HPLC method for the determination and pharmacokinetic studies on puerarin in cerebral ischemia reperfusion rat plasma after intravenous administration of puerariae radix isoflavone

Neuroprotective Mechanisms of Puerarin in Central Nervous System Diseases: Update

Due to global population aging and modern lifestyle changes, the incidence of central nervous system (CNS) disorders, such as neurodegenerative diseases, neuropsychiatric disorders, and cerebrovascular diseases, is increasing and has become a major public health challenge. Current medications commonly used in the clinic are far from satisfactory and may cause serious side effects. Therefore, the identification of novel drugs for the effective management of CNS diseases is very urgent. Puerarin, a highly bioactive ingredient isolated from Pueraria lobata, is known to possess a broad spectrum of pharmacological properties including anti-diabetic, anti-inflammatory, anti-antioxidant, neuroprotective, and cardioprotective features. However, its clinical application is limited due to its poor water solubility. Since puerarin has demonstrated a wide range of neuroprotective functions in various CNS diseases, such as Alzheimer’s disease, Parkinson’s disease, cerebral ischemia, depression, and spinal cord injury, it has been attracting increasingly intense attention worldwide. In this review, we intend to extensively summarize the research progress on neuroprotective mechanisms of puerarin in recent years and discuss the future directions of its application in CNS disease treatment.

A reliable and rapid pharmacokinetic study of pueraria isoflavones using pueraria reference extractive substance in beagle plasma: Application to study of Yufeng Ningxin Tablets

Objective

In order to evaluate the reliability and feasibility of pueraria reference extractive substance (RES) used in biological sample, the pharmacokinetics of 3′‑hydroxy puerarin (3′-HP), puerarin, 3′‑methoxy puerarin (3′-MP), and daidzein-8-C-apiosyl-(1-6)-glucoside (DAG) in beagle plasma following oral administration of Yufeng Ningxin Tablet were quantitated.

Methods

A reliable and sensitive high-performance liquid chromatography-tandem triple quadrupole mass spectrometry (HPLC-QQQ-MS/MS) method developed with chromatographic separation was operated on a Merck C₁₈ column, and acetonitrile-5 mmol/L ammonium was used as mobile phase in gradient elution. The plasma samples were deproteinized by acetone, detected by triple quadrupole mass spectrometry with an electrospray ionization interface, and quantified using selected ion monitoring mode. The pharmacokinetic parameters were calculated by Winnonlin 4.1.

Results

The calibration curves of the reference extractive substance and standard substance methods were linear over the ranges 0.0417–11.3309 µg/mL and 0.0394–10.0000 µg/mL. The intra-day and inter-day precision of the two methods at three concentrations were less than 13.63%, and the average recoveries of 3′-HP, puerarin, 3′-MP, and DAG were more than 70.67%. The RSD of the mean plasma concentrations of the analytes calculated by the two methods was less than 5%, and cos (ϑ) = =1.000. Among the analytes, puerarin showed the highest blood concentration [(940 ± 185) ng/mL] and the longest retention time [(5 ± 1) h] in the dog's bodies.

Conclusion

Pueraria reference extractive substance can be seen as an alternative to the standard substance to overcome the scarcity of standard substance for the analysis of biological samples.

A UPLC-MS/MS Method for Simultaneous Determination of Six Bioactive Compounds in Rat Plasma, and its Application to Pharmacokinetic Studies of Naoshuantong Granule in Rats

Background:

It is urgently needed to clarify the pharmacokinetic mechanism for the multibioactive constituents in Traditional Chinese Medicines for its clinical applications. A rapid, sensitive and reliable ultra-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of Danshensu, Ferulic acid, Astragaloside IV, Naringin, Neohesperidin and Puerarin after oral administration of Naoshuantong Granule using Carbamazepine as internal standard (IS).

Methods:

The plasma samples were pretreated by liquid-liquid extraction method using ethyl acetate after acidification, and separated on a Waters ACQUITY UPLC® BEH C18 column (50×2.1 mm, i.d., 1.7 µm) by gradient elution with a mobile phase composing of water (containing 0.1% formic acid) and acetonitrile at a flow rate of 0.2 mL/min. Multiple reaction monitoring (MRM) mode with both positive and negative ion mode was operated using an electrospray ionization (ESI) to detect the six compounds.

Result:

All calibration curves showed good linearity (r>0.99) over a wide concentration range. The intra- and inter-day precision (RSD%) was below 8.4% and the accuracy (RE%) ranged from 91.1% to 107.5%. The extraction recoveries of the six analytes and IS in the plasma were more than 77.9% and no severe matrix effect was observed.

Conclusion:

The fully validated method was successfully applied to the pharmacokinetics of Naoshuantong Granule.

Distribution kinetics of puerarin in rat hippocampus after acute local cerebral ischemia

Puerarin, isolated from the roots of Pueraria lobata, is widely used for treating cerebral ischemia in China. The time- and dose-dependent distribution characteristics of puerarin in the ischemic hippocampus are unknown. In this study, puerarin concentration was determined by an indirect competitive ELISA using anti-puerarin monoclonal antibody. Area under the curve (AUC_{0-120 min}) of puerarin (80 mg/kg) in the embolic hippocampus was higher than that in the normal hippocampus; the increase was significant only at 40 and 20 mg/kg. The maximum concentration (C_max) of puerarin in the embolic hippocampus was higher than that in the normal hippocampus at all doses. The increase in both AUC_{0-120 min} and C_max was dose-dependent. Time to reach the maximum concentration (Tmax) of puerarin in the embolic and normal hippocampus was similar. Although the mean residence time in the embolic hippocampus differed from that in the normal hippocampus at 40 and 80 mg/kg, it was higher in the embolic hippocampus than in the normal hippocampus at 20 mg/kg. This is the first study to report that the time- and dose-dependent distribution characteristics of puerarin in the normal and embolic hippocampus after middle cerebral artery occlusion in rats dictate puerarin dose and duration to treat stroke.

Effects of Acanthopanax senticosus on Brain Injury Induced by Simulated Spatial Radiation in Mouse Model Based on Pharmacokinetics and Comparative Proteomics

The active compounds in Acanthopanax senticosus (AS) have different pharmacokinetic characteristics in mouse models. Cmax and AUC of Acanthopanax senticosus polysaccharides (ASPS) were significantly reduced in radiation-injured mice, suggesting that the blood flow of mouse was blocked or slowed, due to the pathological state of ischemia and hypoxia, which are caused by radiation. In contrast, the ability of various metabolizing enzymes to inactivate, capacity of biofilm transport decrease, and lessening of renal blood flow accounts for radiation, resulting in the accumulation of syringin and eleutheroside E in the irradiated mouse. Therefore, there were higher pharmacokinetic parameters-AUC, MRT, and t1/2 of the two compounds in radiation-injured mouse, when compared with normal mouse. In order to investigate the intrinsic mechanism of AS on radiation injury, AS extract's protective effects on brain, the main part of mouse that suffered from radiation, were explored. The function of AS extract in repressing expression changes of radiation response proteins in prefrontal cortex (PFC) of mouse brain included tubulin protein family (α-, β-tubulin subunits), dihydropyrimidinase-related protein 2 (CRMP2), γ-actin, 14-3-3 protein family (14-3-3ζ, ε), heat shock protein 90β (HSP90β), and enolase 2. The results demonstrated the AS extract had positive effects on nerve cells' structure, adhesion, locomotion, fission, and phagocytosis, through regulating various action pathways, such as Hippo, phagosome, PI3K/Akt (phosphatidylinositol 3 kinase/protein kinase B), Neurotrophin, Rap1 (Ras-related protein RAP-1A), gap junction glycolysis/gluconeogenesis, and HIF-1 (Hypoxia-inducible factor 1) signaling pathways to maintain normal mouse neurological activity. All of the results indicated that AS may be a promising alternative medicine for the treatment of radiation injury in mouse brain. It would be tested that whether the bioactive ingredients of AS could be effective through the blood-brain barrier in the future.

Extraction of isoflavones from Puerariae lobata using subcritical water

As an alternative to organic solvents, subcritical water was employed for the first time as an effective solvent for the extraction of isoflavones from Puerariae lobata. Optimum experimental conditions for the extraction of the four main isoflavones were established by single factor experiments, and the optimum experimental conditions for total isoflavone extraction were established further by response surface methodology. With an extraction time of 45 min and a liquid/solid ratio of 1 : 20, the extraction yields of puerarin, 3′-methoxypuerarin, and daidzin reached maxima at extraction temperatures of 120 °C, 140 °C and 200 °C, respectively. Moreover, puerarin, 3′-methoxypuerarin and daidzin were degraded and produced various byproducts due to hydrothermal reactions at higher temperatures. The maximum extraction yields of the total isoflavones were obtained by response surface methodology (extraction time of 45 min, solid/liquid ratio of 1 : 15 and extraction temperature of 120 °C). Compared to conventional solvents, subcritical water utilized less solvent and required a shorter extraction time.

Four main isoflavones from Puerariae lobata were successfully extracted using subcritical water. Maximum yields of total isoflavones by response surface methodology were obtained.

Pharmacokinetics and Tissue Distribution Kinetics of Puerarin in Rats Using Indirect Competitive ELISA

Puerarin (PUE) is a compound isolated from the roots of Pueraria lobata. We studied the pharmacokinetics and tissue distribution kinetics of PUE in Sprague-Dawley rats following intraperitoneal administration of three concentrations. Indirect competitive ELISA based on an anti-PUE monoclonal antibody was used to determine the concentration of PUE in the blood, heart, liver, spleen, lung, kidney, hippocampus, cerebral cortex, and striatum. The plasma and tissue distribution kinetic characteristics following a single injection of PUE (20, 40 and 80 mg/kg) were calculated using a non-compartment model. In the high-dose (80 mg/kg) and medium-dose (40 mg/kg) groups, the kinetic profile of PUE in blood and kidney samples showed two absorption peaks, while that of the other tissues showed only one peak. In the low-dose (20 mg/kg) group, there was only one peak, irrespective of the sample type. Pharmacokinetic parameters, such as the area under the curve, C_max, and T_max varied according to the administered dose. AUC and C_max values increased dose-dependently. PUE was widely distributed in areas of the brain such as the hippocampus, cerebral cortex, and striatum, providing a foundation for guiding the use of PUE in the treatment of cerebral ischaemic stroke and neurodegenerative diseases.

Comparative pharmacokinetics of puerarin, daidzin, baicalin, glycyrrhizic acid, liquiritin, berberine, palmatine and jateorhizine by liquid chromatography-mass spectrometry after oral administration of Gegenqinlian decoction and active components alignment (ACA) to rats

An LC-MS/MS method was developed for simultaneous analysis of puerarin, daidzin, baicalin, glycyrrhizic acid, liquiritin, berberine, palmatine and jateorhizine of Gegenqinlian Decoction (GQD) and active components alignment (ACA) in rat plasma using hesperidin as the internal standard (I.S.). Chromatography was performed using a C18 column, with gradient elution with 1% acetic acid-0.001 mol/L ammonium acetate and acetonitrile at 0.2 ml/min. All analytes including I.S. were monitored under positive ionization conditions by selected reaction monitoring with an electrospray ionization source. The optimized mass transition ion-pairs (m/z) for quantitation were 471/297 for puerarin, 471/255 for daidzin, 447/271 for baicalin, 823/453 for glycyrrhizic acid, 419/257 for liquiritin, 336/320 for berberine, 352/336 for palmatine, 338/322 for jateorhizine and 611/303 for hesperidin. The calibration curves were linear over the concentration ranges from 0.15-63.0 to 6.3-6340.0 ng/mL. Intra-day and inter-day precisions (RSD%) were within 15.0%, and accuracy (RE%) ranged from -7.4 to 13.2%. The extraction recoveries were ranged from 60.4 to 93.3%. The proposed method was further applied to compare the pharmacokinetics of all analytes following a single oral administration of GQD and ACA. In conclusion, the eight analytes of GQD and ACA had partly similar pharmacokinetics, which were different from single composition (such as puerarin).

Simultaneous determination of puerarin and its active metabolite in human plasma by UPLC-MS/MS: application to a pharmacokinetic study

A rapid, selective and sensitive ultra-performance liquid chromatography (UPLC)-tandem mass spectrometry method about the simultaneous determination of puerarin and its major active metabolite, daidzein, in human plasma was developed and validated in order to investigate the pharmacokinetics (PKs) of Gegen after the usual oral dose administration to human. Chromatography was carried out on a Kinetex C18 column (2.1mm×50mm, 1.7μm) using 0.05% acetic acid in water and 0.05% acetic acid in methanol as mobile phase with a gradient elution. Liquid-liquid extraction with ethyl acetate in acidic condition could remove the interference and minimize the matrix effect of human plasma. The lower limit of quantification in human plasma was 0.2ng/mL for both of compounds, puerarin and daidzein. The calibration curves for puerarin and daidzein in human plasma were linear over all the concentration range of 0.2-100ng/mL with correlation coefficients greater than 0.998. This assay procedure was successfully applied to the PKs of puerarin and daidzein, after the usual oral dose of Gegen extract powder (2.56g, containing 9.984mg puerarin) in human subjects.

Simultaneous determination of gastrodin and puerarin in rat plasma by HPLC and the application to their interaction on pharmacokinetics

Gastrodin (Gas) and puerarin (Pur) are bioactive substances derived from traditional Chinese medicine Gastrodia elata and Radix Puerariae, respectively, which were often used together in Chinese clinical prescriptions. Their injections were used in combined way for treatment of some cardiocerebrovascular diseases in clinic, especially for vertigo due to vertebrobasilar ischemia. In this paper, interaction of gastrodin and puerarin in rat plasma pharmacokinetics via intragastic (i.g.)/intravenous (i.v.) administration was investigated. A reliable HPLC method was developed for simultaneous determination of Gas and Pur in rat plasma with a linear range of 0.101-101 μg/mL for Gas and 0.0500-5.98 μg/mL for Pur (r(2)>0.993). The LLOQ, LOD of Gas and Pur were determined to be 0.101, 0.0486 μg/mL, and 0.05, 0.0245 μg/mL, respectively. The intra-day and inter-day precision were all less than 12.0%, whilst the accuracy were all within 96.4±6.00%. The proposed method has been successfully applied to the pharmacokinetic study of the analytes in rats after i.g./i.v. administration of Gas and Pur alone or combined with each other (i.g.: 40 mg/kg Gas, 400 mg/kg Pur; i.v.: 20 mg/kg Gas, 20 mg/kg Pur). Blood samples were collected from retinal vein plexus of rats at predetermined time points and plasma containing the internal standard tyrosol (IS) were precipitated by methanol and chromatography was carried out on a C(18) column with a gradient mobile phase of ACN-H(2)O with 0.05% phosphoric acid as a modifier. The pharmacokinetic profiles of combined administration were found to be distinct from those of given alone. The C(max), T(max), T(1/2), MRT of Gas administrated alone or combined with Pur via i.g. were 21.7 μg/mL, 0.250 h, 2.81 h, 0.830 h and 18.4 μg/mL, 0.550 h, 0.970 h, 1.37 h, respectively, of Pur administrated alone or combined with Gas via i.g. were 0.490 μg/mL, 1.95 h, 1.33 h, 2.10 h and 2.01 μg/mL, 0.570 h, 4.00 h, 5.10 h, respectively. The relative oral bioavailability of Pur in combined administration was 10.7 times as much as that of single administration, whilst 1.52 folds in Gas. These results indicate that co-administration of Gas and Pur is a promising combination to gain higher bioavailability and it is suggested that doctors pay more attention to the dosages of the two when simultaneously using both of them.

Comparative pharmacokinetics of five rhubarb anthraquinones in normal and thrombotic focal cerebral ischemia-induced rats

A comparative oral pharmacokinetic study of five anthraquinones (aloe-emodin, emodin, rhein, chrysophanol and physcion) from the extract of Rheum palmatum L. was performed in normal and thrombotic focal cerebral ischemia (TFCI)-induced rats. The plasma samples were clarified through solid phase extraction prior to simultaneous determination of the anthraquinones with a validated high-performance liquid chromatography-fluorescence system. The results indicated that the Cmax, t(1/2) and AUC(0-t), of aloe-emodin, rhein, emodin and chrysophanol in TFCI-induced rats were nearly double, whereas the CL values were remarkably decreased (p < 0.05) over those of the normal rats. The plasma drug concentration-time data of five anthraquinones to rats fitted a two-compartment open model. The five anthraquinones in rat plasma were absorbed quickly and eliminated slowly in both groups. The obtained results could be helpful for evaluating the impact of the efficacy and safety of the drug in clinical applications.

Use of multivariate statistical techniques to optimize the separation of isoflavones by liquid chromatography

The aim of this paper is to optimize and validate a high performance liquid chromatography (HPLC) method for separation and quantification of five isoflavones. A statistical central composite design was used to separate all peaks. These multivariate procedures were efficient in determining the optimal separation condition using resolution, capacity factor, asymmetry and number of theoretical plates. The effective separation of the examined compounds was applied on a Develosil RP Aqueous AR 5 RP-30 column with a gradient mobile phase system and a DAD detector. The isolation and preconcentration of the isoflavones from urine and plasma samples were conducted by means of the solid-phase extraction (SPE). For optimize SPE conditions various sorbents were tested. Furthermore, high recoveries and good relative standard deviations were obtained when the samples were passed through the Oasis HLB column. The developed method was validated and successfully applied for determination of isoflavones in urine and plasma.

Determination of puerarin in rabbit aqueous humor by liquid chromatography tandem mass spectrometry using microdialysis sampling after topical administration of puerarin PAMAM dendrimer complex

To study pharmacokinetic properties of puerarin poly(amido amine) (PAMAM) dendrimer complex, a sensitive liquid chromatography tandem mass spectrometry method (LC-MS/MS) was developed and validated to determine puerarin in rabbit aqueous humor using microdialysis sampling. Astilbin was used as the internal standard. The linear range for puerarin was from 2 to 1000ng/mL (r=0.9986) based on 20μL of aqueous humor. The coefficients of variations for intra-day and inter-day precisions were less than 10.0%, and the relative error of accuracy was within ±6.3%. The mean extraction recovery of puerarin varied from 80.4% to 85.5%. Microdialysis provides a complete concentration versus time profile. A significant difference was observed in main pharmacokinetic parameters of C(max), AUC and t(1/2) between puerarin solution and puerarin PAMAM dendrimer complex. Complex formation resulted in an obvious increase in bioavailability of puerarin after topical administration to rabbit according to the above LC-MS/MS assay method.

A support vector machine based pharmacodynamic prediction model for searching active fraction and ingredients of herbal medicine: Naodesheng prescription as an example

The complex chemical composition of herbal medicine leads to the lack of appropriate method for identifying active compounds and optimizing the formulation of herbal medicine. One of the most commonly used method is bioassay-guided fractionation. However, if the herbal medicine was divided into many fractions, it would cost much money and time in carrying out such a full bioassay. So, can we just perform the bioassay of a few fractions, and then develop a method to predict the bioactivities of other fractions? This study is designed to try to answer the question. In this work, a support vector machine (SVM) pharmacodynamic prediction model was introduced to search active fraction and ingredients of Naodesheng prescription. The prescription was first divided into five extracts, yielding a total of 2⁵=32 combinations. Anti-platelet aggregation experiment with SD rats was just carried out on 16 combinations. The effects of the remained 32-16=16 combinations were then predicted by the SVM model. The prediction quality was evaluated by both the rigorous jackknife test and the independent dataset validation test. Furthermore, the present method was compared with the frequently used MLR, PCR and PLSR. The present method outperforms the other 3 methods, yielding: RMSECV=2.40, R=0.895 by the jackknife test and RMSEP=7.41, R=0.910 by the independent dataset test. It indicates that the SVM prediction model has good accuracy and generalization ability. The active fraction and ingredients of Naodesheng prescription were then predicted by the model. It is believed that the present model can be extended to help search the active fraction and ingredients of other herbal medicines.

Characterization and selectivity studies of molecular imprinted membranes of Puerarin using scanning electron microscopy

Molecular-imprinted membranes of Puerarin were prepared by phase inversion technique with acrylonitrile-acrylic acid copolymer (P (AN-co-AA)). To characterize P (AN-co-AA), ubbelohde viscometer was used to measure its viscosity-molecular weight. P (AN-co-AA) with different molecular weight was used to prepare membranes. The copolymer-dimethyl sulfoxide solution with Puerarin (PU) template was coagulated in water at various temperatures. The increase in P (AN-co-AA) molecular weight and the decrease in coagulation temperature caused an increase in PU recognition property of the resultant membrane. The PU imprinted membrane prepared with P (AN-co-AA) showed good selective ability to PU. The purity of PU increased from 56.51 to 98.41 wt%. Surface and cross-section morphology of the membranes were analyzed by using scanning electron micrograph. High-performance liquid chromatography was used for the quantification of Puerarin in isolated fraction.

Analysis of isoflavones and flavonoids in human urine by UHPLC

A rapid, ultra high-performance liquid chromatographic (UHPLC) method has been developed and validated for simultaneous identification and analysis of the isoflavones genistein, daidzein, glycitin, puerarin, and biochanin A, and the flavonoids (±)-catechin, (−)-epicatechin, rutin, hesperidin, neohesperidin, quercitrin, and hesperetin in human urine. Urine samples were incubated with β-glucuronidase/sulfatase. UHPLC was performed with a Hypersil Gold (50 × 2.1 mm, 1.9 μm) analytical column. Elution was with a gradient prepared from aqueous trifluoroacetic acid (0.05%) and acetonitrile. UV detection was performed at 254 and 280 nm. The calibration curves were indicative of good linearity (r² ≥ 0.9992) in the range of interest for each analyte. LODs ranged between 15.4 and 107.0 ng mL⁻¹ and 3.9 and 20.4 ng mL⁻¹ for flavonoids and isoflavones, respectively. Intra-day and inter-day precision (C.V., %) was less than 3.9% and 3.8%, respectively, and accuracy was between 0.03% and 5.0%. Recovery was 70.35–96.58%. The method is very rapid, simple, and reliable, and suitable for pharmacokinetic analysis. It can be routinely used for simultaneous determination of these five isoflavones and seven flavonoids in human urine. The method can also be applied to studies after administration of pharmaceutical preparations containing isoflavones and flavonoids to humans.

Investigation of the inclusions of puerarin and daidzin with beta-cyclodextrin by molecular dynamics simulation

Puerarin and daidzin, two major isoflavonoids of Radix puerariae , are widely adopted in traditional Chinese medicine. Foundational aspects related to separating the two compounds are essential to develop a more economical purification process. Inclusion models of the two compounds with beta-cyclodextrin (beta-CD) have been investigated by molecular dynamics simulation. Computational results reveal that both puerarin and daidzin can induce a conformational change of beta-CD, which is compressed in one direction and stretched in the other. The effect of solvent and media on the conformational change of beta-CD and the movement of guest molecules inside the cavity has been investigated. Furthermore, hydrogen bonding interactions have been analyzed, and the results have been utilized for the explanation of separating puerarin from daidzin.

Pharmacokinetic comparison of puerarin after oral administration of Jiawei-Xiaoyao-San to healthy volunteers and patients with functional dyspepsia: influence of disease state

Objectives

An investigation has been designed and conducted to compare the pharmaco-kinetics of puerarin after oral administration of Jiawei-Xiaoyao-San to healthy volunteers and to patients with functional dyspepsia.

Methods

Quantification of puerarin in serum was achieved using a simple and rapid HPLC method for pharmacokinetic study.

Key findings

After oral administration of decoctions of Jiawei-Xiaoyao-San to healthy volunteers and patients with functional dyspepsia, puerarin was absorbed and reached a maximum concentration of 56.47 ± 15.60 and 29.40 ± 8.89 ng/ml at 51.00 ± 8.22 and 50.00 ± 12.25 min, respectively. Compared with the value of AUC0–360 (5.55 ± 1.47 μg/ml min) in healthy volunteers, a smaller value of AUC0–360 (3.35 ± 1.17 μg/ml min) was observed in patients with functional dyspepsia.

Conclusions

There were statistically significant differences in the pharmacokinetic parameters of puerarin including the values for Cmax, AUC0–360, Cl/F and MRT0–360 between healthy volunteers and patients with functional dyspepsia. The pharmacokinetic parameters showed that functional dyspepsia reduced the absorption of puerarin after oral administration of Jiawei-Xiaoyao-San.

Simultaneous determination of safflor yellow A, puerarin, daidzein, ginsenosides (Rg(1), Rb(1), Rd), and notoginsenoside R(1) in rat plasma by liquid chromatography-mass spectrometry

A liquid chromatograph/mass spectrometry (LC/MS) method was developed for the simultaneous quantitation of seven compounds (safflor yellow A, puerarin, daidzein, ginsenosides (Rg(1), Rb(1), Rd), and notoginsenoside R(1)) in rat plasma samples with sufficient sensitivity to facilitate analysis of samples collected after an intravenous injection of Naodesheng. The plasma samples were subjected to protein precipitation with acetone, and analyzed using negative atmospheric pressure chemical ionization mass spectrometry in selected ion monitoring (SIM) mode with baicalin as an internal standard. Good linearity for all the seven compounds was observed. The intra- and inter-day precision of analysis was <15.0% for each compound, and the accuracy ranged from 90.0% to 109.0%. This quantitation method was successfully applied to a pharmacokinetic study of following intravenous injection of rats with Naodesheng.

Quantitative determination of puerarin in dog plasma by HPLC and study on the relative bioavailability of sustained release tablets

To evaluate the bioavailability of puerarin sustained release tablet (SR-Tab.) and Yufengningxin tablet (YU-Tab.), a liquid chromatography method was developed and validated to determine puerarin in dog plasma. Chromatographic separation was performed on Diamonsil C18 column using a mixture of methanol-acetic acid-water (25:6:69, v/v/v) delivered at a flow rate of 1.0 ml/min and detected by UV. 4-Hydroxybenzaldehyde was used as the internal standard. The linear range for puerarin was from 60 to 1800 ng/ml (r=0.9991) with a limit of quantitation of 60 ng/ml. Within-day accuracy and precision ranged from -3.0 to 2.2% and from 1.2 to 4.3%, between-day accuracy and precision ranged from -4.1 to 2.6% and from 1.3 to 5.7%, respectively. The mean extraction recoveries of puerarin determined over the three concentrations were (90.3+/-5.2)%, (95.7+/-1.4)% and (93.1+/-3.5)%. A significant difference was observed in main pharmacokinetic parameters of Tmax, Cmax and AUC0-infinity between puerarin SR-Tab. and YU-Tab. in dogs. The smoother plasma concentrations were obtained from SR-Tab. in dogs and the results were as expected.

Pharmacokinetic study ofp-coumaric acid in mouse after oral administration of extract ofAnanas comosus L. leaves

Quantification of p-coumaric acid in mouse plasma following oral administration of Ananas comosus L. leaves was achieved by reversed-phase high-performance liquid chromatography using a mobile phase of water-acetonitrile (82:18, v/v) and UV detection at 310 nm. The method was linear (determination coefficient, r2 = 0.9997) within the tested range (0.04-1.28 microg/mL). Intra- and inter-day precision coefficients of variation and accuracy bias were acceptable (maximal CV value was 4.06% for intra-day and 4.19% for inter-day) over the entire range. The recoveries were 90.63, 97.98 and 100.01% for concentrations of 0.04, 0.32 and 1.28 microg/mL, respectively. This is a very rapid, sensitive and economical way to determine p-coumaric acid concentration in mouse plasma after oral administration of A. comosus leaves. The concentration-time curve was fitted to the one-compartment model. This is the first time that p-coumaric acid extracted from A. comosus leaves was detected by HPLC-UV method and its pharmacokinetic characteristic was comprehensively studied.