Pharmacokinetics and metabolism of trans-emodin dianthrones in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Polygonum multiflorum Thunb. (PM) is a common traditional Chinese medicine with diverse biological activities of resolving toxins, nourishing livers and promoting hairs. Nevertheless, in recent years hepatotoxic adverse reactions caused by the administration of PM have raised worldwide concerns. In our previous study, we found that emodin dianthrones showed hepatotoxicity and may be potential toxicity markers. However, the metabolic transformation and pharmacokinetic behavior of emodin dianthrones in vivo have still not been elucidated. AIM OF THE STUDY: Taking trans-emodin dianthrones (TED) as an example, the present study was conducted to investigate the pharmacokinetics and bioavailability of TED in rats and characterized its metabolic transformation in the plasma, urine and feces of rats. MATERIALS AND METHODS: A rapid and sensitive UPLC-qqq-MS/MS method was developed for accurate quantification of TED in plasma and successfully applied to the pharmacokinetic evaluation of TED in rats after intravenous and oral administration. A reliable UFLC-Q-TOF-MS high resolution mass spectrometry combined with a scientific metabolite identification strategy was used to comprehensively characterize the metabolic transformation of TED in plasma, urine and feces in rats. RESULTS: The established UPLC-qqq-MS/MS method had a linear range of 1-500 ng/mL, and the method was accurate and reliable to meet the quantitative requirements. When 20 mg/kg TED was given by gavage rats, it was rapidly absorbed into the circulatory system and had a long half-life time of 6.44 h and wide tissue distribution in vivo. While intravenous injection of 0.4 mg/kg TED in rats, it was rapidly metabolized and eliminated with a half-life time of 1.82 h. The oral absorption bioavailability of TED was only 2.83%. Furthermore with a sensitive UFLC-Q-TOF-MS technique and metabolite identification strategy, 21 metabolites were successfully identified, including 11 in plasma, 12 in urine and 18 in feces. The main Ⅰ and Ⅱ phase metabolic processes involved glucuronidation, oxidation, carbonylation, (de)methylation, sulfation and hydrogenation. CONCLUSION: TED could be rapidly absorbed into the blood circulation and widely distributed and slowly metabolized in the body and underwent extensive cleavage and metabolic transformation in vivo. The study provided a basis for in-depth elucidation of the toxicology and mechanism research of TED, but also laid the foundation for further research on the material basis of hepatotoxicity of PM.

Physcion, a novel inhibitor of 5α-reductase that promotes hair growth in vitro and in vivo.

Androgenic alopecia (AGA) has a high incidence. Excess dihydrotestosterone in blood capillaries, which is converted from testosterone by 5α-reductase, is an AGA causative factor. We identified the inhibitory activity of four Polygonum multiflorum compounds against 5α-reductase via high-performance liquid chromatography, and the results showed that Physcion was a potent 5α-reductase inhibitor. Additionally, we found that through inhibiting 5α-reductase expression, Physcion could shorten the time of dorsal skin darkening and hair growth, improve hair follicle morphology, and significantly increase hair follicle count. Eventually, through molecular docking study, we found the binding energy and molecular interactions between Physcion and 5α-reductase type II. These results suggested that Physcion is a potent 5α-reductase inhibitor, as well as a new natural medicine for treating AGA.

The Health Benefits of Emodin, a Natural Anthraquinone Derived from Rhubarb-A Summary Update.

Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is a naturally occurring anthraquinone derivative found in roots and leaves of various plants, fungi and lichens. For a long time it has been used in traditional Chinese medicine as an active ingredient in herbs. Among other sources, it is isolated from the rhubarb Rheum palmatum or tuber fleece-flower Polygonam multiflorum. Emodin has a wide range of biological activities, including diuretic, antibacterial, antiulcer, anti-inflammatory, anticancer and antinociceptive. According to the most recent studies, emodin acts as an antimalarial and antiallergic agent, and can also reverse resistance to chemotherapy. In the present work the potential therapeutic role of emodin in treatment of inflammatory diseases, cancers and microbial infections is analysed.

Chitosan functionalized graphene oxide nanocomposites for fluorescence imaging of apoptotic processes and targeted anti-inflammation study.

This work reports novel chitosan functionalized graphene oxide (GO) nanocomposites combined fluorescence imaging and therapeutic functions in one agent, which can serve as a promising alternative to alleviate related diseases caused hyperinflammation. Briefly, GO was designed to be conjugated with chitosan, fluorescein-labeled peptide, toll-like receptor 4 antibody and hydroxycamptothecin/aloe emodin. We have demonstrated that such nanocomposites could effectively achieve active targeted delivery of pro-apoptotic and anti-inflammatory drugs into inflammatory cells and cause cells apoptosis by acid-responsive drug release. Moreover, confocal fluorescence imaging confirms that the drug-induced inflammatory cells apoptosis could be visualized the light-up fluorescence of fluorescein activated by caspase-3. Meanwhile, inflammatory-related biomarkers have down-regulated after the nanocomposites' treatment in both vitro and vivo experiments consistent with the results in histological sections. In summary, the bifunctional nanocomposites that possess anti-inflammation and fluorescence imaging could serve as a promising therapeutic agent for reducing hyperinflammation caused by numerous diseases.

Analysis of the Composition of Lyophilisates Obtained from Aloe arborescens Gel of Leaves of Different Ages from Controlled Crops.

The aim of the study is to evaluate the composition of lyophilisates obtained from Aloe arborescens leaf gel at the age of one to four years. The leaves were obtained from controlled crops, which allowed to exclude environmental factors as variables. It was confirmed that the lyophilisates obtained from different years of Aloe arborescens leaf gel varied in chromatographic analyses in terms of aloin A and aloenin A content (high-performance liquid chromatography with diode-array detection HPLC-DAD, high-performance liquid chromatography with tandem mass spectrometric detection HPLC-MS/MS). Similarly, while testing the phenolic acids and the sum of polyphenols content, differences in their levels in leaf gel lyophilisates from plants of individual years were observed (spectrophotometric method UV-VIS). The lyophilisate composition analysis showed that the one-year-old leaves were characterized by the highest content of aloin A and aloenin A. While the content of polyphenols, including phenolic acids, was higher in the leaves of older plants. The antioxidant potential of the tested lyophilisates was assessed simultaneously. Regardless of the research model used (CUPRAC, DPPH, ABTS), an antioxidant effect was noted for Aloe arborescens leaves.

Assessment of the anti-inflammatory effects of three rhubarb anthraquinones in LPS-Stimulated RAW264.7 macrophages using a pharmacodynamic model and evaluation of the structure-activity relationships.

ETHNOPHARMACOLOGICAL RELEVANCE: Rhubarb (Rhei Radix et Rhizoma) is a traditional Chinese medicine, has been used as a strong astringent in China to treat inflammation-related diseases, such as acute pancreatitis, acute cholecystitis, appendicitis and so on. Rhein, emodin and aloe-emodin are the important active anthraquinone in rhubarb, and are considered to be the main ingredients contributing to anti-inflammatory. AIM OF THE STUDY: Rhein, emodin and aloe-emodin, anthraquinones with the same parent structure that are found in rhubarb, have beneficial anti-inflammatory effects in vitro and in vivo. Anthraquinone derivatives also have important clinical roles. However, their pharmacodynamic differences and the structure-activity relationships associated with their anti-inflammatory properties have not been systematically explored. The present study was designed to quantify the effects of three rhubarb anthraquinones on inflammation and to explore the structure-activity relationships of these compounds. MATERIALS AND METHODS: In this study, we detected NF-κB phosphorylation, iNOS protein expression, and IL-6 and NO production in LPS-stimulated RAW264.7 cells and then calculated median effect equations and built a dynamic pharmacodynamic model to quantitatively evaluate the efficacy of these three anthraquinones. Additionally, to determine the structure-activity relationships, we investigated the physicochemical properties and molecular electrostatic potentials of the drug molecules. RESULTS: We found that rhein, emodin, and aloe-emodin exerted at least dual-target (NF-κB, iNOS) inhibition of LPS-induced inflammatory responses. Compared with rhein and emodin, aloe-emodin had a stronger anti-inflammatory effect, and its inhibition of iNOS protein expression was approximately twice that of NF-κB phosphorylation. In addition, aloe-emodin had the strongest hydrophobic effect among the three anthraquinones. CONCLUSIONS: Overall, we concluded that the receptor binding the rhubarb anthraquinones had a hydrophobic pocket. Anthraquinone molecules with stronger hydrophobic effects had higher affinity for the receptor, resulting in greater anti-inflammatory activity. These results suggest that the addition of a hydrophobic group is a potential method for structural modification to design anti-inflammatory anthraquinone derivatives with enhanced potency.

Aloin protects mice from diet-induced non-alcoholic steatohepatitis via activation of Nrf2/HO-1 signaling.

Aloin, a naturally occurring anthraquinone glycoside derived from the Aloe species, has antioxidant and anti-inflammatory activities, but its role in non-alcoholic steatohepatitis (NASH) remains unknown. This study was designed to investigate the anti-inflammatory, antioxidant, and anti-apoptotic effects of aloin and the underlying mechanisms during NASH. Wild-type or nuclear erythroid 2-related factor 2 (Nrf2) knock-out (KO) mice were fed a choline-deficient, l-amino acid-defined, high-fat (CDAAH) diet and treated with aloin (10, 20 or 40 mg per kg bw per day) by gavage for twelve weeks. Liver and blood samples were collected to evaluate liver function, protein abundance, and histopathological status. Supplementing aloin at 20 mg kg-1 was optimal for mitigating liver damage during NASH, as evidenced by reduced alanine transaminase and aspartate aminotransferase activity in serum. Supplementation with aloin significantly reduced serum concentration or liver protein abundance of malondialdehyde, tumor necrosis factor alpha, Interleukin (IL)-1ß and IL-6. Aloin treatment enhanced hepatic superoxide dismutase activity, glutathione and serum IL-10 levels in mice with NASH. Furthermore, supplementation with aloin inhibited hepatocyte apoptosis caused by Bcl-2 up-regulation and cleaved caspase-3 and Bax down-regulation. Mechanistically, by using Nrf2 KO mice, the protective effects of aloin were associated with enhanced antioxidant, anti-inflammatory and anti-apoptotic activity, all of which were mediated by Nrf2/heme oxygenase-1 (HO-1) signaling activation. Data suggested that aloin activates the Nrf2/HO-1 pathway and has protective potential against liver injury during NASH. Therefore, aloin supplementation might contribute to the prevention and treatment of NASH via activation of the Nrf2/HO-1 pathway.

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.

Molecular docking study of potential phytochemicals and their effects on the complex of SARS-CoV2 spike protein and human ACE2.

Angiotensin converting enzyme 2 (ACE2) (EC:3.4.17.23) is a transmembrane protein which is considered as a receptor for spike protein binding of novel coronavirus (SARS-CoV2). Since no specific medication is available to treat COVID-19, designing of new drug is important and essential. In this regard, in silico method plays an important role, as it is rapid and cost effective compared to the trial and error methods using experimental studies. Natural products are safe and easily available to treat coronavirus affected patients, in the present alarming situation. In this paper five phytochemicals, which belong to flavonoid and anthraquinone subclass, have been selected as small molecules in molecular docking study of spike protein of SARS-CoV2 with its human receptor ACE2 molecule. Their molecular binding sites on spike protein bound structure with its receptor have been analyzed. From this analysis, hesperidin, emodin and chrysin are selected as competent natural products from both Indian and Chinese medicinal plants, to treat COVID-19. Among them, the phytochemical hesperidin can bind with ACE2 protein and bound structure of ACE2 protein and spike protein of SARS-CoV2 noncompetitively. The binding sites of ACE2 protein for spike protein and hesperidin, are located in different parts of ACE2 protein. Ligand spike protein causes conformational change in three-dimensional structure of protein ACE2, which is confirmed by molecular docking and molecular dynamics studies. This compound modulates the binding energy of bound structure of ACE2 and spike protein. This result indicates that due to presence of hesperidin, the bound structure of ACE2 and spike protein fragment becomes unstable. As a result, this natural product can impart antiviral activity in SARS CoV2 infection. The antiviral activity of these five natural compounds are further experimentally validated with QSAR study.

Design, Synthesis, Molecular Docking, and Biological Evaluation of New Emodin Anthraquinone Derivatives as Potential Antitumor Substances.

The emodin anthraquinone derivatives are generally used in traditional Chinese medicine due to their various pharmacological activities. In the present study, a series of emodin anthraquinone derivatives have been designed and synthesized, among which 1,3-dihydroxy-6,8-dimethoxyanthracene-9,10-dione is a natural compound that has been synthesized for the very first time, and 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione is a compound that has never been reported earlier. Interestingly, while total seven of these compounds showed neuraminidase inhibitory activity in influenza virus with inhibition rate more than 50 %, specific four compounds exhibited significant inhibition of tumor cell proliferation. The further results demonstrate that 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione showed the best anticancer activity among all the synthesized compounds by inducing highest apoptosis rate to HCT116 cancer cells and arresting their G0/G1 cell cycle phase, through elevation of intracellular level of reactive oxygen species (ROS). Moreover, the binding of 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione with BSA protein has thoroughly been investigated. Altogether, this study suggests the neuraminidase inhibitory activity and antitumor potential of the new emodin anthraquinone derivatives.

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.

Bioassay guided fractionation of rhizome extract of Rheum emodi wall as bio-availability enhancer of antibiotics against bacterial and fungal pathogens.

ETHNOPHARMACOLOGICAL RELEVANCE: Rheum emodi Wall., is an important medicinal plant extensively used in Ayurvedic and Unani systems of traditional medicine. It is known to possess antioxidant, antibacterial, antifungal, anticancer, wound healing and immune enhancing activities. AIM OF THE STUDY: The aim of the current study was to investigate the antimicrobial activity and synergistic potential of different solvent fractions and phytocompounds of Rheum emodi rhizome against bacterial and fungal pathogens. MATERIAL AND METHODS: The antimicrobial and synergistic potential of the crude methanolic extract, different solvent fractions (n-hexane, chloroform, ethyl acetate, and residual aqueous) and isolated phytocompounds of the rhizome of Rheum emodi were assayed by broth microdilution method. The bioactive phytocompounds were isolated through silica TLC and quantified using HPTLC and HPLC. The bioactive phytocompounds were identified by LC-MS analysis. RESULTS: Phytochemical analysis of the sub-fractions showed that the TPC (417.94 ± 1.2 mg g-1 GAE) and TFC (187.40 ± 0.5 mg g-1 RE) were highest in residual aqueous extracts. The chloroform sub-fraction possessed the highest antimicrobial activity against bacterial (Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae) and fungal strains (Candida albicans MTCC 277 and ATCC 90028). The MIC of chloroform sub-fraction against S. aureus, K. pneumoniae, E. coli, C. albicans was 1.95, 3.91, 15.62 and 62.5 µg ml-1, respectively. TLC and LC-MS analysis of chloroform sub-fraction identified phytocompounds namely emodin D4 (m/z 274.262), rhein13c6 (m/z 290.176), chrysophanol dimethyl ether (m/z 282.291), and resveratrol (m/z 340.456). Quantification of emodin content showed that the chloroform sub-fraction (101.4543 µg mg-1, 194.8037 µg mg-1 measured through HPTLC and HPLC, respectively), and its TLC fraction (II) (75.18 µg mg-1, 232.384 µg mg-1 measured through HPTLC and HPLC, respectively) are rich in emodin. Furthermore, chloroform sub-fraction, its TLC fractions and emodin showed profound synergistic activity in combination with antibacterial and antifungal antibiotics and lowered the dosage of antibiotics by 4-257 folds. CONCLUSIONS: The bioassay guided fractionation of R. emodi rhizome methanolic extract identified phytocompounds (emodin, rhein13c6, chrysophanol dimethyl ether and resveratrol) that act as bioavailability enhancers of antibacterial and antifungal antibiotics, hence revealing their potential in treating multidrug resistance.

Antidiabetic potential of anthraquinones: A review.

The present study was designed to review the antidiabetic potential of anthraquinones (AQs) with emphasis on the extent of blood glucose reduction, the half maximal inhibitory concentration values (in vitro studies), the proposed mechanisms of action, and the structure activity relationship studies. We sourced relevant data from the major scientific databases (Pubmed, Science Direct, Medline, and Google Scholar). According to our search, 25 AQs have shown variable antidiabetic potential, whereas one AQ (morindone-6-O-ß-D-primeveroside) showed no blood glucose-lowering ability. Emodin and rhein showed the most promising antidiabetic potential in various models. The proposed mechanisms of antidiabetic action include upregulation of insulin receptor substrates-1, phosphoinositide-3-kinase, and Akt-ser473 expression and elevation of glucagon-like peptide-1 level in diabetic animal models linked to the potent protein tyrosine phosphatase 1B and dipeptidyl peptidase-4 inhibitions. In addition, activation of peroxisome proliferator-activated receptors gamma and inhibition of α-glucosidase activity are other possible targets proposed as the mechanism of AQs antidiabetic action. The position and the number of hydroxyl group showed great influence on the overall antidiabetic potential of AQs. AQs hold promising antidiabetic activity despite scanty information. We hope that the present study will serve as a template to further explore the antidiabetic potential of AQs and subsequent antidiabetic drug development.

Antiglycation Activity and HT-29 Cellular Uptake of Aloe-Emodin, Aloin, and Aloe arborescens Leaf Extracts.

Aloe arborescens is a relevant species largely used in traditional medicine of several countries. In particular, the decoction of leaves is prepared for various medicinal purposes including antidiabetic care. The aim of this research was the study of the antiglycation activity of two A. arborescens leaf extracts and isolated compounds: aloin and aloe-emodin. These phytoconstituents were quantitatively assessed in methanolic and hydroalcoholic extracts using high performance liquid chromatography (HPLC) analysis. In addition, the total phenolic and flavonoid contents were detected. In order to study their potential use in diabetic conditions, the antiglycation and antiradical properties of the two extracts and aloin and aloe-emodin were investigated by means of bovine serum albumin (BSA) and 1,1-diphenyl-2-picryl-hydrazil (DPPH) assays; further, their cytotoxicity in HT-29 human colon adenocarcinoma cells was evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. Furthermore, the ability of aloin and aloe-emodin to permeate the cellular membranes of HT-29 cells was determined in order to estimate their potential in vivo absorption. This assessment indicated that aloe-emodin can substantially pass through cell membranes (~20%), whereas aloin did not permeate into HT-29 cells. Overall, the data show that both the methanolic and the hydroalcoholic A. arborescens extracts determine significant inhibition of glycation and free-radical persistence, without any cytotoxic activity. The data also show that the antiglycation and the antiradical activities of aloin and aloe-emodin are lower than those of the two extracts. In relation to the permeability study, only aloe-emodin is able to cross HT-29 cellular membranes, showing the attitude to pass through the intestinal layer. Overall, the present data surely support the traditional use of A. arborescens leaf extracts against hyperglycemic conditions, while aloin and aloe-emodin as potential drugs need further study.

Host metabolite producing endophytic fungi isolated from Hypericum perforatum.

In the present study, endophytic fungi have been isolated from various parts of the medicinal herb Hypericum perforatum (St. John's Wort), which is known as a source of medically important metabolites. The isolated strains were cultured in liquid media and their ability to synthesize hypericin, the secondary metabolite of the host and its suspected precursor, emodin was tested analyzing the extracts of the fermentation broth and the mycelia. The HPLC-UV analysis of the chloroform/methanol extracts of the mycelia revealed that three isolates were able to produce emodin (SZMC 23771, 19.9 ng/mg; SZMC 23772, 20.8 ng/mg; SZMC 23769, 427.9 ng/mg) and one of them also could synthesize hypericin (SZMC 23769, 320.4 ng/mg). These results were also confirmed via UHPLC-HRMS technique both in full scan and MS/MS mode. The strains producing only emodin belong to the section Alternata of the genus Alternaria, while the isolate producing both metabolites was identified as Epicoccum nigrum. The mycelial extracts of E. nigrum and the Alternaria sp. SZMC 23772 showed higher inhibitory activities in the antimicrobial tests against the six selected bacteria compared to the hypericin and emodin standards in the applied concentration (100 µg/mL), while in case of the Alternaria sp. SZMC 23771 lower inhibition activities were observed on Staphylococcus aureus and Streptomyces albus than the pure compounds.

Pharmacodynamics of Five Anthraquinones (Aloe-emodin, Emodin, Rhein, Chysophanol, and Physcion) and Reciprocal Pharmacokinetic Interaction in Rats with Cerebral Ischemia.

(1) Background: Rhubarb anthraquinones-a class of components with neuroprotective function-can be used to alleviate cerebral ischemia reperfusion injury. (2) Methods: The three pharmacodynamic indicators are neurological function score, brain water content, and cerebral infarction area; UPLC-MS/MS was used in pharmacokinetic studies to detect plasma concentrations at different time points, and DAS software was used to calculate pharmacokinetic parameters in a noncompartmental model. (3) Results: The results showed that the pharmacodynamics and pharmacokinetics of one of the five anthraquinone aglycones could be modified by the other four anthraquinones, and the degree of interaction between different anthraquinones was different. The chrysophanol group showed the greatest reduction in pharmacodynamic indicators comparing with other four groups where the rats were administered one of the five anthraquinones, and there was no significant difference between the nimodipine group. While the Aloe-emodin + Physcion group showed the most obvious anti-ischemic effect among the groups where the subjects were administered two of the five anthraquinones simultaneously. Emodin, rhein, chrysophanol, and physcion all increase plasma exposure levels of aloe-emodin, while aloe-emodin lower their plasma exposure levels. (4) Conclusions: This experiment provides a certain preclinical basis for the study of anthraquinone aglycones against cerebral ischemia and a theoretical basis for the study of the mechanism of interaction between anthraquinones.

Emodin alleviates myocardial ischemia/reperfusion injury by inhibiting gasdermin D-mediated pyroptosis in cardiomyocytes.

BACKGROUND: Emodin has recently been reported to have a powerful antiinflammatory effect, protecting the myocardium against ischemia/reperfusion (I/R) injury. Pyroptosis is a proinflammatory programmed cell death that is related to many diseases. The present study investigated the effect of emodin on pyroptosis in cardiomyocytes. MATERIALS AND METHODS: Sprague Dawley rats were randomly divided into sham, I/R, and I/R+Emodin groups. I/R model was subjected to 30 minutes' ligation of left anterior descending coronary artery, followed by 2 hours of reperfusion. Cardiomyocytes were exposed to hypoxic conditions for 1 hour and normoxic conditions for 2 hours. The level of the pyroptosis was detected by Western blot, real-time PCR analysis, and ELISA. RESULTS: The level of gasdermin D-N domains was upregulated in cardiomyocytes during I/R or hypoxia/reoxygenation (H/R) treatment. Moreover, emodin increased the rate of cell survival in vitro and decreased the myocardial infarct size in vivo via suppressing the levels of I/R-induced pyroptosis. Additionally, the expression of TLR4, MyD88, phospho-IκBα, phospho-NF-κB, and the NLRP3 inflammasome was significantly upregulated in cardiomyocytes subjected to H/R treatment, while emodin suppressed the expression of these proteins. CONCLUSION: This study confirms that emodin treatment was able to alleviate myocardial I/R injury and inhibit pyroptosis in vivo and in vitro. The inhibitory effect of emodin on pyroptosis was mediated by suppressing the TLR4/MyD88/NF-κB/NLRP3 inflammasome pathway. Therefore, emodin may provide an alternative treatment for myocardial I/R injury.

Emodin induces apoptosis and autophagy of fibroblasts obtained from patient with ankylosing spondylitis.

BACKGROUND: Ankylosing spondylitis (AS) is a type of rheumatoid disease, which has been reported to be associated with the excessive proliferation of fibroblasts recently. Emodin, a single component from a traditional Chinese medicine Rheum palmatum, exerts anti-inflammation and antirheumatic arthritis activities. However, could emodin be used to treat AS remains unclear? Thus, this study aimed to investigate the effect of emodin on AS. METHODS: Fibroblasts obtained from patients with AS were used in the current study. In addition, multiple cellular and molecular biology techniques such as Cell Counting Kit-8, Western blotting, flow cytometry, monodansylcadaverine staining, and immunofluorescence assay were applied as well. RESULTS: Emodin-induced apoptosis of fibroblasts obtained from patient with AS via increasing active caspase-9, active caspase-3, and Bax levels and downregulating Bcl-2. Meanwhile, emodin enhanced autophagy in fibroblasts via upregulation of the expression of Atg12, Atg5, and Beclin 1, which was further confirmed by monodansylcadaverine staining. As expected, autophagy inhibitor 3-methyladenine (3MA) completely reversed emodin-induced autophagy in fibroblasts. Moreover, 3MA significantly increased emodin-induced apoptosis of fibroblasts obtained from patient with AS by increasing the levels of γH2AX, active caspase-9, active caspase-3, and cleaved poly ADP-ribose polymerase. CONCLUSION: Our results indicated that emodin effectively induced apoptosis and autophagy of fibroblasts obtained from patient with AS. In addition, suppression of autophagy enhanced emodin-induced apoptosis in fibroblasts. Therefore, we proposed that combination of emodin with autophagy inhibitor might be a potent strategy for improving the symptoms of AS in the future.

Proteoliposome-based model for screening inhibitors targeting histidine kinase AgrC.

AgrC, as an integral membrane receptor protein with histidine kinase activity, is an important component of the agr quorum-sensing system of Staphylococcus aureus. AgrC acts as a sensor for the recognition of environmental signals and transduction of the signals into the cytoplasm. Therefore, AgrC is considered to be a compelling target for the development of novel quorum-sensing inhibitors. Here, we constructed a proteoliposome-based model for screening inhibitors targeting AgrC by incorporating AgrC into liposomes. We demonstrated that the dissolution state of the liposome was a critical factor in the reconstruction of the AgrC proteoliposome, in which AgrC maintained similar orientation and function as those in natural biological membranes. Two monomers, namely, rhein and aloeemodin, were successfully screened out as inhibitors targeting AgrC by the proteoliposome-based model from 14 traditional Chinese medicine monomers. The inhibitory effects of these compounds on the growth of suspended bacteria was dose dependent, and subinhibitory concentrations of these compounds significantly reduced the expression of three virulence factors (hla, clfA, and clpP), that are regulated by the agr system. The results preliminarily indicated that rhein and aloeemodin can inhibit the agr signaling pathway and also indirectly confirmed the feasibility and effectiveness of the AgrC proteoliposome as a drug screening model.

Optimized protocol for multigram preparation of emodin anthrone, a precursor in the hypericin synthesis.

Emodin reduction to emodin anthrone comprise one of three process steps involved in the hypericin synthesis, a powerful natural photosensitiser found in plants of the genus Hypericum. In this communication, an optimized protocol was established for emodin reduction enabling an efficient multigram preparation of emodin anthrone. A screening of reducing agent (SnCl2·2H2O and HClconc) under different reaction times was employed in micro-scale and monitored by electronic absorption spectroscopy technique. Data showed lower yields of emodin anthrone when some experimental conditions previously described in the literature were reproduce. However, using the optimized protocol for the emodin reduction these yields were overcoming, and a gram-scale supply experiment was reproducible for the preparation of 10 grams of emodin anthrone with excellent yield.