title: A study on 17alpha-ethinylestradiol metabolism in rat and Pleurotus ostreatus.
abstract: OBJECTIVE
  17α-Ethinylestradiol (EE2) is an endocrine disruptor that is an ingredient of oral contraceptives. Here, EE2 metabolism catalyzed by cytochromes P450 (CYP) was studied. Two model organisms, rat and ligninolytic fungus Pleurotus ostreatus, were used.
  
  
  METHODS
  To resolve the role of rat and/or fungal CYPs in EE2 oxidation, microsomes were incubated with EE2 and NADPH or cumene hydroperoxide. Using Supersomes™, we examined which of rat CYPs oxidize EE2.
  
  
  RESULTS
  EE2 is effectively degraded by P. ostreatus in vivo. In vitro, EE2 is metabolized by CYPs by the NADPH-dependent and organic hydroperoxide-dependent mechanisms. Rat hepatic microsomes metabolize EE2 in the presence of NADPH to three products; two of them are hydroxylated EE2 derivatives. Using rat Supersomes™ we found that EE2 is hydroxylated by several rat CYPs, among them CYP2C6 and 2C11 are most efficient in 2-hydroxy-EE2 formation, while CYP2A and 3A catalyze EE2 hydroxylation to the second product. On the contrary, the products of the NADPH-dependent hydroxylating reactions were not detected in Pleurotus ostreatus. During the reaction of EE2 in microsomes isolated from rat and P. ostreatus in the presence of the alternate oxidant, cumene hydroperoxide, another metabolite, different from the above mentioned products, is generated. Rat CYP1A1 is the most efficient enzyme catalyzing formation of this EE2 product.
  
  
  CONCLUSIONS
  The results suggest that CYPs play a role in EE2 metabolism in rat and P. ostreatus. To our knowledge this is the first finding describing ligninolythic fungal metabolism of EE2 by CYP in the presence of cumene hydroperoxide.
authors.affiliation: Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Lucie
authors.initials: L
authors.lastname: Borek-Dohalska
authors.affiliation: Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Valaskova
authors.affiliation: Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Bozena
authors.initials: B
authors.lastname: Kubickova
authors.affiliation: Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Sulc
authors.affiliation: Institute of Microbiology, Academy of Sciences of the Czech Republic, Czech Republic.
authors.forename: Zdena
authors.initials: Z
authors.lastname: Kresinova
authors.affiliation: Institute of Microbiology, Academy of Sciences of the Czech Republic, Czech Republic.
authors.forename: Tomas
authors.initials: T
authors.lastname: Cajthaml
authors.forename: Marie
authors.initials: M
authors.lastname: Stiborova
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D000072467:Cytochrome P450 Family 2; D004997:Ethinyl Estradiol / Q000378:metabolism*; D006900:Hydroxylation; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism*; D010084:Oxidation-Reduction; D020076:Pleurotus; D051381:Rats; D017208:Rats, Wistar; D039181:Steroid 16-alpha-Hydroxylase / Q000378:metabolism; D013255:Steroid 21-Hydroxylase / Q000378:metabolism; D013250:Steroid Hydroxylases / Q000378:metabolism
chemical_list: D004997:Ethinyl Estradiol; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; D001189:Aryl Hydrocarbon Hydroxylases; C450279:CYP2C11 protein, rat; C089877:Cyp2c6v1 protein, rat; D019363:Cytochrome P-450 CYP1A1; D051544:Cytochrome P-450 CYP3A; D000072467:Cytochrome P450 Family 2; D039181:Steroid 16-alpha-Hydroxylase; C029009:steroid hormone 7-alpha-hydroxylase; D013255:Steroid 21-Hydroxylase