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Sixty-one selected chemicals were evaluated in rat tracheal epithelial (2C5) cells for their capacity to inhibit induction (or inhibit directly) the enzyme ornithine decarboxylase, the activity of which is associated with cell growth and division. a-Difluoromethylornithine (DFMO) was used as a positive control. At non-toxic concentrations, six test compounds had substantial activity (values for IC 50 DFMO/IC 50 compound >1): N-(2-carboxyphenyl)-all-trans-retinamide, ZK 119010 {2-(4-hydroxyphenyl)-3-methyl-1-[6-(1-pyrrolidinyl)hexyl]-1H-indol-5-ol), curcumin, 18-α-olean-12-ene-3β,23,28-triol, genistein and phenethyl isothiocyanate. These should be considered for further development as cancer preventive agents.

With BRL 3A hepatocytes, a series of selected, potentially chemopreventive chemicals was evaluated for their capacity to elevate glutathione (GSH) levels. Since sodium selenite consistently increased GSH levels by approximately 70%, it was selected as a positive control. Of 62 test chemicals, eighteen stimulated GSH levels by30%, but eleven of these had only a modest effect or displayed considerable toxicity. At non-toxic concentrations, seven compounds had substantial activity: black tea extract (decaffeinated), trans-chalcone, N-ethyl-9-cis-retinamide, indole-3-carbinol, dehydroepiandrosterone (DHEA) curcumin and N-(4-carboxyphenyl)retinamide. These should be considered for further development as cancer preventive agents.

With BRL 3A hepatocytes, a series of selected, potentially chemopreventive chemicals was evaluated for their capacity to elevate glutathione (GSH) levels. Since sodium selenite consistently increased GSH levels by approximately 70%, it was selected as a positive control. Of 62 test chemicals, eighteen stimulated GSH levels by >30%, but eleven of these had only a modest effect or displayed considerable toxicity. At non-toxic concentrations, seven compounds had substantial activity: black tea extract (decaffeinated), trans-chalcone, N-ethyl-9-cis-retinamide, indole-3-carbinol, dehydroepiandrosterone (DHEA) curcumin and N-(4-carboxyphenyl)retinamide. These should be considered for further development as cancer preventive agents.