Isolation of new photoadducts from UVA-irradiated N-nitrosoproline with 2'-deoxyadenosine and characterization of photoadducts from DNA irradiated with N-nitrosoproline

Chiharu Asahi, Shuhei Aoyama, Sachiko Kimura, Toshinori Suzuki, Tsutomu Hatano, Sakae Arimoto-Kobayashi

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish
Article number112621
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume400
DOIs
Publication statusPublished - Sep 1 2020

Keywords

  • Adenine adduct
  • DNA adduct
  • N-nitrosoproline
  • Photoreaction
  • Reactive oxygen species

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Physics and Astronomy(all)

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