Simultaneous determination and pharmacokinetic study of eight components in rat plasma by UHPLC-MS/MS after oral administration of Hypericum japonicum Thunb extract

A rapid and sensitive assay based on ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was established and validated for the simultaneous determination of gallic acid, protocatechuic acid, vanillic acid, caffeic acid, epicatechin, isoquercitrin, vincetoxicoside B and quercetin in rat plasma using catechin and daidzein as the internal standards (IS). Plasma samples added internal standards were acidified with formic acid then pretreated by direct protein precipitation with acetonitrile. The separation of eight constituents was achieved on a C18 column with gradient elution using methanol and 0.2% acetic acid aqueous solution as the mobile phase and detected by multiple reaction monitoring using electrospray ionization source in the positive-negative ionization mode. The method was validated for sufficient specificity, precision, accuracy, and sensitivity over the concentration range of 10-6000 ng mL(-1) for gallic acid, 1.5-3000 ng mL(-1) for protocatechuic acid, 10-15000 ng mL(-1) for vanillic acid, 2-3600 ng mL(-1) for caffeic acid, 1.5-3600 ng mL(-1) for epicatechin, 4-6000 ng mL(-1) for isoquercitrin, 2-9000 ng mL(-1) for vincetoxicoside B, and 20-18000 ng mL(-1) for quercetin. The overall intra‑run precision and the inter‑run precision were showed in the range of 1.0-14.2% and 2.8-12.9%, respectively, and the accuracy was no more than 12.8%. This analytical method was successfully applied to investigate the pharmacokinetics of eight ingredients in rats after oral administration of Hypericum japonicum Thunb extract.