Protective Effects Of Emodin Research Articles

Emodin alleviates intestinal ischemia–reperfusion injury through antioxidant stress, anti-inflammatory responses and anti-apoptosis effects via Akt-mediated HO-1 upregulation

BackgroundIntestinal ischemia–reperfusion (I/R) injury is a severe vascular emergency. Previous research indicated the protective effects of Emodin on I/R injury. Our study aims to explore the effect of Emodin on intestinal I/R (II/R) injury and elucidate the underlying mechanisms.MethodsC57BL/6 mice and Caco-2 cells were used for in vivo and in vitro studies. We established an animal model of II/R injury by temporarily occluding superior mesenteric artery. We constructed an oxygen–glucose deprivation/reoxygenation (OGD/R) cell model using a hypoxia-reoxygenation incubator. Different doses of Emodin were explored to determine the optimal therapeutic dose. Additionally, inhibitors targeting the protein kinase B (Akt) or Heme oxygenase-1 (HO-1) were administered to investigate their potential protective mechanisms.ResultsOur results demonstrated that in animal experiments, Emodin mitigated barrier disruption, minimized inflammation, reduced oxidative stress, and inhibited apoptosis. When Akt or HO-1 was inhibited, the protective effect of Emodin was eliminated. Inhibiting Akt also reduced the level of HO-1. In cell experiments, Emodin reduced inflammation and apoptosis in the OGD/R cell model. Additionally, when Akt or HO-1 was inhibited, the protective effect of Emodin was weakened.ConclusionsOur findings suggest that Emodin may protect the intestine against II/R injury through the Akt/HO-1 signaling pathway.

Emodin alleviates intestinal ischemia/reperfusion-induced lung injury by upregulating HO-1 expression via PI3K/AkT pathway

BackgroundEmodin, a natural anthraquinone derivative found in various Chinese medicinal herbs, has been proved to be an effective therapeutic agent in the treatment of many diseases. However, its effect on lung injury after intestinal ischemia/reperfusion injury remains unknown. This research was designed to investigate whether emodin protects against intestinal ischemia/reperfusion-induced lung injury and to elucidate the underlying molecular mechanisms in vivo and in vitro. MethodsIntestinal ischemia/reperfusion injury was induced by occluding the superior mesenteric artery in mice, and mouse lung epithelial-12 cells were subjected to oxygen-glucose deprivation and reoxygenation to establish an in vitro model. ResultsOur data indicated that emodin treatment reduced intestinal ischemia/reperfusion-induced oxidative stress, inflammation and apoptosis in lung tissues and alleviated lung injury. However, the protective effects of emodin on intestinal ischemia/reperfusion-induced lung injury were reversed by the protein kinase B inhibitor triciribine or the heme oxygenase-1 inhibitor tin protoporphyrin IX. The protein kinase inhibitor triciribine also downregulated the expression of heme oxygenase-1. ConclusionIn conclusion, our data suggest that emodin treatment protects against intestinal ischemia/reperfusion-induced lung injury by enhancing heme oxygenase-1 expression via activation of the PI3K/protein kinase pathway. Emodin may act as a potential therapeutic agent for the prevention and treatment of lung injury induced by intestinal ischemia/reperfusion.

Emodin ameliorates doxorubicin-induced cardiotoxicity by inhibiting ferroptosis through the remodeling of gut microbiota composition.

The relationship between gut microbiota and doxorubicin-induced cardiotoxicity (DIC) is becoming increasingly clear. Emodin (EMO), a naturally occurring anthraquinone, exerts cardioprotective effects and plays a protective role by regulating gut microbiota composition. Therefore, the protective effect of EMO against DIC injury and its underlying mechanisms are worth investigating. In this study, we analyzed the differences in the gut microbiota in recipient mice transplanted with different flora using 16S-rDNA sequencing, analyzed the differences in serum metabolites among groups of mice using a nontargeted gas chromatography-mass spectrometry coupling system, and assessed cardiac function based on cardiac morphological staining, cardiac injury markers, and ferroptosis indicator assays. We found EMO ameliorated DIC and ferroptosis, as evidenced by decreased myocardial fibrosis, cardiomyocyte hypertrophy, and myocardial disorganization; improved ferroptosis indicators; and the maintenance of normal mitochondrial morphology. The protective effect of EMO was eliminated by the scavenging effect of antibiotics on the gut microbiota. Through fecal microbiota transplantation (FMT), we found that EMO restored the gut microbiota disrupted by doxorubicin (DOX) to near-normal levels. This was evidenced by an increased proportion of Bacteroidota and a decreased proportion of Verrucomicrobiota. FMT resulted in changes in the composition of serum metabolites. Mice transplanted with EMO-improved gut microbiota showed better cardiac function and ferroptosis indices; however, these beneficial effects were not observed in Nrf2 (Nfe2l2)-/- mice. Overall, EMO exerted a protective effect against DIC by attenuating ferroptosis, and the above effects occurred by remodeling the composition of gut microbiota perturbed by DOX and required Nrf2 mediation.NEW & NOTEWORTHY This study demonstrated for the first time the protective effect of emodin against DIC and verified by FMT that its cardioprotective effect was achieved by remodeling gut microbiota composition, resulting in attenuation of ferroptosis. Furthermore, we demonstrated that these effects were mediated by the redox-related gene Nrf2.

Emodin Exerts its Therapeutic Effects Through Metabolic Remodeling in Severe Acute Pancreatitis-Related Intestinal Injury

Background Intestinal injury caused by severe acute pancreatitis (SAP) can induce peripancreatic and systemic infection, and aggravate systemic inflammation. Emodin has demonstrated efficacy in mitigating SAP-associated intestinal injury. Although metabolites in tissues cause histopathophysiological changes, data on the mechanisms of emodin on metabolic processes remain scant. Methods The SAP-related intestinal injury rat model was induced by injection of 3.5% sodium taurocholate solution through the biliopancreatic duct. The protective effect of emodin on intestinal injury was evaluated by histologic analyses. On the other hand, we assessed the effect of emodin on metabolic remodeling in intestinal tissues using untargeted metabolomics. Results Out of the analyzed 1187 metabolites, untargeted metabolomics identified 99 differential metabolites in the intestinal tissues. Emodin significantly alleviated the inflammatory injury in the pancreas and intestines. Emodin treatment led to significant changes in bile acid metabolism, amino acid metabolism, intestinal microbiota related metabolism, and glycerol phospholipid metabolism in the intestinal tissues. In addition, using the weighted gene co-expression network analysis, we constructed emodin related metabolite–metabolite interaction network and showed that intestinal microbiota related metabolites and glycerol phospholipid metabolism were associated with emodin treatment. Glycine, LPC (0:0/22:6), Spermidine, 11β-hydroxyprogesterone, and N1-methyl-2-Pyridone-5-carboxamide may be efficient molecules after emodin treatment. Conclusion Taken together, our data demonstrated that intestinal injury caused by SAP induces an obvious metabolic disorder. Emodin exerts its therapeutic effects through metabolic remodeling.

Emodin alleviates lung ischemia-reperfusion injury by suppressing gasdermin D-mediated pyroptosis in rats.

Pyroptosis refers to programmed cell death associated with inflammation. Emodin has been reported to alleviate lung injuries caused by various pathological processes and attenuate ischemia-reperfusion (I/R) injuries in diverse tissues. Lewis rats were assigned into the sham, the I/R, and the I/R + emodin groups. Emodin and phosphate-buffered saline were intraperitoneally injected into rats of the emodin group and I/R group for 30 min, respectively. These rats were then subjected to left thoracotomy followed by 90-min clamping of the left hilum and 120-min reperfusion. Sham-operated rats underwent 210-min ventilation. Lung functions, histological changes, lung edema, and cytokine levels were assessed. Protein levels were measured by western blotting. Immunofluorescence staining was conducted to evaluate pyroptosis. Emodin alleviated the I/R-induced lung dysfunction, lung damages, and inflammation. Protective effects of emodin against I/R-mediated endothelial pyroptosis was observed in vivo and in vitro. Mechanistically, emodin inactivated the TLR4/MyD88/NF-κB/NLRP3 pathway. Emodin attenuates lung ischemia-reperfusion injury by inhibiting GSDMD-mediated pyroptosis in rats.

Emodin Ameliorates High Glucose-Induced Podocyte Apoptosis via Regulating AMPK/mTOR-Mediated Autophagy Signaling Pathway.

To investigate the effect of emodin on high glucose (HG)-induced podocyte apoptosis and whether the potential anti-apoptotic mechanism of emodin is related to induction of adenosine-monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)-mediated autophagy in podocytes (MPC5 cells) in vitro. MPC5 cells were treated with different concentrations of HG (2.5, 5, 10, 20, 40, 80 and 160 mmol/L), emodin (2, 4, 8 µ mol/L), or HG (40 mmol/L) and emodin (4 µ mol/L) with or without rapamycin (Rap, 100 nmol/L) and compound C (10 µ mol/L). The viability and apoptosis of MPC5 cells were detected using cell counting kit-8 (CCK-8) assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, autophagy marker light chain 3 (LC3) I/II, and AMPK/mTOR signaling pathway-related proteins were determined by Western blot. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy. HG at 20, 40, 80 and 160 mmol/L dose-dependently induced cell apoptosis in MPC5 cells, whereas emodin (4 µ mol/L) significantly ameliorated HG-induced cell apoptosis and caspase-3 cleavage (P<0.01). Emodin (4 µ mol/L) significantly increased LC3-II protein expression levels and induced RFP-LC3-containing punctate structures in MPC5 cells (P<0.01). Furthermore, the protective effects of emodin were mimicked by rapamycin (100 nmol/L). Moreover, emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 µ mol/L) reversed emodin-induced autophagy activation. Emodin ameliorated HG-induced apoptosis of MPC5 cells in vitro that involved induction of autophagy through the AMPK/mTOR signaling pathway, which might provide a potential therapeutic option for diabetic nephropathy.

Protective Effects of Emodin on Oxidized Fish Oil-Induced Metabolic Disorder and Oxidative Stress through Notch-Nrf2 Crosstalk in the Liver of Teleost Megalobrama amblycephala.

Dietary oxidized lipids are key perpetrator to accumulate excessive reactive oxygen species (ROS) that induce oxidative stress for animals. Immoderate oxidative stress dysregulates cell fate, perturbs cellular homeostasis, thereby interrupts metabolism and normal growth. Therefore, a 12-week feeding trial with fish oil (FO, control group), oxidized fish oil (OF), and emodin-supplemented (OF+E) diets was conducted to evaluate the therapeutic mechanism of emodin on metabolic and oxidative resistance in Megalobrama amblycephala liver. Morphologically, emodin remits oxidized fish oil-induced cellular constituents damage, evidenced by lipid droplets enlargement and accumulation, mitochondria rupture, and nucleus aggregation, which were functionally related to oxidative stress, metabolism, and cell fate determination. Consecutively, glucose, lipid, and amino acid metabolism were retained under emodin stimulation. Specifically, fatty acid metabolic genes optimized fatty acid utilization and metabolism, featured as total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) alternation. Physiologically, inflammation, autophagy, apoptosis, as well as antioxidant capacity were alleviated by emodin. Interactively, fatty acid metabolism was correlated with antioxidant capacity; while the crosstalk and dynamic equilibrium between apoptosis and autophagy determine the cell fate under oxidative stress amelioration. Synergistically, Nrf2 and Notch signaling were active to antioxidant defense. In particular, oxidative stress blocked the crosstalk between Notch and Nrf2 signaling, while emodin rescued Notch-Nrf2 interaction to ameliorate oxidative stress. In conclusion, these results suggest that elevated ROS levels by oxidative stress activates Notch and Nrf2 signaling but intercepts Notch-Nrf2 crosstalk to stimulate cell fate and antioxidant program; dietary emodin alleviates oxidative stress and returns overall ROS levels to a moderate state to maintain homeostatic balance. The crosstalk between Notch and Nrf2 signaling might be the potential therapeutic target for emodin to ameliorate oxidative stress and metabolic disorder in M. amblycephala liver.

Emodin Protects Sepsis Associated Damage to the Intestinal Mucosal Barrier Through the VDR/ Nrf2 /HO-1 Pathway.

Aims: Emodin is an anthraquinone extracted from Polygonum multiflorum, which has potential anti-inflammatory and anti-oxidative stress effects. However, the possible protective mechanism of emodin is unclear. The purpose of this study was to investigate the protective mechanism of emodin against cecal ligation and puncture and LPS-induced intestinal mucosal barrier injury through the VDR/ Nrf2 /HO-1 signaling pathway. Methods: We established a mouse model of sepsis by cecal ligation and puncture (CLP), and stimulated normal intestinal epithelial cells with lipopolysaccharide (LPS). VDR in cellswas down-regulated by small interfering ribonucleic acid (siRNA) technology.Mice were perfused with VDR antagonists ZK168281 to reduce VDR expression and mRNA and protein levels of VDR and downstream molecules were detected in cells and tissue. Inflammation markers (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6)) and oxidative stress markers (superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione (GSH)) were measured in serum and intestinal tissueby enzym-linked immunosorbent assay. The expression of VDR in intestinal tissue was detected by immunofluorescence. Histopathological changes were assessed by hematoxylin and eosin staining. Results: In NCM460 cells and animal models, emodin increased mRNA and protein expression of VDR and its downstream molecules. In addition, emodin could inhibit the expressions of TNF-α, IL-6 and MDA in serum and tissue, and increase the levels of SOD and GSH. The protective effect of emodin was confirmed in NCM460 cells and mice, where VDR was suppressed. In addition, emodin could alleviate the histopathological damage of intestinal mucosal barrier caused by cecal ligation and puncture. Conclusion: Emodin has a good protective effect against sepsis related intestinal mucosal barrier injury, possibly through the VDR/ Nrf2 /HO-1 pathway.

Emodin Attenuates Acetaminophen-Induced Hepatotoxicity via the cGAS-STING Pathway.

Emodin is a natural bioactive compound from traditional Chinese herbs that exerts anti-inflammatory, antioxidant, anticancer, hepatoprotective, and neuroprotective effects. However, the protective effects of emodin in acetaminophen (APAP)-induced hepatotoxicity are not clear. The present study examined the effects of emodin on APAP-induced hepatotoxicity and investigated the potential molecular mechanisms. C57BL/6 mice were pretreated with emodin (15 and 30mg/kg) for 5 consecutive days and then given APAP (300mg/kg) to establish an APAP-induced liver injury model. Mice were sacrificed to detect the serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and albumin (ALB) and the liver tissue levels of glutathione (GSH), malondialdehyde (MDA), and superoxide dismutase (SOD). Histological assessment, Western blotting, and ELISA were performed. Emodin pretreatment significantly reduced the levels of ALT, AST, and ALP; increased the levels of ALB; alleviated hepatocellular damage and apoptosis; attenuated the exhaustion of GSH and SOD and the accumulation of MDA; and increased the expression of antioxidative enzymes, including nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1), and NAD(P)H quinone dehydrogenase 1 (NQO1). Emodin also inhibited the expression of NLRP3 and reduced the levels of pro-inflammatory factors, including interleukin-1 beta (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α). Emodin inhibited interferon (IFN)-α, cyclic GMP-AMP synthase (cGAS), and its downstream signaling effector stimulator of interferon genes (STING) expression to protect the liver against APAP-induced inflammatory responses and apoptosis. These results suggest that emodin protected hepatocytes from APAP-induced liver injury via the upregulation of the Nrf2-mediated antioxidative stress pathway, the inhibition of the NLRP3 inflammasome, and the downregulation of the cGAS-STING signaling pathway.

Emodin protects knee joint cartilage in rats through anti-matrix degradation pathway: An in vitro and in vivo study

AimsOsteoarthritis (OA) is a common joint disease and the main cause of disability. We sought to determine the effective concentration of emodin on chondrocytes and to identify the dosage of emodin that induces a comparable therapeutic effect with the COX-2 inhibitor drug, celecoxib that is currently used to treat OA. Material and methodsIn vitro experiments induced inflammation of chondrocytes by IL-1β, and an osteoarthritis model was established in vivo by cutting rat anterior cruciate ligament. Western Blot, Real-time PCR, HE staining, Safranin O-green staining and immunohistochemistry were performed to detect MMP-3, MMP-13, ADAMTS-4, iNOS and COL2A1 on the chondrocytes or the tibial plateau. The cytokine activity and content in serum of six groups of rats were measured by kit. ResultsIt was found that the surface layer of the cartilage was thicker and smoother after the administration of emodin. Tissue expression of MMP-3, MMP-13, ADAMTS-4 and iNOS were significantly (p < 0.05) decreased in chondrocytes and cartilage treated with different doses of emodin, and the content of COL2A1 was reversed. Emodin also significantly decreased the blood levels of COX-2 and PGE2. The effective emodin in vitro was 5 μmol/L, whereas emodin at 80 mg/kg was equivalent to celecoxib in vivo. ConclusionEmodin reduces the expression of cartilage matrix degradation biomarkers, thereby reducing the degradation of cartilage matrix and protecting the knee joint cartilage. Emodin at 5 μmol/L shows the best concentration to treat chondrocytes, and the protective effect of emodin at 80 mg/kg is comparable to that of celecoxib.

Emodin Alleviates Hydrogen Peroxide-Induced Inflammation and Oxidative Stress via Mitochondrial Dysfunction by Inhibiting the PI3K/mTOR/GSK3β Pathway in Neuroblastoma SH-SY5Y Cells.

Emodin is an active monomer extracted from rhubarb root, which has many biological functions, including anti-inflammation, antioxidation, anticancer, and neuroprotection. However, the protective effect of emodin on nerve injury needs to be further elucidated. The purpose of this study is to investigate the effect of emodin on the neuroprotection and the special molecular mechanism. Here, the protective activity of emodin inhibiting H2O2-induced apoptosis and neuroinflammation as well as its molecular mechanisms was examined using human neuroblastoma cells (SH-SY5Y cells). The results showed that emodin significantly enhanced cell viability, reduced cell apoptosis and LDH release. Simultaneously, emodin downregulated H2O2-induced inflammatory factors, including IL-6, NO, and TNF-α, and alleviated H2O2-induced oxidative stress and mitochondrial dysfunction in SH-SY5Y cells. In addition, emodin inhibited the activation of the PI3K/mTOR/GSK3β signaling pathway. What is more, the PI3K/mTOR/GSK3β pathway participated in the protective mechanism of emodin on H2O2-induced cell damage. Collectively, it suggests that emodin alleviates H2O2-induced apoptosis and neuroinflammation potentially by regulating the PI3K/mTOR/GSK3β signaling pathway.

Emodin attenuates adenosine triphosphate‑induced pancreatic ductal cell injury in vitro via the inhibition of the P2X7/NLRP3 signaling pathway.

Acute pancreatitis (AP) is an inflammatory disease with high morbidity and mortality rates. Pancreatic ductal cells are the most susceptible of all cell types that are exposed to the noxious stimuli of pancreatitis. Our previous studies demonstrated that emodin, a natural product extracted from Rheum palmatum L., protected pancreatic acinar cells from injutyh due to its anti‑inflammatory activity. In the present study, in order to investigate the protective effects and molecular mechanisms of action of emodin on injured pancreatic ductal cells, an adenosine triphosphate (ATP)‑induced model of cell injury was established using the human pancreatic ductal epithelial cell line, HPDE6‑C7. The results revealed that emodin attenuated ATP‑induced HPDE6‑C7 cell injury by decreasing the levels of inflammatory factors, including interleukin (IL)‑1β and IL‑18. Furthermore, emodin significantly downregulated the protein levels of purinergic receptor P2X, ligand‑gated ion channel, 7 (P2X7), NOD‑like receptor protein 3 (NLRP3), apoptosis‑associated speck‑like protein containing a CARD (ASC) and caspase‑1 in the injured HPDE6‑C7 cells. The results also indicated that emodin attenuated HPDE6‑C7 cell injury at least partially through the inhibition of the P2X7/NLRP3 signaling pathway. The protective effects of emodin were abrogated upon pre‑treatment with P2X7 overexpression plasmid, which further confirmed that the P2X7 signaling pathway is the drug target of the effects of emodin against ATP‑induced pancreatic ductal cell injury. Collectively, the findings of this study demonstrate that emodin attenuates ATP‑induced pancreatic ductal cell injury in AP mainly through the inhibition of the P2X7/NLRP3 signaling pathway. This study suggests that emodin may be further developed for its application in future medical therapy.

Emodin alleviated kidney damage in high fat diet induced obese mice

Objective To explore the protective effect of emodin on kidney damage in high-fat diet-induced obese mice. Methods Male C57bl/6 mice were divided into groups according to diet and treatment. Collagen Ⅳ(Col4), phosphatidylinositide 3-kinase(PI3K), phosphorylated phosphoinositol 3-kinase(p-PI3K), protein kinase(Akt), and phosphorylated protein kinase(p-Akt) were measured by Western blotting method. Results Col4 was increased, while p-PI3K and p-Akt were decreased in kidney tissue in high-fat diet-induced obese mice. However, there was lower level of Col4, but higher levels of p-PI3K and p-Akt in kidneys. Conclusion Kidney damage of high-fat diet-induced obese mice seems to be alleviated by emodin via improving insulin sensitivity. (Chin J Endocrinol Metab, 2018, 34: 946-950) Key words: Obesity; Emodin; Kidney damage; Insulin resistance; Collagen Ⅳ

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.

Emodin attenuates cell injury and inflammation in pancreatic acinar AR42J cells

The study was intended to investigate the protective effects of emodin against cell injury and inflammation in AR42J cells. We determined trypsin and lipase activity, intracellular ROS and MMP using specific assay kits. The related protein expression and TNF-α and IL-6 in the medium were assayed by Western blot and ELISA kits. Results showed that emodin could protect AR42J cells against cell injury caused by cerulein and lipopolysaccharide which were possibly associated with inhibition of mitochondrial damage, ROS production, and then significantly inhibited ROS-mediated pathway, and ameliorated pancreatic cells injury by depleting the levels of inflammatory cytokines.

Aloe-Emodin Relieves High-Fat Diet Induced QT Prolongation via MiR-1 Inhibition and IK1 Up-Regulation in Rats

Background/Aims: High-fat diet (HFD) causes cardiac electrical remodeling and increases the risk of ventricular arrhythmias. Aloe-emodin (AE) is an anthraquinone component isolated from rhubarb and has a similar chemical structure with emodin. The protective effect of emodin against cardiac diseases has been reported in the literature. However, the cardioprotective property of AE is still unknown. The present study investigated the effect of AE on HFD-induced QT prolongation in rats. Methods: Adult male Wistar rats were randomly divided into three groups: control, HFD, and AE-treatment groups. Normal diet was given to rats in the control group, high-fat diet was given to rats in HFD and AE-treatment groups for a total of 10 weeks. First, HFD rats and AE-treatment rats were fed with high-fat diet for 4 weeks to establish the HFD model. Serum total cholesterol and triglyceride levels were measured to validate the HFD model. Afterward, AE-treatment rats were intragastrically administered with 100 mg/kg AE each day for 6 weeks. Electrocardiogram monitoring and whole-cell patch-clamp technique were applied to examine cardiac electrical activity, action potential and inward rectifier K⁺ current (I_K1), respectively. Neonatal rat ventricular myocytes (NRVMs) were subjected to cholesterol and/or AE. Protein expression of Kir2.1 was detected by Western blot and miR-1 level was examined by real-time PCR in vivo and in vitro, respectively. Results: In vivo, AE significantly shortened the QT interval, action potential duration at 90% repolarization (APD₉₀) and resting membrane potential (RMP), which were markedly elongated by HFD. AE increased I_K1 current and Kir2.1 protein expression which were reduced in HFD rats. Furthermore, AE significantly inhibited pro-arrhythmic miR-1 in the hearts of HFD rats. In vitro, AE decreased miR-1 expression levels resulting in an increase of Kir2.1 protein levels in cholesterol-enriched NRVMs. Conclusions: AE prevents HFD-induced QT prolongation by repressing miR-1 and upregulating its target Kir2.1. These findings suggest a novel pharmacological role of AE in HFD-induced cardiac electrical remodeling.

Protective Effect of Emodin against Hyperthermia‐induced Stress in Hepatic Cells of Grass Carp, Ctenopharyngodon idellus

AbstractEmodin is an anthraquinone exhibiting several positive benefits of anti‐inflammatory, free radical scavenging, and resistance to stress. The goal of this study is to investigate the effects of emodin on the hepatic cell line of grass carp exposed to hyperthermic stress. Cultured cells were treated with various emodin concentrations (0, 0.04, 0.2, and 1.0 µg/mL) at 27 C for 24 h. Then all cultured cells were exposed to thermal stress by increasing the culture temperature (32 ± 0.5 C) for 0.5 h. Increased temperatures significantly reduced cell viability and increased lactate dehydrogenase (LDH) release in three of the four experimental groups (0, 0.2, and 1 µg/mL emodin) compared with the control. Additionally, reactive oxygen species (ROS) were significantly higher in cells exposed to elevated temperatures and treated with 0.2 or 1 µg/mL emodin and mitochondrial membrane potential was significantly lower in cells treated with 0, 0.2, or 1 µg/mL emodin. Expressions of heat shock proteins (HSP60, HSP70, and HSP90) were significantly higher in all but one of the experimental groups. Our results suggest that 0.04 µg/mL emodin can increase cell viability and HSP90 mRNA level, reduce LDH release and concentration of ROS, and contribute to enhance the resistance to high temperature stress in the hepatic cells of grass carp.

Emodin ameliorates cisplatin-induced apoptosis of rat renal tubular cells in vitro by activating autophagy

A previous report shows that emodin extracted from the Chinese herbs rhubarb and giant knotweed rhizome can ameliorate the anticancer drug cisplatin-induced injury of HEK293 cells. In this study, we investigated whether and how emodin could protect renal tubular epithelial cells against cisplatin-induced nephrotoxicity in vitro. The viability and apoptosis of normal rat renal tubular epithelial cells (NRK-52E) were detected using formazan assay and flow cytometry analysis, respectively. The expression levels of cleaved caspase-3, autophagy maker LC3 I/II, and AMPK/mTOR signaling pathway-related proteins were measured with Western blot analysis. The changes of morphology and RFP-LC3 fluorescence were observed under microscopy. Cisplatin (10-50 μmol/L) dose-dependently induced cell damage and apoptosis in NRK-52E cells, whereas emodin (10 and 100 μmol/L) significantly ameliorated cisplatin-induced cell damage, apoptosis and caspase-3 cleavage. Emodin dose-dependently increased LC3-II levels and induced RFP-LC3-containing punctate structures in NRK-52E cells. Furthermore, the protective effects of emodin were abolished by bafilomycin A1 (10 nmol/L), and mimicked by rapamycin (100 nmol/L). Moreover, emodin increased the phosphorylation of AMPK and suppressed the phosphorylation of mTOR. The AMPK inhibitor compound C (10 μmol/L) not only abolished emodin-induced autophagy activation, but also emodin-induced anti-apoptotic effects. Emodin ameliorates cisplatin-induced apoptosis of rat renal tubular cells in vitro through modulating the AMPK/mTOR signaling pathways and activating autophagy. Emodin may have therapeutic potential for the prevention of cisplatin-induced nephrotoxicity.

Emodin isolated from Rheum palmatum prevents cytokine-induced β-cell damage and the development of type 1 diabetes

Emodin is an anthraquinone derivative from rhubarb and buckthorn, and is also produced by many species of fungi. Although its anti-diabetic effect in type 2 diabetes has been reported, the potential effects of emodin on type 1 diabetes remain unclear. Therefore, in this study, we isolated emodin from rhubarb (Rheum palmatum) and investigated its effects on cytokine- or streptozotocin-induced β-cell damage and dysfunction. Emodin protected RINm5F cells or mouse islets against cytokine-induced damage by suppressing inducible nitric oxide synthase expression and nitric oxide production. The cytoprotective potential of emodin was associated with the inhibition of NF-κB signaling by reducing IκB kinase activity. The protective effects of emodin were further demonstrated by normalizing insulin secretion of cytokine-treated islets in response to glucose. In multiple low-dose streptozotocin-induced diabetes model, emodin-pretreated mice were fully resistant to the development of diabetes with normal islet morphology and insulin secretion. Immunohistochemical analysis revealed that emodin significantly decreased the number of TUNEL-positive and nuclear p65-positive pancreatic islets. These results suggest that emodin blocks the NF-κB pathway, thus protecting β-cells against diabetogenic insults. Emodin may have therapeutic value in preventing the development of type 1 diabetes by delaying the process of insulitis and by protecting against β-cell damage.

Protection of vascular endothelial cells from high glucose-induced cytotoxicity by emodin

Induction of endothelial cytotoxicity by hyperglycemia in diabetes has been widely accepted. Emodin is a natural anthraquinone in rhubarb used for treatment of diabetes, but its mechanism of action is not fully understood. This study aimed to examine the potential beneficial effects of emodin on endothelial cytotoxicity caused by high glucose milieu. Culture of human umbilical vein endothelial cells (HUVECs) with high concentrations of glucose resulted in damage to the cells, leading to decreased formazan products by 14–27%, reduced DNA contents by 12–19%, and increased hypodiploid apoptosis by 40–109%. These adverse effects of high glucose could be prevented to a large extent by co-culture with 3μM of emodin which per se did not affect HUVECs viability. In addition, CCL5 expression of HUVECs cultured in high glucose medium was significantly elevated at both mRNA and protein levels, an effect abolished after treatment with emodin. Moreover, the enhanced adhesion of monocytes to HUVECs (2.1–2.2 fold over control) and elevated chemotaxis activities (2.3–2.4 fold over control) in HUVECs cultured in high glucose medium were completely reversed by emodin. Emodin also suppressed activation of p38 MAPK and ERK1/2 due to high glucose. Our data demonstrated that endothelial cytotoxicity occurred clearly when HUVECs were exposed to high glucose milieu and emodin was able to alleviate the impairments. The protective effects of emodin might be related to the inhibition of CCL5 expression and subsequent cell stress/inflammatory events possibly mediated by activation of MAPK signaling pathways.