Analysis of anthraquinones in rhubarb (Rheum palmatum and Rheum officinale) by supercritical fluid chromatography

Rheum khorasanicum. Hydroalcoholic root extract induces cell death in human colorectal adenocarcinoma: An in vitro and in silico study

Colorectal cancer (CRC) is the second greatest cause of cancer-related death in the world and chemotherapy, as an important part of CRC treatment, has some drawbacks, including systemic toxicity. Therefore, it is crucial to discover new and more effective CRC treatment plans. Rheum khorasanicum (R. khorasanicum) is a medicinal plant with high flavonoids, stilbenes, and anthraquinone contents, so it can be a potential source of antioxidants and can be used for therapeutic purposes and trigger apoptosis in cancer cells. In this study, we investigated the effects of hydroalcoholic root extract of R. khorasanicum treatment on inducing mitochondrial apoptosis of HT-29 and Caco-2 human colorectal adenocarcinoma cells. Firstly, the total phenolic and flavonoid content was determined. Then, the cytotoxic effects of R. khorasanicum on cells of three different types, including HT-29 and Caco-2 colon cancer cells as well as normal 3T3 cells were assessed using the MTT assay. To investigate the characteristics of cellular death, flow cytometry, and western blotting were performed. The results of this study indicated considerable phenolic (356.4±9.4 GAE/gDW) and flavonoid (934.55±17.1 QE/gDW) contents in R. khorasanicum. MTT assay's finding indicated that 100, 60, and 30μg/mL concentrations of R. khorasanicum reduce cell viability in HT-29 and Caco-2 cell lines significantly (P<0.05). It has been also revealed that R. khorasanicum extract induces apoptosis rather than necrosis in these cell lines. Moreover, Bcl-2 expression was significantly reduced in both HT-29 and Caco-2 cell lines, while Bax and cleaved caspase-3 expression soared considerably in the groups under R. khorasanicum treatment (P<0.05). In conclusion, our findings have suggested that high phenol and flavonoid contents of R. khorasanicum root extract possibly play an important role in cell cytotoxicity and apoptosis induction in HT-29 and Caco-2 colon cancer cells.

Possible NLO response and electrical/charge transfer capabilities of natural anthraquinones as p-type organic semiconductors: a DFT approach

CONTEXT

Organic semiconductors (OSCs) have attracted a great deal of interest in recent days. There are various types of OSCs, among which small molecules have various inherent benefits. Further research is needed to advance this new kind of material because the field is still developing, and the current focus is on creating small molecules that exist naturally for OSCs. OSCs with nonlinear optical (NLO) characteristics offer a significant advantage over others. Thus, this study theoretically investigates naturally occurring anthraquinones such as chrysophanol and rhein as potential OSCs, as well as their NLO properties. The calculated properties include the ionization potential (IP), electron affinity (EA), and bandgap (Eg). The FMO energy levels together with the Eg, IP (8.17-8.53 eV), and EA (1.87-2.44 eV) suggest the semiconductor nature of the studied compounds. The calculated values of reorganization energy (λ) and transfer integrals (V) suggest the p-type character of both molecules. Rhein has the lowest λh (0.19 eV) and Eg (3.28 eV) and the highest Vh, predominantly because of its better p-type character. The polarizability increases due to the presence of an electron-withdrawing substituent, leading to better NLO performance for Rhein, which is supported by its lower LUMO and Eg values.

METHODS

The studied molecules were optimized with the DFT/B3LYP-GD3/6-31+G(d,p) method using Gaussian 16 software. The crystal structure was simulated with Materials Studio 7.0, and the V values were calculated with the ADF package. The CDD and DOS plots were obtained with the Multiwfn 3.8 program.

Plant anthraquinones: Classification, distribution, biosynthesis, and regulation

Anthraquinones are polycyclic compounds with an unsaturated diketone structure (quinoid moiety). As important secondary metabolites of plants, anthraquinones play an important role in the response of many biological processes and environmental factors. Anthraquinones are common in the human diet and have a variety of biological activities including anticancer, antibacterial, and antioxidant activities that reduce disease risk. The biological activity of anthraquinones depends on the substitution pattern of their hydroxyl groups on the anthraquinone ring structure. However, there is still a lack of systematic summary on the distribution, classification, and biosynthesis of plant anthraquinones. Therefore, this paper systematically reviews the research progress of the distribution, classification, biosynthesis, and regulation of plant anthraquinones. Additionally, we discuss future opportunities in anthraquinone research, including biotechnology, therapeutic products, and dietary anthraquinones.

Optimal timing of free total rhubarb anthraquinones on immune regulation in rats with severe acute pancreatitis

ETHNOPHARMACOLOGICAL RELEVANCE

Rhubarb is the peeled and dried root of Rheum palmatum L., Rheum tanguticum Maxim. ex Balf. or Rheum officinale Baill. Free total rhubarb anthraquinones (FTRAs) isolated and extracted from rhubarb display the beneficial effects of anti-inflammation and immunological modulation. The timing of immune regulation is a major problem in the immunotherapy for severe acute pancreatitis (SAP). several studies reported that FTRAs could reduce systemic inflammatory responses by inhibiting early immune overactivity in the gut in rats with SAP. But, the optimal timing of rhubarb and FTRAs administration is not clear in clinical practice. Therefore, the time window for the best efficacy of rhubarb and FTRAs in the treatment of SAP patients should be further elucidated.

AIM OF THE STUDY

The main purpose of the present study was to evaluate the efficacy and optimal timing of immune modulation with FTRAs in the treatment of SAP in rats.

MATERIALS AND METHODS

FTRAs (22.5, 45 and 90 mg/kg), Rhubarb (RHU) (900 mg/kg, positive control) or normal saline (vehicle control) were initiated at 0 (immediately), 48 and 72 h every 12 h for three times in total. The therapeutic effects of FTRAs and RHU on pancreas and intestinal tissues injury, secondary infection with pseudomonas aeruginosa (PA), amylase, lipase, D-lactic acid (DLA), endotoxin (ET), proinflammatory and anti-inflammatory cytokines, macrophages, dendritic cells and regulatory T cells (Tregs) in the blood, small intestine and/or mesenteric lymph node (MLN) were determined in rats with SAP after treatment.

RESULTS

The results showed that administration of FTRAs at 0 h was superior to 48 h and 72 h, which significantly protected the injury of pancreas and intestinal tissues, reduced the mortality induced by secondary infection with PA, decreased the levels of amylase, lipase, DLA, ET, tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), IL-6, IL-8, IL-18 and Tregs, and increased the levels of IL-4, sTNF-αR, macrophages and dendritic cells, secretary immunoglobulin A (SIgA) in the blood and/or small intestinal tissues in rats with SAP.

CONCLUSIONS

In conclusion, our studies indicate that the treatment window of FTRAs for SAP is within 48 h of development, administration of FTRAs at the early stage (0 h, immune overreaction period) was the optimal time and superior to that of 48 h and 72 h for its therapeutic efficacy. The earlier the administration of FTRAs, the better the therapeutic efficacy. Therefore, our data may provide a scientific rationale for the clinical application and optimal timing of FTRAs in the treatment of SAP.

Facile and selective separation of anthraquinones by alizarin-modified iron oxide magnetic nanoparticles

Anthraquinones are widely distributed in higher plants and possess broad biological activities. The conventional separation procedures for isolating anthraquinones from the plant crude extracts require multiple extraction, concentration, and column chromatography steps. In this study, we synthesized three alizarin (AZ)-modified Fe₃O₄ nanoparticles (Fe₃O₄@AZ, Fe₃O₄@SiO₂-AZ, and Fe₃O₄@SiO₂-PEI-AZ) by thermal solubilization method. Fe₃O₄@SiO₂-PEI-AZ showed strong magnetic responsiveness, high methanol/water dispersion, good recyclability, and high loading capacity for anthraquinones. To evaluate the feasibility of using Fe₃O₄@SiO₂-PEI-AZ for separating various aromatic compounds, we employed molecular dynamics simulations to predict the adsorption/desorption effects of PEI-AZ for various aromatic compounds in different methanol concentrations. The results showed that the anthraquinones could be efficiently separated from the monocyclic and bicyclic aromatic compounds by adjusting the methanol/water ratio. The Fe₃O₄@SiO₂-PEI-AZ nanoparticles were then used to separate the anthraquinones from the rhubarb extract. At 5% methanol, all the anthraquinones were adsorbed by the nanoparticles, thus allowing their separation from other components in the crude extract. Compared with the conventional separation methods, this adsorption method has the advantages of high adsorption specificity, simple operation, and solvent saving. This method sheds light on the future application of functionalized Fe₃O₄ magnetic nanoparticles to selectively separate desired components from complex plant and microbial crude extracts.

Review on melanosis coli and anthraquinone-containing traditional Chinese herbs that cause melanosis coli

Backgrounds: The incidence of melanosis coli (MC) has gradually increased annually, attracting significant attention and efforts into this field. A potential risk for MC is the long-term use of anthraquinone laxatives in patients with constipation. Most traditional cathartic drugs are made from herbs containing anthraquinone compounds. This review aims to provide guidance for the application of traditional Chinese herbs containing anthraquinones for physicians and researchers. Materials and methods: We reviewed risk factors and pathogenesis of MC, and natural anthraquinones isolated from TCM herbs. We searched Pubmed and CNKI databases for literature related to MC with keywords such as"traditional Chinese medicine", "Chinese herbs", "anthraquinones", and "melanosis coli". The literature is current to January 2023 when the searches were last completed. After the literature retrieval, the TCM herbs containing anthraquinones (including component identification and anthraquinone content determination) applied in clinical were selected. According to the collected evidence, we provide a list of herbs containing anthraquinones that could cause MC. Results: We identified 20 herbs belonging to 7 families represented by Polygonaceae, Fabaceae, Rhamnaceae, and Rubiaceae, which may play a role in the pathogenesis of MC. Among these, the herbs most commonly used include Dahuang (Rhei Radix et Rhizome), Heshouwu (Radix Polygoni Multiflori), Huzhang (Rhizoma Polygoni Cuspidati), Juemingzi (Semen Cassiae), Luhui (Aloe) and Qiancao (Rubiae Radix et Rhizoma). Conclusion: Due to a lack of awareness of the chemical composition of TCM herbs, many patients with constipation and even some TCM physicians take cathartic herbal remedies containing abundant anthraquinones to relieve defecation disturbances, resulting in long-term dependence on these herbs, which is potentially associated with most cases of MC. When such treatments are prescribed, TCM physicians should avoid long-term use in large doses to reduce their harm on colonic health. Individuals who take healthcare products containing these herbs should also be under the supervision of a doctor.

An alternative strategy based on ultra-high-performance supercritical fluid chromatography for full monosaccharide compositional analysis of polysaccharides in Schisandra chinensis fruits

Due to green and environment-friendly characteristics, ultra-high-performance supercritical fluid chromatography has been widely used in analytical fields in recent years, but until now few reports are available for monosaccharide compositional analysis of macromolecule polysaccharides. In this study, an ultra-high-performance supercritical fluid chromatography technology with an unusual binary modifier is used to determine the monosaccharide compositions of natural polysaccharides. Each carbohydrate herein is simultaneously labeled as 1-pheny-3-methyl-5-pyrazolone and acetyl-derivative via pre-column derivatizations aiming to increase UV absorption sensitivity and decrease water solubility. Ten common monosaccharides are fully separated and detected on ultra-high-performance supercritical fluid chromatography combined with a photo-diode array detector by systematic optimization of multiple relevant parameters, for example, column stationary phases, organic modifiers, additives, flow rates, and so on. Compared with carbon dioxide as a mobile phase, the addition of a binary modifier increases the resolution of analytes. Additionally, this method has the advantages of small consumption of organic solvent, safety, and being environmental-friendly. It has been successfully applied for full monosaccharide compositional analysis of heteropolysaccharides from Schisandra chinensis fruits. To sum up, a new alternative approach is provided for monosaccharide compositional analysis of natural polysaccharides.

Comparative study of the Rheum tanguticum's chemical contents based on spatial distribution characteristics

Rheum tanguticum (R. tanguticum) has been widely used for the treatment of inflammatory diseases in clinical. However, limited research exist on the quality evaluation of various R. tanguticum locations, which has certain drawbacks. In this study, Fourier-transform infrared spectroscopy (FTIR) and high-performance liquid chromatography (HPLC) were used to comparative study on the chemical contents of R. tanguticum, to clarify the relationship between the chemical contents and the spatial distribution of R. tanguticum. First of all, the FTIR spectra of 18 batches of R. tanguticum were examined. Following the cluster analysis, the FTIR spectra of various production locations differed. To some extent, establishing the double index analysis sequence of common and variation peaks may differentiate distinct production locations of medicinal materials. The HPLC fingerprint of R. tanguticum was constructed to further explore the link between components and their origin. PCA of common peaks of 18 batches of R. tanguticum indicated that R. tanguticum grown in Gannan and Qinghai had a tendency to separate t[2], however this trend was not noticeable. Then, OPLS-DA model was established, and the key differential components of R. tanguticum produced in Gannan and Qinghai were discovered to be R16, R37, R46, and R47 (Aloe emodin) (VIP ≥ 1 and P < 0.05). At last, Pearson's test was used to examine the relationship between longitude, latitude, altitude, and composition. Longitude was significantly positively correlated with R28 and R30 (P < 0.05), and a very significantly positively correlated with R35, R36, R37, R46, and R47 (P < 0.01). Latitude was significantly negatively correlated with R34, R35, and R40 (P < 0.05), and extremely significantly negatively correlated with R28, R30, R36, R37, R46, and R47 (P < 0.01). Altitude was significantly positive correlation with R36 and R37 (P < 0.01). The results of our study can provide insights into R. tanguticum quality control and aid in establishing a natural medication traceability system.

Biochemical Characteristics and Elemental Composition Peculiarities of Rheum tataricum L. in Semi-Desert Conditions and of European Garden Rhubarb

Biochemical and mineral peculiarities of plants inhabiting desert and semi-desert areas may provide important information about the mechanism of their adaptability and reveal the prospects of their utilization. Rheum tataricum L., known for its high tolerance to drought, salinity, and nutritional deficiency, is the least studied species of wild rhubarb. Using biochemical and ICP-MS analysis, the antioxidant status and mineral composition of R. tataricum were determined. Extremely high levels of antioxidant activity (148–155 mg GAE g−1 d.w.), polyphenols (24.6–25.1 mg GAE g−1 d.w.) and carotenoids (1.94 mg-eq β-carotene g−1 d.w.) were revealed in roots, proline in leaves (71.1 ± 6.2 mg kg−1 d.w.) and malic acid in stems (3.40 ± 0.50 mg g−1 d.w.). Compared to garden rhubarb, R. tataricum demonstrated significant root–leaves translocation of Li, Se, Si, and Mo, known to participate in plant antioxidant defense. Under high levels of Ca, Na, Mg, Fe, Cr and Si in soil, R. tataricum demonstrated the ability to significantly increase the accumulation of these elements in roots, showing a hyperaccumulation ability for Sr. The first broad picture of R. tataricum biochemical and mineral characteristics in semi-desert habitat and its nutritional value indicate the prospects of R. tataricum utilization in plant breeding, medicine, and nutrition.

The progress and prospect of natural components in rhubarb (Rheum ribes L.) in the treatment of renal fibrosis

Background: Renal fibrosis is a key pathological change that occurs in the progression of almost all chronic kidney diseases . CKD has the characteristics of high morbidity and mortality. Its prevalence is increasing each year on a global scale, which seriously affects people’s health and quality of life. Natural products have been used for new drug development and disease treatment for many years. The abundant natural products in R. ribes L. can intervene in the process of renal fibrosis in different ways and have considerable therapeutic prospects.

Purpose: The etiology and pathology of renal fibrosis were analyzed, and the different ways in which the natural components of R. ribes L. can intervene and provide curative effects on the process of renal fibrosis were summarized. Methods: Electronic databases, such as PubMed, Life Science, MEDLINE, and Web of Science, were searched using the keywords ‘R. ribes L.’, ‘kidney fibrosis’, ‘emodin’ and ‘rhein’, and the various ways in which the natural ingredients protect against renal fibrosis were collected and sorted out.

Results: We analyzed several factors that play a leading role in the pathogenesis of renal fibrosis, such as the mechanism of the TGF-β/Smad and Wnt/β-catenin signaling pathways. Additionally, we reviewed the progress of the treatment of renal fibrosis with natural components in R. ribes L. and the intervention mechanism of the crucial therapeutic targets.

Conclusion: The natural components of R. ribes L. have a wide range of intervention effects on renal fibrosis targets, which provides new ideas for the development of new anti-kidney fibrosis drugs.

Advanced Development of Supercritical Fluid Chromatography in Herbal Medicine Analysis

The greatest challenge in the analysis of herbal components lies in their variety and complexity. Therefore, efficient analytical tools for the separation and qualitative and quantitative analysis of multi-components are essential. In recent years, various emerging analytical techniques have offered significant support for complicated component analysis, with breakthroughs in selectivity, sensitivity, and rapid analysis. Among these techniques, supercritical fluid chromatography (SFC) has attracted much attention because of its high column efficiency and environmental protection. SFC can be used to analyze a wide range of compounds, including non-polar and polar compounds, making it a prominent analytical platform. The applicability of SFC for the separation and determination of natural products in herbal medicines is overviewed in this article. The range of applications was expanded through the selection and optimization of stationary phases and mobile phases. We also focus on the two-dimensional SFC analysis. This paper provides new insight into SFC method development for herbal medicine analysis.

Tissue-specific transcriptome for Rheum tanguticum reveals candidate genes related to the anthraquinones biosynthesis

Rheum tanguticum (Maxim. ex Regel) Maxim. ex Balf. is a herbaceous perennial plant indigenous to China, and its root and rhizomes were usually used as an important traditional Chinese medicine. However, the genomic resources are still scarce for R. tanguticum and even for Rheum genus. Transcriptome datasets from different tissues of R. tanguticum were obtained to screen the genes related to anthraquinones biosynthesis, and five free anthraquinones were also determined. Nine cDNA libraries of roots, stems and leaves were generated, and a total of 272 million high-quality reads were assembled into 257,942 unigenes. Based on the functional annotation, A total of 227 candidate enzyme genes involved in the MVA, MEP, shikimate and polyketide pathways were identified, and several differentially expressed genes found functionally associated with anthraquinones biosynthesis showed distinct tissue-specific expression patterns. Especially, we found that the expression levels of PKS III genes might result in the content differences of free anthraquinones in different tissues of R. tanguticum. Besides, 137,400 SSR loci were identified, and 64,081 SSR primer pairs were successfully designed based on these loci. Our results not only provide cues for the genetic mechanism of anthraquinone content differences in different tissues of R. tanguticum, but also lay genomic foundation for the subsequent genetic engineering and breeding for Rheum species.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-021-01099-8.

Diverse host-associated fungal systems as a dynamic source of novel bioactive anthraquinones in drug discovery: Current status and future perspectives

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Diversity and distribution of host-living fungi producing AQs in the terrestrial ecosystem are assembled.

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AQs biosynthesis and their SAR are elucidated to guide the approaches in novel drugs design and development.

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Several examples of true endophytic fungi producing AQs like their different host plants have been reported as interesting alternative sources of drugs.

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The review recapitulates the novel AQs with rare chemical skeleton that could open future venues for investigation of their biological activities.

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Lichens are assembled as unique source of several bioactive classes of AQs.

Background

Despite, a large number of bioactive anthraquinones (AQs) isolated from host-living fungi, only plant-derived AQs were introduced in the global consumer markets. Host-living fungi represents renewable and extendible resources of diversified metabolites to be exploited for bioactives production. Unique classes of AQs from fungi include halogenated and steroidal AQs, and absent from planta are of potential to explore for biological activity against urging diseases such as cancer and multidrug-resistant pathogens. The structural diversity of fungal AQs, monomers, dimers, trimers, halogenated, etc… results in a vast range of pharmacological activities.

Aim of review

The current study capitalizes on uncovering the diversity and distribution of host-living fungal systems producing AQs in different terrestrial ecosystems ranging from plant endophytes, lichens, animals and insects. Furthermore, the potential bioactivities of fungal derived AQs i.e., antibacterial, antifungal, antiviral (anti-HIV), anticancer, antioxidant, diuretic and laxative activities are assembled in relation to their structure activity relationship (SAR). Analyzing for structure–activity relationship among fungal AQs may facilitate bioengineering of more potential analogues. Withal, elucidation of AQs biosynthetic pathways in fungi is discussed from different fungal hosts to open up new possibilities for potential biotechnological applications. Such comprehensive review unravels terrestrial host-living fungal systems as a treasure trove in drug discovery, in addition to future perspectives and trends for their exploitation in pharmaceutical industries.

Key Scientific Concepts of Review

Such comprehensive review unravels terrestrialhost-living fungal systems as a treasure trove in drug discovery, in addition to future perspectives and trends for their exploitation in pharmaceutical industries.

Supercritical fluid chromatography for the analysis of natural dyes: From carotenoids to flavonoids

Plant-derived natural dyes are used in a variety of formulated products, from food to cosmetics and pharmaceutics. In addition to their color, they also provide some bioactivity. While they are mostly analyzed with high-performance liquid chromatography, supercritical fluid chromatography was also employed for several dye families, mostly for carotenoids and chlorophylls, and more recently for anthraquinones and flavonoids. These supercritical fluid chromatography methods are described in this review. Because the dyes have different structures and structural variations (polarity, isomers, etc.), the best chromatographic system to achieve their separation is not always the same. Hydrophobic stationary phases are preferred for the most hydrophobic dyes (chlorophylls and carotenoids) while polar stationary phases are preferred for the polar dyes (anthraquinones and flavonoids). Regarding the mobile phase composition, chlorophylls and carotenoids are best eluted with moderate proportions of co-solvent in CO₂ (about 40%), while the most polar glycosylated flavonoids require higher proportions of co-solvent and acidic additives. Because dyes are colorful, ultraviolet-visible detection is often sufficient, while mass spectrometry offers additional structural information. Furthermore, fundamental information can also be gained through chromatographic analysis of dyes: either solubility in supercritical fluids, in view of their extraction, or retention behavior providing an understanding of stationary phase properties.

Q-marker Prediction Analysis of Rhubarb in Fengyin Decoction Based on Fingerprint and Network Pharmacology

Fengyin Decoction (FYD) is a traditional Chinese medicine for the treatment of epilepsy and wind paralysis. However, the potential antiepileptic active component in rhubarb (which is the most effective Chinese medicine in FYD) has not been defined. In this study, we analyzed and predicted the potential quality marker (Q-marker) of rhubarb in FYD based on fingerprint and network pharmacology. The fingerprints of FYD and rhubarb were established to analyze the transmission law of active components. Ultra-high performance liquid chromatography (UPLC) was used to study quantitatively the active components obtained by different extraction methods of FYD. Combined with network pharmacological analysis, a “components-targets-pathways” network was constructed to predict the potential Q-marker. Eight peaks were identified by FYD fingerprint: aloe-emodin, rhein, emodin, chrysophanol, physcion, cinnamaldehyde, 6-gingerol, and glycyrrhizic acid ammonium salt. The determination of the 8 active components in FYD with different extraction methods suggested that rhubarb anthraquinone may be a potential antiepileptic active component. Twelve core components, 19 targets, and 21 pathways of rhubarb were screened by network pharmacology, which further demonstrated that rhubarb played a role mainly through these components, targets, and pathways. We preliminarily predicted that compounds such as rhubarb anthraquinones were a potential Q-marker. The UPLC fingerprint and the content determination method of the 8 components established in this study were effective and feasible. The findings in this study may provide a reference for further study of quality control of FYD and lay a theoretical foundation for the study of its action mechanism. In addition, our study may provide a novel idea for the study of the Q-marker of other classical compound traditional Chinese medicines.

Ameliorative effects of the traditional Chinese medicine formula Qing-Mai-Yin on arteriosclerosis obliterans in a rabbit model

CONTEXT

Qing-Mai-Yin (QMY) is a clinically used herbal formula for treating arteriosclerosis obliterans (ASO).

OBJECTIVE

To evaluate the chemical constituents and effects of QMY on ASO rabbit model.

MATERIALS AND METHODS

Forty-eight New Zealand rabbits were divided into six groups (n = 8): normal (normal rabbits treated with 0.5% CMC-Na), vehicle (ASO rabbits treated with 0.5% CMC-Na), positive (simvastatin, 1.53 mg/kg), and QMY treatment (300, 600, and 1200 mg/kg). ASO rabbit model was prepared by high fatty feeding, roundly shortening artery, and bovine serum albumin immune injury. QMY (300, 600 and 1200 mg/kg) was orally administered for 8 weeks. The effects and possible mechanisms of QMY on ASO rabbits were evaluated by pathological examination, biochemical assays, and immunohistochemical assays. The compositions of QMY were analysed using HPLC-Q-TOF-MS/MS analysis.

RESULTS

Compared to the vehicle rabbit, QMY treatment suppressed plaque formation and intima thickness in aorta, and decreased intima thickness, whereas increased lumen area of femoral artery. Additionally, QMY treatment decreased TC, TG and LDL, decreased CRP and ET, and increased NO and 6-K-PGF1α in serum. Furthermore, the potential mechanisms studied revealed that QMY treatment could suppress expression of TNF-α, IL-6, ICAM-1 and NF-κB in endothelial tissues, and increase IκB. In addition, HPLC analysis showed QMY had abundant anthraquinones, stilbenes, and flavonoids.

CONCLUSION

QMY has ameliorative effects on ASO rabbit, and the potential mechanisms are correlated to reducing inflammation and down-regulating NF-κB. Our study provides a scientific basis for the future application and investigation of QMY.

A Network Pharmacology Approach to Investigate the Anticancer Mechanism and Potential Active Ingredients of Rheum palmatum L. Against Lung Cancer via Induction of Apoptosis

Rheum palmatum L. (RPL) is a known traditional herbal medicine with the functions of “heat-clearing and damp-drying” in traditional Chinese medicine. Its anti-cancer effect against lung cancer has been confirmed previously, but the related mechanisms and active substances for its action has been little studied. This study adopted the network pharmacology, built the network map of drug ingredients and disease targets (DDN), and discussed the effective components of RPL and its possible mechanisms. All constituents of RPL were collected through database search and literature mining, and the potential active constituents were screened. The inverse pharmacophore matching model was used to predict the targets of active ingredients, and the method was supplemented by database retrieval and literature mining. Compounds-target data were inputted into Cytoscape software to build the DDN of RPL, and functional annotation analysis and pathway enrichment analysis were carried out. Finally, 20 active compounds were screened, which acted on 817 targets. A total of 22,418 lung cancer-related targets were collected, and 761 overlapped with drug targets. By bioinformatics annotation of these overlapping genes, a total of 235 gene ontology (GO) functional annotation analyses and 46 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were obtained. It was found that the enrichment of GO and KEGG was associated with apoptosis, suggesting RPL plays an anti-lung cancer role via inducing cell apoptosis. Subsequent cell experiment results showed RPL and its active constituents inhibited the proliferation of A549 cells and reduced clone formation rate of A549 cells via induction of apoptosis. In this study, the pharmacodynamic basis and mechanism of RPL against lung cancer were studied from the perspective of systematic pharmacology, which would be beneficial for further elucidating the anticancer effect of RPL on lung cancer.

Phytochemical and Antioxidant Studies on a Rare Rheum cordatum Losinsk. Species from Kazakhstan

An optimisation of extraction towards an increased antioxidant capacity and the study on the extracts' composition by HPLC-ESI-Q-TOF-MS were performed on different organs of a rarely studied plant: Rheum cordatum Losinsk (Polygonaceae) growing in Kazakhstan. More than 20 compounds from anthraquinones and phenolics were identified in an optimised method. The plant was proven to contain a wide variety of phenolic compounds (catechins, flavonoids, and their glucosides and phenolic acids) in contrast to the anthraquinone composition, which was mainly represented by emodin and its analogues. The results of the studies could determine the plant as a rich source of pharmacologically precious polyphenols. It was evidenced that the extracting solvents, the time of collection, and the organs tested affected both the chemical content and the antioxidant potential of the extracts. Ethanol : water (50 : 50 v/v) was selected as the most beneficial extractant for all metabolites, and based on the principal component analysis of raw data, the radical scavenging potential of the plant was strictly related to the presence of epicatechin gallate (ECG), kaempferol glucoside, and epigallocatechin gallate (EGCG) occurring in this extract at the concentration of 1.69-5%, 0.16-0.47%, and 0.001-2.93%, respectively.

Protic Ionic Liquids as Efficient Solvents in Microwave-Assisted Extraction of Rhein and Emodin from Rheum palmatum L

Rheum palmatum L. (R. palmatum L.) is a traditional Chinese herb and food, in which rhein and emodin are the main bioactive components. The extraction of the two compounds from R. palmatum L. is, thus, of great importance. In this work, protic ionic liquids (PILs) were applied in the microwave-assisted extraction (MAE) of rhein and emodin from R. palmatum L., which avoids the toxicity of organic solvents. The results of the present study indicate that PILs possessing higher polarity exhibit higher extraction ability due to their stronger absorption ability for microwave irradiation. Compared with conventional solvents, such as methanol, trichloromethane, and deep eutectic solvents (DESs), the PIL, 1-butyl-3-himidazolium methanesulfonate ([BHim]MeSO3) reported herein is more efficient. The selected extraction conditions of liquid-solid ratio, microwave irradiation time, microwave irradiation power, and PIL concentration were 40 g·g-1, 50 s, 280 W, and 80%, respectively. Under the selected conditions, the extraction yields of rhein and emodin were 7.8 and 4.0 mg·g-1, respectively. These results suggest that PILs are efficient extraction solvents for the separation of active components from natural products.

Supercritical fluid chromatography-a technical overview and its applications in medicinal plant analysis: an update covering 2012-2018

Medicinal plants with complex matrices are endowed with a wide scope of biological activities. The separation, quantification, characterization and purification of bioactive components from herbal medicine extracts have always challenged analysts. Fortunately, the advancement of various emerging techniques has provided potent support for improving the method selectivity, sensitivity and run speeds in medicinal plant analyses. In recent years, the advent of new-generation supercritical fluid chromatography (SFC) instruments and a wide diversity of column chemistries, coupled with the intrinsic technical features of SFC, have made it an alternative and prominent analytical platform in the medicinal plant research area. This work aims to give a comprehensive overview of the fundamentals, technical advancement and investigating parameters of SFC in combination with three prevalent detectors. Moreover, the latest research progress of SFC applications in medicinal plant analyses is illuminated, with focus on herbal medicine-related SFC papers on the analytical and preparative scale that were published during the period of 2012 to December 2018. The most relevant applications were classified based on the constituents to be analysed. As for the respective research cases, analytical protocols and data processing strategies were provided, along with the indicated restrictions or superiority of the method; thus, the current status of SFC in medicinal plant analysis was presented.

Physcion reduces lipid accumulation and prevents the obesity in mice

Background

Obesity increases the risk of metabolic dysfunction such as dyslipidemia, hypertension, and fatty liver. Physcion (PY) is an anthraquinone that reportedly has anti-inflammatory and anti-bacterial properties. However, few studies have addressed the effect of PY on high-fat diet-induced obesity in mice. The purpose of this study was to investigate the effects of PY on obesity.

Methods

Male C57BL/6 J mice were randomly divided into three groups and fed normal diet (ND, 5% fat, w/w), high-fat diet (HFD, 20% fat, 1% cholesterol, w/w), and HFD supplemented with 0.002% PY (w/w) for 16 weeks. Obesity-related biomarkers were analyzed including whole body and white adipose tissue (WAT) weight, in addition to lipid and inflammatory factors in the plasma, feces, liver and epididymal WAT. Significant differences among the groups were determined using Student’s t-test. Differences were considered statistically significant at p < 0.05.

Results

Body and WAT weights were significantly decreased by the PY supplement relative to the HFD groups. Energy expenditure was enhanced by the PY supplement, which led to ameliorate plasma lipids, adipokines, cytokines, and fecal lipids. Fatty acid (FA) synthesis decreased in the liver, while FA oxidation increased. Finally, lipid synthesis markedly decreased whereas lipolysis and oxidation increased in WAT.

Conclusions

The PY supplement suppressed lipid accumulation in WAT and the liver by regulating enzyme and gene levels. These results indicate that PY can improve diet-induced obesity and its complications such as dyslipidemia, hepatic steatosis, and inflammation.

Observation on the curative effect of long intestinal tube in the treatment of phytobezoar intestinal obstruction

The aim of the study was to observe the curative effect of long intestinal tube (LT) in the treatment of phytobezoar intestinal obstruction.We performed a retrospective study of patients with phytobezoar intestinal obstruction who underwent decompression with different tube insertion method. A total of 80 patients were collected and divided into nasogastric tube (NGT) group (n = 36) and LT group (n = 44) between August 2015 and August 2018 at our hospital. Univariate analysis was used to assess the clinical efficacy of 2 groups of patients.There were no significant differences in the mean age, sex ratio, and previous surgical history between the 2 groups. There were statistically significant differences between the 2 groups in terms of improvement time of clinical indications (4.2 ± 1.4 vs 2.5 ± 0.6 days; P = .008), liquid decompression amount on the first day of catheterization (870.4 ± 400.8 vs 1738.4 ± 460.2 mL; P = .000), transit operation rate (4/36 vs 0/44; P = .023), clinical cure rate (25/36 vs 40/44; P = .014), total treatment efficiency (32/36 vs 44/44; P = .023), and total hospitalization cost (3.25 ± 0.39 vs 2.07 ± 0.41 ¥ ten thousand; P = .000).The curative effect of LT in the treatment of phytobezoar intestinal obstruction is accurate and reliable, which can effectively improve the clinical symptoms of patients, comprehensively improve the non-surgical rate of intestinal obstruction treatment, reduce the total cost of hospitalization, and is worthy of promotion in clinical application.

Near-infrared spectroscopy for rapid and simultaneous determination of five main active components in rhubarb of different geographical origins and processing

Rhubarb (Rhei Radix et Rhizoma) is a classic herbal laxative medicine in Europe and a very famous natural medicine in Asia, especially in China. In this study, near-infrared spectroscopy (NIRS) was first used for rapid and simultaneous analysis of five main active components (chrysophanol, aloe-emodin, rhein, emodin and physcion) in rhubarb of 6 geographical origins, processing and spurious samples. A total of 124 samples (73 raw, 40 processed and 11 spurious samples) were collected. With the reference values determined by HPLC, two calibration strategies, partial least squares (PLS) as a linear regression method and artificial neural networks (ANN) as a non-linear regression method, were studied. For the PLS strategy, 11 spectral pre-processing methods, 5 spectral regions and different latent variables (LVs) were systematically compared, while 3 spectral pre-processing methods and 5 ANN algorithms were studied for the ANN strategy. The results indicated that PLS was more suitable for the analysis of chrysophanol, aloe-emodin, emodin and physcion, whereas ANN was better for rhein. For the optimal NIR models of chrysophanol, aloe-emodin, rhein, emodin and physcion, the correlation coefficients of the calibration set (R_cal) were 0.9916, 0.9762, 0.9839, 0.9794 and 0.9800, respectively; the correlation coefficients of the prediction set (R_pre) were 0.9888, 0.9359, 0.9410, 0.9805 and 0.9785, respectively; the root mean square error of validation (RMSEP) were 0.0402, 0.0197, 0.0593, 0.0133 and 0.0192, respectively. Subsequently, the optimal NIR models were used to study the effects of geographical regions and processing, and identify the spurious rhubarb. Collectively, NIRS may be a well-acceptable method for quality evaluation of rhubarb and other traditional Chinese medicine (TCM).

Investigation of species and environmental effects on rhubarb roots metabolome using 1H NMR combined with high performance thin layer chromatography

INTRODUCTION

The pharmacological activities of medicinal plants are reported to be due to a wide range of metabolites, therein, the concentrations of which are greatly affected by many genetic and/or environmental factors. In this context, a metabolomics approach has been applied to reveal these relationships. The investigation of such complex networks that involve the correlation between multiple biotic and abiotic factors and the metabolome, requires the input of information acquired by more than one analytical platform. Thus, development of new metabolomics techniques or hyphenations is continuously needed.

OBJECTIVES

Feasibility of high performance thin-layer chromatography (HPTLC) were investigated as a supplementary tool for medicinal plants metabolomics supporting ¹H nuclear magnetic resonance (¹H NMR) spectroscopy.

METHOD

The overall metabolic difference of plant material collected from two species (Rheum palmatum and Rheum tanguticum) in different geographical locations and altitudes were analyzed by ¹H NMR- and HPTLC-based metabolic profiling. Both NMR and HPTLC data were submitted to multivariate data analysis including principal component analysis and orthogonal partial least square analysis.

RESULTS

The NMR and HPTLC profiles showed that while chemical variations of rhubarb are in some degree affected by all the factors tested in this study, the most influential factor was altitude of growth. The metabolites responsible for altitude differentiation were chrysophanol, emodin and sennoside A, whereas aloe emodin, catechin, and rhein were the key species-specific markers.

CONCLUSION

These results demonstrated the potential of HTPLC as a supporting tool for metabolomics due to its high profiling capacity of targeted metabolic groups and preparative capability.

Cytochrome P450 mediated metabolic activation of chrysophanol

Chrysophanol, a major anthraquinone component occurring in many traditional Chinese herbs, is accepted as important active component with various pharmacological actions such as antibacterial and anticancer activity. Previous studies demonstrated that exposure to chrysophanol induced cytotoxicity, but the mechanisms of the toxic effects remain unknown. In the present metabolism study, three oxidative metabolites (M1-M3, aloe-emodine, 7-hydroxychrysophanol, and 2-hydroxychrysophanol) and five GSH conjugates (M4-M8) were detected in rat and human liver microsomal incubations of chrysophanol supplemented with GSH, and the formation of the metabolites was NADPH dependent except M4 and M5. M4 and M5 were directly derived from parent compound chrysophanol, M6 arose from M2, and M7 and M8 resulted from the oxidation of M4 and M5. Metabolites M5 and M6 were also observed in bile of rats after exposure to chrysophanol, M1-M3 and one NAC conjugate (M9) were detected in urine of rats administrated chrysophanol, and urinary metabolite M9 originated from the degradation of biliary GSH conjugation M6. Recombinant P450 enzyme incubation and microsome inhibition studies demonstrated that P450 1A2 was the primary enzyme responsible for the metabolic activation of chrysophanol and that P450 2B6 and P450 3A4 also participated in the generation of the oxidative metabolites. These findings helped us to understand the mechanisms of chrysophanol-induced cytotoxicity.

Quantitative determination of major alkaloids in Cinchona bark by Supercritical Fluid Chromatography

Chinoline alkaloids found in Cinchona bark still play an important role in medicine, for example as antimalarial and antiarrhythmic drugs. For the first time Supercritical Fluid Chromatography has been utilized for their separation. Six respective derivatives (dihydroquinidine, dihydroquinine, quinidine, quinine, cinchonine and cinchonidine) could be resolved in less than 7 min, and three of them quantified in crude plant extracts. The optimum stationary phase showed to be an Acquity UPC² Torus DEA 1.7 μm column, the mobile phase comprised of CO₂, acetonitrile, methanol and diethylamine. Method validation confirmed that the procedure is selective, accurate (recovery rates from 97.2% to 103.7%), precise (intra-day ≤2.2%, inter-day ≤3.0%) and linear (R² ≥ 0.999); at 275 nm the observed detection limits were always below 2.5 μg/ml. In all of the samples analyzed cinchonine dominated (1.87%-2.30%), followed by quinine and cinchonidine. Their total content ranged from 4.75% to 5.20%. These values are in good agreement with published data, so that due to unmatched speed and environmental friendly character SFC is definitely an excellent alternative for the analysis of these important natural products.

Free Total Rhubarb Anthraquinones Protect Intestinal Injury via Regulation of the Intestinal Immune Response in a Rat Model of Severe Acute Pancreatitis

Intestinal mucosal immune barrier dysfunction plays a key role in the pathogenesis of severe acute pancreatitis (SAP). Rhubarb is a commonly used traditional Chinese medicine as a laxative in China. It markedly protects pancreatic acinar cells from trypsin-induced injury in rats. Free total rhubarb anthraquinones (FTRAs) isolated and extracted from rhubarb display the beneficial effects of antibacteria, anti-inflammation, antivirus, and anticancer. The principal aim of the present study was to investigate the effects of FTRAs on the protection of intestinal injury and modification of the intestinal barrier function through regulation of intestinal immune function in rats with SAP. We established a rat model of SAP by injecting 3.5% sodium taurocholate (STC, 350 mg/kg) into the biliopancreatic duct via retrograde injection and treated the rats with FTRAs (36 or 72 mg/kg) or normal saline (control) immediately and 12 h after STC injection. Then, we evaluated the protective effect of FTRAs on intestinal injury by pathological analysis and determined the levels of endotoxin (ET), interleukin 1β (IL-1β), tumor necrosis factor α (TNF-α), nitric oxide (NO), myeloperoxidase (MPO), capillary permeability, nucleotide-binding oligomerization domain-like receptors 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD domain (ASC), casepase-1, secretary immunoglobulin A (SIgA), regulatory T cells (Tregs), and the ratio of Th1/Th2 in the blood and/or small intestinal tissues or mesenteric lymph node (MLN) cells. Moreover, the chemical profile of FTRAs was analyzed by HPLC-UV chromatogram. The results showed that FTRAs significantly protected intestinal damage and decreased the levels of ET, IL-1β, TNF-α, and NO in the blood and TNF-α, IL-1β, and protein extravasation in the intestinal tissues in SAP rats. Furthermore, FTRAs significantly decreased the expressions of NLRP3, ASC, and caspase-1, the number of Tregs and the ratio of Th1/Th2, while significantly increased the expression of SIgA in the intestinal tissues and/or MLN cells in SAP rats. Our results indicate that FTRAs could protect intestinal injury and improve intestinal mucosal barrier function through regulating immune function of SAP rats. Therefore, FTRAs may have the potential to be developed as the novel agent for the treatment of SAP clinically.

Natural deep eutectic solvents as new green solvents to extract anthraquinones from Rheum palmatum L

Natural deep eutectic solvents (NADESs) are efficient in extracting natural products. However, traditional organic solvents are toxic in the extraction of anthraquinones from Rheum palmatum L. To solve this problem, we applied natural deep eutectic solvent ultrasound-assisted extraction in this study for the extraction of total anthraquinones from R. palmatum L. Principal component analysis revealed that the selected NADES which consisted of lactic acid, glucose and water (LGH), was highly efficient in extracting anthraquinones from R. palmatum L. The ratio of lactic acid/glucose and the addition of water in LGH were investigated via a single-factor experiment. With a lactic acid/glucose ratio of 5 : 1 (mol/mol), and 10% of water (v/v), LGH had a high extraction yield to anthraquinones. Optimized by response surface methodology (RSM), the optimized extraction conditions of extraction time, extraction temperature and solvent-to-solid ratio of 1.5 h, 82 °C and 26 mL g⁻¹, respectively. Under optimum conditions, the extraction yields of aloe-emodin, rhein, emodin, chrysophanol, physcion and total anthraquinones were 2.60 ± 0.01, 5.78 ± 0.02, 2.21 ± 0.02, 5.87 ± 0.02, 8.81 ± 0.01 and 25.27 ± 0.07 mg g⁻¹, respectively. The enrichment and separation of five anthraquinones in LGH extraction solution were efficiently achieved using DM130 macroporous resin, with purities of 90.98%, 96.67%, 92.37%, 95.80% and 91.61% as indicated by HPLC, and recovery yields of 84.08%, 79.51%, 84.96%, 81.83% and 78.35%, respectively. LGH was environmentally friendly and highly efficient in extracting anthraquinones from R. palmatum L., and NADESs showed potential for the extraction of effective components from natural products.

Natural deep eutectic solvents ultrasound-assisted extraction (NADES-UAE) was applied to extract total anthraquinones from Rheum palmatum L.

Pharmacognostic outlooks on medical herbs of Sasang typology

The purpose of this study was to review the pharmacognostic characteristics of Sasang type-specific medical herbs and suggest biological mechanisms that might be related to the personalized treatment of the East.

Major compounds and their pharmacological activities of medical herbs for each Sasang types were systematically reviewed. The pharmacognostic characteristics of its main compounds were systematically analyzed with previous studies and three web-based databases.

Sasang type-specific medical herbs were selected, and biological effects of their phytochemicals were reviewed from the pathophysiological features of each Sasang types. Phenolics were dominant in Tae-Yang type-specific herbs, iridoids and triterpenes with antipyretic and diuretic effects were in So-Yang type-specific, saponins (triterpene saponins and steroidal saponins) with antitussive effects were in Tae-Eum type-specific, and monoterpene and sesquiterpenes with stomachic effect were in So-Eum type-specific herbs.

Pharmacognostic understandings on Sasang type-specific medical herbs with consideration of type-specific pathophysiological features were provided for the first time. This study would contribute to in-depth understandings on the pathophysiology of Sasang typology and integration of East-Asian and Western personalized medicine.

Effect of external application of traditional Chinese medicine combined with chewing gum on gastrointestinal function in patients after surgery for esophageal carcinoma

AIM

To explore the effect of external application of traditional Chinese medicine combined with chewing gum on the recovery of gastrointestinal function in patients after surgery for esophageal carcinoma (EC).

METHODS

One hundred and eight patients who underwent surgical treatment for EC at our hospital from March 2014 to August 2016 were selected and randomly divided into an observation group (abdominal application of traditional Chinese medicine combined with chewing gum) and a control group (routine treatment and nursing care). Clinical efficacy, the recovery of gastrointestinal function and the levels of gastrin and motilin were compared between the two groups.

RESULTS

The effective rate was 94.44% in the observation group and 85.19% in the control group, and there was a significant difference between the two groups (χ² = 6.635, P < 0.05). Times to first defecation, anal exhaust, and recovery of bowel sounds and hospitalization time were significantly shorter in the observation group than in the control group (49.27 h ± 4.82 h vs 65.83 h ± 5.26 h, 31.45 h ± 3.72 h vs 59.26 h ± 4.01 h, 18.43 h ± 2.83 h vs 24.05 h ± 3.26 h, 8.72 h ± 1.26 h vs 11.45 h ± 2.74 h, P < 0.05). Before treatment, there was no significant difference in the levels of gastrin and motilin between the two groups (P > 0.05). After treatment, the levels of gastrin and motilin in the observation group were significantly higher than those in the control group (108.24 ng/L ± 21.36 ng/L vs 91.38 ng/L ± 22.36 ng/L, 612.79 ng/L ± 42.35 ng/L vs 506.23 ng/L ± 51.25 ng/L, P < 0.05).

CONCLUSION

Abdominal application of traditional Chinese medicine combined with chewing gum can significantly improve clinical symptoms and signs and promote the recovery of gastrointestinal function in patients with EC after surgery.

Emodin protects against oxidative stress and apoptosis in HK-2 renal tubular epithelial cells after hypoxia/reoxygenation

The aim of the present study was to determine the effects of emodin, a natural compound with antioxidant properties, on oxidative stress and apoptosis induced by hypoxia/reoxygenation (H/R) in HK-2 human renal tubular cells. In HK-2 cells subjected to H/R, it was observed that pre-treatment with emodin lead to an increase in cellular viability and a reduction in the rate of apoptosis and the B-cell lymphoma 2 (Bcl-2)-associated X protein/Bcl-2 ratio. H/R alone caused a significant increase in the levels of reactive oxygen species and malondialdehyde (P<0.05) and a significant decrease in the activities of superoxide dismutase, catalase and glutathione peroxidase (P<0.05), relative to normoxic cells. In turn, parameters of oxidative stress were improved by emodin pre-treatment. In addition, emodin pre-treatment significantly inhibited the phosphorylation of extracellular signal-regulated protein kinase and c-Jun N-terminal kinase mitogen-activated protein kinases (MAPKs) induced by H/R (P<0.05). These data suggest that emodin may prevent H/R-induced apoptosis in human renal tubular cells through the regulation of cellular oxidative stress, MAPK activation and restoration of the Bax/Bcl-2 ratio.

Determination of coumarins in the roots of Angelica dahurica by supercritical fluid chromatography

The fact that supercritical fluid chromatography (SFC) offers many desirable features is known for a long time. Yet, the number of applications on natural products is still limited, because robust and user-friendly instrumentation became available just a few years ago. As coumarins hardly have been studied by this technique we developed the first SFC assay for their determination in crude plant material. After method optimization eight standard compounds, including simple coumarins, linear and angular furanocoumarins, could be baseline separated in 6min using an Acquity UPC(2) CSH Fluoro-Phenyl 1.7μm column with supercritical CO2, methanol and diethylamine as mobile phase. Method validation confirmed that the assay is linear (R(2)≥0.9995), precise (intra-day variation≤5.8%; inter-day variation≤4.4%) and accurate (recovery rates from 96.5 to 104.2%). Detection limits determined at 300nm were below 2ng on-column, and the method showed to be well suited for the analysis of coumarins in Angelica dahurica roots. It was observed that qualitative as well as quantitative composition vary significantly. In all samples Imperatorin (0.09-0.28%) was the major coumarin, followed either by Isoimperatorin or Oxypeucedanin; the total coumarin content ranged from 0.16 to 0.77%. The results were in good agreement to published data, so that because of its speed and green nature SFC is definitely an interesting alternative for the analysis of this important class of natural products.

Microwave-assisted ionic liquid homogeneous liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of anthraquinones in Rheum palmatum L

The microwave-assisted ionic liquid homogeneous liquid-liquid microextraction (MA-IL-HLLME) coupled with high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones, including aloe-emodin, emodin, chrysophanol and physcion in root of Rheum palmatum L. Several experimental parameters influencing the extraction efficiency, including amount of sample, type and volume of ionic liquid, volume and pH value of extraction medium, microwave power and extraction time, concentration of NH4PF6 as well as centrifugal condition were optimized. When 140μL of ionic liquid ([C8MIM][BF4]) was used as an extraction solvent, target analytes can be extracted from sample matrix in one minute with the help of microwave irradiation. The MA-IL-HLLME is simple and quick. The calibration curves exhibited good linear relationship (r>0.9984). The limits of detection and quantification were in the range of 0.015-0.026 and 0.051-0.088μgmL(-1), respectively. The spiked recovery for each analyte was in the range of 81.13-93.07% with relative standard deviations lower than 6.89%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and heat reflux extraction. The results indicated that the present method can be successfully applied to the determination of anthraquinones in medicinal plant.