Oxidation of 1-N2-etheno-2'-deoxyguanosine by singlet molecular oxygen results in 2'-deoxyguanosine: a pathway to remove exocyclic DNA damage?

Abstract

Exocyclic DNA adducts are considered as potential tools for the study of oxidative stress-related diseases, but an important aspect is their chemical reactivity towards oxidant species. We report here the oxidation of 1-N2-etheno-2'-deoxyguanosine (1,N2-εdGuo) by singlet molecular oxygen (1O2) generated by a non-ionic water-soluble endoperoxide [N,N'-di(2,3-dihydroxypropyl)-1,4-naphthalenedipropanamide endoperoxide (DHPNO2)] and its corresponding oxygen isotopically labeled [18O]-[N,N'-di(2,3-dihydroxypropyl)-1,4- naphthalenedipropanamide endoperoxide (DHPN18O2)], and by photosensitization with two different photosensitizers [methylene blue (MB) and Rose Bengal (RB)]. Products detection and characterization were achieved using high performance liquid chromatography (HPLC) coupled to ultraviolet and electrospray ionization (ESI) tandem mass spectrometry, and nuclear magnetic resonance (NMR) analyses. We found that dGuo is regenerated via reaction of 1O2 with the ε-linkage, and we propose a dioxetane as an intermediate, which cleaves and loses the aldehyde groups as formate residues, or alternatively, it generates a 1,2-ethanediol adduct. We also report herein the quenching rate constants of 1O2 by 1,N2-εdGuo and other etheno modified nucleosides. The rate constant (kt) values obtained for etheno nucleosides are comparable to the kt of dGuo. From these results, we suggest a possible role of 1O2 in the cleanup of etheno adducts by regenerating the normal base.

• Authors: Glaucia Regina Martinez, Hulyana Brum, Guilherme Lanzi Sassaki, Lauro Mera de Souza, Ana Paula de Melo Loureiro, Marisa Helena Gennari de Medeiros, Paolo Di Mascio
• Journal: Biological chemistry (Biol Chem) Vol. 399 Issue 8 Pg. 859-867 (07 26 2018) ISSN: 1437-4315 [Electronic] Germany
• PMID: 29664729 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Singlet Oxygen
• Deoxyguanosine

Topics

• DNA Damage
• Deoxyguanosine (analogs & derivatives, chemistry, isolation & purification)
• Magnetic Resonance Spectroscopy
• Mass Spectrometry
• Molecular Structure
• Oxidation-Reduction
• Singlet Oxygen (chemistry)