Inhibitory Effect Of Emodin Research Articles

Emodin inhibits M1 macrophage activation that related to acute and chronic kidney injury through EGFR/MAPK pathway.

Macrophages are the main inflammatory cells involved in kidney injury and play a significant role in the development of acute kidney injury (AKI) and progression of chronic kidney disease (CKD). Emodin is believed to stabilize macrophage homeostasis under pathological conditions. The objective of this study aimed to explore the underlying mechanisms and effects of Emodin on M1 macrophages. Network pharmacology methods were used to predict target proteins associated with renal injury and identify the pathways affected by emodin. RAW264.7 macrophages were induced into M1 polarization using LPS and then treated with emodin at 20, 40, and 80 µM. The effects of emodin on cell viability, cytokines (IL-1β, IL-6, TNF-α), M1 macrophage markers (F4/80 + CD86+), and the EGFR/MAPK pathway were evaluated. Additionally, we transfected RAW264.7 cells with an EGFR shRNA interference lentivirus to assess its effects on RAW264.7 cells function and MAPK pathway. After RAW264.7 cells were passaged to expanded culture and transfected with EGFR-interfering plasmid, macrophages were induced to polarize towards M1 with LPS and then treated with 80 µM emodin. CKD modeling was performed to test how emodin is regulated during CKD. There are 15 common targets between emodin and kidney injury, of which the EGFR/MAPK pathway is the pathway through which emodin affects macrophage function. Emodin significantly reduced the levels of IL-6, IL-1β and TNF-α (p < 0.05) and the ratio of M1 macrophage surface markers F4/80 + CD86+ (p < 0.01) in the supernatant of RAW264.7 cells in a dose-dependent manner. Furthermore, the inhibitory effect of emodin on RAW264.7 cells was achieved by interfering with the EGFR/MAPK pathway. Moreover, emodin also affected the mRNA and protein expression of EGFR and Ras, leading to a decrease in the rate of M1 macrophages, thus inhibiting the pro-inflammatory effect of M1 macrophages. The addition of emodin reduced the rate of M1 macrophages in CKD and inhibited the further polarization of M1 macrophages, thus maintaining the pro-inflammatory and anti-inflammatory homeostasis in CKD, and these effects were achieved by emodin through the control of the EGRF/ERK pathway. Emodin attenuates M1 macrophage polarization and pro-inflammatory responses via the EGFR/MAPK signalling pathway. And the addition of emodin maintains pro- and anti-inflammatory homeostasis, which is important for maintaining organ function and tissue repair.

Suppression of Helicobacter pylori-induced gastric carcinogenesis by emodin in GES-1 cells through the PI3K/AKT and NRF2 signaling pathways

Helicobacter pylori is recognized as a microbial carcinogen among Gram-negative bacteria and is considered the most significant risk factor for the development of human gastric cancer (GS). Consequently, inhibiting the growth of H. pylori has become a critical strategy for preventing GS. This study focuses on the inhibitory effects of emodin (EMN) against H. pylori-induced gastric carcinogenic signaling in human gastric epithelial cells (GES-1). In vitro cytotoxicity assessments revealed that a concentration of 40 &amp;mu;M of EMN provided remarkable protection to gastric cells, resulting in 85% cell viability without inducing toxicity. Furthermore, EMN prevented the H. pylori-induced depletion of antioxidants, which was mediated by reactive oxygen species generation, DNA damage, and nuclear fragmentation. Our findings indicate that EMN significantly suppresses the expression of phosphorylated forms of phosphatidylinositol 3-kinase (PI3K)/AKT, phosphorylated p38 kinases (p-p38), phosphorylated extracellular signal-regulated kinase-1 (p-ERK1), phosphorylated c-Jun N-terminal kinase (p-JNK) in GES-1 cells infected with H. pylori. In addition, EMN notably enhances the expression of antioxidant proteins nuclear factor erythroid factor-2 (NRF2) in H. pylori-infected cells. In summary, EMN demonstrates promising potential in preventing H. pylori-associated infections and the subsequent development of resistance, making it a viable candidate for the prevention of H. pylori-induced GS.

Emodin alleviates testicular ischemia-reperfusion injury through the inhibition of NLRP3-mediated pyroptosis

Ischemia-reperfusion injury (IRI) is a major cause of injury after testicular torsion and can lead to permanent impairment of spermatogenesis. Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) has potent anti-inflammatory effects and may be protective against IRI in various organs. Herein, we evaluated the effects of emodin on pyroptosis in spermatogenic cells and its role in the process of testicular IRI. A testicular torsion/detorsion (TTD) mouse model and an oxygen-glucose deprivation/reperfusion (OGD/R) germ cell model were established. Hematoxylin and eosin staining was performed to evaluate the testicular ischemic injury. The expression of pyroptosis-related proteins and reactive oxygen species production in testis tissues were detected using Western blotting, quantitative real-time PCR, malondialdehyde and superoxide dismutase assay kits and immunohistochemistry. Cell viability and cytotoxicity were evaluated using Cell Counting Kit-8 and lactate dehydrogenase assay kit. Enzyme-linked immunosorbent assay, immunofluorescence and immunoblotting were performed to assess inflammatory protein levels. The results revealed that pyroptosis and inflammation levels were upregulated after testicular IRI, and emodin inhibited inflammation and pyroptosis by acting on NOD-like receptor thermal protein domain-associated protein 3 (NLRP3). Emodin exerts protective effects on testicular IRI by acting on the NLRP3 signaling pathway and inhibiting IRI-mediated pyroptosis. Emodin treatment attenuated testicular IRI and inhibited pyroptosis. Inhibitory effects of emodin on pyroptosis were attributed to the inhibition of NLRP3 inflammasomes. Thus, emodin could be an alternative treatment for testicular IRI.

Emodin regulates the autophagy via the miR-371a-5p/PTEN axis to inhibit hepatic malignancy

Emodin has been reported to fulfill an important function in suppressing the vicious outcome of liver cancer. We aimed to elucidate the partial underlying molecular mechanism of emodin in inhibiting liver cancer, and we applied miRNA-sequence analysis and corresponding molecular functional experiments to find that the inhibitory effect of emodin on liver cancer was partly mediated by cellular autophagy through the miR-371a-5p/PTEN axis. The expression level of miR-371a-5p was down-regulated after emodin treatment in liver cancer cell lines (LCCLs). Restoring the expression level of miR-371a-5p attenuated the suppression of emodin on LCCLs. Additionally, we performed the prediction in relevant online databases and found that PTEN might functioned as a downstream target of miR-371a-5p to participate in the regulation on the above process. What's more, the detection of autophagy-related protein markers showed that LC3II was elevated accompanied by the decreased P62. The above results revealed that PTEN functioned as a key target to regulate the autophagy in the process where emodin inhibited the malignant outcome of LCCLs via miR-371a-5p, which further provided a theoretical basis for the application of traditional Chinese medicine (TCM) on clinical tumors.

Emodin Protects Against Lipopolysaccharide-Induced Acute Lung Injury via the JNK/Nur77/c-Jun Signaling Pathway.

Background: Acute lung injury (ALI) is a serious inflammatory disease with clinical manifestations of hypoxemia and respiratory failure. Presently, there is no effective treatment of ALI. Although emodin from Rheum palmatum L. exerts anti-ALI properties, the underlying mechanisms have not been fully explored. Purpose: This study aimed to investigate the therapeutic effect and mechanism of emodin on LPS-induced ALI in mice. Methods: RAW264.7 cells and zebrafish larvae were stimulated by LPS to establish inflammatory models. The anti-inflammatory effect of emodin was assessed by ELISA, flow cytometric analysis, and survival analysis. In vitro mechanisms were explored by using Western blotting, luciferase assay, electrophoretic mobility shift assay (EMSA), and small interfering RNA (siRNA) approach. The acute lung injury model in mice was established by the intratracheal administration of LPS, and the underlying mechanisms were assessed by detecting changes in histopathological and inflammatory markers and Western blotting in lung tissues. Results: Emodin inhibited the inflammatory factor production and oxidative stress in RAW264.7 cells, and prolonged the survival of zebrafish larvae after LPS stimulation. Emodin suppressed the expression levels of phosphorylated JNK at Thr183/tyr182 and phosphorylated Nur77 at Ser351 and c-Jun, and increased the expression level of Nur77 in LPS-stimulated RAW264.7 cells, while these regulatory effects of emodin on Nur77/c-Jun were counteracted by JNK activators. The overexpression of JNK dampened the emodin-mediated increase in Nur77 luciferase activity and Nur77 expression. Moreover, the inhibitory effect of emodin on c-Jun can be attenuated by Nur77 siRNA. Furthermore, emodin alleviated LPS-induced ALI in mice through the regulation of the JNK/Nur77/c-Jun pathway. Conclusions: Emodin protects against LPS-induced ALI through regulation on JNK/Nur77/c-Jun signaling. Our results indicate the potential of emodin in the treatment of ALI.

Emodin Suppresses the Migration and Invasion of Melanoma Cells.

Emodin (1,3,8-trihydroxy-6-methylanthraquinone), as an active ingredient in rhubarb roots and rhizomes, has been reported to possess various pharmacological properties including anti-tumor effects. Recent studies have confirmed that emodin inhibited cell proliferation and induced apoptosis of cancer cells. However, the inhibitory effect of emodin on the migration and invasion of melanoma cells and its underlying mechanism are still unclear. In the study, we observed the impercipient effects of emodin in B16F10 and A375 melanoma cells with strong metastatic abilities, focusing on the functions and mechanisms of migration and invasion of B16F10 and A375 melanoma cells. Cell counting kit-8 (CCK-8), colony formation test and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) staining tests confirmed that emodin possessed anti-proliferative and pro-apoptotic activities in B16F10 and A375 cells. The inhibitory effects on the migration and invasion of B16F10 and A375 cells were proved by wound healing assay and Transwell methods. Moreover, immunofluorescence assay approved the decrease in protein expression of matrix metalloproteinas (MMP)-2/-9 by emodin, and Western blot analyses revealed that emodin could increase the Bax/Bcl-2 ratio and inhibit the MMP-2/-9 protein expression and Wnt/β-catenin pathway in a dose-depended manner. BML-284, as an agonist of Wnt/β-catenin signaling pathway, reversed the effects of emodin on cell growth, migration and invasion in B16F10 cells. These findings may suggest that emodin treatment can be a promising therapeutic strategy for melanoma with highly metastatic abilities.

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

BackgroundEmodin 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 methodsSprague 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.ResultsThe 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.ConclusionThis 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 Attenuates Lipopolysaccharide-Induced Acute Liver Injury via Inhibiting the TLR4 Signaling Pathway in vitro and in vivo

Aims: Emodin is an anthraquinone with potential anti-inflammatory properties. However, the possible molecular mechanisms and protective effects of emodin are not clear. The objective of this study was to investigate the possible molecular mechanisms and protective effects of emodin on lipopolysaccharide (LPS)-induced acute liver injury (ALI) via the Toll-like receptor 4 (TLR4) signaling pathway in the Raw264.7 cell line and in Balb/c mice.Methods: This study established an inflammatory cellular model and induced an ALI animal model. TLR4 was overexpressed by lentivirus and downregulated by small interfering RNA (siRNA) technology. The mRNA and protein levels of TLR4 and downstream molecules were detected in cells and liver tissue. The tumor necrosis factor-α (TNF-α) and interleukin (IL)-6 levels in supernatant and serum were determined by ELISA. The distribution and expression of mannose receptor C type 1 (CD206) and arginase 1 (ARG1) in the liver were tested by immunofluorescence. Mouse liver function and histopathological observations were assessed.Results: Administration of emodin reduced the protein and/or mRNA levels of TLR4 and its downstream molecules following LPS challenge in Raw264.7 cells and in an animal model. Additionally, emodin suppressed the expression of TNF-α and IL-6 in cell culture supernatant and serum. The inhibitory effect of emodin was also confirmed in RAW264.7 cells, in which TLR4 was overexpressed or knocked down. Additionally, ARG1 and CD206 were elevated in the emodin groups. Emodin also decreased serum ALT and AST levels and alleviated the liver histopathological damage induced by LPS.Conclusion: Emodin showed excellent hepatoprotective effects against LPS-induced ALI, possibly by inhibiting TLR4 signaling pathways.

Effect of emodin on the proliferation and migration of hypoxia pulmonary artery smooth muscle cells

Objective To observe the inhibitory effect of emodin on the proliferation and migration of pulmonary artery smooth muscle cells. Methods Primary cultured human pulmonary arterial smooth muscle cells (HPASMC) were cultured in a routine manner to establish an hypoxic cell model. Emodin at different concentrations (0, 5, 10, 15 and 20 μmol/L) 48 and 72 h later, the proliferation and migration of hypoxic pulmonary artery were detected by methyl thiazol tetrazolium (MTT) assay and Transwell invasion assay. Western blotting assay was used to determine the expression of p38 protein in hypoxia HPASMC induced by emodin. Results Emodin inhibited the proliferation and migration of hypoxic HPASMC in a time-and concentration-dependent manner. When the concentration was 20 μmol/L, the effect was the most significant, and the inhibitory rates at 12, 24, 48 and 72 h were (53.46±1.81)%, (61.32±2.69)%, (76.34±3.05)% and (84.43±3.18)%, respectively. (68.90±8.49), (46.10±5.63), (27.56±5.38) in the Transwell experimental group (5, 10, 15 and 20 μmol/[(12.61±3.68)] compared with the control group [(88.59±8.56)]. Compared with the control group, the experimental group p38 protein expression was reduced (P=0.001). Conclusion Emodin can significantly inhibit the proliferation and migration of human pulmonary artery smooth muscle cells under hypoxic conditions and down-regulate the expression of p38 protein. Key words: Emodin; Pulmonary artery smooth muscle cells; Proliferation; Migration

Emodin Impairs Radioresistance of Human Osteosarcoma Cells by Suppressing Sonic Hedgehog Signaling.

BackgroundThis study aimed to investigate the possible involvement of sonic hedgehog (Shh) signaling in the radioresistance of human osteosarcoma cells and the inhibitory effects of emodin on radioresistance.Material/MethodsHuman osteosarcoma (OS) cell line MG63 was employed as parent cells. After 30-repeat low-dose (2 Gy) x-ray irradiation on MG63 cells, radioresistant OS cell MG63R cells were produced. Colony formation assay was used to assess the radioresistance. Cell viability was evaluated by CCK-8 assay. TUNEL assay was used to detect cell apoptosis. Protein expression levels and nuclear translocation were evaluated by western blotting.ResultsMore survival colony formation, elevated cell viability, and less cell apoptosis were found in MG63R cells compared to MG63 cells exposed to irradiation. The nuclear translocation of glioma-associated oncogene homolog (Gli), expression levels of Shh and Bcl2 were increased in MG63R cells compared to MG63 cells. Emodin pretreatment significantly inhibited cell viability and survival colony formation but increased cell apoptosis of irradiation exposed MG63R cells in a concentration dependent manner. Moreover, emodin pretreatment inhibited Shh and Bcl2 expressions as well as Gli1 nuclear translocation but increased C-caspase-3 expression of irradiation exposed MG63R cells in a concentration dependent manner.ConclusionsShh signaling activation was involved in the radioresistance of human OS cells. Emodin impaired the radioresistant capacity of OS cells by inhibiting Shh signaling pathway.

Inhibitory effect of emodin on fatty acid synthase, colon cancer proliferation and apoptosis.

Fatty acid synthase (FASN) is a key anabolic enzyme for de novo fatty acid synthesis, which is important in the development of colon carcinoma. The high expression of FASN is considered a promising molecular target for colon cancer therapy. Emodin, a naturally occurring anthraquinone, exhibits an anticancer effect in various types of human cancer, including colon cancer; however, the molecular mechanisms remain to be fully elucidated. Cell viability was evaluated using a Cell Counting Kit-8 assay. The apoptosis rate of cells was quantified via flow cytometry following Annexin V/propidium iodide staining. FASN activity was measured by monitoring oxidation of nicotinamide adenine dinucleotide phosphate at a wavelength of 340 nm, and intracellular free fatty acid levels were detected using a Free Fatty Acid Quantification kit. Western blot analysis and reverse transcription-polymerase chain reaction were used to detect target gene and protein expression. The present study was performed to investigate whether the gene expression of FASN and its enzymatic activity are regulated by emodin in a human colon cancer cell line. Emodin markedly inhibited the proliferation of HCT116 cells and a higher protein level of FASN was expressed, compared with that in SW480, SNU-C2A or SNU-C5 cells. Emodin significantly downregulated the protein expression of FASN in HCT116 cells, which was caused by protein degradation due to elevated protein ubiquitination. Emodin also inhibited intracellular FASN enzymatic activity and reduced the levels of intracellular free fatty acids. Emodin enhanced antiproliferation and apoptosis in a dose- and time-dependent manner. The combined treatment of emodin and cerulenin, a commercial FASN inhibitor, had an additive effect on these activities. Palmitate, the final product of the FASN reaction, rescued emodin-induced viability and apoptosis. In addition, emodin altered FASN-involved signaling pathways, including phosphatidylinositol 3-kinase/Akt and mitogen-activated protein kinases/extracellular signal-regulated kinases 1/2. These results suggested that emodin-regulated cell growth and apoptosis were mediated by inhibiting FASN and provide a molecular basis for colon cancer therapy.

Inhibitory Effects of Emodin, Thymol, and Astragalin on Leptospira interrogans-Induced Inflammatory Response in the Uterine and Endometrium Epithelial Cells of Mice.

Leptospirosis is a systemic infection that causes, among others, acute kidney injury, acute liver disease, muscle pain, vasculitis, bleeding disorders, and reproductive loss. In an effort to reduce uterine inflammatory responses induced by Leptospira, we evaluated the anti-inflammation effects of emodin, thymol, and astragalin in a mouse model. Our results showed that treatment with emodin, thymol, and astragalin alleviated uterine inflammation induced by leptospira infection via suppression of pro-inflammatory cytokine expression and prevented tissue damage. Furthermore, we used primary endometrium epithelial cells to show that treatment with these chemicals inhibited the expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6 using enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. Western blot results showed that these chemicals suppressed the phosphorylation of p38, p65, extracellular signal-regulated kinase, and c-Jun N-terminal kinase. These results indicate that treatment with emodin, thymol, and astragalin suppressed inflammatory response by regulating NF-κB and mitogen-activated protein kinase signaling pathways in leptospira-infected uterine and endometrium epithelial cells of mice.

The anthraquinone derivative Emodin inhibits angiogenesis and metastasis through downregulating Runx2 activity in breast cancer

Emodin (EMD) is an anthraquinone derivative extracted from the root and rhizome of Rheum palmatum L. which exhibits a range of activities, including anti-bacterial, antitumor, diuretic and vasorelaxant effects. The ability to inhibit metastasis and angiogenesis was shown in previous pharmacological studies, but clear information to address EMD affecting angiogenesis and metastasis in human breast cancer is still lacking. In the present study, we evaluated a possible role for EMD in angiogenesis and metastasis induced by breast cancer cells. It was revealed here that EMD attenuated tumor cell-induced metastasis and angiogenesis both in vitro and in vivo. Furthermore, it was found that these inhibitory effects were caused by MMPs and VEGFR-2 inhibition in metastatic breast cancer cells and endothelial cells, respectively. Western blot analysis showed reduction of Runx2 activation in the EMD-treated cells. ELISA based Runx2 transcription factor assay showed that the interaction between Runx2 and target sequences was inhibited by EMD. Our findings suggested that the inhibitory effects of EMD on tumor-induced metastasis and angiogenesis were caused by MMPs and VEGFR-2 inhibition, which may be associated with the downregulation of Runx2 transcriptional activity.

Inhibitory effect of emodin on migration, invasion and metastasis of human breast cancer MDA-MB-231 cells in vitro and in vivo.

In breast cancer, metastasis is the main reason for patient mortality. In the present study, we used breast cancer MDA-MB-231 cells and a mouse xenograft model to demonstrate the effect of emodin on the migration, invasion and metastasis of human breast cancer MDA-MB-231 cells and the related mechanisms. In vitro, wound healing and Transwell assays showed that emodin dose-dependently inhibited the migration and invasion of MDA-MB-231 cells. Enzyme-linked immunosorbent assay (ELISA) showed that emodin decreased the secretion of MMP-2 and MMP-9. Western blot analysis showed that emodin downregulated the expression levels of MMP-2, MMP-9, uPA and uPAR as well as p38 inhibitor SB203580 and ERK inhibitor PD980559, even though TIMP-1 and TIMP-2 were not obviously changed in the MDA-MB-231 cells. Furthermore, emodin inhibited the activity of p38 and ERK1/2 in the MDA-MB-231 cells. In vivo, emodin inhibited lung metastasis in mice bearing the breast cancer MDA-MB-231 xenografts with no obvious changes in body weight, liver and kidney functions. These results indicated that emodin inhibited the lung metastasis of human breast cancer in a mouse xenograft model, and inhibited the invasion of MDA-MB-231 cells associated with the downregulation of MMP-2, MMP-9, uPA and uPAR expression as well as decreased activity of p38 and ERK.

The distinct mechanisms of the antitumor activity of emodin in different types of cancer (Review)

Emodin, a tyrosine kinase inhibitor, is a natural anthraquinone derivative found in the roots and rhizomes of numerous plants. The inhibitory effect of emodin on mammalian cell cycle modulation in specific oncogene-overexpressing cells has formed the basis for using this compound as an anticancer drug. Previous reviews have summarized the antitumor properties of emodin. However, the specific molecular mechanisms of emodin-mediated tumor inhibition have not been completely elucidated over the last 5 years. Recently, there has been great progress in the preclinical study of the anticancer mechanisms of emodin. Our recent study revealed that emodin has therapeutic effects on pancreatic cancer through various antitumor mechanisms. Notably, the therapeutic efficacy of emodin in combination with chemotherapy was found to be higher than the comparable single chemotherapeutic regime, and the combination therapy also exhibited fewer side-effects. Despite these encouraging results, further investigation is warranted as emodin has been shown to modulate one or more key regulators of cancer growth. This review provides an overview of the distinct mechanisms of anticancer action of emodin in different body systems identified over the past 5 years. These new breakthrough findings may have important implications for targeted cancer therapy and for the future clinical use of emodin.

Emodin inhibits ATP-induced IL-1β secretion, ROS production and phagocytosis attenuation in rat peritoneal macrophages via antagonizing P2X7 receptor

Context: Previous in vitro studies have demonstrated that emodin (1,3,8-trihydroxy-6-methyl-anthraquinone), an anthraquinone derivative from the rhizome of Rheum palmatum L., can inhibit the activation of P2X7 receptors (P2X7R) as a potential antagonist. However, the effects of emodin on P2X7R-related inflammatory processes remain unclear.Objective: This study aimed to investigate the effects of emodin on different inflammation responses of macrophages induced by ATP, the natural ligand of P2X7R.Materials and methods: Rat peritoneal macrophages were treated with millimolar ATP and emodin (0.1, 0.3, 1, 3, 10 µM) or brilliant blue G (BBG, 0.1, 1, 10 µM). Cytosolic Ca2+ concentration ([Ca2+]c) was detected by fluorescent Ca2+ imaging. Interleukin-1β (IL-1β) release was measured by rat IL-1β ELISA kits. Reactive oxygen species (ROS) generation was examined by dihydroethidium (DHE) fluorescent staining. Phagocytic activity was tested by neutral red uptake assay.Results: We found that the [Ca2+]c increase evoked by ATP (5 mM) was inhibited by emodin, in a dose-dependent manner with IC50 of 0.5 μM. Furthermore, emodin reduced the IL-1β release induced by ATP (2 mM) in lipopolysaccharide (LPS)-activated macrophages, with an IC50 of 1.6 μM. Emodin also strongly suppressed the ROS production and phagocytosis attenuation triggered by ATP (1 mM), with IC50 values of 1 μM and 0.7 μM, respectively. Besides, BBG, a specific antagonist of P2X7R, exhibited similar suppressive effects on these inflammation responses.Conclusion: These results showed the inhibitory effects of emodin on ATP-induced [Ca2+]c increase, IL-1β release, ROS production and phagocytosis attenuation in rat peritoneal macrophages, by inhibiting the activation of P2X7R.

Characteristics of emodin on modulating the contractility of jejunal smooth muscle

Emodin is traditionally used as a laxative and is found to increase or decrease the contractility of intestinal smooth muscle in low doses and high doses, respectively. In this study, we propose that bidirectional regulation (BR) on the contractility of jejunal smooth muscle (CJSM) is inducible by emodin in the absence of control by the central nervous system. The results indicated that emodin-induced BR had the following characteristics. A stimulatory effect on CJSM was induced by emodin at 7 low contractile states, and an inhibitory effect was induced on CJSM at 7 high contractile states. Emodin-induced BR on myosin phosphorylation was also observed. BR was not observed in the presence of tetrodotoxin, suggesting that enteric nervous system is required for producing BR. The stimulatory effect of emodin on CJSM was abolished by atropine and diphenhydramine, respectively, suggesting that BR was correlated with cholinergic and histamine system while jejunal smooth muscle was at low contractile state. The inhibitory effect of emodin on CJSM was abolished by phentolamine, propranolol, and L-NG-nitroarginine (L-NNA), respectively, suggesting that BR was related to adrenergic hyperactivity and with a nitric oxide relaxing mechanism while jejunal smooth muscle was in a high contractile state. The exact mechanism, however, needs further investigation.

Emodin Triggers DNA Double-Strand Breaks by Stabilizing Topoisomerase II-DNA Cleavage Complexes and by Inhibiting ATP Hydrolysis of Topoisomerase II

Emodin, an anthraquinone derived from a plant and fungi, has been reported to possess potential genotoxicity, but the mechanism is not entirely clear. Here, we report that emodin causes DNA double-strand breaks (DSBs) through stabilization of topoisomerase (Topo) II-DNA cleavage complexes and inhibition of ATP hydrolysis. In our study, emodin did not induce mutagenecity in the salmonella mutation assay but caused genotoxicity in the thymidine kinase gene mutation assay and in the micronucleus test. Moreover, emodin induced DNA DSBs demonstrated by induction of comet tails, the expression of phosphorylated histone H2AX, and phosphorylation of ataxia telangiectasia mutated. Our studies also revealed that emodin exerted strong inhibitory activity against Topo II in the supercoiled pBR322 relaxation assay and in Topo II-mediated kinetoplast DNA decatenation, similar to the previous report. We also showed that the inhibitory effect of emodin on Topo II was because of its ability to stabilize Topo II-DNA complexes and to inhibit the ATP hydrolysis of Topo II. Furthermore, emodin was found to trigger DNA DSBs in a Topo II-dependent manner using the Topo II catalytic inhibitor aclarubicin and in Topo II-deficient mitoxantrone-resistant variant HL-60/MX2 cells. Together, these results suggest that in emodin-induced DNA DSBs and genotoxicity, stabilization of Topo II-DNA cleavage complexes and inhibition of ATP hydrolysis play an important role.

Inhibitory effect of emodin and Astragalus polysaccharideon the replication of HBV

To evaluate the anti-viral effect of emodin plus Astragalus polysaccharide (APS) in hepatitis B virus (HBV) transgenic mice. Sixty HBV transgenic mice (HBV TGM) whose weight varied between 18 and 24 g were randomly divided into 3 groups, with 20 mice in each group. Group A was the normal control, where the mice were treated with physiological saline; group B was the positive control where the mice were treated with lamivudine solution (100 mL/kg per day). Group C was the experimental group where the mice were treated with physiological saline containing emodin and APS (57.59 mg/kg per day and 287.95 mg/kg per day, respectively). The mice were treated daily for 3 wk. After 1 wk recovery time, the mice were sacrificed and serum as well as liver tissues were collected for ELISA and histological examination. After 21 d treatment, HBV DNA levels in group B and group C significantly declined when compared with group A (P < 0.05). However, a significant increase in HBV DNA content was observed in group B, whereas this phenomenon was not observed in group C. A reduction in the contents of HBsAg, HBeAg and HBcAg in the mice from group B and C was observed when compared with group A. Emodin and APS have a weak but persistent inhibitory effect on HBV replication in vivo, which may function as a supplementary modality in the treatment of hepatitis B infection.

Emodin is a novel alkaline nuclease inhibitor that suppresses herpes simplex virus type 1 yields in cell cultures

Background and purpose:Most antiviral therapies directed against herpes simplex virus (HSV) infections are limited to a small group of nucleoside analogues that target the viral polymerase. Extensive clinical use of these drugs has led to the emergence of resistant viral strains, mainly in immunocompromised patients. This highlights the need for the development of new anti-herpesviral drugs with novel targets. Herein the effects of a plant anthraquinone, emodin, on the HSV-1 alkaline nuclease activity and virus yields were investigated.Experimental approach:HSV-1 alkaline nuclease activity was examined by nuclease activity assay. Inhibition of virus yields was measured by plaque reduction assay and immunohistochemical staining. Interaction between emodin and alkaline nuclease was analysed by docking technology.Key results:Emodin specifically inhibited the nuclease activity of HSV-1 UL12 alkaline nuclease in a biochemical assay. Plaque reduction assay revealed that emodin reduced the plaque formation with an EC50 of 21.5±4.4 μM. Immunohistochemical staining using the anti-nucleocapsid protein antibody demonstrated that emodin induced the accumulation of viral nucleocapsids in the nucleus in a dose-dependent manner. Docking analysis further suggested that the inhibitory effect of emodin on the UL12 activity may result from the interaction between emodin and critical catalytic amino acid residues of UL12.Conclusions and implications:Our findings suggest that emodin is a potent anti-HSV agent that inhibits the yields of HSV-1 via the suppression of a novel target, UL12.