title: Structural elucidation of in vitro metabolites of emodin by liquid chromatography-tandem mass spectrometry.
abstract: Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was employed to investigate the in vitro metabolism of emodin. Emodin was incubated with rat liver microsomes in the presence of a NADPH-generating system, followed by extraction with ethyl acetate. After separation on a reversed-phase C18 analytical column with a linear gradient elution of methanol and 0.1% formic acid in water, negative electrospray ionization tandem mass spectrometry experiments were performed. As a result, the parent drug and its six metabolites were detected from rat liver microsomal incubations. The identification of the metabolites and elucidation of their structure were performed by comparing the changes in molecular masses (DeltaM), retention times and MS(2) spectral patterns of metabolites with those of parent drug. Besides three mono-hydroxylated metabolites (omega-hydroxyemodin, 2-hydroxyemodin, 4-hydroxyemodin), three other metabolites were identified, which were emodic acid, 3-carbomethoxy-6-methoxy-1,8-dihydroxyanthraquinone and physcion, respectively.
authors.affiliation: Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education, Nanjing 210009, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: Song
authors.forename: Fengguo
authors.initials: F
authors.lastname: Xu
authors.forename: Zunjian
authors.initials: Z
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Haijuan
authors.initials: H
authors.lastname: Dong
authors.forename: Yuan
authors.initials: Y
authors.lastname: Tian
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D004365:Drugs, Chinese Herbal / Q000737:chemistry / Q000378:metabolism*; D004642:Emodin / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012250:Rheum / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D004365:Drugs, Chinese Herbal; D004642:Emodin