title: Simultaneous determination of esculin and its metabolite esculetin in rat plasma by LC-ESI-MS/MS and its application in pharmacokinetic study.
abstract: A new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method operated in the negative electrospray ionization (ESI) switching mode has been developed and validated for the simultaneous determination of esculin and its metabolite esculetin in rat plasma. After addition of internal standards scopoletin, the plasma sample was pretreated by solid-phase extraction (SPE), and separated on a reversed phase C(18) column with a mobile phase of 0.01% formic acid in water (solvent A) and methanol (solvent B) using isocratic elution (A:B=20:80, v/v). The detection of target compounds was done in multiple reaction monitoring (MRM) mode. The MRM detection was operated in the negative ESI mode using the transitions of m/z 339.1 ([M-H](-))→176.7 for esculetin, m/z 176.9 ([M-H](-))→133.0 and m/z 191.0 ([M-H](-))→175.9 for scopoletin. The standard curves, which ranged from 25 to 3200 ng/mL for esculin with the lowest limit of quantification (LLOQ) of 0.25 ng/mL and from 1.25 to 160 ng/mL for esculetin with the LLOQ of 1.25 ng/mL, were fitted to a 1/x weighted quadratic regression model. The method also afforded satisfactory results in terms of the sensitivity, specificity, precision (intra- and inter-day, RSD<8.73%), accuracy, recovery as well as the stability of the analyte under various conditions. The method was successfully applied to study the pharmacokinetics of esculin and its metabolite esculetin in rat plasma after oral administration of esculin at a dose of 100mg/kg.
authors.affiliation: Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou 510405, Guangdong Province, China.
authors.forename: Ying-yi
authors.initials: YY
authors.lastname: Li
authors.forename: Ye-ying
authors.initials: YY
authors.lastname: Song
authors.forename: Chang-hui
authors.initials: CH
authors.lastname: Liu
authors.forename: Xiao-tao
authors.initials: XT
authors.lastname: Huang
authors.forename: Xia
authors.initials: X
authors.lastname: Zheng
authors.forename: Neng
authors.initials: N
authors.lastname: Li
authors.forename: Mei-li
authors.initials: ML
authors.lastname: Xu
authors.forename: Sui-qing
authors.initials: SQ
authors.lastname: Mi
authors.forename: Ning-sheng
authors.initials: NS
authors.lastname: Wang
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D004929:Esculin / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D016014:Linear Models; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014468:Umbelliferones / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics
chemical_list: D014468:Umbelliferones; D004929:Esculin; C007628:esculetin