Strain-specific mutagenicity of NDMA and CPNP: insights from TA1535, TA100, and WP2 uvrA (pKM101) under metabolic activation

Chetan K Kajavadara; Darshan T Valani; Satyam N Patel; Rushikesh M Shukla; Laxit K Bhatt; Rajesh J Patel; Sunny P Kumar; Rajesh Sundar; Mukul R Jain

doi:10.1016/j.etap.2025.104752

Strain-specific mutagenicity of NDMA and CPNP: insights from TA1535, TA100, and WP2 uvrA (pKM101) under metabolic activation

Environ Toxicol Pharmacol. 2025 Jun 30:117:104752. doi: 10.1016/j.etap.2025.104752. Online ahead of print.

Authors

Chetan K Kajavadara¹, Darshan T Valani², Satyam N Patel³, Rushikesh M Shukla⁴, Laxit K Bhatt⁵, Rajesh J Patel⁶, Sunny P Kumar⁷, Rajesh Sundar⁸, Mukul R Jain⁹

Affiliations

¹ Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: chetan.kajavadara@zyduslife.com.
² Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: darshanvalani@zyduslife.com.
³ Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: satyam.patel@zyduslife.com.
⁴ Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: rushikesh.shukla@zyduslife.com.
⁵ Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: LaxitK.Bhatt@zyduslife.com.
⁶ Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: Rajesh.J.Patel@zyduslife.com.
⁷ Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: sunny.p.kumar@zyduslife.com.
⁸ Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: Rajesh.Sundar@zyduslife.com.
⁹ Department of Pharmacology and Toxicology, Zydus Research Centre, Zydus Lifesciences Limited, Ahmedabad, 382213, India. Electronic address: mukul.jain@zyduslife.com.

PMID: 40602473
DOI: 10.1016/j.etap.2025.104752

Abstract

The Ames test is a critical assay for assessing the mutagenic potential of chemical compounds; however, its conventional version (OECD TG 471) falls short in detecting nitrosamine mutagenicity due to insufficient metabolic activation. Given the ubiquity of nitrosamines as environmental contaminants and drug impurities, an enhanced protocol incorporating 30 % v/v hamster and rat liver S9 fractions with a 30-minute pre-incubation is warranted. This study streamlined the enhanced Ames test by evaluating the sensitivity of S. typhimurium strains TA1535 and TA100, and E. coli WP2 uvrA (pKM101), against N‑nitrosodimethylamine (NDMA) and 1‑cyclopentyl‑4‑nitrosopiperazine (CPNP). Dose‑normalized fold‑induction metrics revealed that TA1535 offers superior sensitivity across varied S9 conditions. Hamster liver S9 generally enhanced mutagenic responses compared to rat liver S9. Notably, CPNP was more potent in TA1535 and TA100, while NDMA was more active in WP2 uvrA (pKM101) with rat S9. This optimized screening strategy minimizes resources and is recommended for initial nitrosamine impurity mutagenicity detection.

Keywords: Nitrosamines; TA1535; WP2 uvrA (pKM101); enhanced Ames test; genotoxicity; metabolic activation.