These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: The effects of bay-region methyl substitution on 6-nitrochrysene mutagenicity in Salmonella typhimurium and tumorigenicity in newborn mice.
    Author: el-Bayoumy K, Shiue GH, Amin S, Hecht SS.
    Journal: Carcinogenesis; 1989 Sep; 10(9):1685-9. PubMed ID: 2670305.
    Abstract:
    The mutagenic activities in Salmonella typhimurium and tumorigenic activities in newborn mice of 6-nitrochrysene (6-NC), 5-methyl-6-nitrochrysene (5-Me-6-NC), 11-methyl-6-nitrochrysene (11-Me-6-NC) and 5-methylchrysene (5-MeC) were compared. In S. typhimurium TA100 in the absence of rat liver 9000 g supernatant, 11-Me-6-NC was the most active compound followed by 6-NC; 5-Me-6-NC and 5-MeC were inactive. In the assays conducted in the presence of rat liver 9000 g supernatant, the order of activity was 11-Me-6-NC greater than 6-NC greater than 5-Me-6-NC approximately 5-MeC. In S. typhimurium TA98 a similar trend was observed. For the tumorigenicity studies, groups of mice were treated with the appropriate compounds in DMSO by i.p. injections on the 1st, 8th and 15th day of life. At a dose of 100 nmol/mouse 6-NC induced significantly more lung tumors than 5-MeC, which in turn was more active than 11-Me-6-NC and 5-Me-6-NC. All compounds induced significant numbers of liver tumors in treated males compared to controls; the order of activity was the same as that observed for lung tumor induction. The results of this study clearly indicate that bay region methyl substitution can either inhibit (5-position) or enhance (11-position) the mutagenic activity of 6-NC. In contrast, bay region methyl substitution (5- and 11-positions) inhibited the tumorigenic activity of 6-NC in newborn mice. Since ring oxidation and nitroreduction are involved in the metabolic activation of 6-NC in newborn mice, bay region methyl substitution may either inhibit the nitroreduction pathway or hinder the formation of the appropriate bay region diol epoxide. Steric factors may be important in determining the tumorigenicity of methylated nitrochrysenes.
    [Abstract] [Full Text] [Related] [New Search]