title: Identification of novel substrates for human cytochrome P450 2J2.
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 mul/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.
authors.affiliation: Pfizer Global Research & Development, 10646 Science Center Dr., San Diego, CA 92121, USA. caroline.lee01@pfizer.com
authors.forename: Caroline A
authors.initials: CA
authors.lastname: Lee
authors.forename: David
authors.initials: D
authors.lastname: Neul
authors.forename: Andrea
authors.initials: A
authors.lastname: Clouser-Roche
authors.forename: Deepak
authors.initials: D
authors.lastname: Dalvie
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wester
authors.forename: Ying
authors.initials: Y
authors.lastname: Jiang
authors.forename: J P
authors.initials: JP
authors.lastname: Jones
authors.forename: Sascha
authors.initials: S
authors.lastname: Freiwald
authors.forename: Michael
authors.initials: M
authors.lastname: Zientek
authors.forename: Rheem A
authors.initials: RA
authors.lastname: Totah
mesh_terms: D000465:Algorithms; D020134:Catalytic Domain; D002851:Chromatography, High Pressure Liquid; D000090762:Cytochrome P-450 CYP2J2; D051544:Cytochrome P-450 CYP3A / Q000737:chemistry / Q000378:metabolism; D065692:Cytochrome P-450 CYP3A Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D008961:Models, Structural; D009928:Organ Specificity; D004364:Pharmaceutical Preparations / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013379:Substrate Specificity; D053719:Tandem Mass Spectrometry
chemical_list: C000717350:CYP2J2 protein, human; D065692:Cytochrome P-450 CYP3A Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D004364:Pharmaceutical Preparations; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System; D000090762:Cytochrome P-450 CYP2J2; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human