Tumor-promoting activity of certain extracts of tobacco.

Tumor-promoting activities of extracts of fluecured and cigarette tobacco were evaluated. Initially, fluecured tobacco was extracted consecutively with hexane, chloroform, acetone, ethyl alcohol, methyl alcohol, and water; and the extracts were tested for tumor-promoting activity on mouse skin. The hexane and chloroform extracts were fractionated on silicic acid, and the fractions were devoid of tumorigenic activity. The acetone and alcohol extracts showed marginal activity. Subsequently, chloroform-extracted cigarette tobacco was extracted with water, and the aqueous extract was partitioned by solvent precipitation methods. Bioassay results showed tumor-promoting activity for the aqueous extract, with tumors in 38% of the animals. The aqueous extract appeared about five times as active as smoke condensate derived from an equal weight of tobacco.