title: [In vitro O-demethylation of rotundine by recombinant human CYP isoenzymes].
abstract: Rotundine (1 micromol L(-1)) was incubated with a panel of rCYP enzymes (1A2, 2C9, 2C19, 2D6 and 3A4) in vitro. The remained parent drug in incubates was quantitatively analyzed by an Agilent LC-MS. CYP2C19, 3A4 and 2D6 were identified to be the isoenzymes involved in the metabolism of rotundine. The individual contributions of CYP2C19, 3A4 and 2D6 to the rotundine metabolism were assessed using the method of total normalized rate to be 31.46%, 60.37% and 8.17%, respectively. The metabolites of rotundine in incubates were screened with ESI-MS at selected ion mode, and were further identified using MS2 spectra and precise molecular mass obtained from an Agilent LC/Q-TOF-MSMS, as well as MS(n) spectra of LC-iTrap-MS(n). The predominant metabolic pathway of rotundine in rCYP incubates was O-demethylation. A total 5 metabolites were identified including 4 isomerides of mono demethylated rotundine and one di-demethylated metabolite. The results also showed that CYP2C19, 2D6 and 3A4 mediated O-demethylation of methoxyl groups at different positions of rotundine. Furthermore, the ESI-MS cleavage patterns of rotundine and its metabolites were explored by using LC/Q-TOF-MSMS and LC/iTrap-MS(n) techniques.
authors.affiliation: Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing 100850, China.
authors.forename: Chun-zheng
authors.initials: CZ
authors.lastname: Li
authors.forename: Qing-hui
authors.initials: QH
authors.lastname: Lin
authors.forename: Xiao-mei
authors.initials: XM
authors.lastname: Zhuang
authors.forename: Jian-wei
authors.initials: JW
authors.lastname: Xie
authors.forename: Hua
authors.initials: H
authors.lastname: Li
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000378:metabolism; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D001600:Berberine Alkaloids / Q000378:metabolism*; D002853:Chromatography, Liquid; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism; D065731:Cytochrome P-450 CYP2C19; D065729:Cytochrome P-450 CYP2C9; D019389:Cytochrome P-450 CYP2D6 / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008745:Methylation; D011994:Recombinant Proteins / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D018712:Analgesics, Non-Narcotic; D001600:Berberine Alkaloids; D018492:Dopamine Antagonists; D007527:Isoenzymes; D011994:Recombinant Proteins; C014215:tetrahydropalmatine; D003577:Cytochrome P-450 Enzyme System; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D019388:Cytochrome P-450 CYP1A2; D065731:Cytochrome P-450 CYP2C19; D019389:Cytochrome P-450 CYP2D6; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human