A novel synthesis of malondialdehyde adducts of deoxyguanosine, deoxyadenosine, and deoxycytidine.

Malondialdehyde (MDA) is a mutagenic product of lipid peroxidation and prostaglandin biosynthesis. MDA reacts with DNA bases to produce adducts of deoxyguanosine (M1G), deoxyadenosine (M1A), and deoxycytidine (M1C). A novel synthesis of these MDA nucleoside adducts has been developed, which significantly improves their availability. For the deoxyguanosine adduct, M1G, an amine equivalent to MDA, 4-amino-3-(phenylselenyl)butane-1,2-diol, was reacted with 2-fluoro-O6-(2-(trimethylsilyl)ethyl)-2'-deoxyinosine via a nucleophilic aromatic substitution reaction followed by acid hydrolysis of the O6-protecting group to give an N2-modified deoxyguanosine intermediate. Periodate oxidation of this intermediate under slightly acidic conditions gave M1G in good overall yield via cleavage of the vicinal diol unit and concomitant oxidation of the phenylselenide group to the corresponding selenoxide and syn beta-elimination. M1A and M1C were synthesized by the same strategy starting from 6-chloropurine 2'-deoxyriboside and 1-(2-deoxy-beta-d-erythro-pentofuranosyl)-4-(1H-1,2,4-triazol-1-yl)-2-(1H)pyrimidinone, respectively. An advantage of this approach is that similar chemistry has been shown to be directly applicable to the synthesis of site specifically adducted oligonucleotides containing activated nucleobases such as those used in this study. This strategy may offer an improved synthesis to oligonucleotides containing M1G and a feasible approach to M1A and M1C containing oligonucleotides.