratrol. 3, 3', 4, 4', 5, 5'-Hexahydroxy-trans-stilbene (PSOH d ) performs the best repair activity to oxidizing base-OH-adduct radicals, and 3', 4', 5, 5'-tetrahydroxy-trans-stibene has the smallest pK a value. The rate constants for the reactions of PSOH d with oxidizing base-OH-adduct radicals are about 10 5 ∼ 10 9 dm 3 mol À 1 s À 1 . Main factors affecting the repair reactions are the vertical ionization potential, the pK a of PSOHs and the vertical electron affinity of oxidizing base-OH-adduct radicals. This study gives information on repairing oxidizing base-OH-adduct radicals by PSOHs in biological environment for the first time and finds more beneficial antioxidant effect polyphenol than trans-resveratrol or piceatannol.

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