Identification of Novel Substrates for Human Cytochrome P450 2J2

Abstract

ABSTRACT:Several antihistamine drugs including terfenadine, ebastine, and astemizole have been identified as substrates for CYP2J2. The overall importance of this enzyme in drug metabolism has not been fully explored. In this study, 139 marketed therapeutic agents and compounds were screened as potential CYP2J2 substrates. Eight novel substrates were identified that vary in size and overall topology from relatively rigid structures (amiodarone) to larger complex structures (cyclosporine). The substrates displayed in vitro intrinsic clearance values ranging from 0.06 to 3.98 l/min/pmol CYP2J2. Substrates identified for CYP2J2 are also metabolized by CYP3A4. Extracted ion chromatograms of metabolites observed for albendazole, amiodarone, astemizole, thioridazine, mesoridazine, and danazol showed marked differences in the regioselectivity of CYP2J2 and CYP3A4. CYP3A4 commonly metabolized compounds at multiple sites, whereas CYP2J2 metabolism was more restrictive and limited, in general, to a single site for large compounds. Although the CYP2J2 active site can accommodate large substrates, it may be more narrow than CYP3A4, limiting metabolism to moieties that can extend closer toward the active heme iron. For albendazole, CYP2J2 forms a unique metabolite compared with CYP3A4. Albendazole and amiodarone were evaluated in various in vitro systems including recombinant CYP2J2 and CYP3A4, pooled human liver microsomes (HLM), and human intestinal microsomes (HIM). The Michaelis-Menten-derived intrinsic clearance of N-desethyl amiodarone was 4.6 greater in HLM than in HIM and 17-fold greater in recombinant CYP3A4 than in recombinant CYP2J2. The resulting data suggest that CYP2J2 may be an unrecognized participant in first-pass metabolism, but its contribution is minor relative to that of CYP3A4.

The Inhibitory Effect of Telmisartan on the Metabolism of Arachidonic Acid by CYP2C9 and CYP2C8: An <i>in Vitro</i> Study

“…34) Our results suggest that CYP2C9 plays a major role in AA metabolism in HLMs, consistent with a previous report. 8) Furthermore, our results indicate that CYP2C8 is also the key enzyme in AA metabolism in the liver, since the CR value of CYP2C8 was calculated to be over 30%.…”

Computational modelling of the binding of arachidonic acid to the human monooxygenase CYP2J2

“…This value is similar to the volumes found by Xia et al [23] (330Å 3 ) and Cong et al [22] (320Å 3 ) but notably smaller than those reported by Lafite et al [19] (945Å 3 ) and Lee et al [9] (1420Å 3 ). There are several potential reasons for this discrepancy.…”

“…can accept a wide range of xenobiotic substrates for detoxification [9][10][11]. Using screens of marketed therapeutic agents, albendazole, amiodarone, cyclosporine A, danazol, mesoridazine, nabumetone, tamoxifen, thioridazine, telmisartan and flunarizine were all shown to be potential xenobiotic substrates for CYP2J2.…”

CYP2J2 and CYP2C19 Are the Major Enzymes Responsible for Metabolism of Albendazole and Fenbendazole in Human Liver Microsomes and Recombinant P450 Assay Systems

“…The concentrations of hydroxyalbendazole and hydroxyfenbendazole in HLM cultures were quantified using LC-MS/MS as described elsewhere, with some modification (2,11). The system consisted of a Thermo Vantage triple-quadrupole mass spectrometer (Thermo Fisher Scientific, San Jose, CA), coupled with a Thermo Accela HPLC system (Thermo Fisher Scientific).…”

“…1). Recently, Lee et al (11) reported that the rates of albendazole sulfoxide formation from albendazole by the recombinant CYP2J2 (rCYP2J2) isoform were significantly higher than those by the recombinant CYP3A4 (rCYP3A4) isoform, indicating the importance of the CYP2J2 isoform in albendazole sulfoxide formation (Fig. 1).…”