Involvement of Radicals in Chemical Carcinogenesis
Chemical carcinogens comprise a large and structurally diverse group of synthetic and naturally occurring compounds. It appears almost axiomatic that such compounds must react with tissue components in order to induce neoplastic transformation. With the exception of the carcinogenic alkylating agents, most chemical carcinogens are not reactive per se and must be converted to reactive forms either chemically or metabolically. Data are emerging to indicate that electrophilic reactants are the ultimate form of most, if not all, chemical carcinogens (Miller, 1970). The proximate forms of a number of chemical carcinogens might be convertible to free radicals, i.e., electrophilic reactants, and suggest a possible role for the free radical in carcinogenesis. The presence of free radicals in tobacco smoke has been demonstrated (Lyons and Spence, 1960; Bluhm et al., 1971) and the increased incidence of lung cancer in cigarette smokers based on epidemiological studies is well known. The chemical and metabolic conversion of a number of chemical carcinogens to free radicals and the interaction of these radicals with DNA will be described in this communication.
KeywordsChemical Carcinogen Electron Spin Resonance Study Covalent Linkage Chemical Carcinogenesis Polycyclic Hydrocarbon
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