ABSTRACT
Combustion processes generate different types of particulate matter (PM) that can have deleterious effects on the pulmonary and cardiovascular systems. Environmentally persistent free radicals (EPFRs) represent a type of particulate matter that is generated after combustion of environmental wastes in the presence of redox-active metals and aromatic hydrocarbons. Cytochromes P450 (P450/CYP) are membrane-bound enzymes that are essential for the phase I metabolism of most lipophilic xenobiotics. The EPFR formed by chemisorption of 2-monochlorophenol to silica containing 5% copper oxide (MCP230) has been shown to generally inhibit the activities of different forms of P450s without affecting those of cytochrome P450 reductase and heme oxygenase-1. The mechanism of inhibition of rat liver microsomal CYP2D2 and purified rabbit CYP2B4 by MCP230 has been shown previously to be noncompetitive with respect to substrate. In this study, MCP230 was shown to competitively inhibit metabolism of 7-benzyl-4-trifluoromethylcoumarin and 7-ethoxyresorufin by the purified, reconstituted rabbit CYP1A2. MCP230 is at least 5- and 50-fold more potent as an inhibitor of CYP1A2 than silica containing 5% copper oxide and silica, respectively. Thus, even though PM generally inhibit multiple forms of P450, PM interacts differently with the forms of P450 resulting in different mechanisms of inhibition. P450s function as oligomeric complexes within the membrane. We also determined the mechanism by which PM inhibited metabolism by the mixed CYP1A2-CYP2B4 complex and found that the mechanism was purely competitive suggesting that the CYP2B4 is dramatically inhibited when bound to CYP1A2.
Subject(s)
Cytochrome P-450 CYP1A2 Inhibitors/toxicity , Cytochrome P-450 CYP1A2/metabolism , Environmental Pollutants/toxicity , Free Radicals/toxicity , Liver/drug effects , Particulate Matter/toxicity , Animals , Aryl Hydrocarbon Hydroxylases/metabolism , Binding Sites , Binding, Competitive , Catalytic Domain , Coumarins/metabolism , Cytochrome P-450 CYP1A2 Inhibitors/metabolism , Cytochrome P450 Family 2 , Dose-Response Relationship, Drug , Environmental Pollutants/metabolism , Free Radicals/metabolism , Liver/enzymology , Oxazines/metabolism , Particulate Matter/metabolism , Protein Binding , Rabbits , Substrate SpecificityABSTRACT
Vorinostat (suberoylanilide hydroxamic acid, SAHA) is the first approved histone deacetylase (HDAC) inhibitor for the treatment of cutaneous T-cell lymphoma after progressive disease following two systemic therapies. The rats were randomly divided into SAHA groups (low, medium and high dosage) and control group. The SAHA group rats were given 12.3, 24.5, and 49 mg/kg SAHA, respectively, by continuous intragastric administration for 7 days. The influence of SAHA on the activities of CYP450 isoforms CYP2B6, CYP1A2, CYP2C19, CYP2D6 and CYP2C9 were evaluated by cocktail method, they were responsed by the changes of pharmacokinetic parameters of bupropion, phenacetin, tolbutamide, metroprolol and omeprazole. The five probe drugs were given to rats through intragastric administration, and the plasma concentration were determined by UPLC-MS/MS. The result of SAHA group compared to control group, there were statistical pharmacokinetics difference for bupropion, phenacetin, tolbutamide and metroprolol. Continuous intragastric administration for 7 days may induce the activities of CYP2C19 of rats, inhibit CYP1A2 and slightly inhibit CYP2B6 and CYP2D6 of rats. This may give advising for reasonable drug use after co-used with SAHA. The results indicated that drug co-administrated with SAHA may need dose adjustment. Furthermore, continuous intragastric administration of SAHA for 7 days, liver cell damaged, causing liver cell edema, in liver metabolism process.
