Mechanistic processes of resveratrol in inhibiting the oxidative damage of guanine, as evidenced by UHPLC-MS.

Resveratrol, as one of the stilbenoids, is present in abundance in wine grapes and has been shown to selectively quench O. DNA is oxidized by O causing irreparable functional damage, and of the nucleic acids, guanine is the most susceptible. An agarose gel electrophoresis assay demonstrated that DNA was damaged by O with less than 5 min of UVA irradiation, and also that 5 mM resveratrol dissolved in MeOH could relieve the observed oxidation stress. Ultra-high performance liquid chromatography coupled with mass spectrometry was performed to reveal the mechanism. Four guanine oxidation products at m/z 140.0334 M-H, DGh, 8-oxoG, Sp and two conjugates at m/z 377.1104 [M-H] and 391.0907 [M-H] were identified and quantified. Thus, we propose the mechanism that the phenol ring of resveratrol links with the free amino groups (NH) of guanine at the beginning of O attack to form m/z 377.1104 [M-H], however, as O is able to attack the amino groups continuously, resveratrol can efficiently react with O prior to damage, and form m/z 391.0907 [M-H] thereby protecting guanine.