title: [Determination of theacrine in rat plasma by RP-HPLC].
abstract: OBJECTIVE
  To establish a method for the determination of theacrine in rat plasma after ig. administration of theacrine.
  
  
  METHODS
  Blood sample was taken timely from the eyes canthus of rats. Plasma was isolated and the protein was precipitated by ethyl acetate. Then the plasma concentration of theacrine was determined with RP-HPLC. Caffeine was used as the internal standard. The chromatographic conditions were as follows: Phenomenex Luna C18 (4.6 mm x 250 mm, 5 microm) at 25 degrees C, a mixture of methanol-water (25: 75) as the mobile phase, at the flow rate of 1.0 mL x min(-1) and the detection wavelength of 290 nm.
  
  
  RESULTS
  The linear range of theacrine was 0.5-100 mg x L(-1) (R2 = 0.998 9). The lower limit of quantification was 0.5 mg x L(-1). The intra-day RSD was 1.49% 4.40% and inter-day RSD was 0.80% -10.27%. The average extraction recoveries of theacrine were 90.3% -95.8% at concentrations of 0.5, 5.0, 50 mg x L(-1). The main pharmacokinetic parameters after ig. administration of theacrine at concentration of 30 mg x kg(-1) were as follow: C(max) (35.45 +/- 30 2.68) mg x L(-1), t(max) (0.51 +/- 0.13) h, t1/2 (3.13 +/- 1.37) h, AUC(0-infinity) (2.65.39 +/- 94.71) mg x L(-1) x h.
  
  
  CONCLUSIONS
  The method has been confirmed to be simple, stable, reproducible and with high specificity, and can be used for the pharmacokinetic study of theacrine in rats.
authors.affiliation: Department of Pharmacology, Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, China.
authors.forename: Wei-Ku
authors.initials: WK
authors.lastname: Zhang
authors.forename: Jie-Kun
authors.initials: JK
authors.lastname: Xu
authors.forename: Jie-Qing
authors.initials: JQ
authors.lastname: Hu
authors.forename: Su-Bo
authors.initials: SB
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Kurihara
authors.initials: K
authors.lastname: Hiroshi
authors.forename: Xin-Sheng
authors.initials: XS
authors.lastname: Yao
authors.forename: Bing-Hua
authors.initials: BH
authors.lastname: Tang
mesh_terms: D000818:Animals; D001774:Blood Chemical Analysis / Q000379:methods*; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D014527:Uric Acid / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D014527:Uric Acid; C077059:1,3,7,9-tetramethyluric acid