Astilbin suppresses delayed-type hypersensitivity by inhibiting lymphocyte migration

Toxicological profile of the Hymenaea courbaril stem bark hydroalcoholic extract using in vitro bioassays and an alternative in vivo Caenorhabditis elegans model

Hymenaea genus has been used in folk medicine in Brazil, but few studies investigated its toxicity profile. Thus, the aim of this study was to determine toxicological parameters of Hymenaea courbaril stem bark hydroalcoholic extract by utilizing three cell lines including murine macrophages (RAW 264.7), mouse fibroblast cells (L929) and human lung fibroblast (MRC-5), as well as Salmonella/microsome assay, and in vivo Caenorhabditis elegans model. The predominant detected phytoconstituents in the extract were coumarins, flavonoids, phenolics, tannins and saponins and by HPLC analysis, astilbin (AST) was found to be the main component. The DPPH assay demonstrated that H. courbaril hydroalcoholic extract exhibited potent antioxidant activity, with an IC50 of 3.12 μg/ml. The extract at concentrations of 400 and 800 μg/ml decreased cell viability 48 hr after treatment in L929 and MRC-5 cell lines. In the Raw 264.7 strain, just the highest concentration (800 μg/ml) lowered cell viability within 48 hr following exposure. The concentration of 100 μg/ml did not markedly affect cell viability in the trypan blue assay. In the alkaline comet assay the extract was found to be non-genotoxic. In the Ames test, the extract exhibited low mutagenic potential without metabolic activation, since only the highest concentrations produced an effect. H. courbaril extract only affected the survival of C. elegans at concentrations of 800 and 1600 μl/ml. These findings demonstrate that H. courbaril extract appears to exert low toxicity as evidenced in vitro and mutagenicity assays; however, the biological relevance of the response of C. elegans survival to safety assessments needs further studies.

The natural source, physicochemical properties, biological activities and metabolism of astilbin

Astilbin is a dihydroflavanol found in many plants and processed foods. Astilbin possesses multiple health-beneficial bioactivities and has received great attention. Hence, the natural source, physicochemical properties, biological activities and metabolism of astilbin are summarized in the present article. Engelhardia roxburghiana Wall. and Smilax glabra Roxb. are the main resource for astilbin purification because of high content. Because of chemical instability, astilbin amount in foods is dependent on the processing and storage conditions. The degradation of astilbin includes isomerization and decomposition. The interconversion of astilbin and its isomers occurs through a chalcone intermediates, which significantly affects the taste of wine during storage. Many factors such as temperature, pH, metal ions and food additives could affect the chemical stability of astilbin. Astilbin exhibits very novel selective immunosuppressive activity, which is not found in other compounds. The rhamnose moiety of astilbin is essential for this bioactivity. After digestion, astilbin was mainly absorbed and transported in circulatory blood in its intact form, and only one metabolite, 3'-O-methylastilbin, was found. Although having many bioactivities, astilbin faces the challenge of poor bioavailability. Some promising strategies were developed for improving its bioavailability, particularly through fabrication the zein nanoparticles.

Astilbin combined with lipopolysaccharide induces IL-10-producing regulatory B cells via the STAT3 signalling pathway

OBJECTIVES

Astilbin exerts immunoregulatory activities and plays anti-inflammatory effects in inflammation-associated diseases. IL-10-producing B cells are the major subset of regulatory B cells (Bregs) and inhibit inflammation and autoimmune diseases. This study aimed to analyse the inducing effect of astilbin on Bregs and investigate the involved molecular mechanisms.

METHODS

The frequencies and activities of IL-10-producing Bregs were observed using the co-treatment of astilbin and lipopolysaccharide (LPS) ex vivo. The protective effect of astilbin/LPS-induced Bregs on dextran sulphate sodium (DSS)-induced colitis was confirmed in vivo. The molecular signalling events of Breg induction were checked via Western blot. CD40^-/- and toll-like receptor (TLR) 4^-/- B cells were treated with astilbin/LPS to determine the modulatory role of CD40 or TLR4 on astilbin/LPS-induced Bregs.

RESULTS

Although astilbin alone could not affect Bregs, the co-treatment of astilbin and LPS remarkably induced CD19⁺ CD1d^hi and CD19⁺ TIM-1⁺ cells which produced IL-10 ex vivo. Colonic CD19⁺ CD1d^hi and CD19⁺ TIM-1⁺ cells were also increased in astilbin-treated mice with DSS-induced colitis. The adoptive transfer of CD19⁺ TIM-1⁺ cells pre-induced by astilbin/LPS directly suppressed the progression of DSS-induced colitis. Combined astilbin and LPS stimulated the STAT3 activation of CD19⁺ TIM-1⁺ cells but had no effects on SOCS3, AKT, NF-κB, Erk, JNK nor P38. Inhibiting the STAT3 phosphorylation of CD19⁺ TIM-1⁺ cells abolished Breg induction by astilbin/LPS. Furthermore, Breg induction was weakened in CD40^-/- B cells with the decrease in STAT3 activation, but had disappeared in TLR4^-/- B cells with no STAT3 activation, thereby confirming the indispensable role of TLR4 signalling in the induction of IL-10-producing Bregs.

CONCLUSIONS

This study reports the new immunoregulatory role of astilbin for promoting IL-10-producing B cells and suggests the possible use of astilbin in the therapy of inflammatory diseases.

ASTILBIN: A PROMISING UNEXPLORED COMPOUND WITH MULTIDIMENSIONAL MEDICINAL AND HEALTH BENEFITS

BACKGROUND

Many flavonoids have various beneficial actions like anti-inflammatory, anti-carcinogenic properties and many other clinical conditions. Astilbin is one such flavanoid compound having many physiological as well as pharmacological actions.

PURPOSE

To summarize the important findings from the research conducted using astilbin having significance to its physiological and pharmacological activities as well as the patents filed using astilbin.

STUDY DESIGN

Systematic review and compilation of the collected literature.

METHOD

An extensive investigation of literature was done using several worldwide electronic scientific databases like PUBMED, SCOPUS, Science Direct and Google Scholar etc. All the article available in the English language that used our compound of interest i.e. astilbin, on the basis of inclusion criteria decided were retrieved from these databases, thoroughly reviewed and were summarized.

RESULT

It has been established that astilbin can play a vital in the management of diseases associated with immune system. It also possesses antibacterial, anti-oxidative and hepatoprotective activity.

CONCLUSION

These researches provide evidence that astilbin possesses great potential and thus can be utilized in the management of various disorders, thus establishing itself as a potential candidate for novel drug development. Also, there is still room for research on astilbin like it can be evaluated for anticancer potential, protective effect in various diabetic complications and many more. Overall observations from data suggested that astilbin is a promising compound and proved its efficacy in every preclinical study which is conducted till date. Some of the pharmacological activity is still unexplored. After successful preclinical trials, astilbin can go for further clinical trials.

Pharmacokinetic, bioavailability and tissue distribution study of astilbin in rats

OBJECTIVE

The purpose of this study is to reveal the pharmacokinetic profiles of astilbin with various doses in rats and investigate the oral absolute bioavailability and tissue distribution of astilbin after oral administration.

METHODS

Wistar rats were orally administered astilbin 12, 24 mg/kg and intravenous administered astilbin 6 mg/kg randomly. The concentration of astilbin in rat plasma and various tissue samples was determined by LC-MS/MS method. Noncompartmental pharmacokinetic parameters including AUC and t_1/2 were calculated from plasma concentration-time data of astilbin with the DAS 3.0.

KEY FINDINGS

After oral administration of astilbin 12 and 24 mg/kg to rats, the oral absolute bioavailability of astilbin were 1.16 ± 0.695% and 1.27 ± 0.379%; the plasma elimination half-lives (t_1/2 ) were 101 ± 35.8 and 109 ± 25.3 min, respectively. Astilbin had a rapid absorption and a wide distribution throughout the whole body except liver and fat following oral administration. Astilbin could penetrate the blood-brain barrier of rat.

CONCLUSIONS

The oral absolute bioavailability of astilbin is poor because of the low permeability and solubility. Both oral absorption and clearance of astilbin in rats are rapid after oral administration.

Astilbin promotes the induction of regulatory NK1.1- CD4+ NKG2D+ T cells through the PI3K, STAT3, and MAPK signaling pathways

Astilbin is a potential agent for autoimmune and inflammatory diseases and has a protective effect in mice with DSS-induced colitis. NK1.1^- CD4⁺ NKG2D⁺ T cells are a subpopulation of regulatory T cells that produce TGF-β1 and IL-10. Whether astilbin directly promotes the induction of NK1.1^- CD4⁺ NKG2D⁺ T cells and whether these astilbin-stimulated T cells exert an immune-regulatory role remain unclear. Here, we show that astilbin efficiently induces the production of NK1.1^- CD4⁺ NKG2D⁺ T cells with high expressions of TGF-β1, IL-10, CCR6, and CCR9 in a dose-dependent manner ex vivo. These regulatory T cells also substantially inhibit the activities of CD8⁺ T cells and macrophages. Intraperitoneal injection of astilbin ameliorates the severity of colitis with an increase in the frequency of NK1.1^- CD4⁺ NKG2D⁺ T cells in the colon tissue of DSS-treated mice. Moreover, adoptive transfer of NK1.1^- CD4⁺ NKG2D⁺ T cells induced by astilbin remarkably protects against the onset of DSS-induced colitis. Finally, the PI3K, STAT3, and MAPK signaling pathways are involved in the induction of NK1.1^- CD4⁺ NKG2D⁺ T cells by astilbin. Taken together, our study elucidates a new immune-regulatory mechanism of astilbin by inducing the regulatory NK1.1^- CD4⁺ NKG2D⁺ T cells and indicates a potential clinical use of astilbin for patients with inflammatory bowel diseases.

Astilbin ameliorates experimental autoimmune myasthenia gravis by decreased Th17 cytokines and up-regulated T regulatory cells

Astilbin, a major bioactive compound extracted from Rhizoma smilacis glabrae (RSG), has been reported to possess immunosuppressive properties. Our study first evaluated the effect of astilbin on experimental autoimmune myasthenia gravis (EAMG) in Lewis rats. The results showed that astilbin could attenuate the severity of EAMG by decreasing antigen-specific autoantibodies with up-regulation of regulatory T cells and down-regulation of Th17 cells. In addition to, astilbin also reduced the efficiency of the antigen presenting cells on which the expression of MHC class II decreased. These results suggest that astilbin might be a candidate drug for immunoregulation of EAMG, and provide us new treatment ideas for human myasthenia gravis (MG).

Sarsaparilla (Smilax Glabra Rhizome) extract inhibits migration and invasion of cancer cells by suppressing TGF-β1 pathway

Sarsaparilla, also known as Smilax Glabra Rhizome (SGR), was shown to modulate immunity, protect against liver injury, lower blood glucose and suppress cancer. However, its effects on cancer cell adhesion, migration and invasion were unclear. In the present study, we found that the supernatant of water-soluble extract from SGR (SW) could promote adhesion, inhibit migration and invasion of HepG2, MDA-MB-231 and T24 cells in vitro, as well as suppress metastasis of MDA-MB-231 cells in vivo. Results of F-actin and vinculin dual staining showed the enhanced focal adhesion in SW-treated cells. Microarray analysis indicated a repression of TGF-β1 signaling by SW treatment, which was verified by real-time RT-PCR of TGF-β1-related genes and immunoblotting of TGFBR1 protein. SW was also shown to antagonize TGF-β1-promoted cell migration. Collectively, our study revealed a new antitumor function of Sarsaparilla in counteracting invasiveness of a subset of cancer cells by inhibiting TGF-β1 signaling.

Induction of TGF-β and IL-10 production in dendritic cells using astilbin to inhibit dextran sulfate sodium-induced colitis

Astilbin, a major bioactive compound from Rhizoma smilacis glabrae, has been reported to possess anti-inflammatory properties. Our study first evaluated astilbin on dextran sulfate sodium (DSS)-induced acute colitis in mice. By intraperitoneal injection of astilbin, the severity of colitis was attenuated, and the serum levels of IL-10 and TGF-β were increased. Using flow cytometry, a higher number of IL-10(+) dendritic cells (DCs) and TGF-β(+) DCs and a lower number of CD86(+) DCs, IL-12 p40(+) DCs, and IL-1β(+) DCs were detected in the spleen of mice with colitis after astilbin treatment. The administration of astilbin also resulted in the upregulation of CD103(+) expression in colonic DCs. In a coculture system, murine bone marrow-derived DCs pretreated with astilbin resulted in an enhanced production of CD4(+)CD25(+)Foxp3(+) T cells. The results of this study show that astilbin could be a candidate drug for inflammatory bowel disease by mediating the regulatory functions of DCs.

Phytochemical study guided by the myorelaxant activity of the crude extract, fractions and constituent from stem bark of Hymenaea courbaril L

ETHNOPHARMACOLOGICAL RELEVANCE

Hymenaea courbaril L. (Caesalpinoideae) is used in Brazilian folk medicine to treat anemia, kidney problems, sore throat and other dysfunctions of the respiratory system, such as bronchitis and asthma, although such properties are yet to be scientifically validated.

AIM OF THE STUDY

In order to give a scientific basis to support the traditional use of Hymenaea courbaril, this study was designed to evaluate antioxidant, myorelaxant and anti-inflammatory properties of the ethanol extract from stem bark and its fractions. The myorelaxant effect of astilbin, a flavonoid isolated from the bioactive ethyl acetate fraction (EAF), has also been evaluated.

MATERIAL AND METHODS

In the present study ethanol extract from stem bark (EEHC) and fractions were analyzed using bioassay-guided fractionation. The following activities were investigated: antioxidant by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, myorelaxant on rat tracheal smooth muscle, and anti-inflammatory using ovalbumin-induced leukocytosis and airway hyperresponsiveness in rats.

RESULTS

The results of the present investigation show that the whole extract of Hymenaea courbaril and some of its fractions strongly scavenged DPPH radical. The extract showed myorelaxant activity on rat trachea, being EAF its highest efficient fraction. Bio-guided study allowed the isolation of astilbin, a well-known flavonoid. The activity induced by this compound indicates that it may be partly responsible for the myorelaxant effect of EAF. EAF reduced contractions that depended on divalent cation inflow through voltage-operated Ca(2+) channels (VOCCs) or receptor-operated Ca(2+) channels (ROCCs), but it was more potent to inhibit VOCC- than ROCC-dependent contraction induced by Ca(2+) addition in ACh-enriched Ca(2+)-free medium. Oral pretreatment of antigen-challenged animals with EAF prevented airway hyperresponsiveness on KCl-induced contraction and reduced the number of total white cells, particularly eosinophils and neutrophils in bronchoalveolar lavage.

CONCLUSIONS

This study provided scientific basis that Hymenaea courbaril presents potential antioxidant, myorelaxant and anti-inflammatory actions, which support its use in folk medicine to treat inflammatory airway diseases.

PVP and surfactant combined carrier as an effective absorption enhancer of poorly soluble astilbin in vitro and in vivo

CONTEXT

Astilbin is considered to be a new and promising immunosuppressant for immune related diseases, but limited in clinical application due to its poor water solubility, difficult oral absorption and low bioavailability.

OBJECTIVE

The present work studied the effect of PVP and surfactant combined carrier on its capability to improve drug absorption.

MATERIALS AND METHODS

PVP K30-Tween 80 combined carries was applied into the astilbin solid dispersions, tested both in vivo in beagle dogs and in vitro in transport experiments across Caco-2 cell monolayers.

RESULTS AND DISCUSSION

In the animal studies a many fold increase in plasma AUC was observed for the solid dispersions of drug in PVP K30-Tween 80 combined carries compared to active pharmaceutical ingredient (API). The applicability of Caco-2 monolayers as a tool for predicting the in vivo transport behavior of Astilbin in combination with a solubility enhancing carries was shown. In vitro transport studies confirmed the effect of combined carries on the absorption behavior of the astilbin. MTT studies showed the cell viability gradually decreased with the increase of the drug concentration in a dose dependent manner for astilbin and that in solid dispersions. The permeability and apparent permeability coefficients (Papp) increased with drug in the Caco-2 cell.

CONCLUSION

In this study, it was found that PVP K30 and Tween 80 promoted the permeability of drugs best within a certain amount. For astilbin PVP K30 and surfactant combined carrier had a strong potential to improve oral bioavailability.

Astilbin inhibits proliferation of rat aortic smooth muscle cells induced by angiotensin II and down-regulates expression of protooncogene

This study examined the effect of astilbin on the proliferation of rat aortic smooth muscle cells (RASMCs) induced by angiotensin II (AngII) and explored the possible mechanisms. Cell proliferation model of RASMCs was induced by treatmente with AngII. Cells were randomly divided to 8 groups. Normally cultured VSMCs serves as blank control group; in AngII model group, cells were treated with AngII at 10(-7) mol/L; in three astilbin groups, cells were treated with 10, 15, 30 mg/L of astilbin; in three AngII+astilbin groups, cells were treated with AngII (at 10(-7) mol/L) and astilbin at 10, 15, 30 mg/L. Cell proliferation ability was detected by MTT method and the cell cycles and proliferation index were flow cytometrically determined. The expression of c-myc mRNA was assessed by using reverse transcription polymerase chain reaction (RT-PCR), and the expression of NF-κB in RASMCs was immunocytochemically observed. Our results showed that MTT metabolism in RASMCs in the basic and AngII stimulated situation was inhibited by astilbin, and the cells numbers of G(0)/G(1) phase were increased and that of G(2)/S phase were decreased markedly. Not only highly expression of c-myc gene stimulated by AngII could be inhibited by Astilbin significantly, but also the expression of NF-κB protein can be down regulated by Astilbin. We are led to conclude that astilbin astilbin can inhibit the AngII-mediated proliferation of RASMCs by blocking the transition of RASMCs from G(0)/G(1) phase to S phase and by down-regulating the expression of NF-κB, c-myc gene.

Astilbin prevents concanavalin A-induced liver injury by reducing TNF-α production and T lymphocyte adhesion

The aim of this study was to evaluate the effect of astilbin on concanavalin A (Con A)-induced hepatitis, a T cell-dependent model of liver injury. Con A administration resulted in a severe liver injury in mice, with a strong increment in spleen cell adhesion and liver infiltration of T cells, as well as in tumour necrosis factor (TNF)-α production. Against this liver injury, astilbin significantly inhibited the elevation in transaminase activity, reduced the TNF-α production, and improved the histological changes, including inflammatory infiltration, hepatocyte necrosis and degeneration and Kupffer cell hyperplasia. In addition, astilbin inhibited the adhesion of spleen cells and purified T lymphocytes isolated from the liver-injured mice to fibronectin, laminin and type IV collagen. Moreover, the adhesion of human Jurkat T cells to endothelial cell line ECV-304 was also inhibited by astilbin. These results suggest that the improvement of the T cell-mediated liver injury by astilbin may be related to the reduction in TNF-α production and in T cell adhesion to extracellular matrices and endothelial cells.

The inhibitory effect of astilbin on the arteriosclerosis of murine thoracic aorta transplant

The inhibitory effect of astilbin on transplant arteriosclerosis in murine model of thoracic aorta transplantation was examined. Model of rat thoracic aorta transplantation was established. Ninety rats were divided into three groups. In isograft group, the thoracic aorta of Brown Norway (BN) rat was anastomosed with the abdominal aorta of another BN rat. In allograft group, the thoracic aorta of BN rat was anastomosed with the abdominal aorta of Lewis rat. In astilbin group, the rats receiving allo-transplantation were given astilbin 5 mg/kg per day for a time of 28 days. The donor thoracic aorta and the recipient abdominal aorta were anastomosed by means of a polyethylene cannula (inner diameter: 1.5 mm, length: 3 mm length). The grafts were histologically examined for structural changes. The areas of arterial lumen and endatrium were calculated. Our results showed that, in the allograft group, 28 days after allografting, conspicuous proliferation of smooth muscles and infiltration with a great number of inflammatory cells were found in the tunica intima and tunica media. Astilbin significantly inhibited the proliferation of smooth muscles and ameliorated the infiltration of inflammatory cells thereby prevent against the development of transplant arteriosclerosis. It is concluded that asltilbin can effectively prevent the development of arteriosclerosis in allotransplant by inhibiting the proliferation of smooth muscles and inhibit the proliferation of smooth muscles in tunica of intima and media and reducing infiltration of the inflammatory cells.

Chinese herbal medicine (Tuhuai extract) exhibits topical anti-proliferative and anti-inflammatory activity in murine disease models

While psoriasis is one of the most common skin disorders in humans, effective, safe and inexpensive treatments are still largely unavailable. Chinese herbal medicine (CHM) has been used for centuries for treating psoriasis and several reports claim that systemic administration of one such CHM, Tuhuai, mainly composed of flos sophorae, smilax glabra roxb and licorice, is effective in psoriasis. However, the mechanisms by which this CHM improves psoriasis are not yet clear. Two universal features of psoriasis are epidermal hyperplasia and inflammation. Moreover, drugs that specifically inhibit epidermal hyperplasia and/or inflammation are widely used to treat psoriasis. Here, we investigated whether topical applications of Tuhuai extract exhibit anti-proliferative and anti-inflammatory activities in two murine models of inflammatory dermatoses. To assess Tuhuai's potential anti-proliferative effect, we disrupted epidermal barrier function twice-daily for 4 days in normal hairless mice followed by topical applications of either 1% Tuhuai extract or Vehicle to both flanks immediately after each barrier perturbation. Changes in epidermal proliferation and apoptosis were evaluated by immunohistochemistry and TUNEL staining. To assess the anti-inflammatory effects of Tuhuai, both irritant (phorbol ester) and acute allergic contact dermatitis (oxazolone) models were used. Whereas topical Tuhuai extract did not alter epidermal proliferation or induce irritation in normal skin, it both reduced epidermal hyperplasia in the epidermal hyperproliferative model, and reduced inflammation in both irritant and allergic contact dermatitis models. As topical Tuhuai extract exhibits anti-proliferative and anti-inflammatory properties in a variety of human models of inflammatory dermatoses, Tuhuai could provide an effective, relatively safe and inexpensive therapeutic alternative for the treatment of inflammatory dermatoses, including psoriasis.

Wnt signaling induces matrix metalloproteinase expression and regulates T cell transmigration

Wnts are a family of secreted glycoproteins with diverse developmental roles, including regulation of cell migration; however, little is known about wnt signaling in mature T cells. We find that endothelial-cell-derived wnts, acting through Frizzled receptors, induce matrix metalloproteinase (MMP) 2 and MMP9 expression in effector T cells. Blocking wnt signaling, or MMP activity, reduces T cell migration through the basement membrane in vitro and into inflamed skin in vivo. Wnt signaling stabilizes beta-catenin protein in T cells and directly targets the MMP promoters through tandem TCF sites. Thus, our data support a necessary and previously unexpected role for wnt signaling in T cell extravasation.

Identification of a New Metabolite of Astilbin, 3′-O-Methylastilbin, and Its Immunosuppressive Activity against Contact Dermatitis

Background: Astilbin is a flavonoid isolated from the rhizome of Smilax glabra. In a previous study, we revealed its unique immunosuppressive activity, a selective inhibition against activated T lymphocytes. This characteristic of astilbin is beneficial for the treatment of human immune diseases.

Methods: We incubated astilbin with rat liver microsomal/cytosolic fractions and isolated the metabolite of astilbin, which was fully characterized by mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. We administered astilbin orally via a gastric tube to rats at 0.22 mmol/kg and collected whole blood samples after 30 min and urine samples after 0 to 12 h. We applied HPLC and liquid chromatography/MS to measure the metabolite in the samples, and we assayed cytokine expression by reverse-transcription PCR.

Results: After incubation of astilbin with rat liver microsomal/cytosolic fractions, we detected a new metabolite of astilbin and isolated it from the culture solution. We characterized this metabolite by MS and NMR techniques as 3′-O-methylated astilbin. We detected the metabolite in both blood and urine samples after oral administration of astilbin, and the metabolite inhibited picryl chloride–induced ear swelling in mice and suppressed the expression of tumor necrosis factor-α and interferon-γ, similarly to astilbin.

Conclusion: This is the first identification of 3′-O-methylastilbin as a new flavonoid, as well as an active metabolite of astilbin in vivo, and is helpful for studying the kinetics of astilbin and its clinical applications.

Simultaneous quantification of five major bioactive flavonoids in Rhizoma smilacis glabrae by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method was developed for the simultaneous determination of five flavonoids, taxifolin, neoastilbin, astilbin, neoisoastilbin and isoastilbin, contained in rhizoma smilacis glabrae. The optimal conditions of separation and detection were achieved on a Lichrospher C18 column (250 mm x 4.6 mm, 5 microm), with a gradient elution program, detected at 291 nm. The correlation coefficients of all the calibration curves showed good linearity (r>0.999) within test ranges. The relative deviation of this method was less than 3% for intra- and inter-day assays, and the average recoveries (n=3) were between 96.2 and 103.1%. The extraction process was also optimized as 2 h immersion and 30 min sonication in 60% ethanol. Eight samples of rhizoma smilacis glabrae from different locations in China were analyzed. The results indicate that the assay is reproducible and precise and could be readily utilized for the quality control of rhizoma smilacis glabrae.

Effects of Astilbe thunbergii rhizomes on wound healing Part 1. Isolation of promotional effectors from Astilbe thunbergii rhizomes on burn wound healing

The dried rhizomes of Astilbe thunbergii (Sieb. et Zucc) Miq (Saxifragaceae) have been traditionally used for the treatments of a sword cut, wound bitten by animals, frost-bite, burn, suppurative dermatitis or skin inflammatory diseases from the Tang period (about 8th century) in China. The physiological actions, especially the wound-healing effects of this drug are not yet well understood. In this study, we examined the effects of an ethanol extract of Astilbe thunbergii rhizomes on burn wound healing in mice. The topical application at a dose of 100mg ointment per wound of 70% ethanol extract (0.5 or 1.0% (w/w) ointment) of this drug promoted the burn wound healing. The ethanol extract was divided into two fractions (ethyl acetate-soluble and -insoluble fractions), and it was found that the topical application at a dose of 100mg ointment per wound of the ethyl acetate-soluble fraction (0.5 and 1.0% ointment) promoted the burn wound healing. Based on this finding, we attempted to isolate the active substance(s) from the ethyl acetate-soluble fraction. Three active substances 1, 2 and 3, were obtained from A. thunbergii rhizomes as promotional effectors of burn wound healing in mice. Based on the analysis of (1)H and (13)C NMR spectra, compounds 1, 2 and 3 were identified as eucryphin (1), bergenin (2) and astilbin (3), respectively. The effective dose (ED(50)) of compounds 1, 2 and 3 on burn wound healing were 4, 190 and 64 microg/wound, respectively. Among these three compounds, eucryphin (1) promoted the burn wound healing most strongly.

Quantitative determination of astilbin in rabbit plasma by liquid chromatography

A simple method for determining the concentration of astilbin, a flavanone, in rabbit plasma has been developed. After liquid-liquid extraction, the flavanone was detected by HPLC on a 4.6-microm octadecylsilica column (Nova-Pak C-18) at 291 nm. Linear calibration graphs for astilbin were constructed from 0.44 to 22.17 microM. The limit of quantitation was 0.44 microM in plasma. The method has been applied to pharmacokinetic studies after a single i.v. and an oral administration of the compound to rabbits.