Simultaneous determination of albiflorin and paeoniflorin in rat urine by solid-phase extraction and high-performance liquid chromatography following oral administration of Si-Wu decoction

A high performance liquid chromatographic method (HPLC), together with solid phase extraction (SPE), was developed for simultaneous determination of albiflorin and paeoniflorin in rat urine after oral administration of Si-Wu decoction. The samples were pretreated with solid phase extraction using Extract-Cleantrade mark cartridges. Analysis of the extract was performed on a reversed-phase C18 column and a mobile phase made up of acetonitrile and 0.03% formic acid (17:83, v/v). UV detection was set at 230 nm. The assay was linear over the range 2.625-52.50 mg/mL for albiflorin and 3.875-77.50 microg/mL for paeoniflorin. The average percentage recoveries of three spiked urines were 97.01 +/- 3.32 and 102.32 +/- 6.97 for albiflorin and paeoniflorin, respectively. The intra-day precision (RSD) ranged from 0.21 to 1.79% at concentrations of 4.20, 10.50, 26.25 and 39.375 microg/mL of albiflorin and 0.12 to 2.92% at concentrations of 3.875, 10.85, 23.25 and 58.125 microg/mL of paeoniflorin, and inter-day precision (RSD) was from 1.02 to 1.86% for albiflorin and 0.94 to 3.30% for paeoniflorin, at the same four concentrations. This method was applied in order to analyze albiflorin and paeoniflorin in rat urine following oral administration of traditional Chinese medicinal preparation of Si-Wu decoction.     

LC-MS/MS determination and pharmacokinetic study of albiflorin and paeoniflorin in rat plasma after oral administration of Radix Paeoniae Alba extract and Tang-Min-Ling-Wan

A rapid, sensitive and selective liquid chromatography/tandem mass spectrometry method (LC‐MS/MS) was developed and validated for simultaneous determination of albiflorin and paeoniflorin in rat plasma using geniposide as an internal standard. Plasma samples were extracted by solid‐phase extraction. Chromatographic separation was carried out on a Zorbax SB‐C₁₈ analytical column (150 × 2.1 mm × 5 µm) with 0.1% formic acid–acetonitrile (70:30, v/v) as the mobile phase. Detection was performed by multiple reaction monitoring mode using electrospray ionization in the positive ion mode. The total run time was 3.0 min between injections. The calibration curves were linear over a range of 1–1000 ng/mL for albiflorin and 2–2000 ng/mL for paeoniflorin. The overall precision and accuracy for all concentrations of quality controls and standards were better than 15%. Mean recovery was determined to be 87.7% for albiflorin and 88.8% for paeoniflorin. The validated method was successfully applied to the pharmacokinetic study of albiflorin and paeoniflorin in rat plasma after oral administration of Radix Paeoniae Alba extract and Tang‐Min‐Ling‐Wan. The pharmacokinetic parameters showed that albiflorin and paeoniflorin from Tang‐Min‐Ling‐Wan were absorbed more rapidly with higher concentrations in plasma than that from Radix Paeoniae Alba extract. The results provided a meaningful basis for evaluating the clinical applications of traditional Chinese medicine. Copyright © 2010 John Wiley & Sons, Ltd.     

Monoterpene Glycosides from the Roots of Paeonia lactiflora

The roots of Paeonia lactiflora Pall. is one of the most important traditional Chinese medicines, which has been used for the treatment of dizziness, spasm, menstrual disorder, spontaneous and night sweating, and as a general analgesic1. Chemical constitu…     

Sensitive high-performance anion-exchange chromatographic determination of paeoniflorin and albiflorin by pulsed amperometric detection after solid-phase extraction

We developed a method to simultaneously determine paeoniflorin and albiflorin levels using high-performance anion-exchange liquid chromatography with pulsed amperometric detection (HPAEC-PAD). The main principle of our method includes solid-phase extraction step using Amberlite XAD-2 sorbent to remove sugars and to selectively determine glycosides by PAD. Under these conditions, the linear dynamic range was 0.01–100 μg/mL, and the albiflorin and paeoniflorin detection limits (S/N = 3) were 5 and 10 pg, respectively. The intra- and inter-day precisions (RSDs) were <5.07%, and the average recoveries from Paeoniae Radix and Si-ni-san ranged from 97.12 to 101.15%. Our method showed high selectivity, high sensitivity, and good repeatability for analyzing albiflorin and paeoniflorin in oriental medicinal preparation.     

Analysis of sodium adduct paeoniflorin, albiflorin and their derivatives by (+)ESI-MSn, DFT calculations and computer-aided mass spectrometry analysis program

In order to analyze paeoniflorin, albiflorin and their derivatives (PADs) in Paeonia Lactiflora rapidly and effectively, (+)ESI-MS(n) experiments were conducted, from which two diagnostic fragment patterns were acquired. Meanwhile, the dehydration ability of aglycones of PADs was obtained by calculating their activation energy using density functional theory, through which the unique dehydration phenomenon of benzoylalbiflorin, compared with benzoylpaeoniflorin, was interpreted. In addition, a computer-aided mass spectrometry analysis program was developed to facilitate the analysis of the unknown compound by suggesting the possible structure of the analyte.     

Simultaneous LC Determination of Major Constituents in Red and White Peony Root

A reversed phase high performance liquid chromatography method was established for the simultaneous determination of eight major constituents, namely gallic acid, paeoniflorin sulfonate, catechin, albiflorin, paeoniflorin, benzoic acid, pentagalloylglucose and benzoylpaeoniflorin in red and white peony roots, the two commonly used traditional Chinese medicinal herbs. The optimal conditions of separation and detection were achieved on a C₁₈ analytical column with a gradient mobile phase consisting of acetonitrile and 0.015% phosphoric acid at the flow rate of 1.0 mL min^?1 and detection wavelength set at 230 nm. All calibration curves showed good linear regression (r>0.9995) within test ranges. This method provided good reproducibility with overall intra-and inter-day precision of less than 5% and 4% and good accuracy with recovery of more than 93%, respectively. The method was successfully applied to determine 71 samples of red and white peony roots collected from different areas. The results indicated that the contents of eight compounds varied significantly among the samples determined, which mainly resulted from processing procedure and habitat variation. The roots of Paeonia veitchii Lynch. contained a much higher amount of gallic acid and pentagalloylglucose than that of Paeonia lactiflora Pall., which could be used to distinguish the two similar species.     

Detection of albiflorin and paeoniflorin in Paeoniae Radix by reversed-phase high-performance liquid chromatography with pulsed amperometric detection

We have developed a reversed-phase high-performance liquid chromatography-pulsed amperometric detection (RP-HPLC-PAD) method for the detection of albiflorin and paeoniflorin in Paeoniae Radix and Wu-ji-san. Albiflorin and paeoniflorin were completely separated using 10% acetonitrile in 5 mM sodium phosphate buffer (pH 3.0) as an eluent and detected by PAD under alkaline conditions after using a post-column delivery system. The limit of detection (S/N = 3) and the limit of quantification (S/N = 10) were 0.10 and 0.35 ng for albiflorin, and 0.20 and 0.50 ng for paeoniflorin, respectively. The coefficients of linear regression were 0.9995 and 0.9999 for concentrations between 0.035 and 100 μg/mL. The intra- and inter-day precision (RSDs) was less than 3.56% in Paeoniae Radix and Wu-ji-san. The average recoveries from Paeoniae Radix and Wu-ji-san were 99.01–100.94% and 99.46–100.64%. This method shows higher selectivity than HPLC–UV method for analyzing albiflorin and paeoniflorin in Chinese medicinal preparation.     

Simultaneous determination of ferulic acid,paeoniflorin, and albiflorin in rat plasma by ultra‐high performance liquid chromatography with tandem mass spectrometry: Application to a pharmacokinetic study of Danggui‐Shaoyao‐San

A rapid, selective, and sensitive ultra‐high performance liquid chromatography‐tandem mass spectrometry method was developed for simultaneous determination of ferulic acid, paeoniflorin, and albiflorin, the major active constituents of Danggui‐Shaoyao‐San, in rat plasma using geniposide as the internal standard. The plasma samples were processed by protein precipitation with acetonitrile, and then separated on a Shim‐Pack XR‐ODS C₁₈ column (75 mm × 3.0 mm, 2.2 μm) using gradient elution program with a mobile phase consisting of 0.1% aqueous formic acid and acetonitrile at a flow rate of 0.4 mL/min. The detection was achieved on a 3200 QTRAP mass spectrometer equipped with electrospray ionization source in negative ionization mode. Quantification was performed using multiple reaction monitoring mode by monitoring the fragmentation of m/z 192.9→134.0 for ferulic acid, m/z 525.0→120.9 for paeoniflorin, m/z 525.2→121.0 for albiflorin, and m/z 433.1→225.1 for the internal standard, respectively. The calibration curve was linear in the range of 5–2500 ng/mL for all the three analytes (r ≥ 0.9972) with the lower limit of quantitation of 5 ng/mL. The intraday and interday precisions were below 12.1% for all the analytes in terms of relative standard deviation, and the accuracy was within ±11.5% in terms of relative error. The extraction recovery, matrix effect and stability were satisfactory in rat plasma. The validated method was successfully applied to a pharmacokinetic study of ferulic acid, paeoniflorin, and albiflorin after oral administration of Danggui‐Shaoyao‐San to rats.     

Studies on metabolism of total glucosides of paeony from Paeoniae Radix Alba in rats by UPLC‐Q‐TOF‐MS/MS

Total glucosides of paeony are the active constituents of Paeoniae Radix Alba. In this study, a novel strategy was proposed to find more metabolites and the differences between paeoniflorin, albiflorin and total glucosides of paeony (TGP). This strategy was characterized as follows: firstly, the animals were divided into three groups (paeoniflorin, albiflorin and TGP) to identify the source of TGP metabolites from paeoniflorin or albiflorin; secondly, a generic information‐dependent acquisition scan for the low‐level metabolites was triggered by the multiple mass defect filter and dynamic background subtraction; thirdly, the metabolites were identified with a combination of data‐processing methods including mass defect filtering, neutral loss filtering and product ion filtering; finally, a comparative study was used in the metabolism of paeoniflorin, albiflorin and TGP. Based on the strategy, 18 metabolites of TGP, 10 metabolites of paeoniflorin and 13 metabolites of albiflorin were identified respectively. The results indicated that the hydrolysis, conjugation reaction and oxidization were the major metabolic pathways, and the metabolic sites were the glycosidic linkage, the ester bond and the benzene ring. This study is first to explore the metabolism of TGP, and these findings enhance our understanding of the metabolism and the interactions of paeoniflrin and albiflorin in TGP. Copyright © 2015 John Wiley & Sons, Ltd.     

Chemical profiling by LC–MS/MS and HPLC fingerprint combined with chemometrics and simultaneous determination of 16 characteristic ingredients for the quality consistency evaluation of Shaoyao‐Gancao Decoction

In this paper, to evaluate the effect of the region of origin on the quality consistency of Shaoyao‐Gancao Decoction (SGD), the SGD fingerprint was developed for the first time. Chemometric methods including similarity analysis, hierarchical clustering analysis and principal component analysis were employed to study the quality consistency of SGD. Meanwhile, high‐performance liquid chromatography coupled with electrospray ionization quadrupole time‐of‐flight mass spectrometry was applied for comprehensive analysis of SGD and 93 compounds were tentatively characterized. Furthermore, a high‐performance liquid chromatography method with multi‐wavelength switching for simultaneous determination of 16 characteristic ingredients comprising gallic acid, oxypaeniflorin, albiflorin, paeoniflorin, liquiritin apioside, liquiritin, isoliquiritin apioside, galloylpaeoniflorin, 1,2,3,4,6‐penta‐O‐galloyl‐d ‐galactopyranose (PGG), ononin, isoliquiritin, liquiritigenin, benzoylpaeoniflorin, glycyrrhizic acid, isoliquiritigenin and formononetin, was established. All 16 analytes show excellent linearity (R² ≥ 0.9990) with recoveries ranging from 96.58 to 104.61% and limits of detection and quantification of 0.022–0.291 and 0.037–0.635 μg/mL, respectively. Finally, it was successfully applied to determine 15 batches of SGD. The results of our research indicate that different regions of origin have a significant effect on the quality consistency of SGD, and its fingerprint combined with chemometrics and multi‐ingredient determination comprise an efficient and reliable approach for quality consistency evaluation.     

Quantitative analysis of different batches of raw,wine‐processed,and vinegar‐processed Paeoniae Alba Radix using ultra‐performance convergence chromatography coupled with photo diode array detection

Supercritical fluid chromatography is a safe and ecofriendly analytical technique that has not been fully applied to the analysis of traditional Chinese medicine. This is the first study on the separation of six quality markers—paeoniflorin, albiflorin, benzoyl paeoniflorin, oxypaeoniflorin, gallic acid and benzoic acid—from raw, wine‐baked and vinegar‐baked Paeoniae Alba Radix (PAR) by Supercritical fluid chromatography. Optimum separation was achieved on an HSS C₁₈ SB column (100 × 3.0 mm, 1.8 μm particles) with a gradient elution of high‐purity carbon dioxide as mobile phase A and methanol–acetonitrile (70:30, v/v) with 0.10% phosphoric acid as mobile phase B. The flow rate was set at 0.7 mL/min for 15.0 min. The method was validated in terms of the overall intraday and interday precision, with relative standard deviations (RSDs) of 0.87–2.87 and 1.47–3.63%, respectively. The recoveries were 98.10–103.60% with an RSD of 1.00–3.40%. The stability of the RSD values was in the range 1.10–3.78%. The developed approach was successfully applied and provides a valuable reference for the quality assessment of PAR and processed PAR. The results also revealed that the standardization of processing technology is of great significance to the fluctuations in quality before and after the processing of traditional Chinese medicine.     

Rapid screening and quantification of sulfonate derivatives in white peony root by UHPLC–MS–MS

A rapid ultra-high-performance liquid chromatographic–tandem mass spectrometric (UHPLC–MS–MS) method has been developed for rapid screening and quantitative analysis of sulfonate derivatives (SDs) in commercial white peony root. Separation was performed on an Agilent Zorbax Eclipse Plus-C18 column by gradient elution with acetonitrile–0.1% (v/v) formic acid as the mobile phase. In-source fragmentation was used to generate the characteristic fragment ion at m/z 259 and to screen for nine SDs. Detection of these SDs was further performed in multiple reaction monitoring (MRM) mode to improve sensitivity and to quantify the two SDs paeoniflorin sulfonate and benzoylpaeoniflorin sulfonate. The method was validated for specificity, linearity, limits of detection and quantification, precision, accuracy, and matrix effects. Nine commercial white peony root samples were examined by use of this method, which revealed great variety in the paeoniflorin sulfonate and benzoylpaeoniflorin sulfonate content.     

Screening,separation, and evaluation of xanthine oxidase inhibitors from Paeonia lactiflora using chromatography combined with a multi‐mode microplate reader

Natural products have become one of the most important resources for discovering novel xanthine oxidase inhibitors, which are commonly employed in the treatment of hyperuricemia and gout. However, to date, few reports exist regarding the use of monoterpene glycosides as xanthine oxidase inhibitors. Thus, we herein report the use of ultrafiltration coupled with liquid chromatography in the screening of monoterpene glycoside xanthine oxidase inhibitors from the extract of Paeonia lactiflora (P. lactiflora ), and both high‐performance counter‐current chromatography and medium‐pressure liquid chromatography were employed to separate the main constituents. Furthermore, the xanthine oxidase inhibitory activities and the mechanisms of inhibition of the isolated compounds were evaluated using a multi‐mode microplate reader by Molecular Devices. As a result, three monoterpene glycosides were separated by combined high‐performance counter‐current chromatography and medium‐pressure liquid chromatography in purities of 90.4, 98.0, and 86.3%, as determined by liquid chromatography. These three compounds were identified as albiflorin, paeoniflorin, and 1‐O‐β‐ᴅ‐glucopyranosyl‐8‐O‐benzoylpaeonisuffrone by electrospray ionization tandem mass spectrometry, and albiflorin and paeoniflorin were screened as potential xanthine oxidase inhibitors by ultrafiltration with liquid chromatography. The evaluation results of xanthine oxidase inhibitory activity corresponded with the screening results, as only albiflorin and paeoniflorin exhibited xanthine oxidase inhibitory activity.     

Simultaneous determination of ginsenoside Rb1, ginsenoside Rg1, paeoniflorin,albiflorin and oxypaeoniflorin in rat plasma by liquid chromatography–tandem mass spectrometry: Application to a pharmacokinetic study of wen‐Yang‐Huo‐Xue soft capsule

A simple and sensitive HPLC–MS/MS method was developed and fully validated for simultaneous determination of ginsenoside Rb1, ginsenoside Rg1, paeoniflorin, albiflorin and oxypaeoniflorin in rat plasma. Plasma samples were pretreated with protein precipitation using acetonitrile. The chromatographic separation was carried out on a C₁₈ column with a gradient mobile phase consisting of acetonitrile and water (containing 0.1% formic acid). All analytes and digoxin (internal stand, IS) were quantitated through electrospray ionization in negative ion multiple reaction monitoring mode. All calibration curves exhibited good linearity (r > 0.9960) over a wide concentration range for all components. The intra‐day and inter‐day precisions (RSD) at three different levels were all <12.0% and the accuracies (RE) ranging from −6.1 to 6.2%. The extraction recoveries of the five compounds ranged from 89.2 to 97.1%. The validated method was successfully applied in a comparative pharmacokinetic study of Wen‐Yang‐Huo‐Xue soft capsule (WYHXSC) in rats. Compared with single pure component, the exposure of the investigated components, except for oxypaeoniflorin, increased after oral administration of WYHXSC in rats, which suggested a synergistic effects between the herbs in the WYHXSC preparations.     

Chemical interaction between Paeonia lactiflora and Glycyrrhiza uralensis,the components of Jakyakgamcho‐tang,using a validated high‐performance liquid chromatography method: Herbal combination and chemical interaction in a decoction

The herbal combination is the basic unit of a herbal formula that affects the chemical characteristics of individual herbs. In the present study, a method of simultaneous determination of the 11 marker compounds in Jakyakgamcho‐tang was developed using high‐performance liquid chromatography with photodiode array detection. The validated analytical method was successfully applied to approach the chemical interaction between Paeonia lactiflora and Glycyrrhiza uralensis in co‐decoction. In P. lactiflora, the contents of gallic acid, oxypaeoniflorin, (+)‐catechin, paeoniflorin, and benzoylpaeoniflorin were decreased, while those of albiflorin and benzoic acid were increased; in G. uralensis, the contents of liquiritin, isoliquiritin, ononin, and glycyrrhizin were decreased, when decocting two herbs together. Moreover, as the ratio between P. lactiflora and G. uralensis was increased, the contents of chemical contents from each herb were proportionally increased. However, each content of marker compound per the gram of herbal medicine was decreased as the ratio of combinative herbs increased. The results showed that P. lactiflora and G. uralensis affect the extraction efficiency of chemical compounds in a Jakyakgamcho‐tang decoction. Overall, the method established in this study was simple, rapid, and accurate, and would be useful for the determination of marker compounds and for the investigation of the chemical interaction between herbal medicines.     

Rapid determination of Paeoniae Radix using near infrared spectroscopy

A rapid and nondestructive near infrared spectroscopy (NIRS) was used to differentiate different geographical Paeoniae Radix and quantitatively predict the content of main active components. Paeoniflorin, albiflorin and benzoylalbiflorin were analyzed simultaneously with an Agilent Zorbax SB-C₁₈ column by gradient elution under high-performance liquid chromatography-UV detection (HPLC-UV). Multiplicative scatter correction (MSC), first derivative and Savitsky-Golay were utilized together to correct the scattering effect and eliminate the baseline shift in all near infrared diffuse reflectance spectra in order to give a better correlation with the results obtained by HPLC-UV. Multiplicative regression methods were discussed. The spectra calibration equations produced highest correlation coefficient values (R²) and lowest root mean square error of prediction (RMSEP) were used for the determination of paeoniflorin, albiflorin and benzoylalbiflorin. The RMSEP of paeoniflorin, albiflorin and benzoylabiflorin were 0.866 mg/g, 0.369 mg/g and 0.084 mg/g, respectively, and the R² of cross validation were 0.986, 0.939 and 0.971, respectively. Furthermore with the use of principle component analysis (PCA), Paeoniae Radix was clustered according to different cultivation area. The results indicated that the NIRS method could be used for the quality control of Chinese herbal medicine.     

Quantitative and qualitative determination of Liuwei Dihuang tablets by HPLC-UV-MS-MS

A method is developed for the analysis of allantoin, gallic acid, dihydromelittoside, loganin, paeoniflorin, benzoylpaeoniflorin, and paeonol in Liuwei Dihuang tablets by high-performance liquid chromatography (HPLC)-UV-mass spectrometry (MS)-MS. Gradient elution with methanol-acetonitrile-water-formic acid solvent system is employed in the HPLC-electrospray ionization-MS study. The positive-ion ESI mode is suitable for these compounds. The peaks of gallic acid, loganin, dihydromelittoside, paeoniflorin, benzoylpaeoniflorin, and paeonol are identified by their mass spectra and the fragments of their MS-MS spectra. Allantoin, gallic acid, loganin, paeoniflorin, and paeonol are simultaneously determined by UV detection at 210 nm for quantitative purposes.     

Simultaneous determination of ten constituents in herbal formulation Sipjeondaebo-tang using HPLC-PDA

A simple, rapid, and accurate high-performance liquid chromatographic method was applied to the quantitative determination of 10 components, namely, 5-hydroxymethyl-2-furaldehyde, albiflorin, paeoniflorin, liquiritin, ferulic acid, nodakenin, coumarin, cinnamic acid, cinnamaldehyde and glycyrrhizin in the traditional herbal formulation Sipjeondaebo-tang (SJDBT). All components were separated within 40 min using a Gemini C₁₈ column maintained at 40°C. The mobile phase was composed of 1.0% (v/v) aqueous acetic acid and 1.0% (v/v) acetic acid in acetonitrile by gradient elution. The flow rate was 1.0 mL/min and the detector was a photodiode array (PDA) set at 230, 254, 280, 320, and 330 nm. The calibration curves showed good linearity (r ² ≥ 0.9993) in different concentration ranges. The recovery of each component was in the range of 92.3–104.8%, with relative standard deviations (RSDs) less than 2.5%. The RSDs for intra- and inter-day precision were 0.09–2.8% and 0.07–3.2%, respectively. The amounts of the 10 components in SJDBT were in the range of 0.18–5.77 mg/g.     

Structural Characterization of an Artefact and Simultaneous Quantification of Two Monoterpenes and Their Artefacts of Isolation in White‐Peony Root

Sodium benzoylpaeoniflorinsulfonate ( 3 ), a new artefact, was isolated from sulfur‐fumigated white‐peony root and characterized by mass and NMR spectroscopy. A HPLC method was developed for the simultaneous determination of sodium paeoniflorinsulfonate ( 1 ), paeoniflorin ( 2 ), sodium benzoylpaeoniflorinsulfonate ( 3 ), and benzoylpaeoniflorin ( 4 ). The method developed was successfully applied to quantify the four compounds in 14 white‐peony‐root samples. The quantity of four constituents in sulfur‐fumigated white‐peony root may be regarded as an index for the quality assessment of this Chinese medicine.     

Pharmacokinetic comparisons by UPLC‐MS/MS of isomer paeoniflorin and albiflorin after oral administration decoctions of single‐herb Radix Paeoniae Alba and Zengmian Yiliu prescription to rats

Zengmian Yiliu (ZMYL), a traditional Chinese formula, is designed to improve clinical efficacy and reduce adverse effects in combination with cisplatin in ovarian cancer chemotherapy. In ZMYL, Radix Paeoniae Alba (RPA, made from root of Paeonia lactiflora Pall.) acts as an adjunctive drug in cancer treatment by ameliorating side effects induced by radio‐ and chemotherapy. The pharmacokinetics differences between isomer albiflorin and paeoniflorin, the main components of RPA, after oral administration decoction of single‐herb RPA and ZMYL were compared using a sensitive and accurate UPLC‐MS/MS. The results indicate that there are statistically significant differences between the pharmacokinetic parameters: decreasing area under the plasma concentration–time curve (AUC), maximum concentration (C_max), elimination rate constant (K_e) and increasing apparent volume of distribution (V_d) and clearance (CL) for albiflorin, increasing distribution half‐life (T_1/2d) and decreasing elimination half‐life (T_1/2e), distribution rate constant (K_d) and absorption rate constant (K_a) for paeoniflorin in the ZMYL group compared with the single‐herb RPA group. In comparison with albiflorin, the pharmacokinetic parameters of paeoniflorin included significantly increasing mean residence time (MRT) and V_d, decreasing CL and K_e in the single‐herb RPA group and increasing MRT and T_1/2d and decreasing CL, K_e and K_d in the ZMYL group. Both paeoniflorin and albiflorin are more likely, as the main active ingredients in RPA and ZMYL, to play a variety of pharmacological effects, and herb–herb interactions occur, resulting in different pharmacokinetics of albiflorin and paeoniflorin in RPA and ZMYL. Copyright © 2014 John Wiley & Sons, Ltd.