Damaged products of cytosine in hydroxyl radical solution under UV-irradiation

Modification of cytosine in hydrogen peroxide solution by UV-irradiation wa s investigated. Hydroxyl radicals generated from H2O2 under W irradiation o xidized cytosine to the monohydroxy and dihydroxy derivatives at the C5-C6 double bond. Several deamination products of modified cytosine derivative w ere also observed. Moreover, further transformation/rearrangement of some m odified bases led to the formation of five-membered ring derivatives such a s 5-hydroxyhydantoin and 3-amino-4,5-dihydroxypyrazole. Various products re sulting from radical interaction with cytosine were identified by using gas chromatography/mass spectrometry (GC/MS) after trimethylsilylation derivat ization, Some products were identified by comparing their retention time an d mass spectra with those of synthetic compounds that were formed by the tr eatment of cytosine with OsO4. Major products were quantified by GC/MS-sele cted ion monitoring mode. Some of products including uracil glycol were sig nificantly decomposed during formic acid hydrolysis. (C) 2001 Elsevier Scie nce B.V. All rights reserved.