title: Simultaneous Determination of Baicalein and Baicalin in Human Plasma by High Performance Liquid Chromatograph-Tandem Spectrometry and its Application in a Food-Effect Pharmacokinetic Study.
abstract: BACKGROUND
  Baicalein is a flavonoid isolated from skullcap and it is likely to exist in plasma at a low concentration because of the extensive first-pass metabolism in vivo. The aim of our study was to develop and fully validate a sensitive and selective HPLC-MS/MS method for simultaneous determination of baicalein and its main metabolite baicalin (baicalein-7-O-β-glucopyranuronoside) in human plasma.
  
  
  METHODS
  Liquid-liquid extraction was used for pretreatment of plasma samples. The mobile phase consisted of aqueous phase A (0.5% formic acid in 3 mM ammonium acetate solution) and organic phase B (methanol-acetonitrile-formic acid, 50:50:0.5, v:v:v). Detection was performed on a triple-quadrupole tandem mass spectrometer using positive electrospray ionization. Quantification was performed by multiple reaction monitoring mode at m/z transitions of 271.1→123.1 for baicalein and 447.1→271.0 for baicalin, respectively.
  
  
  CONCLUSIONS
  The calibration curve was linear over the range of 1~400 ng/mL (r(2)>0.99) for both baicalein and baicalin. The intra-day and inter-day precision values were below 6.84% for baicalein and 8.56% for baicalin at 3 quality control levels. The mean accuracy was 95.27 ~ 110.56%, 91.82 ~ 105.01% for baicalein and baicalin, respectively. Analytes were stable during sample storage and handling.
  
  
  CONCLUSIONS
  The method was proved to be accurate and specific and was applied to a pharmacokinetic study of baicalein in healthy volunteers under both fasted and fed states.
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang (P.R. China).
authors.forename: H
authors.initials: H
authors.lastname: Pang
authors.affiliation: Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Department of Pharmacy, Beijing Hospital, Beijing (P.R. China).
authors.forename: A
authors.initials: A
authors.lastname: Shi
authors.affiliation: Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Department of Pharmacy, Beijing Hospital, Beijing (P.R. China).
authors.forename: M
authors.initials: M
authors.lastname: Li
authors.affiliation: Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Department of Pharmacy, Beijing Hospital, Beijing (P.R. China).
authors.forename: W
authors.initials: W
authors.lastname: Xue
authors.affiliation: Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Department of Pharmacy, Beijing Hospital, Beijing (P.R. China).
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.affiliation: Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Department of Pharmacy, Beijing Hospital, Beijing (P.R. China).
authors.forename: G
authors.initials: G
authors.lastname: Cao
authors.affiliation: Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Department of Pharmacy, Beijing Hospital, Beijing (P.R. China).
authors.forename: B
authors.initials: B
authors.lastname: Yan
authors.affiliation: Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Department of Pharmacy, Beijing Hospital, Beijing (P.R. China).
authors.forename: F
authors.initials: F
authors.lastname: Dong
authors.affiliation: StateKey Laboratory of New-tech for Chinese Medicine Pharmaceutical Process, Jiangsu Kanion Pharmaceutical CO.LTD, Lianyungang, Jiangsu (P.R. China).
authors.forename: W
authors.initials: W
authors.lastname: Xiao
authors.affiliation: Beijing Key Laboratory of Drug Targets Identification and Drug Screening, Institute of Materia Medica, Chinese Academy of Medical Science and Peking Union Medical College, Beijing (P.R. China).
authors.forename: G
authors.initials: G
authors.lastname: He
authors.affiliation: Beijing Key Laboratory of Drug Targets Identification and Drug Screening, Institute of Materia Medica, Chinese Academy of Medical Science and Peking Union Medical College, Beijing (P.R. China).
authors.forename: G
authors.initials: G
authors.lastname: Du
authors.affiliation: Beijing Key Laboratory of Drug Clinical Risk and Personalized Medication Evaluation, Department of Pharmacy, Beijing Hospital, Beijing (P.R. China).
authors.forename: X
authors.initials: X
authors.lastname: Hu
authors.affiliation: School of Pharmacy, Shenyang Pharmaceutical University, Shenyang (P.R. China).
authors.forename: G
authors.initials: G
authors.lastname: Cheng
mesh_terms: D000284:Administration, Oral; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004355:Drug Stability; D005215:Fasting; D005260:Female; D044950:Flavanones / Q000008:administration & dosage* / Q000097:blood* / Q000493:pharmacokinetics; D005419:Flavonoids / Q000097:blood* / Q000493:pharmacokinetics; D018565:Food-Drug Interactions; D006801:Humans; D059625:Liquid-Liquid Extraction; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization; D013607:Tablets; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D044950:Flavanones; D005419:Flavonoids; D013607:Tablets; C038044:baicalin; C006680:baicalein