The activities of some polycyclic hydrocarbons and their "K region" epoxides in an in vitro-in vivo carcinogenicity test system

Absence of mutagenicity of coralyne and related antileukemic agents: structural comparison with the potent carcinogen 7,12-dimethylbenz[a]anthracene

The structural similarity between antileukemic alkaloid coralyne and the carcinogenic and antineoplastic hydrocarbon 7, 12-dimethylbenz[a]anthracene, as well as the similarity between the antileukemic alkaloid nitidine and the carcinogenic hydrocarbon 5-methylchrysene, prompted a mutagenicity evaluation of coralyne sulfoacetate, nitidine chloride, the 8-ethyl homolog of coralyne, nitidine methosulfate, and the tetramethoxy analog of nitidine by the Ames method against the histidine-auxotroph strains of Salmonella typhimurium TA-1537, TA-1538, TA-98, and TA-100; 7,12-dimethylbenz[a]anthracene was used as a reference standard. The mutagenicity of these antileukemic compounds was either completely eliminated or drastically reduced, but the mutagenic response was generally high for 7,12-dimethylbenz[a]anthracene. The results suggest that the presence of a quaternary nitrogen atom and alkoxy groups could be important in alleviating the mutagenicity of the parent mutagenic and carcinogenic hydrocarbons.

The activity of 7-methylbenz(a)anthracene metabolites in an in vitro-in vivo carcinogenicity test using mouse lung tissue

7-Methylbenz(a)anthracene (7-MBA) and its 5,6-oxide and trans-5,6- and trans-8,9-dihydrodiol were tested for carcinogenic activity in a system in which mouse lung tissue was incubated in the presence of a test compound for 1 h and then implanted into isologous mice. All four compounds gave small yields of adenomas and in addition the 5,6-oxide gave two carcinomas.

Skin-tumor-initiating ability of benzo(a)pyrene-7,8-diol-9,10-epoxide (anti) when applied topically in tetrahydrofuran

The skin-tumor-initiating abilities of various metabolites of benzo(a)pyrene (BP) were determined in mice by using a two-stage system of tumorigenesis. We previously reported that BP-7,8-dihydrodiol (+/- trans) was approximately as potent as BP, suggesting that it may be a proximate carcinogen, but the alleged ultimate carcinogen of BP [BP-7,8-dihydrodiol-9,10-epoxide (anti)] was a weak tumor initiator (Cancer Lett.2: 115, 1976). Because of its high reactivity, the tumor-initiating ability of the BP-7,8-dihydrodiol-9,10-epoxide (anti) was determined by using acetone, benzene, and tetrahydrofuran (THF) as the solvent vehicles. The 'diol-epoxide' of BP was found to be an effective tumor initiator when applied topically in THF. The effectiveness of the various vehicles for the 'diol-epoxide' was as follows: THF greater than benzene greater than acetone; however, acetone was the best solvent for BP tumor initiation. The BP-9,10-dihydrodiol and BP-3-hydroxy were found to be weak tumor initiators. BP-3-hydroxy was also tested for tumor-promoting ability and was found to be inactive in this capacity.

Skin tumor initiating ability of benzo(a)pyrene 4,5- 7,5- and 7,8-diol-9,10-epoxides and 7,8-diol

The skin tumor initiating abilities of both K-region and non-K-region epoxides of benzo(a)pyrene(BP) were determined in mice using a two-stage system of tumorigenesis. BP-4,5-epoxide and BP-7,8-dihydrodiol-9,10-epoxide (anti) were found to be weak tumor initiators whereas BP-7,8-epoxide had about a third of the activity as the parent hydrocarbon, BP. However, the 7,8-dihydrodiol of BP was found to be approximately as potent as BP suggesting that it may be a proximate carcinogen.