Revisiting the mutagenicity and genotoxicity of N-nitroso propranolol in bacterial and human in vitro assays

• Published in: Regulatory toxicology and pharmacology Vol. 141; no. C; p. 105410
• Main Authors: Li, Xilin, Le, Yuan, Seo, Ji-Eun, Guo, Xiaoqing, Li, Yuxi, Chen, Si, Mittelstaedt, Roberta A., Moore, Nyosha, Guerrero, Sharon, Sims, Audrey, King, Sruthi T., Atrakchi, Aisar H., McGovern, Timothy J., Davis-Bruno, Karen L., Keire, David A., Elespuru, Rosalie K., Heflich, Robert H., Mei, Nan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.06.2023; Elsevier
• Subjects: Animals; Chromosomal damage; Cricetinae; Cytochrome P450s; DNA Damage; Gene mutation; Hamster liver S9; Humans; Legal Medicine; Mammals; Mutagenesis; Mutagenicity Tests - methods; Mutagens - toxicity; Mutation; N-Nitroso propranolol; Nitrosamine impurities; Pharmacology & Pharmacy; Propranolol - toxicity; Rats; Toxicology; Cytochrome P450s; Hamster liver S9; Chromosomal damage; Nitrosamine impurities; Gene mutation; N-Nitroso propranolol
• ISSN: 0273-2300; 1096-0295; 1096-0295
• DOI: 10.1016/j.yrtph.2023.105410

Propranolol is a widely used β-blocker that can generate a nitrosated derivative, N-nitroso propranolol (NNP). NNP has been reported to be negative in the bacterial reverse mutation test (the Ames test) but genotoxic in other in vitro assays. In the current study, we systematically examined the in vitro mutagenicity and genotoxicity of NNP using several modifications of the Ames test known to affect the mutagenicity of nitrosamines, as well as a battery of genotoxicity tests using human cells. We found that NNP induced concentration-dependent mutations in the Ames test, both in two tester strains that detect base pair substitutions, TA1535 and TA100, as well as in the TA98 frameshift-detector strain. Although positive results were seen with rat liver S9, the hamster liver S9 fraction was more effective in bio-transforming NNP into a reactive mutagen. NNP also induced micronuclei and gene mutations in human lymphoblastoid TK6 cells in the presence of hamster liver S9. Using a panel of TK6 cell lines that each expresses a different human cytochrome P450 (CYP), CYP2C19 was identified as the most active enzyme in the bioactivation of NNP to a genotoxicant among those tested. NNP also induced concentration-dependent DNA strand breakage in metabolically competent 2-dimensional (2D) and 3D cultures of human HepaRG cells. This study indicates that NNP is genotoxic in a variety of bacterial and mammalian systems. Thus, NNP is a mutagenic and genotoxic nitrosamine and a potential human carcinogen. •NNP induced concentration-dependent mutations in the Ames test in TA98, TA100, and TA1535.•NNP induced micronuclei and gene mutations in TK6 cells in the presence of hamster liver S9.•CYP2C19 was identified as the most active enzyme in the bioactivation of NNP.•NNP induced concentration-dependent DNA strand breakage in metabolically competent human HepaRG cells.