title: Formation of benzoquinol moiety in cornoside by salidroside mono-oxygenase, a cytochrome P450 enzyme, from Abeliophyllum distichumcell suspension cultures.
abstract: A microsomal fraction prepared from Abeliophyllum distichumNakai (Oleaceae) cell suspension cultures oxidized salidroside, a glucoside of 4-hydroxyphenylethyl alcohol, to cornoside possessing a unique benzoquinol ring. The enzyme named salidroside mono-oxygenase required NADPH as the only cofactor, and molecular oxygen. The reaction was strongly inhibited by CO as well as several cytochrome P450 inhibitors, such as cytochrome c and miconazole, indicating the involvement of a cytochrome P450 enzyme. Salidroside mono-oxygenase accepted salidroside as the only substrate, but did not oxidize 4-hydroxyphenylethyl alcohol, the salidroside aglucone, and 4-hydroxybenzoic acid. The optimum pH of the reaction was 7.5, and apparent K(m) values for salidroside and NADPH were 44 micro M and 33 micro M, respectively. The benzoquinol ring formation mechanism is discussed in comparison to the mechanism for ipso substitution of 4-hydroxybenzoate by active oxygen species followed by elimination leading to hydroquinone.
authors.affiliation: Medicinal Plants Garden, School of Pharmaceutical Sciences, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
authors.forename: Hirobumi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Hori
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kuwajima
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Inoue
mesh_terms: D016227:Benzoquinones / Q000378:metabolism; D002248:Carbon Monoxide / Q000494:pharmacology; D002478:Cells, Cultured; D003512:Cyclohexanones / Q000737:chemistry / Q000378:metabolism*; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003574:Cytochrome c Group / Q000494:pharmacology; D005960:Glucosides / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008825:Miconazole / Q000494:pharmacology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D029592:Oleaceae; D010100:Oxygen / Q000494:pharmacology; D010636:Phenols / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D016227:Benzoquinones; D003512:Cyclohexanones; D065607:Cytochrome P-450 Enzyme Inhibitors; D003574:Cytochrome c Group; D005960:Glucosides; D010636:Phenols; D017382:Reactive Oxygen Species; C473622:cornoside; D009249:NADP; D008825:Miconazole; D002248:Carbon Monoxide; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C009172:rhodioloside; D010100:Oxygen