title: An UHPLC-MS/MS method for simultaneous quantification of gallic acid and protocatechuic acid in rat plasma after oral administration of Polygonum capitatum extract and its application to pharmacokinetics.
abstract: BACKGROUND
  Polygonum capitatum Buch.-Ham. ex D. Don has been traditionally used by Hmong for the treatments of urinary tract infections and pyelonephritis. Gallic acid (GA) and protocatechuic acid (PCA) are regarded as two of the main bioactive compounds in the herb.
  
  
  METHODS
  A rapid, selective and sensitive UHPLC-ESI-MS/MS method was established and validated for the quantification of GA and PCA in rat plasma after oral administration of P. capitatum extract. Concentrations of GA and PCA were determined at different time points after dosing 20 mg/kg (equivalent to 4 mg/kg of GA and 0.3 mg/kg of PCA), 60 mg/kg and 120 mg/kg of P. capitatum extract. The main pharmacokinetic parameters of GA and PCA were obtained based on the analysis of the plasma sample by non-compartmental analysis.
  
  
  RESULTS
  After oral administration of P. capitatum extract, GA and PCA were quickly absorbed and showed a dose-dependent profile. Pharmacokinetic parameters for GA and PCA following oral administration of the extract were respectively: Cmax 246.24-806.27 and 15.73-30.72 ng/mL; Tmax 40-100 and 20-40 min. In the rats treated with P. capitatum t1/2 and Tmax of GA were prolonged by comparing with that of its pure form.
  
  
  CONCLUSIONS
  Other compounds in P. capitatum extract may be metabolized to GA, which affected the pharmacokinetic profiles of GA. This pharmacokinetic study seems to be useful for a further clinical study of P. capitatum extract.
authors.affiliation: Guizhou Key Laboratory for Mountainous Environmental Information and Ecological Protection, Guiyang 550001, China; The Research Center for Quality Control of Natural Medicine, Guizhou Normal University, Guiyang 550001, China.
authors.forename: Fengwei
authors.initials: F
authors.lastname: Ma
authors.affiliation: Guizhou Key Laboratory for Mountainous Environmental Information and Ecological Protection, Guiyang 550001, China; The Research Center for Quality Control of Natural Medicine, Guizhou Normal University, Guiyang 550001, China.
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Gong
authors.affiliation: Guizhou Key Laboratory for Mountainous Environmental Information and Ecological Protection, Guiyang 550001, China; The Research Center for Quality Control of Natural Medicine, Guizhou Normal University, Guiyang 550001, China. Electronic address: alice9800@sina.com.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Guizhou Key Laboratory for Mountainous Environmental Information and Ecological Protection, Guiyang 550001, China; The Research Center for Quality Control of Natural Medicine, Guizhou Normal University, Guiyang 550001, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Guizhou Warmen Pharmaceutical Co., Ltd., Guiyang, Guizhou 550018, China.
authors.forename: Menglin
authors.initials: M
authors.lastname: Li
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005707:Gallic Acid / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D062385:Hydroxybenzoates / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D008297:Male; D015394:Molecular Structure; D010936:Plant Extracts / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics; D028502:Polygonum / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D062385:Hydroxybenzoates; D010936:Plant Extracts; C009091:protocatechuic acid; D005707:Gallic Acid
keywords: Bergenin (PubChem CID: 378697); Gallic acid; Gallic acid (PubChem CID: 370); P. capitatum extract; Pharmacokinetics; Protocatechuic acid; Protocatechuic acid (PubChem CID: 72); UHPLC–MS/MS