Protective effect against hydroxyl radical-induced DNA damage and antioxidant mechanism of [6]-gingerol: A chemical study

Abstract

[6]-Gingerol is known as the major bioactive constituent of ginger. In the study, it was observed to effectively protect against ·OH-induced DNA damage (IC50 328.60 ± 24.41 μM). Antioxidant assays indicated that [6]-gingerol could efficiently scavenge various free radicals, including ·OH radical (IC50 70.39 ± 1.23 μM), ·O2- radical (IC50 228.40 ± 9.20 μM), DPPH· radical (IC50 27.35 ± 1.44 μM), and ABTS+· radical (IC50 2.53 ± 0.070 μM), and reduce Cu2+ ion (IC50 11.97 ± 0.68 μM). In order to investigate the possible mechanism, the reaction product of [6]-gingerol and DPPH· radical was further measured using HPLC combined mass spectrometry. The product showed a molecular ion peak at m/z 316 [M+Na]+, and diagnostic fragment loss (m/z 28) for quinone. On this basis, it can be concluded that: (i) [6]-gingerol can effectively protect against ·OH-induced DNA damage; (ii) a possible mechanism for [6]-gingerol to protect against oxidative damage is ·OH radical scavenging; (iii) [6]-gingerol scavenges ·OH radical through hydrogen atom (H·) transfer (HAT) and sequential electron (e) proton transfer (SEPT) mechanisms; and (iv) both mechanisms make [6]-gingerol be oxidized to semi-quinone or quinone forms.