Endogenous and background DNA adducts by methylating and 2-hydroxyethylating agents

Mutat Res. 1999 Mar 8;424(1-2):117-25. doi: 10.1016/s0027-5107(99)00013-5.


Detection of 7-alkylguanine DNA adducts is useful to assess human exposure to and the resulting DNA damage caused by simple alkylating agents. The background 7-methylguanine (7-MG) and 7-hydroxyethylguanine (7-HEG) adduct levels were determined in human and rat tissues, using thin-layer chromatography (TLC) combined with high pressure liquid chromatography (HPLC). In addition, these two adduct levels were also compared in various tissues between smokers and non-smokers. The results demonstrated that the background level of 7-alkylguanine adducts in WBC and lung tissues of non-smokers was 2.9 and 4.0 adducts/107 nucleotides, respectively. In smokers with lung cancers 7-MG adduct level in lung samples (6.3+/-1.9 adducts/107 nucleotides) and in bronchus samples (6.1+/-1.5 adducts/107 nucleotides) was significantly higher than that in WBC samples (3.3+/-0.9 adducts/107 nucleotides). 7-HEG adduct levels obtained from the same individuals were 0.8+/-0.3 in lung, 1.0+/-0.8 in bronchus and 0.6+/-0.2 adducts/107 nucleotides in WBC, respectively. Animal studies showed that background levels of 7-MG (2.1-2.5 adducts/107 nucleotides) in control rats were approximately 2-4-fold higher than 7-HEG levels (0.6-0.9 adducts/107 nucleotides). After a 3-day exposure to 300 ppm ethene, 7-HEG adducts accumulated to a similar extent in different tissues of rats, with the mean adduct level of 5.6-7.0 in liver, 7.4 in lymphocytes and 5.5 adducts/107 nucleotides in kidney.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromatography, High Pressure Liquid
  • DNA Adducts
  • DNA Damage*
  • DNA Methylation
  • Guanine / analogs & derivatives*
  • Humans
  • Male
  • Rats
  • Rats, Sprague-Dawley


  • DNA Adducts
  • N(7)-hydroxyethylguanine
  • Guanine
  • 7-methylguanine