Oxygen and nitrogen are pro-carcinogens, Damage to DNA by reactive oxygen,chlorine and nitrogen species: measurement, mechanism and the effects of nutrition

Humans are exposed to many carcinogens, but the most significant may be the reactive species derived from metabolism of oxygen and nitrogen. Nitric ox ide seems unlikely to damage DNA directly, but nitrous acid produces deamin ation and peroxynitrite leads to both deamination and nitration. Scavenging of reactive nitrogen species generated in the stomach may be an important role of flavonoids, flavonoids and other plant-derived phenolic compounds. Different reactive oxygen species produce different patterns of damage to D NA bases, e.g., such patterns have been used to implicate hydroxyl radical as the ultimate agent in H2O2-induced DNA damage. Levels of steady-state DN A damage in vivo are consistent with the concept that such damage is a majo r contributor to the age-related development of cancer and so such damage c an be used as a biomarker to study the effects of diet or dietary supplemen ts on risk of cancer development, provided that reliable assays are availab le. Methodological questions addressed in this article include the validity of measuring 8-hydroxydeoxyguanosine (8OHdG) in cellular DNA or in urine a s a biomarker of DNA damage, the extent of artifact formation during analys is of oxidative DNA damage by gas chromatography-mass spectrometry and the levels of oxidative damage in mitochondrial DNA. (C) 1999 Elsevier Science B.V. All rights reserved.