Simultaneous determination of gallic acid and p-coumaric acid in rat plasma by UPLC-MS/MS and its application to a comparative pharmacokinetic study after oral administration of monomer compound and red wine extract

A rapid,sensitive and selective ultra high performance liquid chromatography-tandem mass spectrometry(UPLCMS/MS)method was developed and validated for simultaneous determination of gallic acid(GA)and p-coumaric acid(CA)in rat plasma.Plasma samples were extracted by methanol and separated on an ACQUITY UPLC BEH C18 column(1.7μm,100 mm×2.1 mm)using gradient elution consisting of acetonitrile–0.2%formic acid within a runtime of 4.0 min.The detection was performed in multiple reaction monitoring(MRM)mode with negative ionization.The linear range was 20–20000 ng/mL for both GA and CA,with lower limits of quantification of 20 ng/mL.Intra-day and inter-day precisions were within 5.4%and 10.0%,respectively and the accuracy(relative error,RE,%)was less than 7.2%and–4.9%,respectively.The mean absolute extraction recoveries of both analytes and IS from rat plasma were all more than 82.6%.The validated method was successfully applied to the comparative pharmacokinetic study of GA and CA in rat plasma after oral administration of GA and CA monomers and red wine extract,respectively.It was found that both the area under the curve(AUC)and t1/2 of the two constituents were remarkably increased for red wine extract group than that in monomer group,indicating the priority of intake of red wine to active component monomer.