- Isolation of new photoadducts from UVA-irradiated N-nitrosoproline with 2'-deoxyadenosine and characterization of photoadducts from DNA irradiated with N-nitrosoproline
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N-nitrosoproline (NPRO) is formed from nitrosation of proline and has been reported to be non-carcinogenic and non-mutagenic. However, earlier studies in our laboratory showed that pre-irradiated NPRO can be converted to a mutagenic form. We previously investigated the reaction of NPRO with dA or dG under UVA irradiation and identified the formation of 2-pyrrolidyl-dA adducts (P1 & P2) and 8-pyrrolidyl-dG adducts (G1 & G2) as well as four known modified nucleosides, although several peaks found in the HPLC profiles of UVA-irradiated mixtures of dA and NPRO remain unidentified. In the present study we isolated new photoproducts from irradiated mixtures of dA and NPRO and identified (R)- and (S)-8-(2-pyrrolidyl)-2′-deoxyadenosine (A1 and A2) as products by MS and NMR. We also investigated the photoadducts formed in DNA treated with NPRO under UVA irradiation, and detected A1 and/or A2 (probably both), P1, P2, G1 and/or G2, and 8-oxodG as products. Under anaerobic conditions, formation of A1 and A2 was greater than that under aerobic conditions, suggesting that photo-reactions comprising pyrrolidyl radical with dA may increase under anaerobic conditions given reduced competition with oxidative photo-reactions which may decompose pyrrolidyl-dA adducts.
- Aoyama, Shuhei,Arimoto-Kobayashi, Sakae,Asahi, Chiharu,Hatano, Tsutomu,Kimura, Sachiko,Suzuki, Toshinori
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- Near ultraviolet radiation-mediated reaction between N-nitrosoproline and DNA: Isolation and identification of two new adducts, (R)- and (S)-8-(2-pyrrolidyl)-2′-deoxyguanosine
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To explore possible genotoxicity of N-nitrosoproline (NPRO), we investigated near-ultraviolet radiation (UVA)-mediated chemical reaction of NPRO with 2′-deoxyguanosine (dG). An acidic solution containing NPRO and dG was irradiated with UVA and products we
- Aoyama, Shuhei,Sano, Kayoko,Asahi, Chiharu,Machida, Masaki,Okamoto, Keinosuke,Negishi, Tomoe,Kimura, Sachiko,Suzuki, Toshinori,Hatano, Tsutomu,Arimoto-Kobayashi, Sakae
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- Formation of 2-chloroinosine from guanosine by treatment of HNO2 in the presence of NaCl
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We investigated the reaction of Guo with nitrous acid in the presence of NaCl. When 1 mM Guo was incubated with 100 mM NaNO2 and 2 M NaCl in sodium acetate buffer at pH 3.2 and 37°C, 2-chloroinosine (2-Cl-Ino) was produced in addition to oxanosine (Oxo) and xanthosine (Xao). The yield of 2-Cl-Ino was 0.033 mM at an incubation time of 2 h. Under the same reaction conditions, GMP and dGuo gave rise to the corresponding 2-chloro derivatives with comparable yields. All the 2-chloro derivatives were fairly stable (t1/2>360 h) at physiological pH and temperature. To elucidate the reaction mechanism of the chlorination, the diazoate derivative of Guo, a reaction intermediate of the Guo-HNO2 system, was employed as a starting compound. When the diazoate was incubated with 2 M NaCl in a neutral solution, 2-Cl-Ino was produced in addition to Oxo and Xao. These results suggest that the 2-chloro derivatives can be produced from foodstuffs in the human stomach and may have potential importance as a carcinogen causing gastric cancer.
- Suzuki, Toshinori,Ide, Hiroshi,Yamada, Masaki,Morii, Takashi,Makino, Keisuke
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p. 2937 - 2941
(2007/10/03)
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- Synthesis of 2',3'-didehydro-2',3'-dideoxyisoinosine and oxidation of fluorescent 2-hydroxypurine nucleosides by xanthine oxidase
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The syntheses of 2',3'-didehydro-2',3'-dideoxyisoinosine (d4isoI, 4) as well as 7-deaza-2',3'-didehydro-2',3'-dideoxyisoinosine (d4c7isoI, 5) are described. Compounds 4 and 5 show both strong fluorescence. Compound 4 is oxidized by xanthine oxi
- Seela, Frank,Chen, Yaoming,Sauer, Markus
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- A new synthesis of oxanosine and 2'-deoxyoxanosine
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An easy and more efficient synthesis of oxanosine and 2'-deoxyoxanosine has been developed, a key step in the reported synthesis is a new photochemical transformation by UV irradiation of 1-hydroxy derivatives of inosine.
- De Napoli, Lorenzo,Di Fabio, Giovanni,Messere, Anna,Montesarchio, Daniela,Piccialli, Gennaro,Varra, Michela
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p. 7397 - 7400
(2007/10/03)
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- 2'-Deoxyisoinosine: Synthesis of a highly fluorescent nucleoside and its incorporation into oligonucleotides
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The synthesis of 2'-deoxyisoinosine (2a) and the related 2',3'- dideoxynucleosides 2b and 3 is reported. The 3'-phosphonate 4b as well as the phosphoramidite 4c were prepared and employed in solid-phase oligonucleotide synthesis.
- Seela,Chen
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p. 863 - 866
(2007/10/02)
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- Oligodeoxynucleotides embodying the ambiguous base Z, 5-amino-imidazole- 4-carboxamide
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Short oligomers containing 5-amino-1-(2-deoxy-β-D- ribofuranosyl)imidazole -4-carboxamide (dZ) were synthesized in solution using the phosphotriester methodology. Usual acyl groups were used for the canonical bases. For the exocyclic amino function of Z residue, the hydrogenolyzable benzyloxycarbonyl group was introduced.
- Pochet,Dugue
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p. 1195 - 1210
(2007/10/02)
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- PREPARATION OF 2'-DEOXYXANTHOSINE BY NITROSATIVE DEAMINATION OF 2'-DEOXYGUANOSINE UNDER ALKALINE AQUEOUS CONDITIONS
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2'-Deoxyxanthosine (dXao) has been prepared by treating 2'-deoxyguanosine (dGuo) wiyh basic nitroprusside.Succesful conversion appears to be favored by ionizing both dGuo (increasing its nucleophilicity) and dXao (protecting it from protolysis).
- Moschel, Robert C.,Keefer, Larry K.
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p. 1467 - 1468
(2007/10/02)
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