title: Inhibitory effects of calf thymus DNA on metabolism activity of CYP450 enzyme in human liver microsomes.
abstract: The present study investigated the effect of calf thymus DNA (ctDNA) on human hepatic cytochrome P450s (CYP450s) in vitro. Specific substrate probes for each isoform, CYP1A2, 2C9, 2C19, 2D6 and 3A4, were incubated using pooled human liver microsomes with or without ctDNA, and liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) method was developed for the analysis of probe metabolites. Enzyme kinetics parameters Ki and IC50 values were estimated to determine the types and strength of inhibition. ctDNA could specifically inhibit the metabolism of CYP2C9 probe substrates, with the IC50 = 0.9955 µg/ml, while it was not able to inhibit CYP1A2, CYP2C19, CYP2D6 or CYP3A4 (IC50 > 100 µg/ml). The results showed that ctDNA was a potent inhibitor of CYP2C9 enzyme, and has the metabolic interaction potential with the model drugs which are metabolism substrates of CYP2C9. The inhibition mechanism study suggested ctDNA may inhibit CYP2C9 by decreasing the activity of CYP450 reductase. These findings indicated that when the medical agents catalyzed mainly by CYP2C9 were co-administered in vivo with adsorptive material in vitro, the potential inhibitory effect of ctDNA on enzyme activity and the following metabolism character changes of the former should be highly focused on.
authors.affiliation: College of Bioengineering, Henan University of Technology.
authors.forename: Shuoye
authors.initials: S
authors.lastname: Yang
authors.forename: Zhixia
authors.initials: Z
authors.lastname: Qiu
authors.forename: Qiuyang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Jiayin
authors.initials: J
authors.lastname: Chen
authors.forename: Xijing
authors.initials: X
authors.lastname: Chen
mesh_terms: D002853:Chromatography, Liquid; D065729:Cytochrome P-450 CYP2C9 / Q000378:metabolism*; D065688:Cytochrome P-450 CYP2C9 Inhibitors / Q000494:pharmacology*; D004247:DNA / Q000494:pharmacology*; D004347:Drug Interactions; D006801:Humans; D007700:Kinetics; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology; D015203:Reproducibility of Results; D018570:Risk Assessment; D013379:Substrate Specificity; D053719:Tandem Mass Spectrometry
chemical_list: D065688:Cytochrome P-450 CYP2C9 Inhibitors; D004247:DNA; C427203:calf thymus DNA; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9