The Tumor-Promoting Agents of Tobacco Leaf and Tobacco Smoke Condensate2

Abstract

Extracts from flue-cured cigarette tobacco leaf were taken successively with ether, chloroform, and methyl alcohol. These extracts, a reconstituted whole extract, and known tobacco phenols were tested for tumor-promoting activity on mouse skin after an initiating treatment with 7,12-dimethylbenz[a]anthracene. The ether extract, the methyl alcohol extract, and the reconstituted whole extract of unburned tobacco leaf showed notable promoting activity. In parallel experiments, whole cigarette smoke condensate showed remarkable promoting activity and no tumorigenicity without initiation at these dose levels; eugenol, a known tobacco leaf phenol, showed weak promoting activity. Several tobacco tar aromatic hydrocarbons were tested for initiating activity with croton resin used as the promoter. Benzo[a]pyrene, benzo[b]fluoranthene, and chrysene were potent initiators, whereas benzo[m,n,o]fluoranthene and 1-methylpyrene were inactive.