Emodin palliates high-fat diet-induced nonalcoholic fatty liver disease in mice via activating the farnesoid X receptor pathway.

BACKGROUND: Cassia mimosoides Linn (CMD) is a traditional Chinese herb that clears liver heat and dampness. It has been widely administered in clinical practice to treat jaundice associated with damp-heat pathogen and obesity. Emodin (EMO) is a major bioactive constituent of CMD that has apparent therapeutic efficacy against obesity and fatty liver. Here, we investigated the protective effects and underlying mechanisms of EMO against high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD). OBJECTIVE: We aimed to investigate whether EMO activates farnesoid X receptor (FXR) signaling to alleviate HFD-induced NAFLD. MATERIALS AND METHODS: In vivo assays included serum biochemical indices tests, histopathology, western blotting, and qRT-PCR to evaluate the effects of EMO on glucose and lipid metabolism disorders in wild type (WT) and FXR knockout mice maintained on an HFD. In vitro experiments included intracellular triglyceride (TG) level measurement and Oil Red O staining to assess the capacity of EMO to remove lipids induced by oleic acid and palmitic acid in WT and FXR knockout mouse primary hepatocytes (MPHs). We also detected mRNA expression of FXR signaling genes in MPHs. RESULTS: After HFD administration, body weight and serum lipid and inflammation levels were dramatically increased in the WT mice. The animals also presented with impaired glucose tolerance, insulin resistance, and antioxidant capacity, liver tissue attenuation, and pathological injury. EMO remarkably reversed the foregoing changes in HFD-induced mice. EMO improved HFD-induced lipid accumulation, insulin resistance, inflammation, and oxidative stress in a dose-dependent manner in WT mice by inhibiting FXR expression. EMO also significantly repressed TG hyperaccumulation by upregulating FXR expression in MPHs. However, it did not improve lipid accumulation, insulin sensitivity, or glucose tolerance in HFD-fed FXR knockout mice. CONCLUSIONS: The present study demonstrated that EMO alleviates HFD-induced NAFLD by activating FXR signaling which improves lipid accumulation, insulin resistance, inflammation, and oxidative stress.

The isolation of secondary metabolites from Rheum ribes L. and the synthesis of new semi-synthetic anthraquinones: Isolation, synthesis and biological activity.

Rheum ribes L. (Rhubarb) is one of the most important edible medicinal plants in the Eastern Anatolia region and is called "Iskin" by local people. Resveratrol and 6-O-methylalaternin were isolated from the Rhubarb for the first time in addition to well-known secondary metabolites including emodin, aloe-emodin, ß-sitosterol and rutin. The new semi-synthetic anthraquinone derivatives with the NαFmoc-l-Lys and ethynyl group were synthesized from the isolated anthraquinones emodin and aloe-emodin of Rhubarb to increase the bioactivities. Aloe-emodin derivative with NαFmoc-l-Lys shows the highest inhibition values by 94.11 ± 0.12 and 82.38 ± 0.00% against HT-29 and HeLa cell lines, respectively, at 25 µg/mL. Further, modification of the aloe-emodin with both the ethynyl and the NαFmoc-l-Lys groups showed an antioxidant activity-enhancing effect. From molecular docking studies, the relative binding energies of the emodin and aloe-emodin derivatives to human serum albumin ranged from -7.30 and -10.62 kcal/mol.

A New Depsidone from Teloschistes flavicans and the Antileukemic Activity.

Lichens produce a variety of secondary metabolites that could be potential sources of pharmaceutically useful chemicals. However, only a limited number of lichen metabolites have been investigated for their biological significance. The objective of this study was to identify the potential compounds responsible for the antileukemic activity of lichen Teloschistes flavicans. Among three fractions (n-hexane, EtOAc, and MeOH-H2O), the ethyl acetate (EtOAc) fraction of T. flavicans methanolic extract showed the strongest inhibition in the HL-60 cell line. Additionally, the EtOAc fraction was further purified to obtain a new depsidone, 2,7-dichloro-3,8-dimethoxy-1,6,9-trimethyl-11H-dibenzo[b,e][1,4]dioxepin-11-one, named as flavicansone, along with rhizonic acid, parietin, and vicanicin. Flavicansone demonstrated the most significant inhibitory action against cell proliferation among the four isolated compounds.

Identification and characterization of anti-diabetic principle in Senna alata (Linn.) flower using alloxan-induced diabetic male Wistar rats.

ETHNO-PHARMACOLOGICAL RELEVANCE: The age-long folkloric use of Senna alata flower (SAF) was recently substantiated with scientific evidence. However, the study did not account for the anti-diabetic principle(s) in SAF. AIM OF THE STUDY: The study aimed to identify and characterize the bioactive principle(s) responsible for the anti-diabetic activity in SAF. MATERIALS AND METHODS: Ninety-one male Wistar rats were used for the two phases of this study. In phase 1, forty-two of these were allotted into six groups (A-F) of seven rats each. Animals in group A received distilled water while those in groups B-F were made diabetic by treatment with 150 mg/kg body weight (b.w.) of alloxan. Group B received 0.5 mL of distilled water; C, D and E were treated each with 75 mg/kg b.w. of ethyl acetate, n-butanol and aqueous residual fractions of SAF, while F received 2.5 mg/kg b.w. of glibenclamide. In the second phase, forty-nine rats were assigned into seven groups (A-G) of seven rats each. Group A received distilled water. Animals in Groups B-G were also made diabetic by alloxan treatment. B received 0.5 mL of distilled water; C, D, E and F were treated with 5.77, 25.96, 15.40, 27.87 mg/kg b.w (equivalent dose of 75 mg/kg b.w.) of sub-fractions obtained from the ethyl acetate fraction of SAF respectively whereas G received 2.5 mg/kg b.w. of glibenclamide. Fasting blood glucose (FBG), serum lipids, albumin, globulin, liver glycogen, urine ketone, hexokinase and glucose-6-phosphate dehydrogenase activities, α-glucosidase and α-amylase inhibitory activities and cardiac function indices were evaluated using standard methods. Compounds D, E and F isolated from ethyl acetate sub-fraction B were evaluated for in vitro anti-diabetic activity. The structure of the anti-diabetic compound was identified using FTIR, 1H-NMR, 1³C-NMR, HCOSY, HSQC and HMBC. Data were subjected to Analysis of Variance and Duncan Multiple Range Test at p < 0.05. RESULTS: Alloxan treatment increased the levels of FBG, total cholesterol, LDL-cholesterol, VLDL-cholesterol, urine ketone and cardiac function indices and reduced the levels of globulin, albumin, HDL-cholesterol, globulin, liver glycogen, hexokinase and glucose-6-phosphate dehydrogenase activities. Ethyl acetate fraction and sub-fraction B reversed the level and/or activities of these biochemical indices to levels and/or activities that compared favourably with the distilled water treated non-diabetic animals. Of the three compounds (D, E and F) that were obtained from the sub-fraction B, compound E which was Emodin (1, 3, 8-trihydroxy-6-methylanthraquinone) produced the highest α-glucosidase and α-amylase inhibitory activities. CONCLUSION: Emodin is one of the bioactive constituents present in Senna alata flower.

Solid phase adsorption of emodin on hydrotalcites and inorganic oxides: A preliminary study.

Solid phase extraction applied to plant matrices is nowadays a well validated technique allowing the concentration and purification of selected secondary metabolites for subsequent analysis. In this short communication we screened the efficiency of 16 selected solid supports including layered structures (hydrotalcites and zirconium phosphate), magnesium oxide and hydroxide, and finally the phyllosilicates talc and bentonite for the selective concentration of the anthraquinone emodin from raw solid extracts of Polygonum cuspidatum Siebold & Zucc. (sin. Reynoutria japonica Houtt.) (Polygonaceae), commonly known as "Japanese knotweed". An ethanolic solution of sample extract from this plant was vigorously mixed with fixed quantities of each solid support. Subsequent HPLC analysis, coupled to photodiode array detection, revealed that, among the solid supports assayed, the hydrotalcite zinc aluminum oleate and magnesium oxide were largely the most effective to this concern. Both were able to extract emodin from the raw extract in percentages of 81.5 % and 92.4 %, respectively. The application of the title supports for the extraction and concentration in the solid phase of anthraquinones from raw plant extracts have been reported herein for the first time.

Radix Polygoni Multiflori and Its Main Component Emodin Attenuate Non-Alcoholic Fatty Liver Disease in Zebrafish by Regulation of AMPK Signaling Pathway.

PURPOSE: Nonalcoholic fatty liver disease (NAFLD) has become a predictor of death in many diseases. This study was carried out to investigate the therapeutic effect of Radix Polygoni Multiflori Preparata (RPMP) and its main component emodin on egg yolk powder-induced NAFLD in zebrafish. Further investigation was performed to explore whether emodin was the main component of RPMP for the treatment of NAFLD as well as the underlying therapeutic mechanism of RPMP and emodin. METHODS: Zebrafish were divided into control group, egg yolk powder group, RPMP group and emodin group. The obesity of zebrafish was evaluated by body weight, body length and BMI. The content of lipid was detected by triglyceride (TG), total cholesterol (TC) reagent kit and the fatty acid was detected by nonesterified free fatty acids (NEFA) reagent kit. HE staining was used to detect the histological structure of liver. Whole-mount Oil red O staining and Frozen oil red O staining were carried out to investigate the lipid accumulation in liver. KEGG and STRING databases were performed to analyze the potential role of AMPK between insulin resistance (IR) and fatty acid oxidation. Western blot and RT-qPCR were carried out for mechanism research. RESULTS: RPMP and emodin significantly reduced zebrafish weight, body length and BMI. Both RPMP and emodin treatment could reduce the lipid deposition in zebrafish liver. RPMP significantly reduced the content of TG. However, emodin significantly reduced the contents of TG, TC and NEFA in zebrafish with NAFLD. The protein interaction network indicated that AMPK participated in both IR and fatty acid oxidation. Further investigation indicated that RPMP and emodin reduced hepatic lipogenesis via up-regulating the expressions of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT2), amp-activated protein kinase alpha (AMPKα), proliferator-activated receptor alpha (PPARα), carnitine palmitoyl transferase 1a (CPT-1a) and acyl-coenzyme A oxidase 1 (ACOX1). CONCLUSION: These findings suggest that emodin is the main component of RPMP for the treatment of NAFLD, which is closely related to the regulation of AMPK signaling pathway which increases IR and fatty acid oxidation.

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.

Quantification of eight active ingredients in crude and processed radix polygoni multiflori applying miniaturized matrix solid-phase dispersion microextraction followed by UHPLC.

A rapid, efficient, and green sample preparation method has been developed to extract eight active ingredients (gallic acid, catechins, epicatechin, polydatin, 2,3,5,4'-tetrahydroxystilbene-2-O-ß-d-glucoside, resveratrol, emodin, and physcion) in radix polygoni multiflori by miniaturized matrix solid-phase dispersion microextraction. Simple and sensitive ultra high performance liquid chromatography combined with ultraviolet detection has been applied to analyze the multiple compounds. The best results were obtained by adding 25 mg sample into 25 mg adsorbent and grinding for 2 min with disorganized silica as adsorbent and 1 mL 150 mM 1-dodecyl-3-methylimidazolium bromide as a green eluting solvent. Good linearity (r2  > 0.998) for each analyte was obtained by this method. The intra-day and inter-day precision (RSD) were both below 5.31%, and the recoveries of the analytes ranged from 93.3 to 100.0%. This simple miniaturized matrix solid-phase dispersion microextraction method for analyzing the compounds in radix polygoni multiflori needs a short time and requires little sample and reagent. Thus, this method is far more eco-friendly and efficient than traditional extraction methods (reflux and ultrasound-assisted extraction). The present investigation provided a promising method for the fast preparation and discrimination of chemical differences in crude and processed radix polygoni multiflori.

Physcion 8­O­ß­glucopyranoside extracted from Polygonum cuspidatum exhibits anti­proliferative and anti­inflammatory effects on MH7A rheumatoid arthritis­derived fibroblast­like synoviocytes through the TGF­ß/MAPK pathway.

The present study aimed to investigate the anti­arthritic effect of physcion 8­O­ß­glucopyranoside (POGD) and its possible mechanisms. The anti­proliferative effects of POGD on MH7A cells were detected using a CCK­8 assay, and the release of pro­inflammatory cytokines, interleukin (IL)­1ß, IL­6, IL­8, IL­12 and IL­17A, were determined by ELISA. A type II collagen­induced arthritis (CIA) rat model was established to evaluate the anti­arthritic effect of POGD in vivo. The paw volumes, arthritis indices and serum levels of tumor necrosis factor (TNF)­α, IL­1ß, IL­6, IL­8, IL­17A were determined by ELISA. The mRNA expression levels of matrix metalloproteinase (MMP)­2, MMP­3, MMP­9, vascular endothelial growth factor and cyclooxygenase­2 were determined by reverse transcription­quantitative polymerase chain reaction analysis, and the expression levels of transforming growth factor (TGF)­ß1, small mothers against decapentaplegic (Smad)4, Smad7, c­Jun N­terminal kinase (JNK), phosphorylated (p­)JNK, p­P38, P38, p­extracellular signal­regulated kinase (ERK)1/2, ERK1/2, nuclear factor (NF)­κB p65 in the nucleus (N), cytosolic NF­κB p65 (C), and inhibitor of NF­κB (IκB) were determined by western blot analysis. The results indicated that POGD significantly inhibited MH7A cell growth. POGD markedly inhibited paw swelling and the arthritis indices of the CIA rats, and POGD may also inhibit the release of pro­inflammatory cytokines. Furthermore, POGD downregulated the expression levels of TGF­ß1, Smad4, NF­κB p65 (N), p38, p­p38, p­ERK1/2, JNK, p­JNK, TGF­ß1, Smad4, p­JNK, JNK, p­P38, P38, p­ERK1/2, ERK1/2 and NF­κB p65 (N), and upregulated the Smad7, NF­κB p65 (C) and IκB in TNF­α induced MH7A cells. In conclusion, the results suggested that POGD is a promising potential anti­inflammatory drug, and that POGD may decrease the expression of pro­inflammatory cytokines and mediators via inhibiting the TGF­ß/NF­κB/mitogen­activated protein kinase pathways.

Evaluation of an antiparasitic compound extracted from Polygonum cuspidatum against Ichthyophthirius multifiliis in grass carp.

Ichthyophthirius multifiliis is a ciliated parasite that infests almost all freshwater fish species and causes great economic losses to the aquaculture industry. In this study, a compound with anti-I. multifiliis activity was isolated from Polygonum cuspidatum and identified as emodin. In vitro anti-I. multifiliis results showed that emodin at 1 mg/L killed all I. multifiliis theronts for 96.0 min, and at 0.5 mg/L or lower concentrations could not kill all I. multifiliis theronts, but could significantly reduce the infectivity of theronts after pretreatment with emodin at the low concentrations mentioned above for 2 h. Additionally, emodin at 1 mg/L and 2 mg/L completely terminated the reproduction of nonencysted and encysted tomonts, respectively. In vivo tests, emodin at 0.5 mg/L could cure infected grass carp and protect naive fish from I. multifiliis infection by continuous adding emodin for 10 days. The 96 h median lethal concentration (LC50) of emodin to grass carp was 3.15 mg/L, which were approximately 18 and 7 times the median effective concentration (EC50) of emodin for killing theronts (0.18 mg/L) and nonencysted tomonts (0.45 mg/L), respectively. On the basis of these results, emodin is an effective compound for the development of a new drug against I. multifiliis.

An optimized protocol for anthraquinones isolation from Rhamnus frangula L.

Different from works described in the literature, which use expansive analytical methods to separation of anthraquinones derivatives (AQs), this communication reported a simple and inexpensive methodology to get them. In this way, the expensive commercial AQs: Chrysophanol, physcione and emodine were extracted from plant material (Rhamnus frangula L.) and isolated by classical column chromatography technique under optimised binary mobile phase gradients (CHCl3 : AcOEt(a), a = 1 to 5%) in excellent yields.

Antibacterial and antibiofilm activities of the metabolites isolated from the culture of the mangrove-derived endophytic fungus Eurotium chevalieri KUFA 0006.

Five previously undescribed metabolites, including acetylquestinol, two prenylated indole 3-carbaldehyde derivatives, an anthranilic acid derivative and an isochromone derivative, were isolated, in addition to eleven known compounds: palmitic acid, ergosterol 5,8-endoperoxide, emodin, physcion, questin, questinol, (11S, 14R)-cyclo(tryptophylvalyl), preechinulin, neoechinulin E, echinulin and eurocristatine, from the culture of the endophytic fungus Eurotium chevalieri KUFA 0006. The structures of the previously undescribed compounds were established based on an extensive 1D and 2D NMR spectral analysis as well as HRMS and IR data. In case of 2-(2, 2-dimethylcyclopropyl)-1H-indole-3-carbaldehyde and 6, 8-dihydroxy-3-(2S-hydroxypropyl)-7-methylisochromone, the absolute configurations of their stereogenic carbons were established based on comparison of their experimental and calculated ECD spectra. All the compounds, except for palmitic acid and ergosterol 5, 8-endoperoxide, were evaluated for their antibacterial and antibiofilm activities against two Gram-positive and two Gram-negative bacteria, as well as multidrug-resistant isolates from the environment. Emodin not only exhibited moderate antibacterial activity against the Gram-positive bacteria but also showed strong synergistic association with oxacillin against MRSA Staphylococcus aureus.

Affinity chromatographic methodologies based on immobilized voltage dependent anion channel isoform 1 and application in protein-ligand interaction analysis and bioactive compounds screening from traditional medicine.

Voltage dependent anion channel isoform 1 (VDAC-1) serves as an attractive target of anti-cancer drugs by mediating the entry and exit of metabolites between cytoplasm and mitochondria. This work reports on the preparation of a VDAC-1-based bioaffinity chromatographic stationary phase by linking the protein on lecithin modified microspheres. An assay of chromatographic methods including frontal analysis, zonal elution, injection dependent analysis and nonlinear chromatography were utilized to investigate the bindings of ATP, NADH and NADPH to VDAC-1. Electrostatic interactions were found to be main forces during these bindings. The calculated association constants of the three ligands to VDAC-1 showed good agreements between diverse chromatographic methods. Validated application of the stationary phase was performed by screening anti-cancer compounds of Rheum officinale Baill. using high performance affinity chromatography coupled with electrospray ionization-quadrupole time of flight mass spectrometry. Chrysophanol, emodin, rhein, aloe-emodin and catechin were identified as the bioactive components of the herb. These compounds targeted VDAC-1 through Thr207 and the N-terminal region of the protein. Taken together, the current stationary phase was possible to become a promising tool for protein-ligand interaction analysis and anti-cancer drug screening from complex matrices.

Parietin: an efficient photo-screening pigment in vivo with good photosensitizing and photodynamic antibacterial effects in vitro.

The photophysical, photoinduced pro-oxidant and antibacterial properties in vitro of the natural occurring parietin (PTN; 1,8-dihydroxy-3-methoxy-6-methyl-9,10-anthraquinone) were evaluated. PTN was extracted from the lichen identified as Teloschistes flavicans (Sw.) Norm. (Telochistaceae). Results indicate that in chloroform solution, PTN presents spectroscopic features corresponding to an excited-state intramolecular proton-transfer (ESIPT) state with partial keto-enol tautomerization. In argon-saturated solutions, the singlet excited state is poorly fluorescent (ΦF = 0.03), decaying by efficient intersystem crossing to an excited triplet state 3PTN*, as detected by laser-flash photolysis experiments. In the presence of triplet molecular oxygen, the 3PTN* was fully quenched producing singlet molecular oxygen (1O2) with a quantum yield of 0.69. In addition, in buffer solutions, PTN has the ability to also generate a superoxide radical anion (O2˙-) in a human leukocyte model and its production was enhanced under UVA-Vis irradiation. Finally, the in vitro antibacterial capability of PTN in the dark and under UVA-Vis illumination was compared in microbial cultures of both Gram positive and negative bacteria. As a result, PTN showed promising photo-induced antibacterial activity through the efficient photosensitized generation of both 1O2 and O2˙- species. Thus, we have demonstrated that PTN, an efficient photo-screening pigment in lichens, is also a good photosensitizer in solution with promising applications in antibacterial photodynamic therapy.

Upregulation of Human ST8Sia VI (α2,8-Sialyltransferase) Gene Expression by Physcion in SK-N-BE(2)-C Human Neuroblastoma Cells.

In this research, we firstly demonstrated that physcion, an anthraquinone derivative, specifically increased the expression of the human α2,8-sialyltransferase (hST8Sia VI) gene in SK-N-BE(2)-C human neuroblastoma cells. To establish the mechanism responsible for the up-regulation of hST8Sia VI gene expression in physcion-treated SK-N-BE(2)-C cells, the putative promoter region of the hST8Sia VI gene was functionally characterized. Promoter analysis with serially truncated fragments of the 5'-flanking region showed that the region between -320 and -240 is crucial for physcion-induced transcription of hST8Sia VI in SK-N-BE(2)-C cells. Putative binding sites for transcription factors Pax-5 and NF-Y are located at this region. The Pax-5 binding site at -262 to -256 was essential for the expression of the hST8Sia VI gene by physcion in SK-N-BE(2)-C cells. Moreover, the transcription of hST8Sia VI induced by physcion in SK-N-BE(2)-C cells was inhibited by extracellular signal-regulated protein kinase (ERK) inhibitor U0126 and p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580, but not c-Jun N-terminal kinase (JNK) inhibitor SP600125. These results suggest that physcion upregulates hST8Sia VI gene expression via ERK and p38 MAPK pathways in SK-N-BE(2)-C cells.

The antibacterial activity and action mechanism of emodin from Polygonum cuspidatum against Haemophilus parasuis in vitro.

Haemophilus parasuis is the causative agent of Glässer's disease, which leads to serious economic loss to the swine industry. Although antibiotics are widely used to control infections, outbreaks of this disease repeatedly happen. In this study, emodin from Polygonum cuspidatum showed potent inhibitory effect against H. parasuis. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of emodin were 32 and 64µg/mL, respectively. The antibacterial kinetic curves indicated the antibacterial activity of emodin was in a concentration-dependent manner. Cell membrane permeability and flow cytometry assays proved that emodin could destroy cell membrane integrity and increase membrane permeability, and fluorescence spectra assay indicated emodin has influenced conformation of membrane protein. Under transmission electron microscopy, serious lesions of H. parasuis exposed to emodin (64µg/mL) were found, including irregular cell shape, plasmolysis, ruptured cell wall and membrane and cytoplasmic vacuolation. These results suggested that emodin could be used as candidate for treating Glässer's disease.

Emodin from Polygonum multiflorum ameliorates oxidative toxicity in HT22 cells and deficits in photothrombotic ischemia.

ETHNOPHARMACOLOGICAL RELEVANCE: Polygonum multiflorum Thunb. has been used widely in East Asia in treatment of diseases associated with aging. Emodin, an active component from Polygonum multiflorum Thunb., provides benefits for brain disturbances induced by severe cerebral injury. AIM OF THE STUDY: We investigated the neuroprotective effect of emodin from Polygonum multiflorum Thunb. against glutamate-induced oxidative toxicity and cerebral ischemia. MATERIALS AND METHODS: For examination of neuroprotective effects of emodin, cell viability, cytotoxicity, flow cytometry, and Western blot were performed in HT22 cells and infarct volume, behavioral tests and Western blot in a mouse model of photothrombotic ischemic stroke. RESULTS: Pretreatment with emodin resulted in significantly reduced glutamate-induced apoptotic cell death in HT22 cells. However, blocking of phosphatidylinositol-3 kinase (PI3K) activity with LY294002 resulted in significantly inhibited cell survival by emodin. Exposure of glutamate-treated cells to emodin induced an increase in the level of Bcl-2 expression, whereas the expression of Bax and active caspase-3 proteins was significantly reduced. In addition, treatment with emodin resulted in increased phosphorylation of Akt and cAMP response element binding protein (CREB), and expression of mature brain-derived neurotrophic factor (BDNF). This expression by emodin was also significantly inhibited by blocking of PI3K activity. In a photothrombotic ischemic stroke model, treatment with emodin resulted in significantly reduced infarct volume and improved motor function. We confirmed the critical role of the expression levels of Bcl-2/Bax, active caspase-3, phosphorylated (p)Akt, p-CREB, and mature BDNF for potent neuroprotective effects of emodin in cerebral ischemia. CONCLUSIONS: These results suggest that emodin may afford a significant neuroprotective effect against glutamate-induced apoptosis through activation of the PI3K/Akt signaling pathway, and subsequently enhance behavioral function in cerebral ischemia.

Emodin isolated from Polygoni Multiflori Ramulus inhibits melanogenesis through the liver X receptor-mediated pathway.

Melanogenesis is a physiological process that results in the synthesis of melanin pigments, which play a crucial protective role against skin photocarcinogenesis. We investigated the effects of a Polygoni Multiflori Ramulus extract on melanogenesis and isolated emodin from Polygoni Multiflori as an active compound. In addition, the possible mechanisms of action were examined. We found that emodin inhibited both melanin content and tyrosinase activity concentration and time dependently. Tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 mRNA levels decreased following emodin treatment. However, while the mRNA levels of microphthalmia-associated transcription factor (MITF) were not affected by emodin, emodin reduced MITF protein levels. Furthermore, expression of the liver X-receptor (LXR) α gene, but not the LXR ß gene was upregulated by emodin. Moreover, emodin regulated melanogenesis by promoting degradation of the MITF protein by upregulating the LXR α gene. The emodin effects on MITF was found to be mediated by phosphorylation of p42/44 MAPK. Taken together, these findings indicate that the inhibition of melanogenesis by emodin occurs through reduced MITF protein expression, which is mediated by upregulation of the LXR α gene and suggest that emodin may be useful as a hyperpigmentation inhibitor.

[Research on certified reference material of emodin in rhubarb and its alcohol extract, water extract].

The certified reference materials (CRMs) of emodin in rhubarb and its alcohol extract, water extract were developed by using quantity transfer technology from single chemical composition to the complex systems. The CRM of emodin was used for quantity transfer, and high performance liquid chromatography (HPLC) method was used to determine the contents of emodin in different matrix composition. By establishing mathematical model and calculating the parts of uncertainty, the uncertainty values were finally gotten. CRMs of emodin in rhubarb, alcohol extract and water extract were accomplished. The content values of emodin were 0.40% ±0.03%, 1.15%±0.18%, 0.16%±0.08% (k=2,P=0.95), respectively. The established method for quantity transfer has successfully solved the technical problems that the value of active ingredient of traditional Chinese medicine can't be traced to SI units. The series of CRMs are assigned as grade primary reference materials, which are useful for quality control of the emodin content, also provide the accurate and reliable CRM, materials standard and standard methods.

Toxicity and antioxidant capacity of Frangula alnus Mill. bark and its active component emodin.

In the present study toxicity of Frangula alnus Mill. bark, widely used as laxative, was investigated. Human peripheral blood lymphocytes (HPBLs) were treated with F. alnus bark extract or emodin (emodin is bark component with laxative property), and cytotoxicity, genotoxicity and parameters of oxidative stress were assessed. Also, polyphenol content of bark extract and antioxidant activity of the extract and emodin measured by DPPH, ABTS and FRAP methods were examined. The bark extract (500 µg/ml) produced cell death and DNA damage, while level of ROS changed at 250 µg/ml. Emodin induced cell death and DNA damage at 150 µg/ml and 200 µg/ml, respectively, and the increase of ROS was observed at 25 µg/ml. These results suggest that both, bark extract and emodin, are cyto/genotoxic to HPBLs and that oxidative stress is involved in the mechanism of their toxicity. The results on antioxidant activity showed that, unlike emodin, bark extract possess moderate antioxidant capacity (44.6%, 46.8% and 2.25 mmol Fe(2+)/g measured by DPPH, ABTS and FRAP assay, respectively) that can be related to relatively high phenolic content (116.07 mg/g). However, due to toxicological properties use of F. alnus bark as well as emodin-containing preparations should be taken with caution.