Mechanism-Based Pharmacokinetic Model for the Deglycosylation Kinetics of 20(S)-Ginsenosides Rh2.

Aim: The 20(S)-ginsenoside Rh2 (Rh2) is being developed as a new antitumor drug. However, to date, little is known about the kinetics of its deglycosylation metabolite (protopanoxadiol) (PPD) following Rh2 administration. The aim of this work was to 1) simultaneously characterise the pharmacokinetics of Rh2 and PPD following intravenous and oral Rh2 administration, 2) develop and validate a mechanism-based pharmacokinetic model to describe the deglycosylation kinetics and 3) predict the percentage of Rh2 entering the systemic circulation in PPD form. Methods: Plasma samples were collected from rats after the I.V. or P.O. administration of Rh2. The plasma Rh2 and PPD concentrations were determined using HPLC-MS. The transformation from Rh2 to PPD, its absorption, and elimination were integrated into the mechanism based pharmacokinetic model to describe the pharmacokinetics of Rh2 and PPD simultaneously at 10 mg/kg. The concentration data collected following a 20 mg/kg dose of Rh2 was used for model validation. Results: Following Rh2 administration, PPD exhibited high exposure and atypical double peaks. The model described the abnormal kinetics well and was further validated using external data. A total of 11% of the administered Rh2 was predicted to be transformed into PPD and enter the systemic circulation after I.V. administration, and a total of 20% of Rh2 was predicted to be absorbed into the systemic circulation in PPD form after P.O. administration of Rh2. Conclusion: The developed model provides a useful tool to quantitatively study the deglycosylation kinetics of Rh2 and thus, provides a valuable resource for future pharmacokinetic studies of glycosides with similar deglycosylation metabolism.

Rebalancing of the gut flora and microbial metabolism is responsible for the anti-arthritis effect of kaempferol.

Kaempferol is a natural flavonol that possesses various pharmacological activities, including anti-arthritis effects, yet the underlying mechanisms remain controversial. To evaluate the anti-arthritis efficacy and the underlying mechanisms of kaempferol, collagen-induced arthritis (CIA) mice were treated with kaempferol intragastrically (200 mg · kg-1 · d-1) and intraperitoneally (20 mg · kg-1 · d-1). Pharmacodynamic and pharmacokinetic studies showed that the oral administration of kaempferol produced distinct anti-arthritis effects in model mice with arthritis in terms of the spleen index, arthritis index, paw thickness, and inflammatory factors; the bioavailability (1.5%, relative to that of the intraperitoneal injection) and circulatory exposure of kaempferol (Cmax = 0.23 ± 0.06 ng/mL) and its primary metabolite kaempferol-3-O-glucuronide (Cmax = 233.29 ± 89.64 ng/mL) were rather low. In contrast, the intraperitoneal injection of kaempferol caused marginal anti-arthritis effects, although it achieved a much higher in vivo exposure. The much higher kaempferol content in the gut implicated a potential mechanism involved in the gut. Analysis of 16S ribosomal RNA revealed that CIA caused imbalance of 14 types of bacteria at the family level, whereas kaempferol largely rebalanced the intestinal microbiota in CIA mice. A metabolomics study showed that kaempferol treatment significantly reversed the perturbation of metabolites involved in energy production and the tryptophan, fatty acid and secondary bile acid metabolisms in the gut contents of the CIA mice. In conclusion, we demonstrate for the first time that the high level of kaempferol in the gut regulates the intestinal flora and microbiotic metabolism, which are potentially responsible for the anti-arthritis activities of kaempferol.

[Differences of brain pathological changes and cognitive function after bilateral common carotid artery occlusion between Sprague-Dawley and Wistar rats].

The aim of the present study was to investigate the differences of the pathological changes and cognitive function after bilateral common carotid artery occlusion (BCCAO) between Sprague-Dawley (SD) and Wistar rats. Male SD and Wistar rats were randomly divided into 2 groups, respectively: sham operated (S-sham and W-sham) and operated (S-BCCAO and W-BCCAO) groups. The survival rate and the rate of loss of pupillary light reflex (PLR) were observed on day 1, 3, 7, 14 and 28 after the operation, and the light-dark box, Y-maze and odor recognition tests were performed to detect cognitive function on day 28 after the operation. HE and Luxol fast blue staining were used to observe the pathological changes of gray matter (hippocampus), white matter (optical tract), optic nerve, and retina. The results showed that the survival rate of the W-BCCAO group was 62.5%, and PLR loss rate was 100%; whereas the survival rate of the S-BCCAO group was 100%, and PLR loss rate was 58.3%. In the W-BCCAO group, percentages of time spent and distance traveled in the light box were more than those in the W-sham group, but there was no statistical significance between the S-BCCAO and S-sham groups. In the S-BCCAO group, the percentages of time spent and distance traveled in the III arm (labyrinth arm) of the Y-maze were less than those in the S-sham group, but no statistical significance was found between the W-BCCAO group and W-sham group. In the S-BCCAO group, the discrimination ratio of the odor recognition task was less than that in the S-sham group, but no statistical significance could be seen between the W-BCCAO and W-sham groups. Ischemic injury was observed in the CA1 area of the hippocampus in the S-BCCAO group, but no readily visible damage was observed in the W-BCCAO group. Ischemic injury of the visual beam and optic nerve was observed in both the S-BCCAO and W-BCCAO groups. Compared with the corresponding sham groups, the S-BCCAO and W-BCCAO groups showed serious retinal damage with significant thinner retina. The ganglion cell layer (GCL), inner plexiform layer (IPL), and outer plexiform layer (OPL) were thinner in the S-BCCAO group, but no statistical significances were shown in the other layers. All the layers, except the outer nuclear layer (ONL), were significantly thinner in the W-BCCAO group. The results indicate that there are differences of the pathological changes in the hippocampus and visual conduction pathway after BCCAO between SD and Wistar rats, and the degree of learning and memory injury was also different, which suggests that the vascular dementia model of different rat strains should be selected according to research purpose.

[Evaluation of myocardial ischemia rat model based on metabonomic method of small molecule metabolites of plasma and cardiac muscle].

Isoproterenol (ISO)-induced myocardial ischemia animal model has been widely applied to the study of myocardial ischemia and evaluation of drug efficacy. Metabolic profiling of endogenous compounds can make a deep insight into biochemical process of the ISO-induced myocardial ischemia rats. Herein, rats were treated with ISO (2 mg x kg(-1)) for 10 days. After the model was established by measuring myocardial histopathology and plasma creatine kinase, GC/TOF-MS was used to determine endogenous metabolites in plasma and cardiac muscle of rats, and pattern recognition was used to process the data. Results showed that the plasma metabolic profiling of ISO-induced myocardial ischemia rats was significantly different from that of the control, and it had the tendency to the normal state after the discontinue of ISO injection. Besides, the cardiac muscle of rats treated with ISO for 10 days and the normal cardiac muscle could also be separated clearly. The potential biomarkers in plasma and cardiac muscle of model rats had homogeneity and their own specialty. Biochemical metabolic pathway analysis indicated that this myocardial ischemia model was involved in the alternation of energy metabolism, saccharometabolism, lipid metabolism, nucleoside metabolism and amino acid metabolism, and in relationship with oxidative stress. These findings revealed that metabonomics may be a promising tool to evaluate myocardial ischemia rat model induced by ISO and could further extend the study of pharmacodynamic action of drugs at the molecular level.

[Metabonomic phenotype of "formula corresponding to pattern types" based on "qi and yin deficiency pattern" of myocardial ischemia rat model].

In order to explore the scientific connotation of "Fangzhengduiying (formula corresponding to pattern types)", "Qiyinliangxuzheng (Qi and Yin deficiency pattern)" of myocardial ischemia rat model and GC-TOF/MS based metabonomic method were used for comparing the effects of Sheng-mai injection, Salvia injection and propranolol in the present study. After data processing and pattern recognition, Sheng-mai injection showed better efficacy than the other two drugs in accordance with not only visual observation from PLS-DA scores plots but also the number of abnormal endogenous compounds restored to the normal level. Further studies showed that Sheng-mai injection could normalize the level of plasma endothelin-1, the index related to cardiovascular diseases and sleep disorders, which verified the results of metabonomics. Finally, the regulated metabolites and related metabolic pathways were analyzed, and it was supposed that the effects of Sheng-mai injection involved in the alternation of energy metabolism, lipid metabolism, amino acids metabolism, and so on. These findings provided scientific evidence to Shengmai "Fang" used for "Qi and Yin deficiency pattern" correspondingly, indicating that metabonomics has great potential in traditional Chinese medical research, which provides a novel approach and way to modernization of traditional Chinese medicine.

[Metabonomic profiling of plasma metabolites in Wistar rats to study the effect of aging by means of GC/TOFMS-based techniques].

The global metabolite profiles of endogenous compounds of Wistar rats from 12 to 20 weeks old were investigated to take deep insight into and get better understanding of the pathogenesis of development and aging. Plasma from Wistar rats at 12, 14, 16, 18, and 20 weeks old were analyzed using GC/TOFMS. Multivariate data analysis was then used to process the metabonomic data which indicated excellent separation between different weeks and showed that the metabolic profiles of the samples changed with age, enabling age-related metabolic trajectories to be visualized. Decreased concentrations of citric acid, cis-aconitic acid, 9-(z)-hexadecenoic acid along with increased levels of hexanedioic acid, alpha-tocopherol, 3-indole propionic acid, etc contributed to the separation. Several major metabolic pathways were identified to be involved in metabolic regulation. This suggests that GC/TOFMS-based metabonomics is a powerful alternative approach to identifying potential biomarkers and investigating the physiological developments of aging and it is important to employ suitable age-match control group in metabonomic study of physiological monitoring, drug safety assessment, and disease diagnosis, etc.

Quantitative determination of ophiopogonin d by liquid chromatography/electrospray ionization mass spectrometry and its pharmacokinetics in rat.

A sensitive and rapid liquid chromatography-mass spectrometric method for the determination of ophiopogonin D in rat plasma was developed and validated. Chromatographic separation was performed on a C (18) column using a step gradient program with the mobile phase of 0.5 mmol/L ammonium chloride solution and acetonitrile. Ophiopogonin D was quantified using an electrospray negative ionization mass spectrometry in the selected ion monitoring (SIM) mode using digoxin as an internal standard. Good linearity was obtained in the concentration range of 2.5 - 480.0 ng/mL ( R2 = 0.9984). The lower limit of quantification (LLOQ) and lower limit of detection (LLOD) were 2.5 ng/mL and 1.0 ng/mL, respectively. Both the intra- and inter-day precision was less than 8.9 % and the accuracy was within 97.5 - 107.3 %. The pharmacokinetic study of ophiopogonin D in rats was then defined using the method after intravenous dosing (77.0 microg/kg). The plasma concentration-time profile for ophiopogonin D was best fitted to an open two-compartment model with a clearance of 0.024 +/- 0.010 L/min/kg and a terminal half life of 17.29 +/- 1.70 min. A comparison of the pharmacokinetics of ophiopogonin D as a pure compound and as a component of 'SHENMAI' injection revealed a significantly smaller clearance of ophiopogonin D (0.007 +/- 0.002 L/min/kg) for the latter formulation, consistent with an inhibition by one or more other components in the formulation.

Sensitive determination of 20(S)-protopanaxadiol in rat plasma using HPLC-APCI-MS: application of pharmacokinetic study in rats.

20(S)-Protopanaxadiol (PPD), the main metabolite of protopanoxadiol type ginsenosides (e.g. Rg3 and Rh2), is a very promising anti-cancer drug candidate. To evaluate the pharmacokinetic property of PPD, we reported a reliable, sensitive and simple method utilizing liquid chromatography (HPLC)-atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) to determine PPD. PPD and the internal standard, panoxadiol (PD) were extracted from plasma with acetic ether, separated on a C18 reverse column, and then analyzed by APCI-MS. Targeting fragment ion at m/z 425 for both PPD and PD was monitored in selected-ion monitoring (SIM) mode. PPD can be quantitatively determined at the concentration as low as 1 ng/mL using 200 microL plasma. And the sensitive method showed excellent linearity over a range from 1 to 1000 ng/mL, high recovery, accuracy and precision at the concentrations of 2.5, 100.0 and 1000.0 ng/mL, respectively. The method was successfully applied to pharmacokinetic study of PPD in rats. Pharmacokinetic parameters were calculated and absolute bioavailability of PPD was 36.8+/-12.4%, at least ten times higher than that of Rg3 and Rh2, indicating its good absorption in gastrointestinal tract. It was further suggested that PPD be a promising anti-cancer candidate and probably responsible for the observed pharmacological activity of Rg3 and Rh2.

Simultaneous determination of GFA and its active metabolites in human plasma by liquid chromatography electrospray ionization mass spectrometry and its application to pharmacokinetic studies.

A sensitive and rapid liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed and validated for simultaneous quantification of guanfu base A (GFA) and its metabolites guanfu base I (GFI) and guanfu alcohol-amine (AA) in human plasma with phenoprolamine hydrochloride (DDPH) as the internal standard. The analytes were extracted from human plasma by using liquid-liquid extraction with ethyl acetate and the LC separation was performed on a Diamonsil C(18) analytical column (150 mm x 2.1 mm i.d., 5 microm). The MS acquisition was performed in selected ion monitoring (SIM) mode of positive ions. Analysis was carried out in SIM mode at m/z 430.25 for GFA [M+H](+), m/z 388.25 for GFI [M+H](+), m/z 346.25 for AA [M+H](+) and m/z 344.20 for the IS DDPH [M+H](+). The calibration curves were linear over the range of 50-5000 ng/mL for GFA and 5-1000 ng/mL for GFI and AA, with coefficients of correlation above 0.999. The lower limit of quantification for GFA was 1 ng/mL, while for GFI and AA were both 5 ng/mL. The intra- and inter-day precisions (CV) of analysis were within 9%, and the accuracy ranged from 91% to 108%. The overall recoveries for GFA, GFI and AA were about 94.2%, 87.8% and 80.6%, respectively. The total LC-MS run-time was only 5.5 min. This quantitation method was successfully applied to the simultaneous determination of GFA and its metabolites in human plasma for the metabolic study and pharmacokinetic evaluation.

Determination of pitavastatin in human plasma via HPLC-ESI-MS/MS and subsequent application to a clinical study in healthy Chinese volunteers.

BACKGROUND: Pitavastatin is a novel statin used in the treatment of hyperlipemia. We developed and describe a simple and rapid high performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS/MS) assay for the determination of pitavastatin in human plasma. METHODS: A Finnigan TSQ Quantum Discovery max system equipped with an electrospray ionization source and a Finnigan Surveyortrade mark HPLC system (Thermo Electron, San Jose, CA) was used employing lovastatin as internal standard (IS) for pitavastatin. This method entailed a single step of liquid-liquid extraction with ether from 200 microL plasma. The analyte and internal standard were baseline separated on a Gemini analytical column. Quantitation by SRM analysis was performed in the positive ion mode. RESULTS: HPLC-ESI-MS/MS method validation by means of determination of limit of detection (LOD 0.05 ng/ml), lower limit of quantification (LLOQ 0.1 ng/ml), linearity (0.2-200 ng/ml). The intra-and inter-day precision CVs was <10%, and accuracy ranged from 85 to 115%. The proposed method enables the unambiguous identification and quantification of pitavastatin for clinical studies. CONCLUSION: A sensitive and specific method for quantifying Pitavastatin levels in human plasma has been devised and successfully applied to a clinic pharmacokinetic study of pitavastatin administered.