Simultaneous determination of nine constituents by validated UFLC-MS/MS in the plasma of cough variant asthma rats and its application to pharmacokinetic study after oral administration of Huanglong cough oral liquid

•Huanglong cough oral liquid (HL) was treated for pediatric cough variant asthma.•UFLC-MS/MS method was established and validated for determining nine constituents.•The pharmacokinetic studies were performed on cough variant asthma model rats.•This research could lay a good foundation to reveal the metabolism of HL in vivo. Huanglong cough oral liquid (HL), an important traditional Chinese medicine prescription for treating pediatric cough variant asthma (CVA) in Nanjing hospital of traditional Chinese medicine for many years. In this study, a selective, accurate and sensitive ultra fast liquid chromatography extreme resolution coupled with mass spectrometer (UFLC-MS/MS) method was established and validated for the simultaneous determination of nine constituents including morusin, ephedrine, praeruptorin A, praeruptorin B, luteolin, rosmarinic acid, quercetin, amygdalin, caffeic acid in CVA rat plasma sensitized and challenged with ovalbumin and cinnamaldehyde. Plasma samples were prepared by protein precipitation with four-fold amount of methanol. UFLC separation was performed on a Thermo Scientific AcclaimTM RSLC 120 C18 column (2.1 mm × 100 mm, 2.2 μm) with mobile phase containing methanol and 0.1% formic acid-water by gradient elution in 8.1 min at total flow of 0.3 mL/min. The determination of target compounds in plasma was operated by multiple reaction monitoring (MRM) mode with positive and negative electrospray ionization (ESI) source. The correlation coefficients (r) of all compounds were from 0.9930 to 0.9994 in the linear range. Lower limit of quantification (LLOQ, ng/mL) was 0.81, 2.01, 2.11, 1.17, 1.04, 0.89, 0.67, 1.45 and 0.59 for morusin, ephedrine, praeruptorin A, praeruptorin B, luteolin, rosmarinic acid, quercetin, amygdalin and caffeic acid, respectively. Intra- and inter-day accuracy and precision, extraction recovery, matrix effect, carryover effect, dilution integrity, and stability were within the limits specified. The established method was effectively applied to a pharmacokinetic study of the nine compounds in CVA rat plasma following oral administration HL exact (7.5, 15, 30 g/kg).