Pharmacokinetic analysis of rhein in Rheum undulatum L

Effects of food and gender on the pharmacokinetics of rhein and emodin in rats after oral dosing with Da-Cheng-Qi decoction

Da-Cheng-Qi decoction (DCQD), a traditional Chinese medicine preparation used to treat digestive diseases, is composed of dahuang (Rheum officinale Baill, Polygonaceae), houpu (Magnolia officinalis Rehd., Magnoliaceae), zhishi (Citrus aurantium L, Rutaceae) and mangxiao (sodium sulphate). Rhein and emodin are the major active components of Rheum officinale Baill. To investigate the effects of food and gender on the plasma concentrations of rhein and emodin after oral administration of DCQD, a rapid high-performance liquid chromatographic method was developed and validated. A reversed phase C(18) column (150 × 4.6 mm) and a mobile phase of methanol and 0.2% acetic acid (78:22, v/v) were employed with ultraviolet detection at 254 nm. Feeding was observed to decrease the absorption of rhein and emodin in rats receiving DCQD orally. No evidence for gender-based differences in the pharmacokinetics of rhein was observed. However, the half-life and area under the concentration-time curve for emodin differed significantly between male and female rats. Because food intake and gender are anticipated to influence the pharmacokinetics of DCQD in human subjects, it is recommended that oral doses of DCQD be reduced in fasting subjects and that female patients receive lower oral doses compared with male patients.

Toxic effects caused by rhubarb (Rheum palmatum L.) are reversed on immature and aged rats

AIM OF THE STUDY

Rhubarb is generally used to people of broad age, but diverse responses of people at different age to rhubarb have been little clarified. In this study, an attempt was made to access the safety of rhubarb to both immature and aged rats to provide some references for its clinical usage.

MATERIALS AND METHODS

The total extract of rhubarb was administered intragastricly to both immature and aged rats once a day and lasted for 5 weeks. Then histopathologic and biochemical examinations were performed.

RESULTS

No death was observed in immature rat groups, while 23.3% (21/90) subjects in aged rat groups died and most of the death cases were observed in the high-dosage (40 gkg(-1) of body weight per day od, counted on the quantity of crude material) group. The death rate between aged and immature rats was found of significantly statistical difference. Dosage-dependent histopathologic changes in kidney were observed in all the rhubarb-treated rats, principally involving the proximal tubules. Kidney changes in aged rats were severer than those observed in immature ones. Hepatic cells necrosis was occasionally observed in the middle- and high-dosage aged rat groups and minimal biliary hyperplasia was found in all the rhubarb-treated aged rats. Increased incidences of activated Kupffer cells and lymphocytic infiltration were found in all the rhubarb-treated rats. And dosage-dependent increase of interleukin 6 (IL-6) and notable increase of IL-8 was found in aged rat groups.

CONCLUSIONS

The immature and aged rats showed reversed responses to the toxic potential of rhubarb extract. Elderly subjects were susceptible to the toxicity of high-dosage rhubarb, which drove rigorous consideration on rational use of rhubarb to aged people.

Liver targeting effect of vinegar-baked Radix Bupleuri on rhein in rats

Vinegar-baked Radix Bupleuri (VBRB) is usually used to focus other drugs effect on liver in traditional Chinese medicine (TCM). However, no sufficient scientific data are available to support this concept. In this paper, the liver targeting enhancing effect of VBRB on rhein was investigated. 432 of rats were divided into two large groups according to the dose of rhein, low dose group of rhein (LDGR) and high dose group of rhein (HDGR). In each group, the rats were further divided into four subgroups, rhein control and rhein co-administered with three different doses of VBRB peroral. Concentrations of rhein and its metabolite in different tissues were determined by HPLC. Compared to the control group, VBRB significantly increased the distribution of both rhein and its metabolite in liver and meanwhile decreased their distribution in other tissues, indicating a strong liver targeting enhancing effect. This liver targeting effect of VBRB depended on the dose of VBRB and rhein. Low and high dose of VBRB had a more strong effect than medium dose in HDGR; high dose of rhein was more sensitive than low dose of rhein (P<0.05). Rhein existed in two forms after peroral administration in vivo. It was found that the liver targeting effect of VBRB was more remarkable with the native form of rhein compared to its derivative form. The results of this paper demonstrated that co-administration with VBRB is a simple and efficiencient method for liver targeting therapy, and the meridine guide theory of TCM was credible.

In vivo pharmacokinetics comparisons of icariin, emodin and psoralen from gan-kang granules and extracts of herba Epimedii, Nepal dock root, Ficus hirta yahl

ETHNOPHARMACOLOGICAL RELEVANCE

Gan-kang granules (GKG) contains the extracts from eight Chinese herbs and is a traditional Chinese composite prescription for treatment of hepatitis B. Icariin, emodin and psoralen are main effective ingredients of the medicine.

AIM OF THE STUDY

In this research, pharmacokinetic comparisons of icariin, emodin and psoralen from the extracts of herba Epimedii, Nepal dock root and Ficus hirta yahl, and GKG were conducted.

MATERIALS AND METHODS

At different time points (0.25, 0.5, 0.75, 1, 1.5, 2, 4, 6, 8, 12 and 24 h) after administration, the concentrations of icariin, emodin and psoralen in rat plasma were determined by HPLC-UV, and main pharmacokinetic parameters were estimated.

RESULTS

The pharmacokinetic parameters of icariin, emodin and psoralen in GKG were elevated comparing with those of herb extracts.

CONCLUSIONS

Three HPLC-UV methods were developed successfully for the analysis of icariin, emodin and psoralen in SD rat plasma. Some ingredients in GKG may increase the dissolution and absorption, and improve bioavailability of icariin, emodin and psoralen in rats.

Assessment of the renal protection and hepatotoxicity of rhubarb extract in rats

AIM OF THE STUDY

Rhubarb is well used to treat chronic renal failure (CRF) in China and Japan, but recent studies reported that the anthraquinone derivatives contained in rhubarb had nephrotoxicity. In this investigation an attempt was made to assess the value and toxic potential of rhubarb to treat CRF.

MATERIALS AND METHODS

Histopathologic and biochemical tests combined with toxicokinetic analysis were performed to investigate the nephrotoxic potential and protective effect of rhubarb extract.

RESULTS

In normal rat groups, no death was observed and no renal lesion was found after repetitive administration of rhubarb for 3 weeks. The survival rate, pathologic conditions and biochemical indexes of CRF rats treated with rhubarb at two dosages were all improved and significant amelioration was found in the low dosage group compared to the untreated CRF group. Rhein was the mainly absorbable anthraquinone derivative into systemic circulation after oral administration and the area under curve of rhein in CRF groups was lower than that in normal groups at same dosage.

CONCLUSIONS

After 3 weeks of administration of rhubarb extract, there was evidence of protective effect to CRF rats, while incidences of hepatotoxicity with minimal to mild hyaline droplets were also observed in normal rats.

Inhibition of cytochrome P450 enzymes by rhein in rat liver microsomes

Rhein, an active ingredient extensively found in plants such as Aloe, Cassitora L., rhubarb and so on, has been used for a long time in China. Pharmacological tests revealed that rhein not only had a strong antibacterial action, but also may be useful in cancer chemotherapy as a biochemical modulator. Its therapeutic action and toxicity is still the subject of considerable research. With microsome incubation assays in vitro and HPLC methods, the inhibition of rat liver CYP1A2, CYP2C9, CYP2D6, CYP2E1 and CYP3A enzymes by rhein were studied kinetically. The results showed the most inhibition of CYP2E1 by rhein (K(i) = 10 microm, mixed); CYP3A and CYP2C9 were also inhibited by rhein, K(i) = 30 microm (mixed) and K(i) = 38 microm (mixed), respectively; rhein revealed some inhibition of CYP1A2 (K(i) = 62 microm, uncompetitive) and CYP2D6 (K(i) = 74 microm, mixed). Drug-drug interactions, especially cytochrome P450 (CYP)-mediated interactions, cause an enhancement or attenuation in the efficacy of co-administered drugs. Inhibition of the five major CYP enzymes observed for rhein suggested that changes in pharmacokinetics of co-administered drugs were likely to occur. Therefore, caution should be paid to the possible drug interaction of medicinal plants containing rhein and CYP substrates.

Development and validation of a sensitive LC-MS/MS method with electrospray ionization for quantitation of rhein in human plasma: application to a pharmacokinetic study

A highly sensitive and specific LC-MS/MS method has been developed and validated for the estimation of rhein with 100 microL human plasma using celecoxib as an internal standard (IS). The API-4,000 Q-Trap LC-MS/MS was operated under multiple reaction-monitoring mode using the electrospray ionization technique. The assay procedure involved extraction of rhein and IS from human plasma with acetonitrile, which yielded consistent recoveries of 36.01 and 65.85% for rhein and IS, respectively. The total chromatographic run time was 5.0 min and the elution of rhein and IS occurred at approximately 1.60 and 3.96 min, respectively. The resolution of peaks was achieved with 0.01 m ammonium acetate (pH 6.0):acetonitrile:methanol (30:58:12, v/v) on an Inertsil ODS-3 column. The method was proved to be accurate and precise at a linearity range of 0.005-5.00 microg/mL with a correlation coefficient (r) of >or=0.995. The lower limit of quantitation was 0.005 microg/mL. The intra- and inter-day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. Rhein was found to be stable in the battery of stability studies. The application of the assay to pre-clinical pharmacokinetic studies confirmed the utility of the assay to derive pharmacokinetic parameters.

Determination and pharmacokinetic comparison of rhein in rats after oral dosed with Da-Cheng-Qi decoction and Xiao-Cheng-Qi decoction

Da-Cheng-Qi decoction (DCQD) is composed of dahuang, houpu, zhishi and mangxiao, while Xiao-Cheng-Qi decoction (XCQD) just contains dahuang, houpu, and zhishi. A validated high-performance liquid chromatographic (HPLC) method was developed for the determination and pharmacokinetic comparison of rhein in rats. It was performed on a reversed-phase C(18) column (150 x 4.6 mm) with a mobile phase of methanol and 0.2% acetic acid (89:11, v/v) and ultraviolet detection at 254 nm. The assay was linear over the range 30-3000 ng/mL (r(2) = 0.9991), with mean percentage recovery of 101.4%. The RSD of intra- and inter-day precision were less than 3.0%, with accuracy in the range 96.8-102.5% for each of the concentrations tested. Following oral administration, rhein plasma levels revealed curves characterized by peaks at 20.5 and 30.1 min corresponding to dosages of 15 mg/kg (XCQD) and 20 mg/kg (DCQD) at mean concentrations of 1184.67 and 1814.27 ng/mL, respectively. The half-lives of rhein from XCQD and DCQD were 45.3 and 139.6 min, respectively. AUC(0-12h) of rhein after oral dosage with XCQD and DCQD were 3435.68 and 5382.25 microg/L h, respectively. The pharmacokinetic parameters may be used to guide the clinical prescription compatibility of traditional Chinese prescriptions related to dahuang and mangxiao.

Simultaneous determination of berberine, palmatine and jatrorrhizine by liquid chromatography-tandem mass spectrometry in rat plasma and its application in a pharmacokinetic study after oral administration of coptis-evodia herb couple

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to simultaneously determine berberine, palmatine and jatrorrhizine in rat plasma. After mixing with the internal standard (IS) tetrahydropalmatine, plasma samples were pretreated by protein precipitation with acetonitrile-methanol (1:2, v/v). Chromatographic separation was carried out on a C18 column using a mixture of water (containing 0.1% formic acid) and acetonitrile (30:70, v/v) as mobile phase. The detection was performed by selected reaction monitoring (SRM) mode via electrospray ionization (ESI) source operating in the positive ionization mode. The method was linear over the concentration range of 1.0-250.0 ng/mL for all components. The intra- and inter-day precision values were less than 14.6% and the deviations were within +/-4.0%. The fully validated LC-MS/MS method has been successfully applied to the pharmacokinetic study of berberine, palmatine and jatrorrhizine in rat plasma after oral administration of coptis-evodia herb couple. Three peaks were observed in both individual and mean plasma-concentration curves of berberine, palmatine and jatrorrhizine, which may be attributed to distribution re-absorption and enterohepatic circulation.

Simultaneous quantification of five anthraquinones in rat plasma by high-performance liquid chromatography with fluorescence detection

A sensitive high-performance liquid chromatographic method with fluorescence detection (excitation 435 and emission 515 nm) was established and validated for quantification of five anthraquinones (aloe-emodin, rhein, emodin, chrysophanol and physcion) in rat plasma. Following a single-step liquid-liquid extraction, the analytes and internal standard (1,8-dihydroxyanthraquinone) were separated on a reversed-phase C(18) column with water-phosphoric acid-methanol as mobile phase at a flow rate of 1 mL/min. The linear ranges of the calibration curves were 6.5-1300 ng/mL for aloe-emodin, 20-4000 ng/mL for rhein, 40-8000 ng/mL for emodin, 15-3000 ng/mL for chrysophanol and 13-2600 ng/mL for physcion. The lower limit of quantification was 6.5 ng/mL for aloe-emodin, 20 ng/mL for rhein, 40 ng/mL for emodin, 15 ng/mL for chrysophanol and 13 ng/mL for physcion. The mean accuracy was 94.3-105.1% for aloe-emodin, 90.3-108.8% for rhein, 92.6-106.7% for emodin, 95.8-103.8% for chrysophanol and 98.7-101.2% for physcion. The within-batch and between-batch precisions were < or = 5.5% and < or = 13.4%, respectively. This method is suitable for determining the five anthraquinones in plasma simultaneously and thus investigating the pharmacokinetics of anthraquinones from Xiexin decoction in rats.

In vitro anti-cariogenic activity of dichloromethane fraction from Rheum undulatum L. root

This study aimed to evaluate in vitro effects of Rheum undulatum L. root on the development of dental caries, especially its effects on viability, dental plaque formation, and glycolytic acid production of Streptococcus mutans and Streptococcus sobrinus. Methanol extract of Rheum undulatum L. root and its fractions were prepared and tested. Among the test extract and fractions, dichloromethane fraction (DF) showed the most active antibacterial activity (inhibition zone: 13-17 mm) against S. mutans and S. sobrinus in a disc diffusion method. Minimal inhibitory concentrations (MICs) of DF against these bacteria ranged from 0.25 to 0.5 mg/mL. Furthermore, DF significantly inhibited the caries-inducing factors of these bacteria. At sub-MIC levels, DF inhibited in vitro dental plaque formation by S. mutans and S. sobrinus (IC50= 0.079 and 0.142 mg/mL, respectively), which was caused, in part, by the inhibitory effect on the activity of glucosyltransferases. A significant reduction of glycolytic acid production was found at the concentration as low as 0.032 mg/mL for S. mutans and 0.063 mg/mL for S. sobrinus. The possible bioactive compounds that are inducing in vitro anti-cariogenic activity of DF are unknown. Based on the preliminary phytochemical analysis, the activity of DF may be related to the presence of anthraquinones, cardiac glycosides, coumarines, sterols/terpenes, and phenolics. These results indicate that DF is probably useful for the control of dental plaque formation and subsequent dental caries development.

Simultaneous determination of baicalin, rhein and berberine in rat plasma by column-switching high-performance liquid chromatography

A simple HPLC method using column-switching and ultraviolet detection was developed for the simultaneous determination of baicalin (BA), rhein (RH) and berberine (BE) in rat plasma. Plasma samples were injected directly onto a Capcell Pak MF C(8) column (150 mm x 4.6 mm i.d.) to remove protein and to be pre-separated by an isocratic elution using 50 mmol/L phosphate sodium (pH 6.85)-acetonitrile (10:1, v/v). After the drug-containing fractions were transferred to a Kromasil C(18) column (150 mm x 4.6 mm i.d.) by a valve switching step, the valve position was switched back and the main separation was performed by an isocratic elution using triethylamine adjusted 20 mmol/L phosphoric acid (pH 6.78)-acetonitrile (4:1, v/v). The flow rate was always 1.0 mL/min. The calibration curve showed excellent linear relationship (r>or=0.9997) over the concentration range of 0.4-7.9 microg/mL for baicalin, 0.2-7.8 microg/mL for rhein and 0.4-7.7 microg/mL for berberine in rat plasma. The intra- and inter-day assay precisions (R.S.D.) of three analytes were in the range of 0.34-4.3% and the accuracies were between 98.0% and 102.4%. Their recoveries were all greater than 95%. The method was successfully applied to the multi-constituents plasma concentration-time curve study after oral administration of a traditional Chinese medicine prescription Xiexin-Tang in rats.

Pharmacokinetic of rhein in healthy male volunteers following oral and retention enema administration of rhubarb extract: a single dose study

Rhubarb is a common herb used in traditional Chinese medicine. However, few publications exist about its pharmacokinetic profiles in animals or healthy volunteers. Whether retention enema administration of rhubarb extract affects its pharmacokinetics as well as its tolerability is unknown. Therefore, we set out to compare the pharmacokinetic parameters of rhein administered by retention enemas with those of conventional oral dosing of rhubarb extract. Eight healthy male volunteers were enrolled in a prospective crossover study. All subjects received a single dose of rhubarb extract (50 mg.kg(-1)) on two separate occasions, once orally, once by a retention enema. Rhein plasma concentration was measured by HPLC. The C(max), AUC(0-infinity), AUMC were significantly higher in oral administration than those in retention enema administration (p < 0.05), while V(d) of rhein after oral administration of rhubarb extract was significantly lower (p < 0.05) than that after retention enema administration. However, no statistically significant differences between the two treatments were observed for any of the other pharmacokinetic parameters (T(max), t(1/2), MRT(0-infinity), CL). Dosage adjustment is advisable for retention enema administration of rhubarb extract in patients.

Effect of the water extract and ethanol extract from traditional Chinese medicinesAngelica sinensis (Oliv.) Diels,Ligusticum chuanxiong Hort. andRheum palmatum L. on rat liver cytochrome P450 activity

Angelica sinensis (Oliv.) Diels (DG), Ligusticum chuanxiong Hort. (CX) and Rheum palmatum L. (DH), three well known traditional Chinese medicines (TCM), have been used widely for the treatment of various types of disorders in China. Herb-drug interactions, especially cytochrome P450 (CYP)-mediated interactions, cause an enhancement or attenuation in the efficacy of co-administered drugs. In this study, to assess the possible interactions between TCM and drugs, the effect of water and ethanol extracts of DG, CX and DH on cytochrome P450 were studied in rats. The activities of various CYP enzymes were determined by HPLC method. Treatment of rats with water extracts or ethanol extracts of DG, CX and DH at daily dosages equivalent to 3 g (dry herbal material)/kg all increased the microsome protein contents and decreased the total CYP levels. The water extract of DG strongly increased the activities of CYP2D6 and 3A and the water extract of DH significantly increased the activity of 2D6. The other water extracts all showed inhibition against CYP isoforms. Only the ethanol extract of DG and DH increased the CYP2D6 and 3A activities, respectively, and the other ethanol extracts all decreased the level of CYP isoforms. All extract treatments had significant effects on CYP isoforms activities, whether induction or inhibition, compared with the blank control. Thus, caution should be paid to possible drug interactions of DG, CX, DH and CYP substrates.

A new tactic to treat postprandial hyperlipidemia in diabetic rats with gastroparesis by improving gastrointestinal transit

Improvement of gastrointestinal transit was thought to be a new tactic to treat postprandial hypertriglyceridemia in diabetic individuals with gastroparesis. Diabetic gastroparesis, lipid load testing, and the effect of domperidone or aqueous extract of rhizomes of Rheum palmatum L. on postprandial hypertriglyceridemia were evaluated in alloxan-induced diabetic rats. Alloxan diabetic animals had a slow gastrointestinal transit, together with delayed and exaggerated postprandial hypertriglyceridemia, after oral administration of olive oil, which was significantly improved after oral administration of domperidone or R. palmatum L. However, atropine could prevent the effects of R. palmatum L. The reduced postprandial hypertriglyceridemia was highly correlated with the improvement in gastrointestinal transit. These results suggest that promotion of gastrointestinal transit may be useful for the treatment of postprandial hypertriglyceridemia in diabetic patients with gastroparesis. R. palmatum L. may become a new choice for these patients since it has more potential benefits than domperidone.

A new approach to investigate the pharmacokinetics of traditional chinese medicine YL2000

Much progress has been made in the pharmacology of Traditional Chinese Medicine (TCM). However, the question on how to investigate pharmacokinetics of TCM extract remains. In this study, we selected a new TCM extract YL2000 developed in our laboratory as the research object and investigated both the pharmacokinetics of baicalin and berberine in YL2000 and the pharmacodynamics of YL2000 in febrile rats. The correlation analysis between the time-concentration curves of baicalin and berberine and the time-effect curve of YL2000 was conducted in plasma by statistical methods. The results showed that the time-effect data of anti-pyretic effect of YL2000 had a negative correlation (r = -0.8312, P < 0.1) with the time-concentration data of baicalin in plasma, but had no correlation (r = 0.01368, P > 0.5) with berberine. These data suggested that baicalin could be selected as a marker of anti-pyretic effect, and that YL2000 could be used to treat fevers according to the disposition of baicalin in vivo. In this study, we also proposed that one or more active elements in TCM extracts could be selected to represent the pharmacokinetics of TCM extracts in vivo, combined with the pharmacodynamics of TCM extract.