108929-11-9Relevant academic research and scientific papers
Addition of deoxyribose to guanine and modified DNA bases by Lactobacillus helveticus trans-N-deoxyribosylase
Mueller, Michael,Hutchinson, Linda K.,Peter Guengerich
, p. 1140 - 1144 (1996)
The use of bacterial trans-N-deoxyribosylase was evaluated as an alternative method for deoxyribosylation in the synthesis of deoxyribonucleosides containing potentially mutagenic adducts. A crude enzyme preparation was isolated from Lactobacillus helveticus and compared to Escherichia coli purine nucleoside phosphorylase. trans-N-deoxyribosylase was more regioselective than purine nucleoside phosphorylase in the deoxyribosylation of Gua at the N9 atom, as compared to N7, as demonstrated by NMR analysis of the product. 5,6,7,9-Tetrahydro-7-acetoxy-9- oxoimidazo[1,2-a]purine was efficiently deoxyribosylated by trans-N- deoxyribosylase but not at all by purine nucleoside phosphorylase. Other substrates for trans-N-deoxyribosylase were N2-(2-oxoethyl)Gua, pyrimido[1,2-a]purin-10(3H)-one, 1,N2-ε-Gua, N2,3ε-Gua, 3,N4-(-Cyt, 1,N6-ε-Ade, C8-methylGua, and C8-aminoGua, most of which gave the desired isomer (bond at the nitrogen corresponding to N9 in Gua) in good yield. Neither N7-alkylpurines nor C8-(arylamino)-substituted guanines were substrates. The approach offers a relatively convenient method of enzymatic preparation of many carcinogen-DNA adducts at the nucleoside level, for either use as standards or incorporation into oligonucleotides. trans-N- deoxyribosylase can also be used to remove deoxyribose from modified deoxyribonucleosides in the presence of excess Cyt.
4-Hydroxy-2-nonenal and ethyl linoleate form N2,3-ethenoguanine under peroxidizing conditions
Ham, Amy-Joan L.,Ranasinghe, Asoka,Koc, Hasan,Swenberg, James A.
, p. 1243 - 1250 (2000)
In these studies, we demonstrate that N2,3-ethenoguanine (N2,3-∈Gua) is formed from lipid peroxidation as well as other oxidative reactions. Ethyl linoleate (EtLA) or 4-hydroxy-2-nonenal (HNE) was reacted with dGuo in the presence of tert-butyl hydroperoxide (t-BuOOH) for 72 h at 50 °C. The resulting N2,3-∈Gua was characterized by liquid chromatography/electrospray mass spectroscopy and by gas chromatography/high-resolution mass spectral (GC/HRMS) analysis of its pentafluorobenzyl derivative following immunoaffinity chromatography purification. The amounts of N2,3-∈Gua formed were 825 ± 20 and 1720 ± 50 N2,3-∈Gua adducts/106 normal dGuo bases for EtLA and HNE, respectively, corresponding to 38- and 82-fold increases in the amount of N2,3-∈Gua compared to controls containing only t-BuOOH. Controls containing t-BuOOH but no lipid resulted in a > 1000-fold increase in the level of N2,3-∈Gua over dGuo that was not subjected to incubation. EtLA and HNE, in the presence of t-BuOOH, were reacted with calf thymus DNA at 37 °C for 89 h. The amounts of N2,3-∈Gua formed in intact ctDNA were 114 ± 32 and 52.9 ± 16.7 N2,3-∈Gua adducts/106 normal dGuo bases for EtLA and HNE, respectively. These compared to 2.02 ± 0.17 and 2.05 ± 0.47 N2,3-∈Gua adducts/106 normal dGuo bases in control DNA incubated with t-BuOOH, but no lipid [13C18]EtLA was reacted with dGuo to determine the extent of direct alkylation by lipid peroxidation byproducts. These reactions resulted in a 89-93% level of incorporation of the 13C label into N2,3-∈Gua when EtLA and dGuo were in equimolar concentrations, when EtLA was in 10-fold molar excess, and when deoxyribose (thymidine) was in 10-fold molar excess. Similar reactions with ctDNA resulted in an 86% level of incorporation of the 13C label. These data demonstrate that N2,3-∈Gua is formed from EtLA and HNE under peroxidizing conditions by direct alkylation. The data also suggest, however, that N2,3-∈Gua is also formed by an alternative mechanism that involves some other oxidative reaction which remains unclear.
trans,trans-2,4-Decadienal-induced 1,N2-etheno-2'-deoxyguanosine adduct formation
Loureiro, Ana Paula M.,Di Mascio, Paolo,Gomes, Osmar F.,Medeiros, Marisa H. G.
, p. 601 - 609 (2000)
A number of ring-extended DNA adducts resulting from the reaction of α,β-unsaturated aldehydes, or their epoxides, with DNA bases have been characterized in recent years. These adducts may lead to miscoding during DNA replication, resulting, if not repaired, in mutations that can contribute to cancer development, trans,trans-2,4-Decadienal (DDE) is one of the highly cytotoxic aldehydes endogenously formed from lipid peroxidation. To evaluate its DNA damaging potential, we have investigated the reaction of DDE with 2'- deoxyguanosine (dGuo) in the presence of peroxides. Three stable adducts were isolated by reverse-phase HPLC. Adduct A1, 3-(2-deoxy-β-D-erythro- pentafuranosyl)-5,9-dihydro-9H-imidazo[2,1-i]purin-9-hydroxy, is a tautomer of 1,N2-etheno-2'-deoxyguanosine, a well-known reaction product of epoxy aldehydes with dGuo. Two new diasteroisomeric products, A2-1 and A2-2, 1- {[3-(2'-deoxy-β-D-erythropentafuranosyl)-5,9-dihydro-9H-imidazo[2,1- i]purin-9-hydroxy]-7-yl}-2-one-3 octanol, were isolated and characterized on the basis of their spectroscopic features as 1,N2-etheno adducts possessing a carbon side chain with a carbonyl and a hydroxyl group. The proposed reaction mechanism for the formation of adducts A2 involves DDE double epoxidation and hydrolysis of the C4 epoxy group prior to nucleophilic addition of the exocyclic amino group of dGuo to C1 of the aldehyde, followed by cyclization via nucleophilic attack on the C2 epoxy group by N-1 and elimination of H2O. After treatment of calf thymus DNA with DDE, formation of adducts A1 and A2 was detected by the LC/ESI/MS-MS technique. These results can contribute to a better understanding of the chemical structures of adducts resulting from the reaction of aldehydes with nucleic acid bases, a necessary step in assessing the genotoxic risks associated with this class of compounds.
Oxidation of 1-N2-etheno-2′-deoxyguanosine by singlet molecular oxygen results in 2′-deoxyguanosine: A pathway to remove exocyclic DNA damage?
Martinez, Glaucia Regina,Brum, Hulyana,Sassaki, Guilherme Lanzi,De Souza, Lauro Mera,Loureiro, Ana Paula De Melo,De Medeiros, Marisa Helena Gennari,Di Mascio, Paolo
, p. 859 - 867 (2018)
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-?dGuo) 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 ?-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-?dGuo 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.
In vitro synthesis of 1,N6-etheno-2′-deoxyadenosine and 1,N2-etheno-2′-deoxyguanosine by 2,4-dinitrophenol and 1,3-dinitropyrene in presence of a bacterial nitroreductase
Chiron, Serge,Barbati, Stephane,De Meo, Michel,Botta, Alain
, p. 222 - 227 (2007/10/03)
The formation of covalent nitro-PAH DNA adducts and nitro-PAH mediated oxidative lesions are two possible mechanisms for the initiation of nitro-PAH carcinogenesis. Sixty-minute incubation of 1,3-dinitropyrene (100 μM) or 1,4-dinitrophenol (100 μM) with a mixture of 150 μM NADH, 0.5 units of E. coli nitroreductase, 100 μM linoleic acid, 0.5 mM ferrous iron, and 100 μM 2′-deoxyadenosine (2′-dA) or 100 μM 2′-deoxyguanosine (2′-dG) were analyzed by liquid chromatography multistage mass spectrometry. Mixtures of 1,N6-etheno-2′-deoxyadenosine (εdA) plus 4-oxo-2-nonenal (4-ONE) and 1,N2-etheno-2′- deoxyguanosine (εdG) plus 4-ONE could be detected from 2′-dA and 2′-dG, respectively. Addition of 2% propanol inhibited the formation of etheno adducts. Analyses of disappearance kinetics of dA and dG showed that dG was more rapidly eliminated than does dA (t[1/2] = 23.3 min and 98.3 min for dG and dA, respectively). Curves of formation kinetics revealed that the peak of εdG was at 55.6 min while that of εdA was at 186.9 min. These peaks represented 1.43% and 1.25% of the original dG and dA, respectively. In both cases, the peaks were followed by rapid degradations of etheno adducts. The results, obtained in this system, do not allow any extrapolation to realistic cellular responses; nevertheless, these data questioned the validity of the use of unsubstituted etheno adducts as reliable oxidative stress and nitro-PAH exposure biomarkers.
Reactions of 9-substituted guanines with bromomalondialdehyde in aqueous solution predominantly yield glyoxal-derived adducts.
Ruohola, Anne-Mari,Koissi, Niangoran,Andersson, Sanna,Lepistoe, Ilona,Neuvonen, Kari,Mikkola, Satu,Loennberg, Harri
, p. 1943 - 1950 (2007/10/03)
Reactions of 9-ethylguanine, 2'-deoxyguanosine and guanosine with bromomalondialdehyde in aqueous buffers over a wide pH-range were studied. The main products were isolated and characterized by (1)H and (13)C NMR and mass spectroscopy. The final products formed under acidic and basic conditions were different, but they shared the common feature of being derived from glyoxal. Among the 1 : 1 adducts, 1,N(2)-(trans-1,2-dihydroxyethano)guanine adduct (6) predominated at pH 7. In addition to these, an N(2)-(4,5-dihydroxy-1,3-dioxolan-2-yl)methylene adduct (11a,b) and an N(2)-carboxymethyl-1,N(2)-(trans-1,2-dihydroxyethano)guanine adduct (12) were obtained at pH 10. The results of kinetic experiments suggest that bromomalondialdehyde is significantly decomposed to formic acid and glycolaldehyde under the conditions required to obtain guanine adducts. Glycolaldehyde is oxidized to glyoxal, which then modifies the guanine base more readily than bromomalondialdehyde. Besides the glyoxal-derived adducts, 1,N(2)-ethenoguanine (5a-c) and N(2),3-ethenoguanine adducts (4a-c) were formed as minor products, and a transient accumulation of two unstable intermediates, tentatively identified as 1,N(2)-(1,2,2,3-tetrahydroxypropano)(8) and 1,N(2)-(2-formyl-1,2,3-trihydroxypropano)(9) adducts, was observed.
Synthesis of oligonucleotides containing N2-(5-carboxypentyl)-2'-deoxyguanosine and 5-[2-(4'-methyl-2,2'-dipyrid-4-yl-carboxamido)ethylthio]-2'-deoxyuridi ne
Wang,Bergstrom
, p. 6721 - 6724 (2007/10/02)
Synthesis of 2'-deoxyguanosine tethered at N-2 to a carboxypentyl group and 2'-deoxyuridine tethered through C-5 to a bipyridine is described. The modified nucleosides were converted to the corresponding phosphoramidites and incorporated into mono- and di
