Cytochrome P450 enzymes play a central role in the metabolism of xenobiotics to facilitate their excretion. However, this metabolic activity may produce toxic reactive species [1,2].
Aflatoxin B1, a mycotoxin produced by A. flavus and A. parasiticus, is an example of a substance that forms toxic reactive metabolites when metabolized by CYP1A2 and CYP3A4 into the reactive aflatoxin B1 exo-8,9-epoxide [4].
InSphero’s standard “CYP450 causality” assay investigates the role of cytochrome P450 enzymes in the toxicity to a test item by comparing its cytotoxicity in 3D InSight™ Liver microtissues co-treated with and without 1-Aminobenzotriazole, a broad-spectrum cytochrome P450 inhibitor [3].
As shown in Figure 1, aflatoxin B1 is less cytotoxic to 3D InSight™ Liver microtissues cotreated with 1-Aminobenzotriazole, thereby demonstrating the deleterious role of cytochrome P450s in the response to aflatoxin B1.


Resources
[1] Iversen, Ditte B et al. “Drug metabolism and drug transport of the 100 most prescribed oral drugs.” Basic & clinical pharmacology & toxicology vol. 131,5 (2022): 311-324. doi:10.1111/bcpt.13780
[2] Mahajan, Piyush et al. “Drug reactive metabolite-induced hepatotoxicity: a comprehensive review.” Toxicology mechanisms and methods vol. 34,6 (2024): 607-627. doi:10.1080/15376516.2024.2332613
[3] de Montellano, Paul R Ortiz. “1-Aminobenzotriazole: A Mechanism-Based Cytochrome P450 Inhibitor and Probe of Cytochrome P450 Biology.” Medicinal chemistry vol. 8,3 (2018): 038. doi:10.4172/2161-0444.1000495
[4] Eaton, D L, and E P Gallagher. “Mechanisms of aflatoxin carcinogenesis.” Annual review of pharmacology and toxicology vol. 34 (1994): 135-72. doi:10.1146/annurev.pa.34.040194.001031