Abstract
Cytochrome P450 1A2 (CYP1A2) is one of the major CYP450 enzymes (CYPs) in the liver, and participates in the biotransformation of various xenobiotics and endogenous signaling molecules. The expression and activity of CYP1A2 show large individual differences, due to genetic and environmental factors. In order to discover non-invasive serum biomarkers associated with hepatic CYP1A2, mass spectrometry-based, untargeted metabolomics were first conducted, in order to dissect the metabolic differences in the serum and liver between control rats and β-naphthoflavone (an inducer of CYP1A2)-treated rats. Real-time reverse transcription polymerase chain reaction and pharmacokinetic analysis of phenacetin and paracetamol were performed, in order to determine the changes of mRNA levels and activity of CYP1A2 in these two groups, respectively. Branched-chain amino acids phenylalanine and tyrosine were ultimately focalized, as they were detected in both the serum and liver with the same trends. These findings were further confirmed by absolute quantification via a liquid chromatography–tandem mass spectrometry (LC-MS/MS)-based targeted metabolomics approach. Furthermore, the ratio of phenylalanine to tyrosine concentration was also found to be highly correlated with CYP1A2 activity and gene expression. This study demonstrates that metabolomics can be a potentially useful tool for biomarker discovery associated with CYPs. Our findings contribute to explaining interindividual variations in CYP1A2-mediated drug metabolism.
Highlights
As one of the most important enzyme systems for drug metabolism in the human body, CYP450 enzymes (CYPs) play a crucial role in the metabolism of xenobiotics and endogenous substrates [1].Cytochrome P450 1A2 (CYP1A2) is one of the major CYPs in the human liver, and accounts for about 13% of the totalCYP protein content [2]
PK parameters of phenacetin were used as the gold standard for determining CYP1A2 activity in the current study, due to the availability of the parent substrate and metabolite, and the simple and fast High-performance liquid chromatography (HPLC)-MS detection assay with high sensitivity
For the time being, we can conclude that the changes in PK parameters of phenacetin were caused by changes in CYP1A2 activity, rather than CYP2C6
Summary
As one of the most important enzyme systems for drug metabolism in the human body, CYP450 enzymes (CYPs) play a crucial role in the metabolism of xenobiotics and endogenous substrates [1].CYP1A2 is one of the major CYPs in the human liver, and accounts for about 13% of the totalCYP protein content [2]. As one of the most important enzyme systems for drug metabolism in the human body, CYP450 enzymes (CYPs) play a crucial role in the metabolism of xenobiotics and endogenous substrates [1]. CYP1A2 is one of the major CYPs in the human liver, and accounts for about 13% of the total. CYP1A2 is responsible for the oxidative metabolism of 8–10% of the marketed drugs [3] and the metabolic activation of environmental carcinogens, such as polycyclic aromatic hydrocarbons and heterocyclic amines [4,5]. The expression and activity of CYP1A2 varies 40–130 times between individuals [6,7] due to constitutional and environmental factors, such as gene polymorphism, gender, age, ethnicity, smoking status, and diet [8,9,10]. The wide interindividual variability in Metabolites 2019, 9, 77; doi:10.3390/metabo9040077 www.mdpi.com/journal/metabolites
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
