Metabolic profiles and pharmacokinetics of picroside I in rats by liquid chromatography combined with electrospray ionization tandem mass spectrometry.

Picroside I is an iridoid glycoside derived from Picrorhiza kurroa Royle ex Benth and Picrorhiza scrophulariiflora Pennell and characterized by many biological activities. In this study, a fast, selective, and sensitive UHPLC-MS/MS method was developed and validated to determine picroside I in rat plasma. Analytes were separated by using an ACQUITY UPLC® BEH C18 (2.1 × 50 mm, 1.7 μm) column at a running time of 2 min. Selected reaction monitoring (SRM) transitions were m/z 491.1 → 147.1 for picroside I and m/z 511.1 → 235.1 for the internal standard in a negative ion mode. The established UHPLC-MS/MS method achieved good linearity for picroside I within the range of 0.1-500 ng/mL. The validated method was successfully applied for the pharmacokinetic analysis of picroside I in rats after oral administration. Fifteen metabolites of picroside I were tentatively identified through ultra-high-performance chromatography/tandem quadrupole time-of-flight mass spectrometry, and four metabolites were identified by comparing with the standards. Besides, nine of these metabolites were discovered for the first time. The proposed metabolic pathways of picroside I in vivo can be divided into four parts, namely, phase I reaction of picroside I, including hydroxylation and deoxygenation; phase II reaction of picroside I, including glucuronidation, sulfation, and methylation; phase I biotransformations of metabolites, such as reduction and hydroxylation; and phase II biotransformations of metabolites, such as glucuronidation and sulfation. These results could offer insights into the effectiveness and toxicity of picroside I.

Xiong K ，Ju Z ，Zhang T ，Wang Z ，Han H ... -  《-》

Characterization of picroside II metabolites in rats by ultra-high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

Picroside II, a bioactive compound isolated from Picrorhiza scrophulariiflora Pennell, has been reported to have hepatoprotective, neuroprotective, and antioxidant effects. However, the detailed in vivo biotransformation of this compound has been rarely reported. This study aimed to investigate the metabolic profiles of picroside II in rats by using ultra-high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry. Metabolite structures were elucidated based on accurate mass measurements of deprotonated molecules and their fragmentation patterns. Thirteen metabolites were structurally identified, and the detailed metabolic pathways were proposed. The findings revealed that after oral administration, picroside II mainly undergoes four metabolic pathways. In the first pathway, picroside II is deglycosylated to generate aglycone, which is isomerized to a dialdehyde-type intermediate. A series of metabolic reactions, including glucuronidation, subsequently occurs. In the second pathway, picroside II is subjected to ester bond hydrolysis to form vanillic acid, which is further subjected to sulfate conjugation, glycine conjugation, glucuronidation, and demethylation. In the third pathway, picroside II is directly conjugated with glucuronic acid to yield a predominant metabolite (M01) in plasma. In the fourth pathway, picroside II is directly conjugated with sulfate. These findings provide insights into the in vivo disposition of picroside II and are useful to understand the mechanism of effectiveness and toxicity of this compound as well as P. scrophulariiflora-related preparations.

Gao T ，Sheng T ，Zhang T ，Han H ... -  《-》

A pre-clinical pharmacokinetic study in rats of three naturally occurring iridoid glycosides, Picroside-I, II and III, using a validated simultaneous HPLC-MS/MS assay.

A selective and sensitive high-performance liquid chromatography-electro-spray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed for the simultaneous quantitative determination of Picroside-I, II, and III in rat plasma and tissue homogenate to aid the pre-clinical studies. The chromatographic separation was performed on a Hypersil GOLD AQ C18 column using a gradient elution program with a mobile phase consisting of 2mM ammonium acetate and acetonitrile. The detection was achieved using a triple quadrupole tandem MS in negative ionization multiple reaction monitoring (MRM) mode. One-step protein precipitation was selected for plasma and tissue sample preparation while liquid-liquid extraction failed to achieve satisfactory recoveries. The calibration curves of all three analytes in either plasma or tissue homogenate showed good linearity over the concentration range of 0.5-500ng/mL with a limit of quantitation at 0.5ng/mL. Both the intra- and inter-day accuracy and precision were within ±10%. The extraction recoveries were >70%, and the relative matrix effect ranged from 80.4% to 107.4% in all the biological samples. All the analytes were stable in matrices for at least 24h at room temperature, or 21 days in frozen. Three freeze/thaw cycles did not cause degradation. The method was successfully applied for quantification of the three iridoid glycosides in the collected plasma and various tissues following intravenous administration in rats. Picroside-I, II, and III were all eliminated rapidly with large volume of distribution. Among the three glycosides, Picroside-II showed the highest liver uptake, and only Picroside-I and II were found to get across the blood brain barrier (BBB). These results were consistent with their hepatoprotective or neuroprotective effects reported clinically. With the aid of the efficient and reliable simultaneous LC-ESI-MS/MS assay this pharmacokinetic study provided insights into their therapeutic targets of these three iridoid glycosides as well as valuable experimental basis for an expansion of their clinical indications.

Zhu J ，Xue B ，Ma B ，Zhang Q ，Liu M ，Liu L ，Yao D ，Qi H ，Wang Y ，Ying H ，Wu Z ... -  《-》

In vitro - In vivo metabolism and pharmacokinetics of picroside I and II using LC-ESI-MS method.

Picroside I and II, iridoid glycosides, are the major active markers of roots and rhizomes of Picrorhiza kurroa (family: Scrophulariaceae). The rhizomes of P. kurroa have been traditionally used to treat worms, constipation, low fever, scorpion sting, asthma and ailments affecting the liver. Various Ayurvedic and herbal preparations are available in the market which contains P. kurroa e.g. Arogyavadhini vati, Tiktadi kwath, Picrolax capsules and suspension. These preparations are used without any significant pharmacokinetics data. Previously, we have reported that oral bioavailability of picroside I and II is low. Most of the iridoid glycosides are primarily metabolized by intestinal microbial flora. So, it is necessary to determine the metabolic profile of picroside I and II and check the correlation with lower bioavailability. Therefore, this study was designed to check metabolic (in vitro and in vivo) profile along with pharmacokinetic profile of picroside I and II. For this, a sensitive and selective LC-ESI-MS method was developed and validated for simultaneous determination of picroside I and II in rat plasma. Chromatographic separations were performed on C18 column. The mobile phase consisted of acetonitrile: 10 mM ammonium acetate buffer [90:10 v/v], pH 3.5. In-vitro Metabolic study was performed on rat liver microsomes and primary hepatocytes. In-vivo pharmacokinetic and metabolic profile of picroside I and II was generated after oral administration of Kutkin (mixture of picroside I and II) to Sprague-Dawley rats. Various pharmacokinetic parameters viz. Cmax, Tmax, AUC(0-t) were determined. In metabolic study, eight metabolites of picroside I and six metabolites of picroside II were identified in vitro, out of which four metabolites for each picroside I and picroside II were identified in vivo.

Upadhyay D ，Anandjiwala S ，Padh H ，Nivsarkar M ... -  《-》

Simultaneous determination of gentiopicroside and its two active metabolites in rat plasma by LC-MS/MS and its application in pharmacokinetic studies.

Gentiopicroside is a natural secoiridoid glycoside that may require metabolic activation to exert pharmacological effects. In this study, two active metabolites of gentiopicroside (M1 and M2) were isolated from rat urines and identified with our previous method. Most importantly, a fast, sensitive and selective ultra high-performance liquid chromatography-tandem mass spectrometry method was developed to simultaneously determine gentiopicroside and its two metabolites in rat plasma. The analytes and internal standard (swertiamarin) were separated on an ACQUITY UPLC® BEH C18 column (2.1×50mm, 1.7μm) using gradient elution by acetonitrile and 0.1% formic acid at a flow rate of 0.4mL/min. The mass spectrometry detector was operated in the multiple reaction monitoring with positive ionization mode. The method had a good linearity over the concentration range of 0.2-10,000ng/mL for gentiopicroside and 0.1-5000ng/mL for the two metabolites. The validated method was successfully applied to the pharmacokinetic study of gentiopicroside and its metabolites after single oral administration of gentiopicroside (150mg/kg) to rats (n=8). The pharmacokinetic differences between gentiopicroside and its two metabolites were identified.Results provided the evidence for in vivo metabolism-based activation of gentiopicroside.

Xiong K ，Gao T ，Zhang T ，Wang Z ，Han H ... -  《-》