Metabolic transformation of cyclopiazonic acid in liver microsomes from different species based on UPLC-Q/TOF-MS

To investigate the metabolic transformation of cyclopiazonic acid (CPA) in the liver of different species and to supplement accurate risk assessment information, the metabolism of CPA in liver microsomes from four animals and humans was studied using the ultra-high-performance liquid chromatography-quadrupole/time-of-flight method. The results showed that a total of four metabolites were obtained, and dehydrogenation, hydroxylation, methylation, and glucuronidation were identified as the main metabolic pathways of CPA. Rat liver microsomes exhibited the highest metabolic capacity for CPA, with dehydrogenated (C₂₀H₁₈N₂O₃) and glucuronic acid-conjugated (C₂₆H₂₈N₂O₁₀) metabolites identified in all liver microsomes except chicken, indicating significant species metabolic differences. Moreover, C₂₀H₁₈N₂O₃ was only detected in the incubation system with cytochromes P450 3A4 (CYP3A4). The hydroxylated (C₂₀H₂₀N₂O₄) and methylated (C₂₁H₂₂N₂O₃) metabolites were detected in all incubation systems except for the CYP2C9, with CYP3A4 demonstrating the strongest metabolic capacity. The "cocktail" probe drug method showed that CPA exhibited a moderate inhibitory effect on the CYP3A4 (IC₅₀ value = 8.658 μM), indicating that the substrate had a negative effect on enzyme activity. Our results provide new insights to understand the biotransformation profile of CPA in animals and humans.