Furfural, a precursor of the cytokinin hormone kinetin, and base propenals are formed by hydroxyl radical damage of DNA.

Recently, we have detected kinetin (N6-furfuryladenine), a well known cytokinin plant hormone, in commercially available DNA, in freshly extracted cellular DNA and in plant cell extracts. We had suggested that the furfuryl moiety of kinetin originates from furfural which is one of the primary oxidation products of deoxyribose in DNA. Here we show that the human cell extracts treated with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) give rise to oxime derivatives of various aldehydes present in the cell. Mass spectrometric analysis of silylated oximes showed several mass signals of different species, one of which was identified as furfural. Furthermore, detailed inspection of the mass spectra of DNA showed the mass signals of 165, 180, 189 and 206 m/z which correspond to cytosine-propenal, thymine-propenal, adenine-propenal and guanine-propenal, respectively. The presence of furfural, along with four base-propenals in the cell extract, as the primary oxidation products of deoxyribose, suggests that degradation of sugar residues in DNA is one of the major routes of cellular damage in addition to the modification of nucleic acid bases.