MASS-SPECTROMETRIC ANALYSIS OF 2'-DEOXYRIBONUCLEOSIDE AND 2'-DEOXYRIBONUCLEOTIDE ADDUCTS WITH ALDEHYDES DERIVED FROM LIPID-PEROXIDATION

An important emerging issue in chemical carcinogenesis is the role tha t products of endogenous metabolism play in formation of covalently mo dified DNA. One example is the formation of alpha,beta-unsaturated ald ehydes as a result of endogenous and drug-stimulated lipid peroxidatio n. Malondialdehyde (MDA), crotonaldehyde (CR), 2-hexenal (HX), and 4-h ydroxy-2-nonenal (HNE) react covalently with 2'-deoxyguanosine (dG) an d 2'-deoxyadenosine (dA) residues on DNA to form promutagenic cyclic a dducts that may be important in the etiology of cancer in humans and a nimals. The accurate quantification of such adducts provides a powerfu l tool in molecular epidemiology for assessing carcinogenic risks from various lifestyle choices (e.g. diet, drug use) in humans. P-32-Postl abeling is recognized as one of the most sensitive methods available f or detection of DNA adducts in human tissues, but without adequate val idation such methodology can yield inaccurate quantitative measurement s. We have used LC separations in conjunction with electrospray ioniza tion MS and tandem MS (triple quadrupole and hybrid quadrupole-orthogo nal acceleration time of flight analyzers) to characterize MDA-, CR-, HX- and HNE-modified dG and nucleotide (3'- and 5'-monophosphate; 3',5 '-bis-phosphate) adducts. These data have been used to validate P-32-p ostlabeling methods for quantification of low level MDA-dG adducts for med in DNA of human and animal tissues. Availability of reliable metho ds for quantification of endogenous DNA damage in humans and animals i s essential for determining unknown etiologies of cancer and for the a ssessment of cancer risks in humans. (C) 1998 John Wiley & Sons, Ltd.