Free radical chemistry of cigarette smoke and its implication in human cancer.

Multiple components in cigarette smoke were analyzed for their ability to form active oxygen species using a spin trapping agent, 5, 5-dimethyl-1-pyrroline-N-oxide. The main source of O2 and H2O2 was ascribed to polyphenols in a particulate phase, whereas a synergistic effect was also observed between these polyphenols and nicotine. The vapor phase contained a factor which produced OH from H2O2 which was identified as carbonyl sulfide. Nitric oxide in the vapor phase did not show such reactivity. The formation of an active oxygen species in cigarette smoke could provide an important clue to elucidate the mechanism of tobacco carcinogenesis, since they show genotoxic effects to induce DNA strand breaks as well as epigenetic effects to act as cell proliferation signals.