A Sensitive Liquid Chromatography-Mass Spectrometry Method for Determination of 14-Deoxy-12(R)-Sulfo Andrographolide Concentration in Rat Plasma and its Application to a Pharmacokinetic Study

Andrographolide is a promising natural substance with numerous pharmacotherapy uses. 14-deoxy-12(R)-sulfo andrographolide (SAP) is the main metabolite of andrographolide in the intestine.To investigate the pharmacokinetic properties of SAP, a precise and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the determination of SAP concentration in rat plasma was developed and validated in this study.Chromatographic separation was achieved on an Acpuity UPLC BEH C18 column with gradient elution that consisted of methanol and water at a flow rate of 0.3 mL/min. MS/MS detection was carried out by the multiple reaction monitoring (MRM) mode with negative electrospray ionization (ESI-) source, with the transitions of m/z 413.2→m/z 287.2 for SAP and m/z 269→m/z 133 for genistein [which was used as an internal standard (IS)].The calibration curve of SAP was linear over the concentration range of 5-120 ng/mL. The selectivity, precision, accuracy, extraction recovery, matrix effect, and stability of the method were within acceptable ranges. This SAP quantification method was then successfully applied to a pharmacokinetic study of SAP. The area under the curve (AUC) of SAP in rats treated with SAP at 60 mg/kg by intravenous administration was 7498.53 ± 2405.02 mg/L·min. The AUC of SAP in rats treated with SAP at 60 mg/kg by oral administration was 97.74 ± 39.56 mg/L·min. Thus, the absolute oral bioavailability of SAP was determined to be 1.40%.