ABSTRACT
A method, involving a HPLC prepurification followed by a GC/MS analysis, has been set up for the measurement of nucleic acid oxidation products in human urine. For this purpose, isotopically labeled internal standards have been prepared and used for isotope dilution mass spectrometric detection. Using this approach, four oxidized DNA bases, i.e., 5-hydroxyuracil, 5-(hydroxymethyl)uracil, 8-oxo-7,8-dihydroadenine, and 8-oxo-7,8-dihydroguanine, together with 8-oxo-7,8-dihydro-2'-deoxyguanosine have been simultaneously quantified in human urine samples. The levels of the oxidized nucleic acid constituents, as expressed in picomoles per milliliter, were determined to be, in decreasing order: 8-oxo-7,8-dihydroguanine (583 +/- 376) > 5-(hydroxymethyl)uracil (121 +/- 56) > 5-hydroxyuracil (58 +/- 23) > 8-oxo-7,8-dihydro-2'-deoxyguanosine (30 +/- 15) > 8-oxo-7,8-dihydroadenine (7 +/- 4). Attempts to determine the amount of 5,6-dihydroxy-5,6-dihydrothymine, 5-hydroxycytosine, and 2,6-diamino-4-hydroxy-5-formamidopyrimidine using the above HPLC-GC/MS method were unsuccessful.
