title: Metabolism of 7-ethoxycoumarin, safrole, flavanone and hydroxyflavanone by cytochrome P450 2A6 variants.
abstract: CYP 2A6 is a human enzyme that metabolizes many xenobiotics including coumarin, indole, nicotine and carcinogenic nitrosamines. The gene for CYP2A6 is polymorphic. There are few data available to clarify the relationship between P450 genetic variants and the metabolism of materials in food. The CYP 2A6 wild-type protein and 13 mutants (CYP2A6.1, CYP2A6.2, CYP2A6.5, CYP2A6.6, CYP2A6.7, CYP2A6.8, CYP2A6.11, CYP2A6.15, CYP2A6.16, CYP2A6.17, CYP2A6.18, CYP2A6.21, CYP2A6.23 and CYP2A6.25) were co-expressed with NADPH-cytochrome P450 reductase in E. coli. The hydroxylase activities toward 7-ethoxycoumarin, coumarin, safrole, flavanone and hydroxyflavanone were examined. Ten types of CYP2A6 variants except for CYP2A6.2, CYP2A6.5 and CYP2A6.6 showed Soret peaks (450 nm) typical of P450 in the reduced CO-difference spectra and had 7-ethoxycoumarin O-deethylase activities. CYP2A6.15 and CYP2A6.18 showed higher activities for safrole 1'-hydroxylation than CYP2A6.1. CYP2A6.25 and CYP2A6.7 had lower safrole 1'-hydroxylase activities. CYP2A6.7 had lower flavanone 6- and 2'-hydroxylase activities, whereas CYP2A6.25 had higher 6-hydroxylase activity and lower 2'-hydroxylase activity. Hydroxyflavanone was metabolized by CYP2A6.25, but was not metabolized by wild-type CYP2A6.1. These results indicate that CYP2A6.25 possessed new substrate specificity toward flavonoids.
authors.affiliation: Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture, Kobe University, Kobe, Hyogo, 657-8501, Japan. unotom@kobe-u.ac.jp
authors.forename: Tomohide
authors.initials: T
authors.lastname: Uno
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Obe
authors.forename: Chika
authors.initials: C
authors.lastname: Ogura
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Goto
authors.forename: Kohei
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Masahiko
authors.initials: M
authors.lastname: Nakamura
authors.forename: Kengo
authors.initials: K
authors.lastname: Kanamaru
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamagata
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Imaishi
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics / Q000378:metabolism*; D003374:Coumarins / Q000378:metabolism*; D065637:Cytochrome P-450 CYP2A6; D004926:Escherichia coli / Q000235:genetics; D044950:Flavanones / Q000378:metabolism*; D014644:Genetic Variation; D006801:Humans; D006900:Hydroxylation; D009251:NADPH-Ferrihemoprotein Reductase / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012451:Safrole / Q000378:metabolism*
chemical_list: D003374:Coumarins; D044950:Flavanones; D011994:Recombinant Proteins; C017299:7-ethoxycoumarin; D001189:Aryl Hydrocarbon Hydroxylases; C585710:CYP2A6 protein, human; D065637:Cytochrome P-450 CYP2A6; D009251:NADPH-Ferrihemoprotein Reductase; D012451:Safrole