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Effect of 10-aza-substitution on Benzo[a]pyrene Mutagenicity in Vivo and in Vitro

Katsuya Yamada, Takayoshi Suzuki, Arihiro Kohara, Makoto Hayashi, Atsushi Hakura, Takaharu Mizutani, Ken-ichi Saeki

Mutat Res. 2002 Nov 26;521(1-2):187-200.

PMID: 12438015

Abstract:

Benzo[a]pyrene (BaP), an environmental carcinogen, shows genotoxicity after metabolic transformation into the bay-region diol epoxide, BaP-7,8-diol 9,10-epoxide. 10-Azabenzo[a]pyrene (10-azaBaP), in which a ring nitrogen is located in the bay-region, is also a carcinogen and shows mutagenicity in the Ames test in the presence of the rat liver microsomal enzymes. In order to evaluate the effect of aza-substitution on in vivo genotoxicity, BaP and 10-azaBaP were assayed for their in vivo mutagenicity using the lacZ-transgenic mouse (MutaMouse). BaP was potently mutagenic in all of the organs examined (liver, lung, kidney, spleen, forestomach, stomach, colon, and bone marrow), as described in our previous report, whereas, 10-azaBaP was slightly mutagenic only in the liver and colon. The in vitro mutagenicities of BaP and 10-azaBaP were evaluated by the Ames test using liver homogenates prepared from several sources, i.e. CYP1A-inducer-treated rats, CYP1A-inducer-treated and non-treated mice, and humans. BaP showed greater mutagenicities than 10-azaBaP in the presence of a liver homogenate prepared from CYP1A-inducer-treated rodents. However, 10-azaBaP showed mutagenicities similar to or more potent than BaP in the presence of a liver homogenate or S9 from non-treated mice and humans. These results indicate that 10-aza-substitution markedly modifies the nature of mutagenicity of benzo[a]pyrene in both in vivo and in vitro mutagenesis assays.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP24407496 10-Azabenzo[a]pyrene 10-Azabenzo[a]pyrene 24407-49-6 Price
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