The environmental pollutant 6-nitrochrysene (6-NC) is a potent mutagen in bacteria and it induces mammary carcinoma in rats. It is an exceptionally potent carcinogen in newborn mice. 6-NC is metabolically activated by two pathways, which include only nitroreduction and both nitroreduction and ring oxidation. The nitroreduction pathway generates dG-C8, dG-N2, and the dA-C8 adduct, N-(dA-8-yl)-6-AC. Here, we report the synthesis of the phosphoramidite monomer of the major C8-dA adduct of 6-NC from dA in 10 steps and its incorporation into oligonucleotides. The key step in the synthesis of oligonucleotides containing N-(dA-8-yl)-6-AC was palladium-catalyzed Buchwald-Hartwig cross coupling chemistry, which was achieved in 75% yield. The protected N-(dA-8-yl)-6-AC derivative was deprotected and then converted to appropriately protected phosphoramidite monomer for solid-phase DNA synthesis. The resulting phosphoramidite was used to synthesize a 12-mer and a 15-mer oligonucleotide. The adduct-containing oligonucleotides were purified by reversed phase HPLC followed by denaturing polyacrylamide gel electrophoresis and characterized by mass spectrometry. These modified oligonucleotides are now being used to study the mutagenic and repair efficiency of N-(dA-8-yl)-6-AC in a plasmid construct.

Total synthesis of site-specific oligonucleotides containing 2'-deoxyadenosine adduct formed by 6-nitrochrysene and their biological studies

254th National Meeting (2017)

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