Pharmacokinetics of anthraquinones in Xiexin decoction and in different combinations of its constituent herbs

A Review on Bioactive Anthraquinone and Derivatives as the Regulators for ROS

Anthraquinones are bioactive natural products, which are often found in medicinal herbs. These compounds exert antioxidant-related pharmacological actions including neuroprotective effects, anti-inflammation, anticancer, hepatoprotective effects and anti-aging, etc. Considering the benefits from their pharmacological use, recently, there was an upsurge in the development and utilization of anthraquinones as reactive oxygen species (ROS) regulators. In this review, a deep discussion was carried out on their antioxidant activities and the structure-activity relationships. The antioxidant mechanisms and the chemistry behind the antioxidant activities of both natural and synthesized compounds were furtherly explored and demonstrated. Due to the specific chemical activity of ROS, antioxidants are essential for human health. Therefore, the development of reagents that regulate the imbalance between ROS formation and elimination should be more extensive and rational, and the exploration of antioxidant mechanisms of anthraquinones may provide new therapeutic tools and ideas for various diseases mediated by ROS.

Pharmacokinetics, tissue distribution and excretion of five rhubarb anthraquinones in rats after oral administration of effective fraction of anthraquinones from rheum officinale

Rhubarb, a famous traditional Chinese medicine, shows a wide range of physiological activities and pharmacological benefits. Rhubarb anthraquinones are perceived as the pharmacologically active compounds of Rhubarb, and understanding metabolism of them is crucial to assure safety and effectiveness of clinical application. In this study, the pharmacokinetics, tissue distribution and excretion of five rhubarb anthraquinones (aloe-emodin, rhein, emodin, chrysophanol, physcion) were systematically investigated after oral administration of rhubarb extract to rats.An HPLC method was developed and validated for quantitation of five rhubarb anthraquinones in rat plasma, tissues, urine and faeces to investigate the Pharmacokinetic characteristics. The results showed that the proposed method was suitable for the quantification of five anthraquinones in plasma, tissue and excreta samples with satisfactory linear (r > 0.99), precision (<10%) and recovery (85.12-104.20%). The plasma concentration profiles showed a quick absorption with the mean T_max of 0.42-0.75 h and t_1/2 of 6.60-15.11 h for five anthraquinones. The analytes were widely distributed in most of the tissues. Approximately 0.13-10.59% and 28.47-81.14% of five anthraquinones were recovered in urine and faeces within 132 h post-dosing, which indicated the major elimination route was faeces excretion.In summary, this study lays a foundation for elucidating the pharmacokinetic rule of rhubarb anthraquinone and the important data can provide reliable scientific resource for further research.

Systematic chemical characterization of Xiexin decoctions using high performance liquid chromatography coupled with electrospray ionization mass spectrometry

Xiexin decoctions (XXDs) display beneficial anti-inflammatory and anti-diabetic effects, which raises interests on this group of formulae for broad clinical applications. However, there was no report about systematic analysis of XXDs to elucidate the constitution of chemical components, which hampers further investigations on the therapeutic values of XXDs. In this work, crude herbs were extracted and prepared to obtain the XXDs for systemic analysis on their chemical compositions, according to the information described in the ancient Zhang Zhongjing's herbal formulae. LC-MS analysis of five XXDs was carried out to facilitate recognition of the source herbs for compounds in the mixture. A total number of 93 compounds were identified through our methods and their chemical classes encompassed five major groups, including protoberberine alkaloids, flavonoids, stilbenes, anthraquinones and saponins. Our current work provided important information about material basis for pharmacological studies on XXDs and would help shed light on relationships between chemical compositions and therapeutic effects.

Pharmacokinetics of Anthraquinones from Medicinal Plants

Anthraquinones are bioactive natural products, some of which are active components in medicinal medicines, especially Chinese medicines. These compounds exert actions including purgation, anti-inflammation, immunoregulation, antihyperlipidemia, and anticancer effects. This study aimed to review the pharmacokinetics (PKs) of anthraquinones, which are importantly associated with their pharmacological and toxicological effects. Anthraquinones are absorbed mainly in intestines. The absorption rates of free anthraquinones are faster than those of their conjugated glycosides because of the higher liposolubility. A fluctuation in blood concentration and two absorption peaks of anthraquinones may result from the hepato-intestinal circulation, reabsorption, and transformation. Anthraquinones are widely distributed throughout the body, mainly in blood-flow rich organs and tissues, such as blood, intestines, stomach, liver, lung, kidney, and fat. The metabolic pathways of anthraquinones are hydrolysis, glycuronidation, sulfation, methylation/demethylation, hydroxylation/dehydroxylation, oxidation/reduction (hydrogenation), acetylation and esterification by intestinal flora and liver metabolic enzymes, among which hydrolysis, glycuronidation and sulfation are dominant. Of note, anthraquinones can be transformed into each other. The main excretion routes for anthraquinones are the kidney, recta, and gallbladder. Conclusion: Some anthraquinones and their glycosides, such as aloe-emodin, chrysophanol, emodin, physcion, rhein and sennosides, have attracted the most PK research interest due to their more biological activities and/or detectability. Anthraquinones are mainly absorbed in the intestines and are mostly distributed in blood flow-rich tissues and organs. Transformation into another anthraquinone may increase the blood concentration of the latter, leading to an increased pharmacological and/or toxicological effect. Drug-drug interactions influencing PK may provide insights into drug compatibility theory to enhance or reduce pharmacological/toxicological effects in Chinese medicine formulae and deserve deep investigation.

HPLC-DAD-Q-TOF/MS-Based Screening and Analysis of the Multiple Absorbed Bioactive Components in Rat Serum after Oral Administration of Xiexin Tang

Background:

Xiexin Tang (XXT) is a classic Traditional Chinese Medicine (TCM) formula that has been used in herbal clinics for more than 1800 years. Recently, many studies have investigated the pharmacological effects and chemical composition of XXT. However, there is little information about systematic studies on the material basis of its efficacy. In the present study, the serum pharmacochemistry technique and HPLC-DAD-Q-TOF/MS were performed to screen and analyze the multiple absorbed bioactive components and metabolites of orally dosed XXT in rat serum.

Methods:

Bio-samples and herbal extracts were analyzed and detected by HPLC-DAD-Q-TOF/MS. Upon comparison of the chromatograms of the single-constituent decoctions with that of the XXT formulation, the peak quantity and peak intensity of the formulated decoction showed some variation from those of the single-constituent decoctions.

Results:

Twenty-one serum-adsorbed constituents were identified after intragastric administration of herbal extracts, of which 8 originated from Rhei Radix et Rhizoma (RRR), 5 from Coptidis Rhizoma (CR), and 8 from Scutellariae Radix (SR). The results showed that the main adsorbed constituents in the serum were anthraquinones, anthrones, chromones, and butyrophenones, alkaloids, and flavonoids.

Conclusion:

The results demonstrate that an effective and reliable analytical method is set up for screening the bioactive components of Chinese herbal medicine, which provided a meaningful basis for further pharmacology and active mechanism research of XXT.

The Influence of Compatibility of Rhubarb and Radix Scutellariae on the Pharmacokinetics of Anthraquinones and Flavonoids in Rat Plasma

BACKGROUND AND OBJECTIVES

Rhubarb-Radix scutellariae is a classic herb pair, which is commonly used to clear away heat and toxin in clinic. The aim of this study was to investigate the influence of compatibility of Rhubarb and Radix scutellariae on the pharmacokinetic behaviors of anthraquinones and flavonoids in rat plasma.

METHODS

Eighteen rats were randomly divided into three groups, and were orally administered Rhubarb and/or Radix scutellariae extracts. A sensitive and rapid UPLC-MS/MS method was developed and validated to determine the concentrations of baicalin, baicalein, wogonside, wogonin, rhein, and emodin in rat plasma. The concentrations of phase II conjugates of flavonoid aglycones and anthraquinone aglycones were also determined after hydrolyzing the plasma with sulfatase.

RESULTS

Compared with administration of Radix scutellariae alone, co-administration of Rhubarb significantly decreased the first maximum plasma concentration (C _max1) of baicalin, wogonside, and the phase II conjugates of baicalein, wogonin to 46.40, 61.27, 41.49, and 20.50%, respectively. The area under the plasma concentration-time curve from time zero to infinity (AUC_0-∞) was significantly decreased from 82.60 ± 20.22 to 51.91 ± 7.46 μM·h for rhein and 276.83 ± 98.02 to 175.42 ± 86.82 μM·h for the phase II conjugates of wogonin after compatibility. The time to reach the first maximum plasma concentration (T _max1) of anthraquinones was shortened and the second peak of anthraquinones disappeared after compatibility.

CONCLUSIONS

Compatibility of Rhubarb and Radix scutellariae can significantly affect the pharmacokinetic behaviors of characteristic constituents of the two herbs. The cause of these pharmacokinetic differences was further discussed combined with the in vivo ADME (absorption, disposition, metabolism, and excretion) processes of anthraquinones and flavonoids.

Erding Formula in hyperuricaemia treatment: unfolding traditional Chinese herbal compatibility using modern pharmaceutical approaches

Objectives

Traditional Chinese herbal formulas are difficult to be understood because of complex compositions and specific therapeutic principles. To better understand herbal compatibility in Traditional Chinese medicine (TCM), this study was conducted to investigate the effects of a Chinese pharmacopoeia-listed formula, Erding Formula (EF) and its constituent herbs for a new indication, hyperuricaemia.

Methods

A hypoxanthine and potassium oxonate-induced hyperuricemic mouse model, a xylene-induced inflammatory mouse model and an acetic acid-induced pain model were used to test the effects of EF and its constituent herbs. In addition, we investigated whether EF and/or its relevant herbs had an impact on the expression of URAT1 and OAT3 mRNA.

Key findings

The results showed EF and individual herbs had pharmacological effects on selected targets. Only Viola yedoensis Makino (Viola) lowered uric acid levels, while all four herbs had anti-inflammatory and analgesic effects. The EF may lower the uric acid level through inhibiting the expression of URAT1 mRNA and enhancing the expression of OAT3 mRNA.

Conclusions

These findings provide pharmacological insights into the effects of EF and individual herbs on UA excretion. This study suggests that Viola is the main herb in EF. This study facilitates better understanding of TCM principles and theories using modern pharmaceutical approaches.

Pharmacokinetics of mangiferin and its metabolite-norathyriol, Part 2: Influence of UGT, CYP450, P-gp, and enterobacteria and the potential interaction in Rhizoma Anemarrhenae decoction with timosaponin B2 as the major contributor

The poor bioavailability of mangiferin (MGF) is a major obstacle on its further development. Aimed to illustrate the underlying mechanism and improve its poor exposure, the compared PK profiles of MGF and norathyriol (NTR) after different MGF preparation were performed: pure MGF, the Rhizoma Anemarrhenae (Zhi-mu) decoction, MGF, and timosaponin B2 (TB-2) combination. Furthermore, the potential contributing factors, including uridine diphosphoglucuronosyltransferase (UGT), cytochrome P450 (CYP450), P-gp, and enterobacterial were investigated by comparing the PK profiles with and without the corresponding inhibitors or in different rat models. After taking MGF, CYP450 and UGT inhibition could decrease MGF and NTR exposure; P-gp inhibition slightly enhanced (48%) MGF exposure, whereas more apparent for the improved NTR exposure (302%); enterobacterial inhibition almost completely stopped the NTR production, but no such effect was observed for MGF. Compared with the limited improvement by the abovementioned inhibition, the MGF and NTR exposure could significantly increase by 11.5- and 5.9-fold in the Zhi-mu decoction compared with the MGF treatment, probably contributed to TB-2 as an absorption enhancer because the MGF and TB-2 combination produced a similar level of improvement on the PK paremeters of MGF and NTR to the herb treatment. Likewise, most of the effects by UGT, CYP450, P-gp, and enterobacteria followed a similar variation tendency between them. Therefore, the poor bioavailability of MGF possibly mainly attributed to its poor membrane permeability, but not transporters or metabolic enzymes, and the compatibility of MGF and TB-2 could probably expand the prospective application of MGF by improving its bioavailability. © 2016 BioFactors, 42(5):545-555, 2016.

The influence of compatibility of processed radix Aconiti Kusnezoffii on the pharmacokinetic of four components in Glycyrrhiza uralensis Fisch

ETHNOPHARMACOLOGICAL RELEVANCE

Glycyrrhiza uralensis Fisch. and processed radix Aconiti kusnezoffii are the main components in many Chinese traditional patent medicines with the ratio of 1:1, which are used for treatment of rheumatoid arthritis, heart failure and so on. Glycyrrhizic acid, glycyrrhetic acid, liquiritigenin and isoliquiritigenin are the essential bioactive triterpenes and flavones in the extract of G. uralensis, which were analysis by a simple but accurate method.

MATERIALS AND METHODS

In the present study, a specific HPLC method was developed and validated for simultaneous determination of pharmacokinetic parameters of glycyrrhizic acid, glycyrrhetic acid, liquiritigenin and isoliquiritigenin in G. uralensis after oral administration of single herb extract and a combination of two herbs extracts respectively.

RESULTS

The calibration curves of the four components had good linearity higher than 0.9991 in the measured range. The intra-day and inter-day precisions (RSD) at different levels were both within 9.73%, and the accuracies (RE) were in the range of -7.9-8.0%. Compared with pharmacokinetic parameters of G. uralensis administered orally, values of AUC and Cmax of liquiritigenin and isoliquiritigenin decreased significantly (p<0.05), plasma concentrations of glycyrrhizic acid rose slightly and bimodal phenomenon of concentration-time of isoliquiritigenin and glycyrrhetinic acid disappeared after combined administration.

DISCUSSION AND CONCLUSIONS

Some components in the extract of processed radix A. kusnezoffii showed different effects on the pharmacokinetics of the four ingredients in G. uralensis.

The Influence of Aconitum carmichaelii Debx. on the Pharmacokinetic Characteristics of Main Components in Rheum palmatum L

Rhei Radix et Rhizoma was one of the commonly used traditional Chinese medicines, and the compatibility of Rhei Radix et Rhizoma and Aconiti Lateralis Radix Praeparata was the basic herb pair applied in many Chinese traditional prescription. Rhubarb anthraquinones were the main bioactive materials of Rhei Radix et Rhizoma. To elucidate the compatibility of Rhei Radix et Rhizoma and Aconiti Lateralis Radix Praeparata, the pharmacokinetics of rhubarb anthraquinones as the main marker constituents were investigated. In the present study, pharmacokinetic differences of rhubarb anthraquinones were detected after oral administration of extract of Rheum palmatum L. and compatibility with Aconitum carmichaelii Debx. After oral administration, no difference of peak time can be found for anthraquinones between rhubarb group and compatibility group. But Cmax and area under the curve of aloe-emodin, emodin and chrysophanol in compatibility group were significantly higher than that in rhubarb group. Although the Cmax of rhein in compatibility group was much lower than that in rhubarb group, the area under the curve value was similar in two groups. The clearance and t1/2 of rhubarb anthraquinone were also changed after compatibility. The change of pharmacokinetics characteristics of rhubarb anthraquinone after compatibility may be caused by the drug-drug interaction medicated by chemical reaction and cytochromes P450.

The synergism mechanism of Rhubarb Anthraquinones on constipation elucidated by comparative pharmacokinetics of Rhubarb extract between normal and diseased rats

In the study, it was hypothesized that Rhubarb Anthraquinones synergistically enhanced the purgative effect on constipation rat from the direct and indirect pathway at the same time. A validated HPLC method was successfully applied to elucidate the synergism mechanism from pharmacokinetics aspect after oral administration of Rhubarb extract with a dose of 0.25 g to normal and constipation rats. Comparison of the pharmacokinetic data of normal and constipation rats showed that there were significant differences (p < 0.05) in the main pharmacokinetic parameters. The C max and AUC of emodin in constipation rats were about ten times that of normal rats, while the t 1/2 was remarkably decreased (p < 0.05). However, a significant decrease (p < 0.05) in AUC value for aloe-emodin and rhein was observed in model group compared with normal group. The results may be attributed to the direct action of aloe-emodin and rhein on intestinal cell membranes and the indirect action of emodin on bowel movement through the adjustment by nervous system.

Relationships between pharmacokinetics and efficacy of Xie-xin decoction in rats with experimental ulcerative colitis

ETHNOPHARMACOLOGICAL RELEVANCE

Xie-xin decoction (XXD) has been used as a classic formula in China for the treatment of gastrointestinal dysfunction such as ulcerative colitis (UC). However, no potential action mechanisms and active compounds had been systematically investigated.

AIM OF THE STUDY

To explore the effectiveness and the material basis of XXD in trinitrobenzene sulfonic acid (TNBS)-induced UC rats.

MATERIALS AND METHODS

XXD was administered orally for 8 days at a dosage of 2 or 4g/kg/day. Plasma pharmacokinetic properties and colon tissue concentrations of multiple compounds from XXD were detected. Tissue damage scores, production of interleukin (IL)-10 and myeloperoxidase (MPO), expression of tumor necrosis factor-alpha (TNF-α) and nuclear factor-kappa Bp65 (NF-κBp65) in colon tissues were examined. Canonical correlation analysis was performed to evaluate the relationships between pharmacokinetics and efficacy to elucidate significantly active compounds of XXD.

RESULTS

XXD promoted the recovery of colitis and inhibited the colonic inflammation damage in UC rats by reducing the level of MPO and the expression of TNF-α and NF-κBp65, and increasing the production of IL-10 in colon tissues. Efficacy of XXD was positively related with AUC of five plasma compounds (baicalin, berberine, wogonoside, wogonin, and rhein) and concentrations of six colon tissue compounds (coptisine, jatrorrhizine, palmatine, berberine, baicalein and emodin), respectively.

CONCLUSIONS

The multiple compounds in plasma and colon tissues from XXD might be the main material basis for therapeutic potentials in UC rats.

UPLC-ESI/MS determination of 17 active constituents in two categorized formulas of traditional Chinese medicine, Sanhuang Xiexin Tang and Fuzi Xiexin Tang: application in comparing the differences in decoctions and macerations

A rapid and sensitive UPLC-ESI/MS method was established and validated to determine 17 active constituents (aconitine, hypaconitine, mesaconitine, benzoylaconine, benzoylhypaconine, benzoylmesaconine, berberine, palmatine, jatrorrhizine, coptisine, baicalein, wogonin, baicalin, wogonoside, emodin, aloe-emodin and rhein) in Sanhuang Xiexin Tang (SXT) and Fuzi Xiexin Tang (FXT), which are two classic compound recipes from Xiexin Tang categorized formulas in traditional Chinese medicien. The separation was performed on a UPLC BEH C18 column gradient eluted using acetonitrile and 0.1% formic acid as mobile phase. ESI/MS was operated in positive ([M + H](+)) in selected ion recording mode for analysis of alkaloids and flavones, while in negative ([M - H](-)) selected ion recording mode for anthraquinones. All of the 17 constituents exhibited good linearity in a relatively wide concentration ranges with the lowest limits of detection of 0.38 ng/mL. All of the relative standard deviation values of intra- and inter-precisions and stabilities of 17 constituents were within 5%. The method was successfully applied to determine 17 active constituents in decoctions and macerations of SXT and FXT. The results indicated that different preparative methods resulted in significant diversity in concentrations of the 17 analytes. Herb-herb interaction appeared between aconitum alkaloids in Aconiti Lateralis Radix Preparata and another three herbs.

Material basis of Chinese herbal formulas explored by combining pharmacokinetics with network pharmacology

The clinical application of Traditional Chinese medicine (TCM), using several herbs in combination (called formulas), has a history of more than one thousand years. However, the bioactive compounds that account for their therapeutic effects remain unclear. We hypothesized that the material basis of a formula are those compounds with a high content in the decoction that are maintained at a certain level in the system circulation. Network pharmacology provides new methodological insights for complicated system studies. In this study, we propose combining pharmacokinetic (PK) analysis with network pharmacology to explore the material basis of TCM formulas as exemplified by the Bushen Zhuanggu formula (BZ) composed of Psoralea corylifolia L., Aconitum carmichaeli Debx., and Cnidium monnieri (L.) Cuss. A sensitive and credible liquid chromatography tandem mass spectrometry (LC-MS/MS) method was established for the simultaneous determination of 15 compounds present in the three herbs. The concentrations of these compounds in the BZ decoction and in rat plasma after oral BZ administration were determined. Up to 12 compounds were detected in the BZ decoction, but only 5 could be analyzed using PK parameters. Combined PK results, network pharmacology analysis revealed that 4 compounds might serve as the material basis for BZ. We concluded that a sensitive, reliable, and suitable LC-MS/MS method for both the composition and pharmacokinetic study of BZ has been established. The combination of PK with network pharmacology might be a potent method for exploring the material basis of TCM formulas.

Reduced system exposures of total rhein and baicalin after combinatory oral administration of rhein, baicalin and berberine to beagle dogs and rats

ETHNOPHARMACOLOGICAL RELEVANCE

Rhein (Rh), baicalin (BG) and berberine (Be) are important coexisted constituents of San-Huang-Xie-Xin-Tang, which was widely used in traditional Chinese medicine for the treatment of gastritis, hypertension, gastric bleeding and peptic ulcers, etc.

AIM OF THE STUDY

Based on the extensive phase II conjugation reactions of polyphenols (Rh and BG) in vivo, the aims of the present study were to investigate the effects of combination (Rh, BG and Be) on the system exposures of total Rh and BG involving the phase II conjugates metabolites and its possible mechanism.

MATERIALS AND METHODS

A 3×3 Latin square single heavy design was used to investigate the pharmacokinetics influence of total Rh and BG after combination of Be by treating plasma samples with β-glucuronidase/sulfatase both in beagle dogs and Wistar rats. In vitro and in situ experiment models including in situ rat intestinal perfusion, Caco-2 cell monolayer transport and small intestinal flora incubation system were used to discuss the possible mechanism.

RESULTS

The results of pharmacokinetic interactions showed that combination significantly reduced the system exposures of total Rh and BG. Compared with Rh or BG alone, the mean area under concentration-time curves (AUC(0-t)) of total Rh and BG reduced by 31% and 77% in beagle dog experiment. In Wistar rat experiment, the AUC(0-t) of total Rh and BG reduced by 22% and 21%. Subsequently, the results of in situ rat intestinal perfusion and small intestinal flora incubation system tests revealed that combination may decrease the absorption and metabolism of BG. However, combination could not affect the transport profile of BG across the Caco-2 cell. Moreover, combination did not affect the absorption or metabolism profile of Rh in all three in situ/in vitro experiments.

CONCLUSIONS

It was deduced that the possible mechanism of the reduction of the system exposures of total Rh and BG was related to that combination decreased the metabolism of BG to B or the phase II conjugates of Rh/BG excreted from liver/bile duct to their free aglycones in vivo by inhibiting intestinal flora. The potent effects of combination on the phase II conjugates of Rh and B in pharmacokinetics, shown in this paper, indicated that more attention should be paid to the phase II conjugates metabolites of these polyphenols (undergo extensive phase II conjugation reactions in vivo) when applied herbal products composed of these coexist compounds.

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.

The influence of compatibility of traditional Chinese medicine on the pharmacokinetic of main components in Fructus aurantii

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Aurantii is one of the commonly used traditional Chinese medicines and the compatibility of Fructus Aurantii, Radix et Rhizoma Rhei and Semen Crotonis Pulveratum were the main components in a Chinese traditional patent medicine Weichang'an pill. Naringin and neohesperidin are two main flavonoid glycosides in the extract of Fructus Aurantii. The pharmacokinetics of naringin and neohesperidin, as the main marker constituents were analysis by a simple and accurate method.

MATERIALS AND METHODS

In the present study, pharmacokinetic differences of two flavonoid glycosides were detected after oral administration of the extract of single herb and different compatibility of Fructus Aurantii, Radix et Rhizoma Rhei and Semen Crotonis Pulveratum which at doses of approximately 700 mg/kg naringin and 300 mg/kg neohesperidin.

RESULTS

It indicated that the pharmacokinetic process of naringin and neohesperidin in four groups were demonstrated bimodal phenomenon after oral administration. Comparing to pharmacokinetic parameters of the single herbs administration, there were no significant difference after the compatibility of Fructus Aurantii and Radix et Rhizoma Rhei. However, the absorption of two flavonoid glycosides was increased dramatically after the compatibility of Fructus Aurantii or Semen Crotonis Pulveratum. The same results were attained after co-administration of the extract of three herbs.

CONCLUSION

Some components in the extract of Semen Crotonis Pulveratum promoted the absorption of naringin and neohesperidin.

Synergistic effect of rhein in combination with ampicillin or oxacillin against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for a number of infections in humans that are difficult to treat, and as a result, is a substantial contributor to morbidity and mortality. In the present study, in search of natural products capable of inhibiting this multidrug-resistant bacterium, we investigated the antimicrobial activity of rhein isolated from Rheum palmatum L. (Polygonaceae) against 16 different strains of the bacterium. New antimicrobial activity was found using the paper disc diffusion method [minimal inhibitory concentrations (MICs)], MTT test and checkerboard dilution test. Against the 16 strains, the disc diffusion test was in the range of 20-29 mm and the MICs of rhein were in the range of 7.8-31.25 μg/ml. From these results we performed the checkerboard test to determine the synergism of rhein in combination with ampicillin (AM) or oxacillin (OX) against all strains. The combined activity of rhein and the two antimicrobial agents (AM and OX) against all strains resulted in a fractional inhibitory concentration index ranging from 0.28-1 and from 0.18-1, respectively. The effect of rhein with AM and OX was found to be synergistic or partially synergistic. We found that rhein reduced the MICs of AM and OX. Rhein in combination with AM or OX could lead to the development of new combinations of antibiotics against MRSA infection.

Sensitive and robust UPLC-MS/MS method to determine the gender-dependent pharmacokinetics in rats of emodin and its glucuronide

In this study, a sensitive and robust ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed, validated, and applied to determine gender-dependent pharmacokinetics of total emodin (aglycone+glucuronide) in male and female Sprague-Dawley rats. The lower limit of quantification for emodin and emodin glucuronide in rat plasma was 39 and 78 ng/ml, with signal-to-noise ratio of ≥ 10. Precision and accuracy studies showed emodin and emodin glucuronide plasma concentrations well within the 10% range in all studies. Plasma recovery of emodin and emodin glucuronide was always above 86% for low (emodin: 39 ng/ml; glucuronide: 78 ng/ml), 92% for medium (625 ng/ml), and 97% for high (10000 ng/ml) concentrations. Furthermore, emodin showed more than 95% plasma stability under short-term and long-term storage conditions, as well as after three freeze-thaw cycles in the experiments. The developed and validated analytical method was successfully applied to study the gender-dependent 10-fold higher oral bioavailability of total emodin in male than female rats. The oral bioavailability of emodin and emodin glucuronide was also measured separately and showed a statistically significant gender difference in oral bioavailability of emodin and emodin glucuronide in rats.

Synergistic effect of emodin in combination with ampicillin or oxacillin against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a substantial contributor to morbidity and mortality. In search of a natural products capable of inhibiting this multidrug resistant bacteria, we have investigated the antimicrobial activity of emodin (EM) isolated from Rheum palmatum L. (Polygonaceae) against 17 different strains of the bacterium. New antimicrobial activity was found using the paper disc diffusion method, agar dilution as well as checkerboard method. Against the 17 strains, the disc diffusion test was in the range of 18-30 mm, and the minimum inhibitory concentrations (MICs) of EM were in the range of 1.5-25 μg/mL. From those results we performed the checkerboard test to determine the synergism of EM in combination with ampicillin (AM) or oxacillin (OX) against all strains. The combined activity of EM and two antimicrobial agents (AM, OX) against all strains resulted in a fractional inhibitory concentrations index (FICI) ranging from 0.37-0.5 and from 0.37-0.75, respectively. The effect of EM with AM and OX was found to be synergistic or partially synergistic. We found that EM reduced the MICs of AM and OX. EM and in combination with AM or OX could lead to the development of new combination antibiotics against MRSA infection.

Effective constituents in Xiexin Decoction for anti-inflammation

AIM OF THE STUDY

To ascertain the effective constituents in Xiexin Decoction for anti-inflammation and the interactions of these constituents at the pharmacodynamic level.

MATERIALS AND METHODS

Rats were administered oral Xiexin Decoction 1h before intraperitoneal lipopolysaccharide. Nitric oxide production and Xiexin Decoction constituents in venous serum samples were quantified and the correlation between nitric oxide production and each constituent in serum was calculated. Raw264.7 cells were stimulated with lipopolysaccharide and one or more Xiexin Decoction constituents; cell viability and nitric oxide production was quantified.

RESULTS

Xiexin Decoction significantly decreased nitric oxide production in vivo, which correlated well with rhein, baicalin, emodin and aloe-emodin. All the typical constituents of Xiexin Decoction, with the exception of physcione and chrysophanol, dose-dependently inhibited nitric oxide production in vitro. In an orthogonal designed in vitro study, rhein was the most powerful constituent, followed by baicalin then berberine and no synergy was found among these constituents.

CONCLUSIONS

Rhein was the most effective anti-inflammatory constituent in Xiexin Decoction followed by baicalin; no synergy was observed between rhein, baicalin and berberine at the pharmacodynamic level in vitro.