DNA damage by the sulfate radical anion: hydrogen abstraction from the sugar moiety versus one-electron oxidation of guanine

Abstract

The products of oxidative damage to double-stranded (ds) DNA initiated by photolytically generated sulfate radical anions SO4(•-) were analyzed using reverse-phase (RP) high-performance liquid chromatography (HPLC). Relative efficiencies of two major pathways were compared: production of 8-oxoguanine (8oxoG) and hydrogen abstraction from the DNA 2-deoxyribose moiety (dR) at C1,' C4,' and C5' positions. The formation of 8oxoG was found to account for 87% of all quantified lesions at low illumination doses. The concentration of 8oxoG quickly reaches a steady state at about one 8oxoG per 100 base pairs due to further oxidation of its products. It was found that another guanine oxidation product identified as 2-amino-5-(2'-alkylamino)-4H-imidazol-4-one (X) was released in significant quantities from its tentative precursor 2-amino-5-[(2'-deoxy-β-d-erythro-pentofuranosyl)amino]-4H-imidazol-4-one (dIz) upon treatment with primary amines in neutral solutions. The linear dose dependence of X release points to the formation of dIz directly from guanine and not through oxidation of 8oxoG. The damage to dR was found to account for about 13% of the total damage, with majority of lesions (33%) originating from the C4' oxidation. The contribution of C1' oxidation also turned out to be significant (17% of all dR damages) despite of the steric problems associated with the abstraction of the C1'-hydrogen. However, no evidence of base-to-sugar free valence transfer as a possible alternative to direct hydrogen abstraction at C1' was found.

First Direct and Unequivocal Electron Spin Resonance Spin-Trapping Evidence for pH-Dependent Production of Hydroxyl Radicals from Sulfate Radicals

“… ,,, SO 4 • – can be produced from the activation of persulfate (including peroxodisulfate (PDS) and peroxymonosulfate (PMS)) by UV, , heat, base, ozone, transition metals, and quinones . Because of its high reactivity, selectivity, and widely operational pH range, , SO 4 • – has been extensively investigated as an alternative to • OH-based advanced oxidation processes (AOPs), especially for the control of micropollutants such as algal toxins, perfluorinated compounds, flame retardants, and endocrine disruptors. − SO 4 • – has also been widely used in many other fields such as in biological research, ,− analytical chemistry, ,− organic synthesis, , and public health (as a disinfection agent) (For more details, see Table S1). …”

Genotoxicity of Three Micro/Nanocelluloses with Different Physicochemical Characteristics in MG-63 and V79 Cells

“…This phenomenon has been already observed in previous studies with NMs [ 46 , 49 ]. Moreover, a possible explanation of the genotoxicity of CNCs in MG-63 cells at all concentrations may be that the possible cellular influx of the sulphate groups could cause oxidative damage to DNA [ 79 , 80 , 81 , 82 ], leading to double-strand breaks and structural chromosomal alterations, even without cellular uptake. As already mentioned, this hypothesis will have to be studied.…”